1992 Cadillac Brougham Service And Repair Manual – PDF Download by www.heydownloads.com

1987-1992 CADILLAC BROUGHAM SERVICE AND REPAIR MANUAL

ENGINES 5.0L (307CI) V8 - VIN Y

ENGINE IDENTIFICATION NOTE:

For engine repair procedures not covered in this article, see ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION article in the GENERAL INFORMATION section.

This 5.0L engine may be identified from the Vehicle Identification Number (VIN). The VIN is stamped on a plate, on top of the instrument panel. This plate is visible the through windshield. The VIN contains 17 characters. The 8th character of the VIN identifies the engine. The 10th character of the VIN identifies the model year (L = ) of the vehicle. All engines are stamped with an engine identification label. This engine identification label will identify the assembly plant, the month/date produced, and the engine type code. ENGINE IDENTIFICATION CODES Application 4-Bbl.

Engine Code LV2

VIN Code Y

ADJUSTMENTS VALVE ARRANGEMENT I-E-I-E-E-I-E-I (Front-to-rear, both banks). VALVE CLEARANCE ADJUSTMENT Valve clearance is nonadjustable. Tighten rocker arms to specifications. See TORQUE SPECIFICATIONS table at end of this article. NOTE:

For reassembly reference, label all electrical connectors, vacuum hoses and fuel lines prior to removal. Match mark engine hood and all other major components prior to removal.

TROUBLE SHOOTING NOTE:

To trouble shoot mechanical engine components, see appropriate table in TROUBLE SHOOTING article in GENERAL INFORMATION.

REMOVAL & INSTALLATION

ENGINE Removal

1. Disconnect battery and remove air cleaner. Drain radiator. Disconnect radiator hoses and remove upper fan shroud. Remove fan assembly. Disconnect heater hoses at engine. 2. Remove power steering pump and lay aside. Remove A/C compressor and lay aside. Disconnect accelerator and throttle valve cable. Disconnect cooler lines at radiator (if equipped). Remove radiator. 3. Disconnect vacuum hoses. Disconnect Computer Command Control (CCC) wiring harness. Disconnect Air Injection Reaction (AIR) hose at pipe from converter. Remove washer bottle. Disconnect engine wiring harness at bulkhead. Disconnect necessary wires. Remove hood. 4. Remove distributor cap. Disconnect cruise control cable. Disconnect positive battery cable. Disconnect negative battery cable at A/C hose bracket and alternator bracket. Raise and support vehicle. 5. Remove crossover pipe and catalytic converter as an assembly. Remove flexplate cover. Remove torque converter bolts. Remove motor mount bolts. Disconnect fuel inlet hose at fuel pump. Disconnect torque converter clutch wiring at transmission. 6. Disconnect transmission cooler lines at clip on engine oil pan. Remove transmission-to-engine bolts. Lower vehicle. Support transmission. Install lifting device and remove engine. Installation

To install, reverse removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS. With engine off, fill radiator until level is even with base of filler neck. Fill coolant recovery reservoir to COLD FILL mark. Install coolant recovery reservoir cap. Run engine until radiator inlet hose is hot. With engine at idle, add coolant to radiator until level is even with base of filler neck. Install cap. INTAKE MANIFOLD Removal

1. Disconnect battery negative cable and drain coolant. Remove air cleaner. Remove AIR crossover pipe. Disconnect upper radiator hose, thermostat by-pass hose and heater hose(s) at rear of manifold. Mark and disconnect fuel and vacuum lines. Disconnect linkage at carburetor. Mark and remove necessary electrical connectors. 2. Remove rear brace from alternator and A/C compressor. Remove EGR valve, idle load compensator and bracket assembly. Remove intake manifold bolts in reverse sequence of installation. See Fig. 1. Remove intake manifold and gaskets. Clean surfaces thoroughly.

Fig. 1: Intake Manifold Sealing & Tightening Sequence Courtesy of GENERAL MOTORS CORP. Installation

Apply Sealer (1050026) to both sides of intake manifold gasket at all port areas. Apply Sealer (1052915) to both ends of front and rear seals. See Fig. 1. Lubricate intake bolts with engine oil. To complete installation, reverse removal procedure. Tighten bolts in sequence to specifications. See TORQUE SPECIFICATIONS. EXHAUST MANIFOLD Removal & Installation (Left)

Disconnect negative battery cable. Remove air cleaner. Raise and support vehicle. Separate inlet pipe at exhaust manifold. Lower vehicle. Remove exhaust manifold heat shields. Remove lower alternator bracket. Remove exhaust manifold and gasket. To install, reverse removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS. Removal & Installation (Right)

Disconnect negative battery cable. Remove air cleaner. Disconnect O2 sensor wire. Raise vehicle. Remove crossover AIR pipe. Separate inlet pipe at exhaust manifold. Remove right front tire, oil filter adapter, gasket, exhaust manifold and gasket. To install, reverse removal procedure. Tighten bolts to specification. See TORQUE SPECIFICATIONS. VALVE COVERS Removal

1. Disconnect negative battery cable. On left side, mark and remove spark plug wires and necessary electrical connectors. Remove anti-dieseling solenoid. Remove alternator belt and rear brace. Loosen exhaust manifold upper heat shield only. Remove EGR valve and oil dipstick. 2. On right side, reposition and move heater hoses. Remove PCV valve and hose. Disconnect anti-dieseling solenoid vacuum hoses. Disconnect AIR, O2 sensor and anti-dieseling solenoid. Disconnect canister purge hose. Disconnect hoses to AIR switching valve and catalytic converter pipe. Remove AIR switching valve, AIR/AC belt, AIR pump pulley and A/C compressor rear brace. 3. On both sides, remove valve cover bolts/nuts. Install Valve Cover Seal Breaker (BT-8315 or J-34144) midway between the ends of valve cover, on upper side. See Fig. 2. Tighten screw on seal breaker until a load is applied to valve cover. Place cloth on valve cover and strike with rubber mallet. If cloth is not used to absorb mallet, valve cover will be damaged.

Fig. 2: Removing Valve Cover With Special Tool Courtesy of GENERAL MOTORS CORP. Installation

Clean sealing mating surfaces. Apply 1/4" bead of Sealer (1052915) to valve cover. Sealer should be on inner side of bolt holes. Install and tighten valve cover. To complete installation, reverse removal procedure. NOTE:

Check and record compression before removing cylinder head. Ensure components are installed to original position and location.

CYLINDER HEAD Removal

1. Disconnect battery negative cable and drain coolant. Remove intake manifold, exhaust manifold(s) and valve cover(s) as previously described. Disconnect ground cable to cowl. Remove accessories and brackets as necessary. 2. Remove rocker arm bolts, rocker arm pivots, rocker arms and push rods. Note location for installation. If rear cylinder head bolts and/or push rods can not be removed, remove them with cylinder head. Remove cylinder head bolts, cylinder head and gasket. Inspection

1. Clean gasket surfaces. Check head and block gasket surface for warpage. Replace cylinder head if more than .006" (.15 mm) needs to be machined from original surface. Check for cracks and replace as necessary. Check head bolts for damage and stretching. Replace as necessary. Tap threads on bolts and in block. 2. Clean push rods in solvent and blow out oil passage with compressed air. Check ends of push rod for excessive wear and runout. If runout exceeds .015" (.38 mm), replace push rod. Apply Molykote to rocker arm contact points and push rod ends during installation. NOTE:

DO NOT use any sealant on head gaskets.

Installation

Properly install head gasket onto dowel pins. Install cylinder head over dowel pins and gasket. Dip head bolt threads in engine oil and allow to drain. Install head bolts. Tighten in sequence to specifications. See TORQUE SPECIFICATIONS table at end of this article. To complete installation, reverse removal procedure.

Fig. 3: Cylinder Head Tightening Sequence Courtesy of GENERAL MOTORS CORP. FRONT TIMING COVER & SEAL Removal

1. Disconnect negative battery cable. Drain cooling system and remove radiator. Remove A/C and power steering assembly with hoses attached and set aside. Remove cooling fan and pulley. Remove crankshaft balancer hub (damper) with Balancer Puller (J-8614). 2. Remove front timing cover seal, if cover does not require removal, with an inside 3-finger type puller. Remove fuel pump (if removing cover). Remove front timing cover retaining bolts/studs. Remove timing indicator. Remove front timing cover and water pump as an assembly. See Fig. 4. Remove dowel pins.

Fig. 4: Exploded View of Engine Front Courtesy of GENERAL MOTORS CORP.

Fig. 5: Installing Front Timing Cover Seal Courtesy of GENERAL MOTORS CORP. Installation

1. If front timing cover was not removed, install seal with Seal Installer (BT-6405 or J-25264) until proper clearance between installer and cover is achieved. See Fig. 5. 2. If front timing cover was removed, trim protruding oil pan gasket material flush with engine. Apply Sealer (1050026) around coolant holes in new cover gasket and place gasket on block. Trim 1/8" from each end of cover-to-oil pan saddle seal. 3. Apply Sealer (1052915) to joining corners of engine block, oil pan and saddle seal. Glue oil pan saddle seals in place on timing cover. Position bottom of cover with saddle seal to oil pan. Press down to compress saddle seal. Using a small screwdriver, guide saddle seal edges into cavity while installing timing cover. 4. Oil timing cover retaining bolts and install 2 bolts finger tight. Install dowel pins, chamfer end first. To complete installation, reverse removal procedure.

Fig. 6: Timing Gear Alignment Courtesy of GENERAL MOTORS CORP. TIMING CHAIN & GEARS Removal & Installation

1. Remove front timing cover. See FRONT TIMING COVER & SEAL. Remove fuel pump eccentric. See

Fig. 4. Align timing marks on camshaft and crankshaft gears. See Fig. 6. 2. Remove camshaft gear and chain as an assembly. Remove crankshaft key BEFORE attempting to remove crankshaft gear. Remove crankshaft gear with a puller (if replacing). To install, reverse removal procedure. With camshaft and crankshaft gear marks aligned, No. 6 cylinder is at TDC on compression stroke. See Fig. 6. CAMSHAFT NOTE:

Engine must be removed to install camshaft bearings. Ensure oil holes in bearings and block are aligned.

Removal & Installation

1. Remove timing chain and gears. See TIMING CHAIN & GEARS. Discharge A/C system and remove A/C condenser. Remove distributor cap with plug wires. Remove intake manifold and valve covers. See INTAKE MANIFOLD and VALVE COVERS. Mark and remove rocker arms, pushrods and lifters. Note location for installation. 2. Remove camshaft retainer plate. Remove flange adapter. See Fig. 4. Pull camshaft out of engine. If installing new camshaft add EP Lubricant (1051396) to engine oil. To install, reverse removal procedure. Use EP lubricant on components during installation. Inspection

Check bearing and lobe surfaces for wear, galling, gouges and discoloration (overheating). Measure lobe lift, bearing journal runout and diameter with camshaft in "V" block. Replace as necessary. See ENGINE SPECIFICATIONS table at end of article. REAR MAIN BEARING OIL SEAL Removal & Installation

Rear main bearing oil seal is a 2 piece rope seal. The lower portion may be replaced with engine in vehicle. Crankshaft removal is required for replacing upper portion. Use Seal Installer (J-2528A or BT-7923) to install seal. Cut excess seal material flush. Apply Sealer (1050026) to the main bearing cap as shown. See Fig. 7.

Fig. 7: Installing Rear Main Bearing Oil Seal Courtesy of GENERAL MOTORS CORP. WATER PUMP Removal & Installation

Disconnect negative battery. Drain cooling system. Remove necessary accessories and brackets. Remove fan and pulley. Disconnect lower radiator hose and heater hoses from water pump. Remove water pump retaining bolts and remove water pump. See Fig. 4. Apply Sealer (10500026) to new gasket and place on water pump. To complete installation, reverse removal procedure. NOTE:

For further information on cooling systems, see ENGINE COOLING.

OIL PAN 1. Disconnect negative battery cable. Remove air cleaner, fan shroud and distributor cap. Raise vehicle and drain crankcase. Disconnect exhaust pipe at manifold, Air Injection Reaction (AIR) pipe clamp and catalytic converter hanger bolts. 2. Remove front starter brace, starter and flexplate access cover. On models with M/T, it may be necessary to remove oil filter for access to flywheel cover bolts. 3. Remove engine mount through bolts and oil pan bolts. Raise engine and lower pan. Position front crankshaft throw and/or counterweights as to clear oil pan. Remove oil pan.

OIL PUMP Removal & Installation

Remove oil pan. See OIL PAN REMOVAL in this article. Remove oil pump retaining bolts and remove oil pump. To install, reverse removal procedure. See INSPECTION under OIL PUMP at end of this article.

Fig. 8: Exploded View of Cylinder Head Courtesy of GENERAL MOTORS CORP. CYLINDER HEAD OVERHAUL NOTE:

Keep components together and marked to ensure installation in original position.

VALVE SEAL, SPRINGS & ROTATORS These may be replaced with cylinder head installed using compressed air method. Intake and exhaust seals are not interchangeable. Intake seals are Gray and exhaust seals are Ivory. See Fig. 8. VALVE GUIDES Check and service guides prior to valve and seat service. Guide replacement information not available from manufacturer. Valve guides may be reamed .003" (.08 mm) oversize and an oversized valve installed. VALVE SEAT Valve seat replacement information not available from manufacturer. An oscillating type valve grinder is preferred. If after grinding seat is too wide, use a 20 degree stone to lower seat and 70 degree stone to raise seat. If seats are serviced, valves also must be serviced or replaced. VALVES After valve service, measure valve stem and rotator height as shown. See Fig. 9. There should be .015" (.38 mm) clearance between valve stem and gauge. Clearance between valve rotator and valve stem must be greater than .005" (.13 mm). If not within specifications, replace components as necessary.

Fig. 9: Checking Valve Stem & Rotator Height Courtesy of GENERAL MOTORS CORP. HYDRAULIC ROLLER LIFTERS If new lifters are installed, add Conditioner (1052367) to engine oil. Some engines may have both standard and .010" (.25 mm) oversize lifters. Lifters are marked on the side with an "O" if oversized. The outside of lifter bore in cylinder block is also marked with an "O" if oversized. Ensure guide and retainer are installed properly. See Fig. 10.

Fig. 10: Lifter, Guide & Retainer Assembly Courtesy of GENERAL MOTORS CORP. CAMSHAFT OVERHAUL Inspection

Check bearing surfaces and lobes for wear, galling, gouges and discoloration (overheating). Measure lift, bearing journal diameter and runout. Replace camshaft if not within specifications. See ENGINE SPECIFICATIONS tables at end of this article. If bearings are replaced, ensure oil holes are properly aligned. If installing new camshaft, add EP Lubricant (1051396) to engine oil. CYLINDER BLOCK ASSEMBLY OVERHAUL NOTE:

Keep components together and marked to ensure installation in original position.

CYLINDER BLOCK

1. Using a straightedge and feeler gauge, check cylinder block head gasket surface for warpage. If more than .005" (.13 mm) of metal must be removed, replace cylinder block. 2. Check cylinder bore for wear, taper, out-of-round and piston fit. Machine or replace as necessary. See ENGINE SPECIFICATIONS tables at end of this article. NOTE:

Some oil gallery plugs are drilled to feed oil onto timing chain and distributor. Note position for reinstallation.

PISTON & ROD ASSEMBLY Mark rod and rod cap with matching cylinder number. Match mark piston-to-rod prior to disassembly for reassembly reference. Notch on top of piston faces front of engine. Pin is retained by 2 retainers. No special tools needed for pin removal. Check piston ring end gap and side clearance. Properly install rings on piston. Refer to Fig. Fig. 11.

Fig. 11: Positioning Piston Ring End Gaps Courtesy of GENERAL MOTORS CORP. FITTING PISTONS Production and service pistons have same nominal weight and can be intermixed without affecting engine balance. DO NOT cut oversized pistons down as balance will be affected. CAUTION: Manufacturer recommends seating bearing caps with leather or brass mallet BEFORE tightening bearing cap bolts. Tighten in proper sequence. See TORQUE SPECIFICATIONS table at end of this article. CRANKSHAFT & BEARINGS

Bearings are marked with amount of undersize on opposite end of tang or the tang will be marked with a letter. See BEARING IDENTIFICATION table in this article. DO NOT mix standard and undersize bearings. Seat thrust bearing prior to tightening main bearing caps. See CRANKSHAFT THRUST BEARING under CYLINDER BLOCK ASSEMBLY OVERHAUL in this article. BEARING IDENTIFICATION Letter A B C

In. (mm) .0005 (.013) .0010 (.025) .0015 (.038)

CRANKSHAFT THRUST BEARING Lubricate bearings and crankshaft journals with oil. Lubricate thrust surfaces with GM 1050169. Install main bearing caps. See CAUTION under FITTING PISTONS. Tighten main bearing caps to 11 ft. lbs. (15 N.m). Using a block of wood and hammer, bump crankshaft in each direction to align thrust flanges. See Fig. 12. Tighten main bearing caps to specification. See TORQUE SPECIFICATIONS table at end of this article.

Fig. 12: Seating Crankshaft Thrust Bearing

Courtesy of GENERAL MOTORS CORP.

LUBRICATION LUBRICATION SYSTEM A gear-type oil pump provides full pressure lubrication through full flow oil filter. Oil pump is bolted to bottom of cylinder block, inside oil pan. A drive shaft is splined into the distributor and oil pump. Distributor is camshaft driven. Crankcase Capacity

Crankcase capacity is 4 qts. (4.8L) without oil filter and 5 qts. (4.7L) with oil filter. Normal Oil Pressure

Oil pressure is minimum 30 psi (2.1 kg/cm2 ) at 1500 RPM. OIL PUMP Inspection

Check oil pump as shown. See Fig. 13-16. Check outside diameter and width of gears. If not within specifications, replace components as necessary. See OIL PUMP SPECIFICATIONS table in this article. OIL PUMP SPECIFICATIONS Application End Clearance Gear Lash Gear Length Diameter Oil Pump Body Pocket Depth Pocket Diameter Side Clearance Regulator Valve-to-Bore Clearance

In. (mm) .0025-.0065 (.063-.165) .0004-.0065 (.010-.165) 1.5075-1.5095 (38.29-38.34) 1.529-1.531 (38.84-39.89) 1.500-1.509 (38.10-38.33) 1.534-1.539 (38.96-39.09) .0015-.0045 (.038-.114) .0025-.0050 (.063-.13)

Fig. 13: Measuring Oil Pump Gear Lash Courtesy of GENERAL MOTORS CORP.

Fig. 14: Measuring Oil Pump Side Clearance Courtesy of GENERAL MOTORS CORP.

Fig. 15: Measuring Oil Pump Pocket Depth & Diameter Courtesy of GENERAL MOTORS CORP.

Fig. 16: Measuring Oil Pump End Clearance Courtesy of GENERAL MOTORS CORP.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application AIR Manifold-to-Cylinder Head Bolt Camshaft Sprocket Bolt Connecting Rod Cap Nut Step 1 Step 2 Crankshaft Balancer-to-Crankshaft Bolt

18 (24) Additional 70 degrees 200-310 (271-420)

Cylinder Head Bolt (1) Step 1 Step 2: Nos. 1-7 & No. 9 Step 3: Nos. 8 & 10 EGR Valve-to-Manifold Bolt Engine Mount-to-Cylinder Block Bolt

40 (54) Additional 120 degrees Additional 95 degrees 20 (27) 75 (100)

Ft. Lbs. (N.m) 20 (27) 65 (88)

Engine Mount-to-Frame Bolt Exhaust Manifold Bolts Fan-to-Water Pump Bolt Fan Pulley-to-Balancer Bolt Flexplate-to-Converter Bolt Flexplate-to-Crankshaft Bolt Front Timing Cover-to-Block Bolt Fuel Pump Eccentric-to-Camshaft Bolt Intake Manifold Bolts (2) Step 1 Step 2 Main Bearing Cap Bolt Nos. 1-4 No. 5 Oil Filter Adapter Bolt Oil Pan Bolt Nut Oil Pump-to-Main Cap Bolt Rocker Arm Nut Spark Plug Starter Bolt Transmission-to-Block Bolt Water Pump Bolt Valve Cover Valve Lifter Guide Retainer (1) Clean and dip entire bolt in engine oil. Tighten in sequence. See Fig. 3.

55 (73) 25 (34) 20 (27) 28 (40) 46 (63) 60 (81) 35 (47) 65 (88) 15 (20) 40 (54) 80 (108) 120 (163) 35 (47) 10 (14) 17 (23) 35 (48) 22 (30) 25 (34) 32 (44) 35 (47) 11 (14) INCH Lbs. (N.m) 90 (10) 82 (9)

(2) Clean and dip entire bolt in engine oil. Tighten in sequence. See Fig. 1.

ENGINE SPECIFICATIONS GENERAL ENGINE SPECIFICATIONS GENERAL SPECIFICATIONS Application Displacement Bore Stroke Compression Ratio

Specification 307 Cu. In. 3.80" (96.5 mm) 3.39" (86.0 mm) 7.99:1

Fuel System HP @ RPM Torque Ft. Lbs. @ RPM

4-Bbl. 140 @ 3600 240 @ 1600

BEARING SPECIFICATIONS CRANKSHAFT MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS Application In. (mm) Crankshaft End Play .0035-.0135 (.089-.343) Main Bearings Journal Diameter 2.499 (63.48) Journal Out-of-Round .0002 (.005) Journal Taper .0002 (.005) Oil Clearance Journals Nos. 1-4 .0005-.0021 (.0127-.053) Journal No. 5 .0015-.0031 (.040-.081) Connecting Rod Bearings Journal Diameter 2.124 (53.95) Journal Out-of-Round .0002 (.005) Journal Taper .0005 (.013) Oil Clearance .0004-.0033 (.010-.084) CONNECTING ROD SPECIFICATIONS CONNECTING ROD SPECIFICATIONS Application Maximum Bend Maximum Twist Side Play (1) Replace rod if any bend or twist exists.

In. (mm) (1) (1)

.006-.020 (.15-.50)

PISTON/PIN/RING SPECIFICATIONS PISTONS, PINS & RINGS SPECIFICATIONS Application Piston Clearance Pins Diameter Piston Fit Rod Fit Rings

In. (mm) .0008-.0018 (.020-.046) .9804 (24.902) .0004-.0005 (.008-.013) .0002-.0009 (.005-.023)

No. 1 End Gap Side Clearance No. 2 End Gap Side Clearance No. 3 (Oil) End Gap Side Clearance

.009-.019 (.23-.48) .002-.004 (.05-.10) .009-.019 (.23-.48) .002-.004 (.05-.10) .015-.055 (.38-1.40) .001-.005 (.03-.13)

CYLINDER BLOCK SPECIFICATIONS CYLINDER BLOCK SPECIFICATIONS Application Cylinder Bore Diameter Maximum Taper Maximum Out-of-Round

In. (mm) 3.80 (96.5) .0015 (.038) .0015 (.038)

VALVE/VALVE SPRING SPECIFICATIONS VALVES & VALVE SPRINGS SPECIFICATIONS Application Intake Valves Face Angle Minimum Margin Exhaust Valves Face Angle Minimum Margin Valve Springs Free Length Out-of-Square Pressure (1) Valve Closed Valve Open (1) Lbs. @ In. (Kg @ mm).

Specification 44° .025" (.64 mm) 30° .025" (.64 mm) 1.96" (49.8 mm) .062" (1.58 mm) 76-84 @ 1.67 (35-38 @ 42.4) 180-194 @ 1.27 (82-88 @ 32.3)

CYLINDER HEAD SPECIFICATIONS CYLINDER HEAD SPECIFICATIONS Application

Specification

Maximum Warpage Valve Seats Intake Valve Seat Angle Seat Width Maximum Seat Runout Exhaust Valve Seat Angle Seat Width Maximum Seat Runout Valve Guides Intake Valve Guide Oil Clearance Exhaust Valve Guide Oil Clearance

.006" (.15 mm)

45° .037-.075" (.94-1.91 mm) .002" (.05 mm) 31° .05-.10" (1.3-2.5 mm) .004" (.10 mm) .001-.003" (.03-.08 mm) .002-.003" (.05-.08 mm)

CAMSHAFT SPECIFICATIONS CAMSHAFT SPECIFICATIONS Application Journal Diameter Journal No. 1 Journal No. 2 Journal No. 3 Journal No. 4 Journal No. 5 Lobe Lift Intake Exhaust Oil Clearance

In. (mm) 2.035-2.037 (51.69-51.74) 2.015-2.017 (51.18-51.23) 1.995-1.997 (50.67-50.72) 1.975-1.977 (50.17-50.22) 1.955-1.957 (49.66-49.71) .247 (6.27) .251 (6.38) .002-.006 (.05-.15)

ENGINES 5.7L V8 - VIN 7

ENGINE IDENTIFICATION NOTE:

For engine repair procedures not covered in this article, see ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION article in the GENERAL INFORMATION section.

Engine may be identified using Vehicle Identification Number (VIN) stamped on a metal pad, located near lower left corner of windshield. The eighth character identifies the engine model. See ENGINE IDENTIFICATION CODES table. Engine identification code, located on cylinder block below cylinder head, may be required when ordering replacement parts. See ENGINE IDENTIFICATION CODES table. ENGINE IDENTIFICATION CODES Application 5.7L (350") V8 TBI

Engine Code LO5

VIN Code 7

ADJUSTMENTS VALVE ARRANGEMENT E-I-I-E-E-I-I-E (Front-to-rear, both banks). VALVE CLEARANCE ADJUSTMENT NOTE:

Hydraulic valve lifters are used. Under normal use, no valve adjustment is required.

1. Place number one cylinder on TDC of compression stroke. Ensure timing mark on damper and front cover are aligned. Refer to VALVE ADJUSTMENT SEQUENCE . Back off adjusting nut until lash is felt at pushrod. Rotate pushrod while tightening adjusting nut until lash is removed. With lash removed, tighten adjusting nut 3/4 to 1 1/4 additional turn. 2. Rotate crankshaft one revolution and align timing marks. No. 6 cylinder will be on TDC. Adjust remaining valves in same manner. VALVE ADJUSTMENT SEQUENCE Cylinder No. No. One Cylinder On TDC No. 1 No. 2, 5 & 7 No. 3, 4 & 8

Valve Intake & Exhaust Intake Exhaust

No. 6 Cylinder On TDC No. 6 No. 2, 5 & 7 No. 3, 4 & 8

Intake & Exhaust Exhaust Intake

TROUBLE SHOOTING NOTE:

To trouble shoot engine mechanical components, see appropriate table in TROUBLE SHOOTING article in GENERAL INFORMATION.

REMOVAL & INSTALLATION NOTE:

For reassembly reference, label all electrical connectors, vacuum hoses and fuel lines before removal. Also place mating marks on engine hood and other major assemblies before removal.

FUEL PRESSURE RELEASE All TBI engines are equipped with a constant bleed unit to relieve fuel pressure when ignition is turned off. To release fuel tank pressure, remove gas cap. No further procedure is necessary. ENGINE Removal

1. Release fuel pressure. See FUEL PRESSURE RELEASE . Remove hood and air cleaner. Drain coolant from radiator. Disconnect radiator hoses and remove upper fan shroud. Remove fan assembly. Disconnect heater hoses at engine. 2. Remove serpentine belt. Remove power steering pump and set aside. Remove A/C compressor and set aside. Disconnect accelerator and throttle valve cable. Disconnect cooler lines at radiator (if equipped). Remove radiator. 3. Disconnect vacuum hoses. Disconnect Computer Command Control (CCC) wiring harness. Disconnect Air Injection Reaction (AIR) hose at pipe from converter. Remove MAP sensor (if equipped). Disconnect engine wiring harness at bulkhead. Disconnect necessary wires. 4. Remove distributor cap. Disconnect cruise control cable. Disconnect positive battery cable. Disconnect negative battery cable at A/C hose bracket and alternator bracket. Raise and support vehicle. 5. Remove crossover pipe and catalytic converter as an assembly. Remove flexplate cover. Remove torque converter bolts. Remove motor mount bolts. Disconnect fuel hose at in-line filter. Disconnect torque converter clutch wiring at transmission. 6. Disconnect transmission cooler lines at clip on engine pan. Remove transmission-to-engine bolts. Lower vehicle. Support transmission. Install lifting device and remove engine. Installation

1. Disconnect negative battery cable and drain cooling system. Remove air cleaner and throttle body assembly. Disconnect computer control harness and set aside. Remove upper radiator hose at thermostat, and heater hose at intake manifold. 2. Remove thermostat housing and gasket. Mark and remove necessary electrical connectors and vacuum hoses. Mark and remove necessary fuel line clips and lines. Remove throttle cable bracket. Mark and remove spark plug wires at distributor cap. Remove EGR valve and solenoid. Remove distributor cap. 3. Mark distributor position for installation reference. Remove distributor. Remove ignition coil and coolant temperature sensor. Remove A/C compressor brace. Remove intake manifold bolts and studs. Remove intake manifold and gasket. Installation

Clean all gasket surfaces. Apply 3/16" bead of RTV Sealer (1052289) on front and rear of cylinder block and apply 1/2" onto each cylinder head. See Fig. 1 . Install gaskets and intake manifold. Tighten bolts and studs to specifications in sequence. See Fig. 1 . See TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure.

Fig. 1: Exploded View of Intake Manifold & Tightening Sequence Courtesy of GENERAL MOTORS CORP. EXHAUST MANIFOLD Removal & Installation

1. Disconnect negative battery cable. Remove air cleaner as necessary. Remove Air Injection Reaction (AIR) hoses and crossover pipe as necessary. Mark and disconnect spark plug wires at spark plugs. 2. Remove necessary accessory brackets. Separate inlet pipe from exhaust manifold. Remove exhaust manifold bolts. Remove exhaust manifold and gaskets (if equipped). To install, reverse removal procedure. Tighten bolts and nuts to specification. See TORQUE SPECIFICATIONS . VALVE COVERS Removal & Installation

1. Disconnect negative battery cable. 2. Mark and disconnect spark plug wires at spark plugs. Remove necessary Air Injection Reaction (AIR) hoses and air cleaner. Mark and remove necessary electrical connectors. 3. Remove necessary accessories and brackets. Remove valve cover bolts. Use a block of wood and rubber mallet to loosen valve cover (if necessary). Remove valve cover and gasket. To install, reverse removal

procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . ROCKER ARMS & PUSH RODS Removal & Installation

1. Remove valve covers. See VALVE COVERS . Keep components in order for installation in original location and position. 2. Remove rocker arm nuts, balls, rocker arms and push rods. To install, reverse removal procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . Apply Prelube (3755008) to rocker arm and ball mating surface. ROCKER ARM STUD Removal & Installation

1. Remove rocker arm studs with Stud Remover (J 5802-01). Ream stud bore to replacement size of oversize stud. Oversize studs are available in .003" (.08 mm) and .013" (.33 mm). 2. Coat press-fit area of stud with hypoid axle lubricant. Install rocker arm stud with Stud Installer (J 6880) until it bottoms out on cylinder head. CYLINDER HEAD NOTE:

Check and record compression before removing cylinder head. Remove cylinder head when engine is cold.

Removal

1. Remove intake manifold, exhaust manifold and valve covers. See INTAKE MANIFOLD , EXHAUST MANIFOLD and VALVE COVERS . 2. Drain cooling system. Ensure components are kept in order for installation reference. Remove cylinder head bolts in 3 steps, in reverse order of tightening sequence. See Fig. 2 . Remove cylinder head and gasket. Inspection

Clean all carbon and gasket material from mating surfaces. Check cylinder head for warpage or cracks. Clean and tap cylinder head bolt holes and threads. Installation

1. Coat steel-type head gaskets with sealer. DO NOT coat composition-type head gaskets with sealer. Install head gasket on cylinder block. Install cylinder head. Coat head bolts with Sealing Compound (1052080). 2. Install head bolts finger tight. Tighten head bolts to specifications in 3 steps, in proper sequence. See Fig. 2 . See TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure.

Fig. 2: Cylinder Head Tightening Sequence Courtesy of GENERAL MOTORS CORP. FRONT COVER & OIL SEAL NOTE:

It is not necessary to remove timing cover to replace timing cover seal.

Removal

1. Remove negative battery cable and serpentine drive belt. Remove crankshaft pulley bolts and remove pulley. Remove harmonic balancer-to-crankshaft bolt. See Fig. 3 . Remove harmonic balancer using

Harmonic Balancer Remover/Installer (J 23523-E). 2. Remove water pump. See WATER PUMP . Loosen or remove oil pan as necessary. See OIL PAN . 3. Remove front-cover-to engine bolts. Remove cover and gasket. Carefully pry seal from timing cover using a large screwdriver. Installation

1. Install new oil seal in timing cover. Coat timing cover gasket with sealant and position on timing cover. Install timing cover and bolts. Tighten bolts finger tight. 2. Tighten bolts alternately and evenly to specifications. See TORQUE SPECIFICATIONS . Apply sealant to area where oil pan, cylinder block and timing cover join. To complete installation, reverse removal procedure.

Fig. 3: Exploded View of Engine Front Courtesy of GENERAL MOTORS CORP. TIMING CHAIN Removal

1. Remove front timing cover. See FRONT COVER & OIL SEAL . Rotate crankshaft until camshaft gear and crankshaft gear timing marks align when No. 6 cylinder is at TDC of compression stroke. See Fig. 4 . 2. Remove 3 camshaft gear retaining bolts. Remove camshaft gear and chain as an assembly. See Fig. 3 . If replacing crankshaft gear, use Gear Remover (J 5825-A) to pull gear off crankshaft. Installation

Drive crankshaft gear on crankshaft, with timing mark facing out. Align timing marks on camshaft gear and crankshaft gear. When timing marks are properly aligned, No. 6 cylinder should be on TDC of compression

stroke. See Fig. 4 . Install camshaft gear and chain as an assembly. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure.

Fig. 4: Aligning Timing Marks Courtesy of GENERAL MOTORS CORP. CAMSHAFT NOTE:

Rotate crankshaft in direction of normal operation only. Keep components in order for installation reference.

Removal

1. Remove valve covers. See VALVE COVERS . Remove rocker arms but DO NOT remove push rods at this time. See ROCKER ARMS & PUSH RODS . Measure lobe lift of camshaft with push rods installed. 2. To measure lobe lift, attach dial indicator to cylinder head. Position indicator pointer on tip of a push rod. Rotate crankshaft until push rod is at lowest point. Zero indicator and rotate crankshaft until push rod is at highest point. Record reading and repeat procedure for remaining lobes.

3. After lobe lift is measured, remove push rods. See ROCKER ARMS & PUSH RODS . Remove intake manifold. See INTAKE MANIFOLD . Remove timing chain and timing gears. See TIMING CHAIN . Remove radiator and hoses. 4. Using approved refrigerant recovery/recycling equipment, discharge A/C system and remove condenser (if equipped). Remove grille assembly. Remove valve lifters and camshaft retaining plate. Using three 5/16" x 18" x 4" bolts, pull camshaft from engine. Carefully remove camshaft without damaging camshaft bearings. Remove rear camshaft plug. Remove bearings with standard bearing remover. Inspection

Check camshaft for scratches, pits or loose fitting in bearings. Check camshaft journal diameter and lobe lift. See CAMSHAFT under ENGINE SPECIFICATIONS. Replace camshaft if damaged or not to specifications. Installation

1. Install front and rear camshaft bearings first. Position No. 1 camshaft bearing oil holes at equal distance from 6 o'clock position. Position oil hole of No. 5 camshaft bearing at 12 o'clock position. 2. Position oil holes of camshaft bearings No. 2-4 at 5 o'clock position. Install rear camshaft plug flush and .031" (.79 mm) deep into block. Use sealant on camshaft plug. 3. If replacing camshaft, replace lifters, engine oil and filter. Apply Camshaft Prelube (3755008) to camshaft lobes. Apply engine oil to bearings and camshaft bearing journals. To complete installation, reverse removal procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . REAR CRANKSHAFT OIL SEAL Removal

Remove transmission. See appropriate REMOVAL & INSTALLATION - A/T article in AUTOMATIC TRANSMISSIONS. Remove flexplate. Pry out seal with screwdriver, using notches in seal retainer. See Fig. 5 . Installation

1. Coat entire seal with engine oil. Install seal with Seal Installer (J 35621) until installer bottoms. See Fig. 5 . Align crankshaft dowel to proper flywheel hole. 2. Install and tighten flywheel/flexplate-to-crankshaft bolts to specification. See TORQUE SPECIFICATIONS . To complete installation, reverse removal procedure.

Fig. 5: Removing & Installing Rear Seal Courtesy of GENERAL MOTORS CORP. WATER PUMP Removal

1. Disconnect negative battery cable and drain cooling system. Remove air cleaner and intake duct assembly. Remove accessory drive belt(s). 2. Remove fan and pulley. Remove accessories as necessary. Remove coolant hoses from water pump. Remove water pump bolts, water pump and gasket. Installation

To install, reverse removal procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS . Fill and bleed cooling system. To bleed system, leave radiator cap off. Start and run engine until upper hose is hot. With engine at idle, add coolant until level is at bottom of neck. NOTE:

For additional cooling system information, see appropriate ENGINE COOLING article.

OIL PAN Removal

1. Disconnect negative battery cable. Remove air cleaner and fan shroud. Remove cruise control servo bracket (if equipped). Raise and support vehicle. Drain crankcase. 2. Disconnect exhaust pipe at manifold, Air Injection Reaction (AIR) pipe clamp and catalytic converter hanger bolts. Remove exhaust crossover pipe at manifold and converter (if equipped). 3. Remove starter and flexplate access cover. Disconnect transmission line bracket at oil pan. Remove engine mount through bolts. 4. Remove oil pan bolts. Lower pan. Position front crankshaft throw and/or counterweight on horizontal plane so it does not interfere with oil pan removal. Raise engine, reinstall through bolts and remove oil pan. Installation

To install, reverse removal procedure. Apply Sealant (1052914) to oil pan flange. Tighten bolts and nuts to specification. See TORQUE SPECIFICATIONS .

OVERHAUL GENERAL NOTE NOTE:

Mark components and keep together for installation to original location and position.

VALVE GUIDES Check and service guides before servicing valve and seat. Guide replacement information is not available from manufacturer. Valve guides may be reamed to .003" (.08 mm), .015" (.38 mm) or .030" (.76 mm) oversize for installation of oversize valve. VALVE SEAT Valve seat replacement information is not available from manufacturer. Follow instructions of tool manufacturer for servicing valve seats. If seats are serviced, valves must be serviced or replaced. VALVES

Check valves before servicing. Replace valves as necessary. See VALVES & VALVE SPRINGS under ENGINE SPECIFICATIONS. Valves may be machined to specifications. VALVE SEAT CORRECTION ANGLES If seat is too wide after grinding, use a 20-degree stone to lower, or a 70-degree stone to raise seat. PISTON & ROD ASSEMBLY 1. Mark rod and rod cap with matching cylinder number. Before disassembling, match mark piston to rod for reassembly reference. Notch or dot on piston top should face front of engine. Piston pin is a press fit. 2. When measuring, pin bore and piston pin must be free of varnish or scuffing. If piston-to-pin clearance exceeds .001" (.03 mm), replace piston and pin as an assembly. PISTON RINGS Rings are marked and must be installed properly. Marked side of ring must face toward top of piston. Top compression ring is chrome or molybdenum faced. Second compression ring has a tapered face. Oil ring is a 3piece type. Ensure end gaps are positioned properly on piston. See Fig. 6 .

Fig. 6: Positioning Piston Ring End Gaps Courtesy of GENERAL MOTORS CORP. FITTING PISTONS Ensure notch or dot on piston top faces front of engine. Check pistons for wear or damage. Replace pistons as necessary. Check piston-to-cylinder bore clearance. If one cylinder must be bored, all cylinders must be bored to same oversize. ROD BEARINGS

Ensure bearing cap bolt holes and mating surfaces are clean and dry. Use connecting rod stud protectors on all rod cap bolts. Install inserts in connecting rod and cap. Lubricate bearings and crank pin. Install bearing cap. Tighten rod bearing cap bolts to specification. See TORQUE SPECIFICATIONS . CRANKSHAFT & MAIN BEARINGS 1. If bearing clearance is greater than specifications, replace upper and lower bearings. Service bearings are available in .001, .002, .009, .010 and .020" (.03, .05, .23, .25 and .51 mm) undersize. Ensure arrow on main bearing caps face engine front. 2. Tighten main bearing caps, except rear main cap, to 80 ft. lbs. (109 N.m). Tighten rear main cap to 12 ft. lbs. (15 N.m). Tap crankshaft rearward, then forward with lead hammer. This will align rear main bearing and crankshaft and thrust surfaces. Retighten all main bearing caps to 80 ft. lbs. (109 N.m). THRUST BEARING Check crankshaft end play by forcing crankshaft to extreme front position. Measure end play at front end of rear main bearing with a feeler gauge. If end play is not within specifications, replace thrust bearing. See BEARING SPECIFICATIONS under ENGINE SPECIFICATIONS. CYLINDER BLOCK 1. Check cylinder bore for wear, taper, out-of-round and piston fit. Cylinders with less than .005" (.13 mm) wear or taper may be honed. 2. Cylinders with greater than .005" (.13 mm) wear or taper must be bored to smallest oversize piston that will permit complete resurfacing of all cylinders. Machine cylinder or replace as necessary. See CYLINDER BLOCK SPECIFICATIONS under ENGINE SPECIFICATIONS.

LUBRICATION ENGINE OILING SYSTEM A gear-type oil pump provides full pressure lubrication through full-flow oil filter. Oil pump is bolted to bottom of cylinder block, inside oil pan. Intermediate (drive) shaft is splined into the distributor and oil pump. Distributor is camshaft driven. CRANKCASE CAPACITY Crankcase capacity is 4 qts. (3.8L) without oil filter, and 5 qts. (4.7L) with oil filter. MINIMUM OIL PRESSURE Oil pressure with engine at normal operating temperature should be 6 psi (0.4 kg/cm2 ) at 1000 RPM, 18 psi (1.3 kg/cm2 ) at 2000 RPM and 24 psi (1.7 kg/cm2 ) at 4000 RPM. OIL PUMP

Removal & Disassembly

1. Remove oil pan. See OIL PAN under REMOVAL & INSTALLATION. Remove oil pump retaining bolts and remove pick-up screen. Remove oil pump and intermediate shaft. 2. Remove oil pump cover screws and remove cover. Mark gear teeth for reassembly. Remove idler gear, drive gear and shaft. Remove pressure regulator pin, spring and valve from cover. Remove pick-up screen and pipe from cover only if replacing. Inspection

Check oil pump body and gears for cracks, wear and damage. Check oil pump shaft for looseness in housing. Check inside of cover for wear which would permit oil leakage. Replace oil pump assembly as necessary. Oil pump specifications are not available from manufacturer. Reassembly & Installation

Clean all parts in solvent and dry using compressed air. To reassemble, reverse disassembly procedure. To install, reverse removal procedure. Tighten fasteners to specification. See TORQUE SPECIFICATIONS .

TORQUE SPECIFICATIONS TIGHTENING SPECIFICATIONS Application Camshaft Gear Bolt Clutch Pressure Plate Bolts Connecting Rod Cap Nuts Crankshaft Pulley Bolts (Center & Outer) Cylinder Head Bolts (1) Step 1 Step 2 Step 3 Exhaust Manifold Bolts Center Bolt/Studs Outer Bolt/Studs Flexplate-To-Crankshaft Bolts Harmonic Balancer (Damper) Bolt Intake Manifold Bolts (3) Main Bearing Cap Bolts Oil Pan Bolts & Nuts (5/16" Bolts & Nuts) Oil Pan Corner Stud/Nuts Oil Pump Bolts Spark Plugs Torque Converter-To-Flexplate Bolts

Ft. Lbs. (N.m) 21 (28) 30 (41) 44 (60) 43 (58) 22 (30) 45 (61) 67 (91) 20 (27) 26 (35) (2) 74 (100)

70 (94) 35 (47) (4) 80 (109)

14 (19) 16-17 (22-23) 65 (88) 22 (30) 46 (62)

Water Pump-To-Block Bolts Water Pump Pulley Bolts

30 (41) 22 (30) INCH Lbs. (N.m) Front Timing Cover Bolts 80 (9) Oil Pan Bolts & Nuts (1/4" Bolts & Nuts) 80 (9) Valve Cover Bolts 80 (9) (1) Coat threads with Sealing Compound (1052080). Tighten in 3 steps, evenly and in sequence. See Fig. 2. (2) Tighten flywheel bolts evenly, using a crisscross type sequence. (3) Tighten intake manifold-to-cylinder head bolts evenly and in sequence. See Fig. 1 . (4) See CRANKSHAFT & MAIN BEARINGS in CYLINDER BLOCK ASSEMBLY OVERHAUL.

ENGINE SPECIFICATIONS GENERAL ENGINE SPECIFICATIONS GENERAL ENGINE SPECIFICATIONS Application Displacement Fuel System Bore Stroke Compression Ratio Horsepower @ RPM Torque Ft. Lbs. @ RPM

Specification 350 Cu. In. (5.7L) TBI 4.00" (101.6 mm) 3.48" (88.4 mm) 9.3:1 185 @ 3800 290 @ 2400

BEARING SPECIFICATIONS MAIN & CONNECTING ROD BEARINGS SPECIFICATIONS Application Crankshaft End Play Runout (Max.) Main Bearings Journal Diameter Journal No. 1 Journals No. 2, 3 & 4 Journal No. 5

In. (mm) .001-.007 (.03-.17) .001 (.03)

2.4484-2.4493 (62.19862.212) 2.4481-2.4490 (62.18262.205) 2.4479-2.4488 (62.12062.177)

Journal Out-Of-Round (Max.) Journal Taper (Max.) Oil Clearance Journal No. 1 Journals No. 2, 3 & 4 Journal No. 5 Connecting Rod Bearings Journal Diameter Journal Out-Of-Round (Max.) Journal Taper (Max.) Oil Clearance

.001 (.025) .0002 (.005) .0010-.0015 (.025-.038) .0010-.0025 (.025-.064) .0025-.0035 (.064-.089) 2.0893-2.0998 (53.068-53.334) .001 (.025) .001 (.025) .0013-.0030 (.033-.076)

CONNECTING ROD SPECIFICATIONS CONNECTING ROD SPECIFICATIONS Application Maximum Bend Maximum Twist Side Play (1) Replace rod if any bend or twist exists.

In. (mm) (1) (1)

.006-.014 (.16-.35)

PISTON/PIN/RING SPECIFICATIONS PISTONS, PINS & RINGS SPECIFICATIONS Application Piston Clearance Pins Diameter Piston Fit Rod Fit Rings No. 1 End Gap Side Clearance No. 2 End Gap Side Clearance No. 3 (Oil) End Gap Side Clearance

In. (mm) .0007-.0027 (.018-.068) .9270-.9273 (23.546-23.553) .0003-.0010 (.076-.025) .0008-.0016 (.020-.041)

.010-.035 (.25-.88) .0012-.0032 (.030-.081) .010-.025 (.25-.63) .0012-.0032 (.030-.081) .015-.055 (.38-1.39) .002-.008 (.05-.20)

CYLINDER BLOCK SPECIFICATIONS CYLINDER BLOCK SPECIFICATIONS Application Cylinder Bore Diameter Maximum Taper Maximum Out-Of-Round

In. (mm) 4.000-4.002 (101.60-101.65) .001 (.03) .002 (.05)

VALVE/VALVE SPRING SPECIFICATIONS VALVES & VALVE SPRINGS SPECIFICATIONS Application Face Angle Minimum Margin Valve Springs Installed Height

Specification 45° .031" (.80 mm) 1.689-1.768" (42.90-44.50 mm)

Pressure (1) Valve Closed Valve Open (1) Lbs. @ In. (Kg @ mm).

76-84 @ 1.72 (34-38 @ 43.7) 194-206 @ 1.25 (88-94 @ 32.0)

CYLINDER HEAD SPECIFICATIONS CYLINDER HEAD SPECIFICATIONS Application Valve Seats Intake Valve Seat Angle Seat Width Exhaust Valve Seat Angle Seat Width Valve Guides Oil Clearance Intake Valve Exhaust Valve

Specification

46° .031-.063" (.79-1.60 mm) 46° .063-.094" (1.60-2.40 mm) .0011-.0037" (.027-.094 mm) .0011-.0047" (.027-.119 mm)

CAMSHAFT SPECIFICATIONS CAMSHAFT SPECIFICATIONS Application End Play

In. (mm) .004-.012 (.10-.30)

Journal Diameter Lobe Lift Intake Exhaust

1.868-1.869 (47.45-47.48) .255-.259 (6.48-6.58) .267-.271 (6.78-6.88)

GENERAL INFORMATION Commonly Used Abbreviations

* PLEASE READ THIS FIRST * NOTE:

This article is intended for general information purposes only. This information may not apply to all makes and models. Not all abbreviations are covered as manufacturers add new ones every day.

"A" A Amperes ABS Anti-Lock Brakes ABRS Air Bag Restraint System AC Alternating Current A/C Air Conditioning ACCS A/C Cycling Switch ACCUM Accumulator ACCY Accessory ACT

Air Charge Temperature Sensor ADJ Adjust or Adjustable ADV Advance AFS Airflow Sensor AI Air Injection AIR or A.I.R. Air Injection Reactor AIS Air Injection System Alt. Alternator or Altitude Amp./amp/amps Ampere ASCS Air Suction Control Solenoid ASD Auto Shutdown ASDM Air Bag System Diagnostic Module ASV

Air Suction Valve A/T Automatic Transmission/Transaxle ATC Automatic Temperature Control ATDC After Top Dead Center ATF Automatic Transmission Fluid ATS Air Temperature Sensor Aux. Auxiliary Avg. Average AXOD Automatic Transaxle Overdrive (Ford Models Only)

"B" BAC By-Pass Air Control BAP Barometric Absolute Pressure Sensor BARO Barometric

Batt. Battery Bbl. Barrel (Example: 4-Bbl.) BCM Body Control Module BHP Brake Horsepower BMAP Barometric and Manifold Absolute Pressure Sensor BOO Brake On-Off Switch B/P Backpressure BPS Barometric Pressure Sensor BPT Backpressure Transducer BTDC Before Top Dead Center BTSI Brake Transmission Shift Interlock BTU British Thermal Unit

BVSV Bimetallic Vacuum Switching Valve

"C" Â°C Celsius (Degrees) Calif. California CANP Canister Purge CARB California Air Resources Board CAT Catalytic Converter CB Circuit Breaker CBD Closed Bowl Distributor cc cubic centimeter CCC Close Coupled Catalyst CCC Computer Command Control CCD

Computer Controlled Dwell CCOT Cycling Clutch Orifice Tube CCW Counterclockwise CDI Capacitor Discharge Ignition CEC Computerized Engine Control CID Cubic Inch Displacement cm Centimeter CMP Camshaft Position Sensor CO Carbon Monoxide CO2 Carbon Dioxide Cont. Continued CONV Convertible CP

Canister Purge CKP Crankshaft Position Sensor CTS Coolant Temperature Sensor Cu. In. Cubic Inch CVC Constant Vacuum Control CV Check Valve or Constant Velocity CW Clockwise CYL or Cyl. Cylinder C3 I Computer Controlled Coil Ignition C4 Computer Controlled Catalytic Converter

"D" "D" Drive DC

Direct Current Or Discharge DDD Dual Diaphragm Distributor Def. Defrost Defog. Defogger DERM Diagnostic Energy Reserve Module DFI Digital Fuel Injection Diag. Diagnostic DTC Diagnostic Trouble Code DIC Driver Information Center DIS Distributorless Ignition System DIST Distribution DLC Data Link Connector DOC

Diesel Oxidation Catalyst DOHC Double Overhead Cam DOT Department of Transportation DPF Diesel Particulate Filter DRB-II Diagnostic Readout Box DVOM Digital Volt-Ohmmeter

"E" EACV Electric Air Control Valve EATX Electronic Automatic Transaxle EBCM Electronic Brake Control Module EBL Electronic Back Light ECM Engine Control Module ECT Engine Coolant Temperature Sensor

EDIS Electronic Distributorless Ignition System EEC Electronic Engine Control EECS Evaporative Emission Control System EEPROM Electronically Erasable PROM EFE Early Fuel Evaporation EGO Exhaust Gas Oxygen Sensor EGR Exhaust Gas Recirculation EOT Engine Oil Temperature ESA Electronic Spark Advance ESC Electronic Spark Control EST Electronic Spark Timing EVAP Fuel Evaporative System

EVIC Electronic Vehicle Information Center EVP EGR Valve Position Sensor EWMA Exponentially Weighted Moving Average (MODE 6) Exc. Except

"F" Â°F Fahrenheit (Degrees) F/B Fuse Block Fed. Federal FI Fuel Injection FICU Fuel Injection Control Unit FIPL Fuel Injector Pump Lever FLI Fuel Level Indicator FPR-VSV

Fuel Pressure Regulator Vacuum Switching Valve Ft. Lbs. Foot Pounds FWD Front Wheel Drive

"G" g grams Gals. gallons GND or GRND Ground

"H" HAC High Altitude Compensation HC Hydrocarbons H/D Heavy Duty HO2S Heated Exhaust Gas Oxygen Sensor Hg Mercury Hgt.

Height HLDT Headlight HO High Output HO2S Heated Oxygen Sensor HP High Performance HSC High Swirl Combustion HSO High Specific Output HTR Heater Hz Hertz (Cycles Per Second)

"I" IAC Idle Air Control IACV Idle Air Control Valve IAT Intake Air Temperature

IC Integrated Circuit ID Identification I.D. Inside Diameter IFS Independant Front Suspension IFS Inertia Fuel Shutoff (Ford) Ign. Ignition IMRC Intake Manifold Runner Control In. Inches INCH Lbs. Inch Pounds in. Hg Inches of Mercury Inj. Injector IP Instrument Panel

IRS Independant Rear Suspension ISC Idle Speed Control IVD Interactive Vehicle Dynamics (Ford) IVSV Idle Vacuum Switching Valve

"J" J/B Junction Block

"K" KAPWR Keep Alive Power k/ohms kilo-ohms (1000 ohms) kg Kilograms (weight) kg/cm2 Kilograms Per Square Centimeter KM/H Kilometers Per Hour KOEO

Key On, Engine Off KOER Key On, Engine Running KS Knock Sensor kW Kilowatt kV Kilovolt

"L" L Liter lbs. (Lbs. when used in table) Pounds LCD Liquid Crystal Display L/D Light Duty LDP Leak Detection Pump (Part of EVAP system.) LED Light Emitting Diode LH Left Hand

"M" mA Milliamps MA or MAF Mass Airflow MAFS Mass Airflow Sensor MAP Manifold Absolute Pressure MAT Manifold Air Temperature Mem. Memory MEM-CAL Memory Calibration Chip mfd. Microfarads MFI Multiport Fuel Injection MICU Multiplex Integrated Control Unit (Acura/Honda) MIL Malfunction Indicator Light MPI

Multi-Point (Fuel) Injection mm Millimeters MPH Miles Per Hour mV Millivolts

"N" NA Not Available NAC NOx Adsorber Catalyst NCA No Color Available (Wiring Diagrams) NGS New Generation Star N.m Newton Meter No. Number Nos. Numbers NOx Oxides of Nitrogen

"O" O2 Oxygen OBD On-Board Diagnostics OC Oxidation Catalyst OD Overdrive O.D. Outside Diameter OHC Overhead Camshaft OSS Output Speed Sensor O/S Oversize oz. Ounce ozs. Ounces

"P" "P"

Park P/C Printed Circuit PCM Powertrain Control Module PCS Purge Control Solenoid PC-SOL Purge Control Solenoid PCV Positive Crankcase Ventilation PFI Port Fuel Injection PGM-FI Programmed Fuel Injection PID Parameter Identification PIP Profile Ignition Pick-up PNP Park Neutral Position Switch P/N Park/Neutral PRNDL

Park Reverse Neutral Drive Low PROM Programmable Read-Only Memory psi Pounds Per Square Inch P/S Power Steering PSPS Power Steering Pressure Switch PTC Positive Temperature Coefficient PTO Power Take-Off Pts. Pints Pwr. Power

"Q" Qts. Quarts

"R" RABS Rear Anti-Lock Brake System RECIRC

Recirculation RH Right Hand RPM Revolutions Per Minute RWAL Rear Wheel Anti-Lock Brake RWD Rear Wheel Drive

"S" SAS Steering Angle Sensor SBC Single Bed Converter SBEC Single Board Engine Controller SDARS Satellite Digital Audio Radio Service SES Service Engine Soon SFI Sequential (Port) Fuel Injection SIL Shift Indicator Light

SIR Supplemental Inflatable Restraint SOHC Single Overhead Cam SOL or Sol. Solenoid SPFI Sequential Port Fuel Injection SPK Spark Control SPOUT Spark Output SRI Service Reminder Indicator SRS Supplemental Restraint System (Air Bag) STAR Self-Test Automatic Readout STO Self-Test Output SUB-O2 Sub Oxygen Sensor Sw. Switch

Sys. System

"T" TAB Thermactor Air By-Pass TAC Throttle Actuator Module TAD Thermactor Air Diverter TBC Body Control Module (General Motors) TBI Throttle Body Injection TCC Torque Converter Clutch TDC Top Dead Center Temp. Temperature TFI Thick Film Ignition THERMAC Thermostatic Air Cleaner TPM

Tire Pressure Monitor TPMS Tire Pressure Monitor System TPS Throttle Position Sensor/Switch TS Temperature Sensor TV Thermovalve TWC Three-Way Catalyst

"V" V Valve Vac. Vacuum VAF Vane Airflow VAPS Variable Assist Power Steering VCC Viscous Converter Clutch VCRM Variable Control Relay Module

VIN Vehicle Identification Number VM Vacuum Modulator Volt. Voltage VOM Volt-Ohmmeter (Analog) VRV Vacuum Regulator Valve VSS Vehicle Speed Sensor VSV Vacuum Switching Valve

"W" W/ With W/O Without WAC Wide Open Throttle A/C Switch WOT Wide Open Throttle

ANTI-LOCK BRAKE SYSTEM BRAKES General Motors - Bosch 2U Anti-Lock Brake System

DESCRIPTION The Bosch 2U Anti-Lock Brake System (ABS) increases vehicle steerability, directional stability and optimum deceleration in severe braking conditions on most road surfaces. The ABS monitors wheel speed and controls brake line pressure to eliminate uncontrolled skidding. The ABS consists of an Electronic Brake Control Module (EBCM), hydraulic modulator, solenoid valves, pump motor, ABS valve relay, pump relay, wheel speed sensors on front wheels and rear axle speed sensor on rear axle differential. See Fig. 1. NOTE:

 

For more information on brake system, see appropriate BRAKE SYSTEM article listed below.

BRAKE SYSTEM BRAKE SYSTEM - 1992

Fig. 1: Locating Anti-Lock Brake System Components Courtesy of GENERAL MOTORS CORP.

OPERATION

The EBCM is located behind glove box. Wheel speed sensors transmit a small AC voltage signal about wheel acceleration, deceleration and slip value to EBCM. The EBCM controls braking by activating and deactivating electromagnetic modulator valve. The modulator valve consists of 3 rapidly switching solenoid valves, accumulator chamber and a return pump. The valves increase and decrease brake fluid pressure to each wheel (rear wheels are one circuit) to prevent wheel lock-up. The modulator valve can supply only as much fluid pressure as applied by the driver through the master cylinder. The modulator valve alone cannot apply the brakes. When ignition switch is turned to RUN position, amber ANTI-LOCK warning light on instrument panel will glow. After engine is started, light goes out with battery warning light. If ABS warning light fails to go out or comes on while driving, a system fault is indicated. BLEEDING BRAKE SYSTEM Brake system can be bled by either manual or pressure procedure. Use DOT 3 brake fluid only. NOTE:

Deplete brake vacuum reserve by applying brake pedal several times.

MANUAL BLEEDING PROCEDURE 1. With engine off, remove reserve vacuum by applying brakes several times. Fill master cylinder with brake fluid and keep half full during bleeding procedure. 2. Place proper size box end wrench over bleeder valve. Attach one end of clear tube over valve and submerge other end in container partially filled with clean brake fluid. 3. Have an assistant slowly depress and hold brake pedal. Starting at left front wheel, loosen bleeder valve to purge air from cylinder. Tighten bleeder valve and slowly release brake pedal. Repeat sequence until all air is removed. 4. Remove tube and wrench. Proceed to right front wheel, left rear wheel and finish at right rear wheel. Fill master cylinder, and replace cover. PRESSURE BLEEDING PROCEDURE 1. Install Bleeder Adapter (J-33589) to brake master cylinder. Pressurize bleeder to 20-25 psi (1.41-1.76 kg/cm2 ). Connect bleeder hose to adapter, and bleed air from adapter. 2. Place proper size box end wrench over bleeder valve. Attach one end of clear tube over valve and submerge other end in container partially filled with clean brake fluid. 3. Starting at left front wheel, loosen bleeder valve to purge air from cylinder. Tighten bleeder valve when air bubbles are no longer seen in tube. Repeat sequence until all air is removed. 4. Remove tube and wrench. Proceed to right front wheel, left rear wheel and finish at right rear wheel. Remove bleeder adapter, fill master cylinder and replace cover.

DIAGNOSIS & TESTING

NOTE:

To diagnose ABS system, manufacturer recommends using Tech 1 Scan Tester (94-00101-A) with 88-91 Brake Cartridge and Bosch ABS adapter. Some diagnostic procedures will require Pinout Box (J-35592).

PRE-DIAGNOSTIC INSPECTION NOTE:

ABS system has 2 grounds. One ground is located on right front corner of right fender; other is located on left side of engine compartment, near cruise control servo, on fender.

When checking potential ABS system faults, check following before using diagnostic code charts: 1. Check ABS, IGN 1-ISO and STOP/HAZ fuses. 2. Check fusible links on junction block. 3. Ensure overvoltage relay, ABS 6-pin connector and electronic brake control module connectors are properly seated. 4. Ensure parking brake switch is functioning properly. 5. Ensure ground circuit is clean and tight. 6. Perform anti-lock brake system functional check. See Fig. 2. ENTERING DIAGNOSTIC DISPLAY MODE Ground pin "H" to pin "A" of ALDL connector. ALDL connector is located behind left side of instrument panel, left of steering column. See Fig. 3. Turn ignition switch to RUN position (engine off). Diagnostic display mode will remain enabled as long as pin "H" is grounded, serial data link communications has not been initiated and vehicle speed is less than 5 MPH. About 4 seconds after ALDL pin "H" is grounded, EBCM will begin flashing code sequence. Sequence will begin with Code 12, signaling beginning of fault code display. Each stored code will be displayed 3 times. After all codes have been displayed, sequence will repeat starting with Code 12. Some codes can only be read through ALDL connector using Tech 1 scan tester.

Fig. 2: Anti-Lock Brake System Functional Check Courtesy of GENERAL MOTORS CORP.

Fig. 3: Identifying ALDL Connector Pins Courtesy of GENERAL MOTORS CORP. CODE INDEX DIAGNOSTIC TROUBLE CODES Code 12 21 22 25 26 35 36 41 45 55 61 63

Definition Diagnostic System Operational Right Front Wheel Speed Sensor Fault Right Front Toothed Wheel Frequency Error Left Front Wheel Speed Sensor Fault Left Front Toothed Wheel Frequency Error Rear Axle Speed Sensor Fault Rear Axle Toothed Wheel Frequency Error Right Front Solenoid Valve Fault Left Front Solenoid Valve Fault Rear Solenoid Valve Fault Pump Motor Or Relay Fault Solenoid Valve Relay Fault

71 72

EBCM Fault EBCM Serial Data Fault

CLEARING CODES 1. Turn ignition switch to RUN position. Ensure ANTI-LOCK light turns off after 3-4 seconds. If light remains on, a fault is still present and must be corrected. Place a jumper wire between pins "A" and "H" of ALDL connector. When ANTI-LOCK light turns on, remove jumper wire from pin "H". 2. When light turns off, reconnect jumper wire to pin "H". ANTI-LOCK light will turn on again. Remove jumper wire from pin "H". Repeat previous step. When light turns off, reconnect jumper wire to pin "H". ANTI-LOCK light will turn on. Remove jumper wire to pin "H". ABS codes should now be cleared. Verify by checking codes. Code 12 should be displayed. If other codes are present, repeat code clearing process. USING TECH 1 NOTE:

Tech 1 Scan Tester (94-00101-A) with Bosch ABS ALDL Adapter, Pinout Box (J35592) and high impedance multimeter are needed to test parts of ABS system.

1988-91 or 1988-92 BRAKE cartridge must be inserted in Tech 1 to perform diagnostic procedures on anti-lock brake system. Tech 1 is plugged into ALDL connector before turning ignition on. A Bosch ABS adapter is required when testing Bosch 2U anti-lock brake system. Selecting Model Year

Turn ignition switch to RUN position. Select appropriate model year using function keys. Selecting Vehicle

After selecting model year, enter type of vehicle which is being tested. Press NO until "D" is flashing. Pressing EXIT will return Tech 1 to previous screen. Selecting Test Mode

Five test modes are available for diagnosing anti-lock brake system. See Fig. 4. Mode F0 (Data List)

Mode display is actual reading which each wheel speed sensor is sending to EBCM. See Fig. 5. In this mode, vehicle can be driven and wheel speed information can be observed to determine if readings are comparable to actual vehicle speed. By pressing brake pedal, status of brake light switch can be observed.

Fig. 4: Tech 1 Test Selection Courtesy of GENERAL MOTORS CORP.

Fig. 5: Tech 1 Data List Mode Courtesy of GENERAL MOTORS CORP. Mode F1 (Code History)

Mode displays trouble codes and description. See Fig. 6. Ignition cycle information is useful in determining reason vehicle is in for service. If display indicates zero ignition cycles since code was set, fault is currently present. EBCM keeps track of ignition cycles and will automatically erase any code information if no ABS faults are set in 50 cycles. This information is useful to determine if intermittent condition exists. Vehicle speed information and BRAKE light switch information can be used to duplicate fault if an intermittent fault caused code to set. ABS state information is useful in determining driving condition of vehicle when code was set. Mode F2 (Trouble Codes)

Mode displays ABS malfunction codes. Tech 1 will display any error codes and brief description of code number displayed. See Fig. 8. If no codes are stored, Tech 1 will display NO ABS CODES. Tech 1 will respond to a clear codes command by indicating ABS CODES CLEARED or CODE CLEAR FAIL. Mode F3 (ABS Snapshot)

Mode will help isolate intermittent problems by capturing data before and after fault condition. See Fig. 8. If MANUAL TRIGGER is selected, Tech 1 will wait for ENTER to be pressed before storing wheel speed sensor information. All stored information can be displayed and examined for conditions which might indicate a problem. If AUTOMATIC TRIGGER is selected, Tech 1 will capture data which deviates from normal conditions but may not set a code, such as driving over bumpy roads or railroad tracks. Condition may be caused by loose connections or intermittent wiring problems. While Tech 1 is waiting for a trigger, ENTER or F9 key may be used to force a trigger. Mode F4 (ABS Test)

Mode is used to perform following tests.   

SOLENOID VALVE PRESSURE HOLD TEST SOLENOID VALVE PRESSURE RELEASE TEST AUTOMATIC TESTS

By selecting appropriate test and observing results, error conditions and faults can be further identified.

Fig. 6: Tech 1 Code History Mode Courtesy of GENERAL MOTORS CORP.

Fig. 7: Tech 1 Trouble Codes Mode Courtesy of GENERAL MOTORS CORP. Solenoid Valve Pressure Hold Test

1. Raise vehicle on frame contact hoist so wheels to be tested are off ground. 2. Using Tech 1, select SOLENOID TEST. Select wheel circuit solenoid to be tested. If testing rear axle valve, ensure transmission is in Neutral. 3. With foot off brake pedal, have assistant verify wheel can be turned by hand. Press UP ARROW, and then apply and hold brake pedal. Have assistant verify selected wheel can be turned by hand. 4. When UP ARROW is pressed, display will change from OFF to ON. After 15 seconds, display will change back to OFF. Verify selected wheel is now locked. Repeat test if necessary to verify proper operation. Perform SOLENOID VALVE PRESSURE RELEASE TEST. Solenoid Valve Pressure Release Test

1. Raise vehicle on frame contact hoist so wheels to be tested are off ground. 2. Using Tech 1, select SOLENOID TEST. Select wheel circuit solenoid to be tested. See Fig. 9. If testing rear axle valve, ensure transmission is in Neutral. 3. Apply and hold brake pedal. Have assistant verify wheel cannot be turned by hand. Press DOWN ARROW. Have assistant verify selected wheel can be turned by hand. Display on Tech 1 should change from OFF to ON, indicating pressure release has been commanded properly. 4. After 15 seconds, display will change back to OFF. Verify selected wheel is now locked. Repeat test if necessary to verify proper operation. Perform SOLENOID VALVE PRESSURE HOLD TEST if not yet completed. Automatic Tests

Select AUTO TEST. Press ENTER. See Fig. 10. Valves can be heard and felt cycling from hydraulic control unit; have assistant verify pump motor turned on. Go to DIAGNOSTIC CODE CHARTS if codes are set.

Fig. 8: Tech 1 ABS Snapshot Mode Courtesy of GENERAL MOTORS CORP.

Fig. 9: Tech 1 Solenoid Valve Test Mode Courtesy of GENERAL MOTORS CORP.

Fig. 10: Tech 1 Automatic Test Mode Courtesy of GENERAL MOTORS CORP. SYMPTOM DIAGNOSIS

If no trouble codes are stored, use SYMPTOM DIAGNOSTIC CHARTS if necessary. See SYMPTOM DIAGNOSTIC CHART INDEX table. SYMPTOM DIAGNOSTIC CHART INDEX Symptom No System Power Anti-Lock Light On, No Codes Set Anti-Lock Light Inoperative, Key On Valve Cycling (Chattering) During Normal Stops (1) See appropriate chart under SYMPTOM DIAGNOSTIC CHARTS.

(1) Chart

"A" "B" "C" "D"

INTERMITTENTS Failures in anti-lock brake system may be difficult to diagnose accurately. If an intermittent condition is diagnosed, ABS self-diagnostic system can be used to help find suspect circuit. To do so:   



Display and clear any ABS trouble codes present in EBCM. Test drive vehicle. Attempt to repeat failure under condition in which failure occurred. After duplicating condition, stop vehicle, and display any ABS trouble codes which may have been stored. If no trouble codes were stored, use SYMPTOM DIAGNOSTIC CHARTS if necessary.

Most intermittent problems are caused by faulty electrical connectors or wiring. When an intermittent failure is encountered, check suspect circuits for:  

  

Poor mating of connector halves and terminals not fully seated in connector body (backed out). Improperly formed or damaged terminals. All connector terminals in a problem circuit should be carefully reformed to increase contact tension. Poor terminal-to-wire connection. This requires removing terminal from connector body to inspect. Wheel speed sensor cables not attached in retainers or routed too close to spark plug wires. Low system voltage. If low system voltage is detected at EBCM, ABS will turn on ANTI-LOCK light until normal system voltage is achieved.

DIAGNOSTIC CODE CHARTS NOTE:

In some instances, the new format for diagnostic flowcharts will combine what were previously described as (1 Of 1) or (2 Of 2).

CODE 21 - RIGHT FRONT WHEEL SPEED SENSOR FAULT Toothed wheel generates a voltage pulse as it moves past sensor. EBCM uses these pulses to determine wheel speed. EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed. EBCM

performs 2 basic types of checks on wheel speed sensors: sensor continuity and sensor output. NOTE:

Test numbers refer to numbers on diagnostic chart.

1. Determines if code stored is due to a current fault. Current wheel speed sensor faults will be detected when vehicle is driven and reaches speed of 4 MPH. If ANTI-LOCK light comes on, fault is current. 2. Checks for open or short in wheel speed sensor wiring or sensor coil. 3. Checks for conditions which may cause intermittent code setting. Note On Intermittents

Intermittent setting of wheel speed sensor trouble codes may be caused by improper routing (sensor cables next to spark plug wires), cables not retained in mounting bracket, loose fitting or improperly mounted sensors, damaged sensors or toothed rings, poor terminal connectors and intermittent short or open in wiring.

Fig. 11: Code 21 Schematic - RF Wheel Speed Sensor Fault Courtesy of GENERAL MOTORS CORP.

Fig. 12: Code 21 - Flow Chart (1 of 2) RF Wheel Speed Sensor Fault Courtesy of GENERAL MOTORS CORP.

Fig. 13: Code 21 - Flow Chart (2 of 2) RF Wheel Speed Sensor Fault Courtesy of GENERAL MOTORS CORP. CODE 22 - RIGHT FRONT TOOTHED WHEEL FREQUENCY ERROR Toothed wheel generates a voltage pulse as it moves past sensor. EBCM uses these pulses to determine wheel speed. EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed. Code 22 will be set if improper speed signals are generated by toothed ring sensor. Some causes are incorrect number of teeth on sensor ring, sensor rings covered with dirt, grease or metallic particles, and damaged toothed sensor ring.

Code 22 may be set if mini-spare tire has been used or tire sizes on vehicle differ from each other. NOTE:

Correct number of sensor ring teeth is 47.

Note On Intermittents

Fig. 14: Code 22 Schematic - RF Toothed Wheel Frequency Error Courtesy of GENERAL MOTORS CORP.

Fig. 15: Code 22 Flow Chart - RF Toothed Wheel Frequency Error Courtesy of GENERAL MOTORS CORP. CODE 25 - LEFT FRONT WHEEL SPEED SENSOR FAULT Toothed wheel generates a voltage pulse as it moves past sensor. EBCM uses these pulses to determine wheel speed. EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed. EBCM performs 2 basic types of checks on wheel speed sensors: sensor continuity and sensor output. NOTE:

Test numbers refer to numbers on diagnostic chart.

Fig. 16: Code 25 Schematic - LF Wheel Speed Sensor Fault Courtesy of GENERAL MOTORS CORP.

Fig. 17: Code 25 Flow Chart (1 of 2) - LF Wheel Speed Sensor Fault Courtesy of GENERAL MOTORS CORP.

Fig. 18: Code 25 Flow Chart (2 of 2) - LF Wheel Speed Sensor Fault Courtesy of GENERAL MOTORS CORP. CODE 26 - LEFT FRONT TOOTHED WHEEL FREQUENCY ERROR Toothed wheel generates a voltage pulse as it moves past sensor. EBCM uses these pulses to determine wheel speed. EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed. Code 26 will be set if improper speed signals are generated by toothed ring sensor. Some causes are incorrect number of teeth on sensor ring, sensor rings covered with dirt, grease or metallic particles, and damaged toothed sensor ring. Code 26 may be set if mini-spare tire has been used or tire sizes on vehicle differ from each other.

NOTE:

Correct number of sensor ring teeth is 47.

Note On Intermittents

Fig. 19: Code 26 Schematic - LF Toothed Wheel Frequency Error Courtesy of GENERAL MOTORS CORP.

Fig. 20: Code 26 Flow Chart - LF Toothed Wheel Frequency Error Courtesy of GENERAL MOTORS CORP. CODE 35 - REAR AXLE SPEED SENSOR FAULT Toothed wheel generates a voltage pulse as it moves past sensor. EBCM uses these pulses to determine wheel speed. EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed. EBCM performs 2 basic types of checks on wheel speed sensors: sensor continuity and sensor output. NOTE:

Test numbers refer to numbers on diagnostic chart.

1. Determines if code stored is due to a current fault. Current wheel speed sensor faults will be detected even when vehicle is at a standstill. If ANTI-LOCK light turns on, fault is current. Tech 1 will indicate ignition cycle since code was set. 2. Checks for open or short in wheel speed sensor wiring or sensor coil. 3. Checks for conditions which may cause intermittent code setting.

Note On Intermittents

Fig. 21: Code 35 Schematic - Rear Axle Speed Sensor Fault Courtesy of GENERAL MOTORS CORP.

Fig. 22: Code 35 Flow Chart (1 of 2) - Rear Axle Speed Sensor Fault Courtesy of GENERAL MOTORS CORP.

Fig. 23: Code 35 Flow Chart (2 of 2) - Rear Axle Speed Sensor Fault Courtesy of GENERAL MOTORS CORP. CODE 36 - REAR AXLE TOOTHED WHEEL FREQUENCY ERROR Toothed wheel generates a voltage pulse as it moves past sensor. EBCM uses these pulses to determine wheel speed. EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed. Code 36 will be set if improper speed signals are generated by toothed ring sensor. Some causes are incorrect number of teeth on sensor ring, sensor rings covered with dirt, grease or metallic particles, and damaged toothed sensor ring.

Code 36 may be set while driving if one wheel is detected at least 19 MPH faster or 4 MPH less or greater than remaining wheels for an extended period of time. NOTE:

Correct number of sensor ring teeth is 47.

Note On Intermittents

Fig. 24: Code 36 Schematic - Rear Axle Toothed Wheel Frequency Error Courtesy of GENERAL MOTORS CORP.

Fig. 25: Code 36 Flow Chart - Rear Axle Toothed Wheel Frequency Error Courtesy of GENERAL MOTORS CORP. CODE 41 - RIGHT FRONT SOLENOID VALVE FAULT EBCM may command right front solenoid valve in hydraulic modulator to 3 different positions. Valve position is determined by amount of current which is allowed to flow through solenoid coil. Solenoid valve circuits receive power through valve relay on hydraulic modulator. Valve relay is engaged at key on and remains engaged throughout ignition cycle. Solenoid valve circuits should always have battery voltage available. When ignition switch is in RUN position, power is supplied to EBCM. EBCM will complete an internal selfcheck before providing ground to valve relay. When valve relay is energized, battery power is supplied to solenoid valves. Code 41 will be set when expected position of right front solenoid valve does not match commanded position from EBCM. Conditions which could cause Code 41 to set are damage to right front solenoid, open circuit No. 827 and short circuit to ground or battery on circuit No. 827.

NOTE:

If code is current, it cannot be flashed.

Note On Intermittents

Intermittent failures in anti-lock brake system may be difficult to accurately diagnose. If an intermittent condition is being diagnosed, self-diagnostic system may be used in following manner to help isolate suspect circuit:    

Display and clear ABS trouble codes which may be present in EBCM. Test drive vehicle, attempting to repeat fault condition. After duplicating fault condition, stop vehicle, and display ABS codes which may have been stored. If no trouble codes were stored, use symptom diagnosis if necessary. See SYMPTOM DIAGNOSTIC CHART INDEX table under SYMPTOM DIAGNOSIS.

Fig. 26: Code 41 Schematic - RF Solenoid Valve Fault Courtesy of GENERAL MOTORS CORP.

Fig. 27: Code 41 Flow Chart - RF Solenoid Valve Fault Courtesy of GENERAL MOTORS CORP. CODE 45 - LEFT FRONT SOLENOID VALVE FAULT EBCM may command left front solenoid valve in hydraulic modulator to 3 different positions. Valve position is determined by amount of current which is allowed to flow through solenoid coil. Solenoid valve circuits receive power through valve relay on hydraulic modulator. Valve relay is engaged at key on and remains engaged throughout ignition cycle. Solenoid valve circuits should always have battery voltage available. When ignition switch is in RUN position, power is supplied to EBCM. EBCM will complete an internal selfcheck before providing ground to valve relay. When valve relay is energized, battery power is supplied to solenoid valves.

Code 45 will be set when expected position of left front solenoid valve does not match commanded position from EBCM. Conditions which could cause Code 45 to set are damage to left front solenoid, open circuit No. 826 and short circuit to ground or battery on circuit No. 826. NOTE:

If code is current, it cannot be flashed.

Note On Intermittents

Fig. 28: Code 45 Schematic - LF Solenoid Valve Fault Courtesy of GENERAL MOTORS CORP.

Fig. 29: Code 45 Flow Chart - LF Solenoid Valve Fault Courtesy of GENERAL MOTORS CORP. CODE 55 - REAR AXLE SOLENOID VALVE FAULT EBCM may command rear axle solenoid valve in hydraulic modulator to 3 different positions. Valve position is determined by amount of current which is allowed to flow through solenoid coil.

Solenoid valve circuits receive power through valve relay on hydraulic modulator. Valve relay is engaged at key on and remains engaged throughout ignition cycle. Solenoid valve circuits should always have battery voltage available. When ignition switch is in RUN position, power is supplied to EBCM. EBCM will complete an internal selfcheck before providing ground to valve relay. When valve relay is energized, battery power is supplied to solenoid valves. Code 55 will be set when expected position of rear axle solenoid valve does not match commanded position from EBCM. Conditions which could cause Code 55 to set are damage to rear axle solenoid, open circuit No. 828 and short circuit to ground or battery on circuit No. 828. NOTE:

If code is current, it cannot be flashed.

Note On Intermittents

Fig. 30: Code 55 Schematic - Rear Axle Solenoid Valve Fault Courtesy of GENERAL MOTORS CORP.

Fig. 31: Code 55 Flow Chart - Rear Axle Solenoid Valve Fault Courtesy of GENERAL MOTORS CORP. CODE 61 - PUMP MOTOR OR RELAY FAULT Pump motor returns brake fluid to master cylinder brake circuit at hydraulic modulator during anti-lock braking. During normal braking, pump does not operate. When vehicle begins to move after start-up, EBCM will turn on pump motor and perform a self-check of pump motor and pump motor circuit. This self-check may be felt and heard by driver when vehicle begins to move. Pump motor is an integral part of hydraulic modulator and cannot be serviced separately. Code 61 will be set if pump motor voltage is not detected during drive away after engine start or if motor relay is energized while driving and motor voltage is not detected.

Code 61 will also be set if voltage at EBCM pin No. 14 is below system voltage, if pump motor runs continuously and if commanded position of pump motor relay and motor monitor do not agree. Conditions which could cause Code 61 to set are an open or a short to voltage or ground in circuit No. 854 or 1078 and a defective pump motor relay or pump motor.

Fig. 32: Code 61 Schematic - Pump Motor Or Relay Fault Courtesy of GENERAL MOTORS CORP.

Fig. 33: Code 61 Flow Chart (1 of 3) - Pump Motor Or Relay Fault

Courtesy of GENERAL MOTORS CORP.

Fig. 34: Code 61 Flow Chart (2 of 3) - Pump Motor Or Relay Fault Courtesy of GENERAL MOTORS CORP.

Fig. 35: Code 61 Flow Chart (3 of 3) - Pump Motor Or Relay Fault Courtesy of GENERAL MOTORS CORP. CODE 63 - SOLENOID VALVE RELAY FAULT (1 OF 2) Solenoid valve relay provides power to 3 solenoid valves in hydraulic modulator. Solenoid valve relay is located on hydraulic modulator and can be replaced separately. Valve relay is engaged during normal system operation. When ignition switch is in RUN position, EBCM commands solenoid valve relay on by grounding relay actuation circuit No. 879 (EBCM pin No. 27). When ground is provided, valve relay is energized from voltage supply circuit No. 1079 (EBCM pin No. 17). Valve relay switches and battery voltage is provided to 3 solenoid valves and solenoid valve feedback circuit No. 851 (EBCM pin No. 32). Valve relay remains engaged until ignition switch is turned OFF or a failure is detected. Whenever solenoid valve relay is not engaged, amber ANTI-LOCK light will be on. With ignition on and solenoid valve relay not engaged, a path to ground exists from GA/TRANS fuse through ANTI-LOCK light on

circuit No. 39, which turns on ANTI-LOCK light. ANTI-LOCK light can also be commanded on by EBCM on circuit No. 852 (EBCM pin No. 29). EBCM will provide a ground on circuit No. 852 and turn on ANTI-LOCK light when failure is detected. Pump motor relay is not engaged during normal system operation. When anti-lock operation is required, motor relay actuation circuit No. 854 (EBCM pin No. 28) is pulled to ground. Pump motor relay is engaged by relay supply voltage on circuit No. 1079 (EBCM pin No. 17). When relay switches, battery power is provided to pump motor. Code 63 will be set if commanded position of valve relay and valve relay position indicated by feedback circuit do not agree. Conditions which could cause a Code 63 to set are an open circuit or a short to voltage or ground on circuit No. 851 or 879, defective solenoid valve relay and open circuit on circuit No. 854. NOTE:

This code is current; it cannot be flashed.

Fig. 36: Code 63 Schematic - Solenoid Valve Relay Fault Courtesy of GENERAL MOTORS CORP.

Fig. 37: Code 63 Flow Chart (1 of 3) - Solenoid Valve Relay Fault

Courtesy of GENERAL MOTORS CORP.

Fig. 38: Code 63 Flow Chart (2 of 3) - Solenoid Valve Relay Fault Courtesy of GENERAL MOTORS CORP.

Fig. 39: Code 63 Flow Chart (3 of 3) - Solenoid Valve Relay Fault Courtesy of GENERAL MOTORS CORP. CODE 71 - EBCM FAULT Note On Intermittents

Fig. 40: Code 71 Flow Chart - EBCM Fault Courtesy of GENERAL MOTORS CORP. CODE 72 - EBCM SERIAL DATA FAULT ABS Code 72 may set when a momentary serial data communications error exists between EBCM and Tech 1. This code may also be set when power to EBCM is interrupted while Tech 1 remains powered. When this occurs, simply cycle power to Tech 1 and allow it to reset. Clear code before completing diagnosis.

SYMPTOM DIAGNOSTIC CHARTS SYMPTOM DIAGNOSTIC CHART "A" - NO SYSTEM POWER EBCM receives power from Overvoltage Protection (OVP) relay on circuit No. 850 (EBCM pin No. 1). When

ignition is turned to RUN position, OVP relay is energized by GA/TRANS fuse. Normally open relay contacts of OVP relay close. OVP relay is located under dash, mounted near EBCM bracket behind glove box. Battery voltage is supplied to EBCM through ABS fuse and circuit No. 640. If high system voltages occur, ABS fuse will blow in order to prevent damage to ABS system. Intermittent operation of ANTI-LOCK light may be caused by intermittent voltage levels which do not correspond to proper operating range of ABS system. Conditions which may cause lack of system power include improper electrical contact of EBCM connector, low system voltage and improper electrical contact of vehicle power and ground Connections.

Fig. 41: Chart "A" Schematic - No System Power Courtesy of GENERAL MOTORS CORP.

Fig. 42: Chart "A" Flow Chart - No System Power Courtesy of GENERAL MOTORS CORP. SYMPTOM DIAGNOSTIC CHART "B" - ANTI-LOCK LT ON, NO CODES SET Amber ANTI-LOCK light is located in top of instrument cluster and may be lit by EBCM or a path to ground in valve relay on hydraulic modulator. ANTI-LOCK light is powered by IGN-1 (ignition 1) feed and receives power anytime ignition switch is in RUN or START position. Power is provided on circuit No. 39 through GA/TRANS fuse located in fuse block. ANTI-LOCK light is turned on anytime valve relay is not enabled. When relay is not enabled, light is grounded through circuit No. 852 and valve relay to modulator ground on left front fender.

During normal operation, valve will switch, ground will be removed and ANTI-LOCK light will turn off. If EBCM detects a fault in ABS system, EBCM can turn on ANTI-LOCK light by grounding pin No. 29. A ground path exists for light through circuit No. 852. EBCM will disable valve relay when circuit No. 852 is grounded at EBCM pin No. 29. If ANTI-LOCK light is on and no codes can be extracted, EBCM connector should be checked for proper connection. System power should also be checked.

Fig. 43: Chart "B" Schematic - Anti-Lock Lt On, No Codes Set Courtesy of GENERAL MOTORS CORP.

Fig. 44: Chart "B" Flow Chart - Anti-Lock Lt On, No Codes Set Courtesy of GENERAL MOTORS CORP. SYMPTOM DIAGNOSTIC CHART "C" - ANTI-LOCK LT INOP, KEY ON Amber ANTI-LOCK light is located in top of instrument cluster and may be lit by EBCM or a path to ground in valve relay on hydraulic modulator. ANTI-LOCK light is powered by Ignition 1 feed and receives power anytime ignition switch is in RUN or START position. Power is provided on circuit No. 39 through GA/TRANS fuse located in fuse block. ANTI-LOCK light is turned on anytime valve relay is not enabled. When relay is not enabled, light is grounded through circuit No. 852 and valve relay to modulator ground on left front fender. During normal operation, valve will switch, ground will be removed and ANTI-LOCK light will turn off. Whether valve relay is engaged or not, EBCM can turn on ANTI-LOCK light by grounding EBCM pin No. 29. A ground path exists for light through circuit No. 852.

Fig. 45: Chart "C" Schematic - Anti-Lock Lt Inop, Key On Courtesy of GENERAL MOTORS CORP.

Fig. 46: Chart "C" Flow Chart - Anti-Lock Lt Inop, Key On Courtesy of GENERAL MOTORS CORP. SYMPTOM DIAGNOSTIC CHART "D" - VALVE CYCLING (CHATTERING) DURING NORMAL STOPS EBCM uses wheel speed sensor signal to calculate vehicle reference speeds and speed, acceleration and slip values for each wheel. These values are used to determine when anti-lock control is needed. EBCM performs 2 basic types of checks on wheel speed sensors: sensor continuity and sensor output. In order to prevent electromagnetic interference from disturbing wheel speed sensor signal, sensor cables are protected with grounded shielding. Shield surrounds 2 individual sensor wires. A Black conduit surrounds wires and shield. If shielding is disturbed, repair as required.

Fig. 47: Chart "D" Schematic - Valve Cycling During Normal Stops Courtesy of GENERAL MOTORS CORP.

Fig. 48: Chart "D" Flow Chart - Valve Cycling During Normal Stops Courtesy of GENERAL MOTORS CORP.

WIRING DIAGRAM

Fig. 49: Anti-Lock Brake System Wiring Diagram ()

Fig. 50: Anti-Lock Brake System Wiring Diagram (1992)

REMOVAL & INSTALLATION ELECTRONIC BRAKE CONTROL MODULE (EBCM) Removal & Installation

EBCM is located on bracket, below glove box. Remove right close-out panel under instrument panel. Disconnect EBCM electrical connector. Remove glove box liner, and remove EBCM from bracket. To install, reverse removal procedure. HYDRAULIC MODULATOR Removal

Drain or otherwise remove brake fluid from brake master cylinder. Remove left front radiator brace. Remove air

cleaner intake hose. Remove hydraulic modulator relay cover, and disconnect 12-pin electrical connector. Remove ground strap. Label brake lines for installation reference, and then remove brake lines from hydraulic modulator. See Fig. 51. Remove hydraulic modulator from mounting bracket. Installation

To install, reverse removal procedure. Tighten hydraulic modulator mounting nuts to 95 INCH lbs. (11 N.m). Tighten brake lines to 108 INCH lbs. (12 N.m). Refill brake master cylinder, bleed brakes and check for leaks.

Fig. 51: Identifying Brake Line Positions Courtesy of GENERAL MOTORS CORP. MODULATOR RELAYS Removal & Installation

Solenoid valve relay and pump motor relay are plugged into hydraulic modulator and can be accessed by removing cover of hydraulic modulator. See Fig. 52. Solenoid valve relay has a silver case and 6 pins; pump relay has a black case and 4 pins.

Fig. 52: Identifying Modulator Relays Courtesy of GENERAL MOTORS CORP. TOOTHED SENSOR RING NOTE:

Front and rear sensor rings should each have 47 teeth.

Removal & Installation (Front)

1. Front toothed sensor ring is an integral part of front brake rotor. Sensor ring is accessible for inspection by raising vehicle. 2. If front sensor ring replacement is necessary, front brake rotor must be replaced. Raise and support vehicle. Remove wheel. Remove and support caliper. Remove grease cup, cotter pin and nut. Remove rotor. To install, reverse removal procedure. Removal & Installation (Rear)

1. Rear toothed sensor ring is pressed onto rear axle differential pinion gear. Sensor ring can be inspected by removing rear speed sensor and slowly turning drive shaft by hand with vehicle in Neutral. 2. If sensor ring replacement is necessary, rear axle pinion must be removed to replace sensor ring. See DIFFERENTIALS & AXLE SHAFTS article in DRIVE AXLES. WHEEL SPEED SENSOR Removal & Installation (Front)

1. Disconnect wheel speed sensor electrical connector at strut tower. Raise and support vehicle. Remove tire and wheel assembly. Disengage sensor cable grommet from wheelwell pass-through hole, and remove sensor cable from retainers. Remove sensor mounting bolt, and remove sensor. 2. To install, reverse removal procedure. Coat sensor with Anti-Corrosion Compound (1052856) before installing. Tighten sensor mounting bolt to 106 INCH lbs. (12 N.m). Ensure cable is routed correctly and properly installed in retainers. Removal & Installation (Rear)

Rear axle (wheel) speed sensor is mounted in rear axle differential and is not adjustable. Raise and support vehicle. Disconnect sensor electrical connector, and remove sensor cable from retainer brackets. Remove sensor mounting bolt, and remove sensor, plastic spacer and "O" ring. To install, reverse removal procedure.

ADJUSTMENTS STOPLIGHT SWITCH Hold brake pedal in depressed position. Insert stoplight switch into retainer until switch body seats on tube clip. Pull brake pedal upward against internal pedal stop. Switch will be moved in retainer by brake pedal to provide proper adjustment. PARKING BRAKE 1. Clean and lubricate threads on adjusting rod of parking brake cable equalizer. Adjust rear brakes. see BRAKE SYSTEM article listed below. Press parking brake lever 6 ratchet clicks.  BRAKE SYSTEM  BRAKE SYSTEM - 1992 2. Raise and support vehicle. Tighten adjuster nut at equalizer until rear wheel can just be turned rearward with two hands but cannot be turned forward. Release parking brake. Ensure rear wheels turn freely.

SAFETY PRECAUTIONS ANTI-LOCK BRAKE SYSTEM SAFETY PRECAUTIONS WARNING: Failure to depressurize ABS could lead to physical injury.

 

  

NEVER open a bleeder valve or loosen a hydraulic line while ABS is pressurized. NEVER disconnect or reconnect any electrical connectors while ignition is on. Damage to ABS control unit may result. DO NOT attempt to bleed hydraulic system without first referring to the appropriate article. Only use specially designed brake hoses/lines on ABS-equipped vehicles. DO NOT tap on speed sensor components (sensor, sensor rings). Speed rings must be pressed, NOT hammered into hubs. Striking these components can cause demagnetization or a loss of polarization,



 

affecting the accuracy of the speed signal returning to the ABS control unit. DO NOT mix tire sizes. Increasing the width, as long as tires remain close to the original diameter, is acceptable. Rolling diameter must be identical for all 4 tires. Some manufacturers recommend tires of the same brand, style and type. Failure to follow this precaution may cause inaccurate wheel speed readings. DO NOT contaminate speed sensor components with grease. Only use recommended anti-corrosion coating. When speed sensor components have been removed, ALWAYS check sensor-to-ring air gaps when applicable. These specifications can be found in each appropriate article. ONLY use recommended brake fluids. DO NOT use silicone brake fluids in an ABS-equipped vehicle. When installing transmitting devices (CB's, telephones, etc.) on ABS-equipped vehicles, DO NOT locate the antenna near the ABS control unit (or any control unit). Disconnect all on-board computers, when using electric welding equipment. DO NOT expose the ABS control unit to prolonged periods of high heat (185°F/85°C for 2 hours is generally considered a maximum limit).

SUPPLEMENTAL INFLATABLE RESTRAINT SYSTEM SAFETY PRECAUTIONS WARNING: Vehicle may be equipped with Supplemental Inflatable Restraint (SIR) system. All SIR wiring connectors are Yellow. DO NOT use electrical test equipment on these circuits. SIR-related components are located in steering column, dash, upper radiator support and front fenders. AIR BAG DEACTIVATION Disabling System

Turn ignition switch to OFF position. Remove Supplemental Inflatable Restraint (SIR) fuse from fuse block. Remove left sound insulator, located under steering column. Disconnect Yellow 2-pin SIR harness connector, located at base of steering column. System Function Check

Ensure ignition switch is in OFF position. Connect Yellow 2-pin SIR harness connector at base of steering column. Install SIR fuse in fuse box. Install left sound insulator. Turn ignition switch to RUN position. Ensure INFLATABLE RESTRAINT light flashes 7-9 times and then goes out. If INFLATABLE RESTRAINT light does not operate as described, SIR system is malfunctioning and needs repair.

A/C COMPRESSOR SERVICING GENERAL SERVICING Compressor Servicing

HARRISON A-6 6-CYL CLUTCH R & I CAUTION: When discharging air conditioning system, use only approved refrigerant recovery/recycling equipment. Make every attempt to avoid discharging refrigerant into the atmosphere. Removal

1. Using Compressor Fixture (J-9396), mount compressor in a vise. Using Clutch Plate Spanner (J-25030), hold crankshaft and remove crankshaft nut. Using Clutch Plate Remover (J-9401), remove clutch plate. Remove clutch plate key. See Fig. 1 . 2. Remove pulley assembly snap ring. Using Shaft Protector (J-9395) and commercial puller (if necessary), remove pulley assembly. Remove snap ring and disconnect electrical wiring at clutch coil. 3. Place reference marks on clutch coil and shell for reassembly reference. Using large screwdriver, pry clutch coil from shell. Use care as clutch coil is retained on shell with adhesive. Installation

1. Ensure all adhesive is removed from shell and clutch coil. Apply trim detail adhesive on back of clutch coil around the coil locator protrusions. 2. Install clutch coil and snap ring. Ensure reference marks are aligned. Install pulley assembly and snap ring. Install clutch plate key in clutch plate, allowing key to protrude about 3/16" from rear of clutch plate. 3. Install clutch plate on compressor crankshaft. Using Clutch Plate Installer (J-9480-B), press clutch plate on compressor to achieve a clutch assembly clearance of .022-.057" (.56-1.34 mm). Using spanner, install nut and tighten to 20 ft. lbs. (27 N.m). Ensure components rotate freely.

Fig. 1: Exploded View of Harrison A-6 6-Cyl Compressor Courtesy of GENERAL MOTORS CORP.

HARRISON A-6 6-CYL SHAFT SEAL R & I Removal

1. Remove clutch plate and shaft key. Pry out dust seal (if equipped). Remove seal seat snap ring. 2. Using Seal Seat Remover/Installer (J-23128-A) for ceramic type or (J-9393-A) for steel type, remove seal seat. Using Seal Remover (J-9553-01), remove "O" ring seal. 3. Using Shaft Seal Remover/Installer (J-9392-01), remove shaft seal by turning remover/installer slightly clockwise to disengage tangs and pull out shaft seal. Clean all surface areas. Installation

1. Coat new shaft seal with refrigerant oil and install shaft seal on remover/installer. Align compressor shaft machine surface with shaft seal and install. Rotate shaft seal remover/installer slightly counterclockwise to secure shaft seal tangs. 2. Using Seal Installer (J-33011), install "O" ring and coat with refrigerant oil. Coat seal seat with refrigerant oil and install using seal seat remover/installer. Install snap ring. Install dust seal (if supplied in seal kit). To complete installation, reverse removal procedure.

HARRISON HR-6 6-CYL & DA-V5 5-CYL CLUTCH R & I Removal

1. Using Clutch Plate Spanner (J-33027), hold clutch plate and remove nut. Thread Clutch Plate Remover/Installer (J-33013-B) into clutch plate and remove clutch plate. See Fig. 4 and 5. 2. Remove clutch plate key. Remove snap ring and remove pulley assembly. Disconnect clutch coil electrical wiring. Scribe marks on compressor and clutch coil for reassembly reference. Using Puller Adapter (J-33023-A) and 2-jaw puller, remove clutch coil. Inspect all parts for damage and replace as necessary. Installation

1. Align scribe marks. Using Puller Adapter (J-33024), Puller Bar (J-8433-1) and Compressor Fixture (J34992), Compressor Fixture (J-33026) on HR-6, press clutch coil on compressor. Restake clutch coil inner ring in 3 places. Install pulley assembly and snap ring. Install clutch plate key in clutch plate, allowing key to protrude approximately 1/8" from rear of clutch plate. 2. Install clutch plate on compressor crankshaft. Using remover/installer, press clutch plate on compressor to achieve a clutch assembly clearance of .015-.025" (.38-.64 mm). Using spanner, install crankshaft nut and tighten to 12 ft. lbs. (17 N.m). Turn pulley and clutch plate by hand to check for free rotation.

Fig. 2: Exploded View of Harrison HR-6 6-Cyl Compressor

Courtesy of GENERAL MOTORS CORP.

Fig. 3: Exploded View of Harrison DA-V5 5-Cyl Compressor Courtesy of GENERAL MOTORS CORP.

HARRISON HR-6 6-CYL & DA-V5 5-CYL SHAFT SEAL Removal

Discharge system using approved refrigerant recovery/recycling equipment. Remove clutch plate. Using Snap Ring Pliers (J-5403), remove shaft seal snap ring. Install Shaft Seal Protector (J-34614) on crankshaft. Insert Shaft Seal Remover/Installer (J-23128-A) into shaft seal. Tighten handle and remove shaft seal. Using "O" Ring Remover (J-9553-01), remove "O" ring. Clean and inspect all parts. Installation

1. With shaft seal protector in place, lubricate new "O" ring with refrigerant oil and install "O" ring on "O" Ring Installer (J-33011). Insert "O" ring installer in compressor until it bottoms. Move slide on "O" ring installer downward until "O" ring is released into groove. Rotate installer to seat "O" ring. 2. Lubricate shaft seal with refrigerant oil. Expand seal using shaft seal remover/installer and install seal on Seal Protector (J-34614). Place seal protector over shaft and push shaft seal into compressor with a rotary motion until seal bottoms. 3. Install NEW snap ring with flat side against lip seal. To complete installation, reverse removal procedure. Evacuate and recharge system.

HARRISON R-4 4-CYL CLUTCH R & I Removal

1. Mount compressor on Holding Fixture (J-25008-A) and secure in a vise. Using Clutch Plate Spanner (J33027), remove crankshaft nut. Thread Clutch Plate Remover (J-33013-B) into the clutch plate. Hold body of clutch plate remover and tighten center bolt to remove clutch plate. Remove pulley retaining snap ring. See Fig. 4 . 2. On "V" groove drive, remove pulley rim mounting bolts and washers. Install Puller Guide (J-25031) on compressor. Using internal-jaw puller, remove pulley assembly from compressor. 3. On poly-groove drive, install Clutch Plate Puller (J-33021) over Puller Guide (J-25031). Pull clutch plate from compressor. Using internal-jaw puller, remove pulley assembly from compressor. 4. Remove clutch coil electrical wiring. Scribe marks on compressor and clutch coil for installation reference. Using Puller Guide (J-25031) and 2-jaw puller, remove clutch coil. Inspect all parts for damage and replace as necessary. Installation

1. Using Puller Adapter (J-33024), Puller Bar (J-8433-1) and Compressor Fixture (J-25008-A), press clutch coil on compressor. Restake clutch coil inner ring in 3 places and connect electrical wiring. 2. Use Pulley Assembly Installer (J-26271-A), Installer Handle (J-29886) and hammer to drive pulley assembly on compressor. On "V" groove drive, use thread sealant on pulley rim mounting bolts. On all models, ensure clutch coil terminals are aligned correctly and locating tabs are aligned with front head locator holes. Install retaining ring. 3. Install clutch plate key in clutch plate, allowing key to protrude approximately 3/16" from rear of clutch plate. Install clutch plate on compressor crankshaft. Using Clutch Plate Installer (J-9480-B), press clutch plate on compressor to achieve a clutch assembly clearance of .020-.040" (.50-1.00 mm). Using spanner, install crankshaft nut and tighten to 10 ft. lbs. (14 N.m). Turn pulley and clutch plate by hand to check for free rotation.

HARRISON R-4 4-CYL SHAFT SEAL R & I Removal

Discharge system using approved refrigerant recovery/recycling equipment. Remove clutch plate. Using Snap Ring Pliers (J-5403-A), remove shaft seal snap ring. Insert Shaft Seal Remover/Installer (J-23128-A) into shaft seal. Tighten handle and remove shaft seal. Using "O" Ring Remover (J-9553-01), remove "O" ring. Clean and inspect all parts. Installation

1. Lubricate new "O" ring with refrigerant oil and install "O" ring on "O" Ring Installer (J-33011). Insert installer in compressor until it bottoms. Move slide on "O" ring installer downward until "O" ring is released into groove. Rotate installer to seat "O" ring. 2. Coat shaft seal with refrigerant oil and install on shaft seal remover/installer. Expand seal using shaft seal remover/installer and install Shaft Seal Protector (J-34614) through the seal. Seal must be installed on

shaft seal protector so seal lip will be installed toward the compressor. Remove shaft seal remover/installer. 3. Install shaft seal protector over end of compressor shaft. Push shaft seal into compressor until it bottoms. Install NEW shaft seal retaining snap ring with flat side against lip seal. 4. To complete installation, reverse removal procedure. Evacuate and recharge system.

Fig. 4: Exploded View of Harrison R-4 4-Cyl Compressor Courtesy of GENERAL MOTORS CORP.

NIPPONDENSO 10PA20 10-CYL CLUTCH R & I Removal

1. Using Clutch Plate Spanner (J-33027) and a thin-wall socket, remove crankshaft bolt. Using Clutch Plate Remover (J-37252), remove clutch plate. Remove clutch plate shims. 2. Remove pulley assembly snap ring. Using a plastic hammer, tap pulley assembly from compressor.

Remove snap ring and remove clutch coil. Inspect all parts for damage. Installation

Install clutch coil and snap ring. Install pulley assembly and snap ring. Install clutch plate shims. Install clutch plate and bolt. Hold clutch plate with spanner and tighten bolt to 10 ft. lbs. (14 N.m). Using a feeler gauge, check clearance between pulley and clutch plate. Proper clearance is .014-.026" (.36-.66 mm). If clearance is not correct, remove or add shims.

NIPPONDENSO 10PA20 10-CYL SHAFT SEAL R & I Removal

1. Discharge system using approved refrigerant recovery/recycling equipment and drain oil from compressor. Note amount of oil drained. Remove clutch plate, pulley assembly and clutch coil. Using a 6 mm Allen wrench, remove compressor through bolts. Pull front head from compressor. Use care not to scratch sealing surface. 2. Reach down inside front head and remove felt seal and retainer. Remove "O" ring. Remove shaft seal snap ring. Push shaft seal from head. Inspect front head for damage to sealing surface. Replace if necessary. Installation

1. Lubricate new "O" ring with refrigerant oil. Press seal into front head and install snap ring. Install felt seal and retainer. 2. Lubricate Shaft Seal Protector (J-34614) with refrigerant oil and install on crankshaft. Install a new front head "O" ring on compressor housing. 3. Position front head on compressor. Ensure dowel pins are aligned. Use care when guiding shaft seal protector through seal opening. Remove shaft seal protector. 4. Install compressor through bolts using NEW brass washers. Diagonally tighten bolts to 18 ft. lbs. (24 N.m). Fill compressor with the same amount of oil that was drained from compressor. To complete installation, reverse removal procedure. Evacuate and recharge system. Perform leak test.

A/C SYSTEM GENERAL SERVICING GENERAL SERVICING General Servicing Procedures

SAFETY PRECAUTIONS - USING R-12 REFRIGERANT 1. Always work in a well-ventilated, clean area. Refrigerant (R-12) is heavier than oxygen, and will displace oxygen in a confined area. Always wear eye protection when working around air conditioning systems and R-12. The system's high pressure can cause severe injury to eyes and skin if a hose were to burst. R12 evaporates quickly when exposed to atmosphere, freezing anything it contacts. 2. Use care when handling refrigerant containers. DO NOT drop or strike containers or expose refrigerant containers to excessive heat. Containers must never be heated more than 125Â°F (52Â°C). Never expose R12 directly to open flame. CAUTION: When R-12 is exposed to an open flame, drawn into a running engine, or detected with a Halide (propane) leak tester, poisonous phosgene gas is formed. Keep work areas ventilated and avoid running engines near work area.

SAFETY PRECAUTIONS - USING INDIVIDUAL R-12 CANS Disposable refrigerant cans (referred to as one pound cans) have a flat type seal or a screw type seal, and proper can tap must be used for each type. Be sure sealing gasket on can tap is in good condition. A proper safety can tap will prevent refrigerant from flowing back into open can, as tap has a one-way flow control. NOTE:

Recent findings by the EPA indicate that refrigerant is harmful to the Earth's protective Ozone layer. When discharging refrigerant avoid allowing refrigerant to enter the atmosphere. Refrigerant recovery system should be used when discharging the system.

SAFETY PRECAUTIONS - MULTI-CAN DISPENSING VALVES A multi-can dispensing valve allows attachment of several cans of refrigerant, and is a good substitute when a bulk container is not available. Cans are installed onto each leg of multi-can dispensing valve in the same manner as the individual cans, and each leg has its own can tap.

CAN TAP INSTALLATION FLAT TYPE SEAL CANS On cam-lock or one-piece can taps, first turn the handle outward to the fully open position. Securely engage locking lugs over the can flange, and lock them in place by turning cam lock or locking nut. Screw tap assembly into adapter so sealing gasket is fully seated against the can top. Turn tap inward to pierce the can and close the tap. DO NOT open tap until ready to purge the service hose or dispense refrigerant into the system.

On 2-piece can taps, be certain tap handle is turned fully inward to the closed position. Check that locking base is turned to its outer limit. Securely engage locking lugs over the can flange. Turn entire tap assembly (without disturbing the closed setting) downward into the locking base to pierce the can. DO NOT open tap until ready to dispense into system. SCREW TYPE SEAL CANS Ensure can tap is fully closed. Screw refrigerant can into can tap fitting until tight. This will pierce the can. Connect tap to center hose on manifold gauge set. DO NOT open tap until ready to dispense R-12 into system. WARNING: DO NOT open high side hand valve while air conditioning system is in operation. This high pressure could rupture can or fitting at safety can valve, resulting in damage and personal injury.

SIGHT GLASS INDICATORS NOTE:

Receiver-drier may be used on some models, while other models use an accumulator.

A sight glass (if used) is usually mounted in receiver-drier or in discharge line to expansion valve. Through sight glass, a visual check of refrigerant condition passing through the system can be made. There are several "indicators" that help diagnose possible problems. See Fig. 1 . These "indicators" are outlined as follows: CLEAR SIGHT GLASS A clear sight glass indicates system has correct charge of refrigerant or is excessively low on refrigerant for system circulation. Sight glass may be clear and system may contain excessive R-12. This must be verified with test gauge readings. BUBBLY/FOAMY SIGHT GLASS A "bubbly" or "foamy" sight glass indicates system is low on refrigerant, and air has probably entered system. However, if only occasional bubbles are noticed, during clutch cycling or system start-up, this may be a normal condition. OIL STREAKED SIGHT GLASS If oil streaks appear on sight glass, a lack of refrigerant may be indicated, and the system's compressor oil is circulating through the system. CLOUDY SIGHT GLASS A cloudy sight glass indicates desiccant contained in receiver-drier or accumulator has broken down and is being circulated through system. Sight glass readings are not necessarily positive identification of a problem. Readings should be relied upon only in conjunction with other system symptoms.

Fig. 1: Sight Glass Indicators Courtesy of GENERAL MOTORS CORP.

PASSENGER CAR SERVICE VALVES LOCATION PASSENGER CAR SERVICE VALVE LOCATIONS Vehicle

High

Low

Passenger cars (1) "A" Body

(2)

(3)

"B" Body

(4)

(3)

"C" Body

(5)

(3)

"D" Body

(6)

(3)

"E" Body

(7)

(3)

"F" Body

(5)

(3)

"H" Body

(5)

(3)

"J" Body

(2)

(3)

"K" Body

(7)

(3)

"L" Body

(2)

(3)

"N" Body

(8)

(3)

"W" Body

(5)

(3)

"Y" Body

(4)

(3)

(1) Body codes are determined by fifth character of VIN code. (2) In discharge line near compressor. (3) In the line to accumulator or on accumulator. (4) In discharge line near condenser.

(5) In discharge line near fender panel. (6) On muffler in discharge line near the compressor. (7) In discharge line near brake master cylinder. (8) In liquid line near evaporator.

1991 PASSENGER CAR SERVICE VALVES LOCATION 1991 PASSENGER CAR SERVICE VALVE LOCATIONS Vehicle

High

Low

Passenger Cars (1) "A" Body

(2)

(3)

"B" Body

(4)

(3)

"C" Body

(5)

(3)

"D" Body

(6)

(3)

"E" Body

(7)

(3)

"F" Body

(4)

(3)

"H" Body

(5)

(3)

"J" Body

(4)

(3)

"K" Body

(7)

(3)

"L" Body

(4)

(3)

"N" Body

(4)

(3)

"W" Body

(5)

(3)

"Y" Body

(8)

(3)

(1) Body codes are determined by fourth character of VIN code. (2) In discharge line near compressor. (3) In the line to accumulator or on accumulator. (4) In discharge line near condenser. (5) In discharge line near fender panel. (6) On muffler in discharge line near the compressor. (7) In discharge line near brake master cylinder. (8) In liquid line near evaporator.

TRUCK/VAN SERVICE VALVES LOCATION TRUCKS & VANS SERVICE VALVE LOCATIONS

Vehicle

High

Low

Trucks & Vans (1) "C" & "K" Series

(2)

(3)

"G" Series

(2)

(5)

"L" & "M" Series

(4)

(5)

"R" & "V" Series

(2)

(5)

"S" &"T" Series

(2)

(5)

"U" Series

(2)

(5)

(1) Series codes are determined by fifth character of VIN code. (2) In discharge line near evaporator. (3) In suction line near accumulator. (4) In discharge line near compressor. (5) Service valve on accumulator.

1991 TRUCK/VAN SERVICE VALVES LOCATION 1991 TRUCKS & VANS SERVICE VALVE LOCATIONS Vehicle

High

Low

Trucks & Vans (1) "C" & "K" Series

(2)

(3)

"G" Series

(2)

(5)

"L" & "M" Series

(4)

(5)

"P", "R" & "V" Series

(2)

(5)

"S" &"T" Series

(2)

(5)

"U" Series

(2)

(5)

STEM-TYPE VALVE OPERATION This manually operated service valve has adjustable stem, located under a protective cap. Valve stem must be manually positioned when making gauge connections and/or reading system pressure on the gauges. See Fig. 2 .

BACK-SEATED (OPERATING) POSITION This is normal operating position, and position used for connecting and disconnecting manifold gauge set. Stem is turned fully outward to seal the service gauge port.

MID (TEST) POSITION After service gauge manifold set has been installed (valve stem in back-seated position), turn valve stem 1 1/2 to 2 turns inward. This positions valve stem midway, allowing full system operation and permits refrigerant pressure to reach gauges.

FRONT-SEATED (OFF) POSITION With service valve stem turned inward, valve blocks refrigerant flow through system, isolating compressor for service. CAUTION: Never operate A/C system with service valves in front-seated position, as the compressor will be damaged.

Fig. 2: Stem-Type Service Valve Positions Courtesy of GENERAL MOTORS CORP.

SCHRADER-TYPE VALVE OPERATION Schrader valve is similar in construction and operation to a tire valve. When a test gauge hose (which has a valve core depressor) is attached, Schrader stem is pushed inward to the open position and allows system pressure to reach the gauge. If test hose being used does not have a built-in core depressor, an adapter must be used. Never attach hoses or adapters to a Schrader valve unless it is first connected to manifold gauge set.

NOTE:

Although similar in construction and operation to a tire valve, the Schrader-type valve cannot be replaced with a tire valve.

SPECIAL VALVE CONNECTORS Most General Motors vehicles use a high side service valve with a different thread size than that on low side (3/8-24 thread on high side and 7/16-20 on low side). Special adapters are required to make this connection. These adapters are available in 45 degree and 90 degree angles, in addition to straight fixed and flexible adapters.

MANIFOLD GAUGE SET A manifold gauge set is used to determine system's high and low side pressures, correct refrigerant charge, system diagnosis and operating efficiency. High (discharge) and low (suction) pressures must be compared to determine system operation. LOW SIDE GAUGE This gauge, which may have a Blue color identifying feature, is used to measure low side (suction) pressure. It reads from 0 to 150 psi (pressure scale) and from 0 to 30 inches of mercury (vacuum scale). This low side gauge is called a compound gauge because it has a dual purpose, to register either pressure or vacuum. HIGH SIDE GAUGE The high side gauge, which may have a Red identifying feature, is used to measure high side (discharge) pressure. It reads from 0 to 500 psi.

CONNECTING GAUGE SET SCHRADER-TYPE VALVES 1. Put on safety goggles and cover vehicle's fender. Remove protective caps from Schrader valves. Do this slowly to check for leaky valves. CAUTION: Be sure hand valves on manifold gauge set are closed before connecting test hoses to Schrader valves. 2. Be sure service hoses are equipped with valve core depressor to match Schrader valve. If not, install special adapters for this purpose. Ensure both manifold gauge hand valves are closed. 3. Connect low side service hose to low side (suction) service valve. Tighten finger tight. Connect high side service hose to high side (discharge) service valve. Tighten finger tight. STEM-TYPE VALVES 1. Put on safety goggles and cover vehicle's fender. Place valves in back-seated position. Remove protective

caps from service valves. Do this slowly to check for leaky valves. CAUTION: Be sure hand valves on manifold gauge set are closed before turning service valve to the mid-position. 2. Attach low side service hose to the low side (suction) service valve. Connect high side service hose to the high side (discharge) service valve. Tighten both connectors finger tight. NOTE:

After test gauges are installed, you must purge test hoses of all air before proceeding with testing.

PURGING TEST HOSES 1. Be sure high and low side hoses are properly connected to service valves and all hose connections are tight. 2. If stem-type service valves are used, turn stems inward 1 1/2 to 2 turns to mid-position. Place clean shop towel over end of center service hose. 3. Now purge high side test hose by opening hand valve on the high side gauge for 3-5 seconds. This allows system's refrigerant to force air through test hoses and out center service hose into the shop towel. Immediately close high side gauge hand valve. 4. Purge low side test hose in the same manner, using hand valve of low side gauge. Close hand valve after 3-5 seconds. Purging of test hoses is complete. System is ready for testing.

STABILIZING A/C SYSTEM 1. Once manifold gauge set is attached to system, and test hoses have been purged, system is ready for testing. Place all test hoses, gauge set and other equipment away from all engine moving parts. 2. Start engine and turn air conditioner controls to maximum cooling (full cold and "MAX A/C"). Set blower fan on high speed. Open doors and/or windows and operate system for 5-10 minutes. System should now be stabilized and ready for test readings.

PRESSURE GAUGE READINGS The following typical pressure gauge indications represent conditions that may be encountered during system servicing. Temperature and humidity, as well as other factors, affect pressure gauge readings. Pressure gauge indications should be used only as a guide.

EXCESSIVE MOISTURE GAUGE READINGS Low Side Gauge - Normal-to-Low High Side Gauge - Normal OTHER SYMPTOMS

Sight Glass - Tiny bubbles. Discharge Air - Becomes warm as low side cycles into vacuum. As moisture is released by saturated desiccant, it becomes released by saturated desiccant, it becomes trapped and freezes at expansion valve or orifice tube, blocking R-12 flow into the evaporator. As low side drops to a vacuum, high side may rise.

Fig. 3: Excessive Moisture Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION 1. 2. 3. 4. 5.

Discharge refrigerant from system using approved refrigerant recovery/recycling equipment. Replace receiver-drier, accumulator or desiccant bag. Evacuate system with vacuum pump. Charge system with R-12. Operate system and check performance.

DEFECTIVE THERMOSTATIC SWITCH GAUGE READINGS Low Side Gauge - Normal High Side Gauge - Normal OTHER SYMPTOMS Compressor - Cycles on and off too fast.

Low Side Gauge - Not enough range shown on low side gauge.

Fig. 4: Defective Thermostatic Switch Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION 1. Stop vehicle engine and turn air conditioner "OFF". 2. Remove and discard old clutch cycling switch, install a new switch of same type. 3. Operate system and check performance.

MISADJUSTED THERMOSTATIC SWITCH GAUGE READINGS See DEFECTIVE CLUTCH CYCLING SWITCH PRESSURE GAUGE READINGS below.

DEFECTIVE CLUTCH CYCLING SWITCH PRESSURE GAUGE READINGS Low Side Gauge - Low-to-Normal/Normal-to-High High Side Gauge - Normal OTHER SYMPTOMS Compressor

Cycles at incorrect temperature or pressure. Evaporator

May freeze and restrict airflow if switch is allowing compressor to remain on too long.

Fig. 5: Misadjusted Thermostatic Switch or Defective Clutch Cycling Switch Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION WITH THERMOSTATIC SWITCH NOTE:

If no adjusting screw is provided, the switch is nonadjustable and must be replaced.

1. Stop engine and turn air conditioner off. 2. Remove components necessary to gain access to thermostatic adjustment screw. 3. Make certain that all wiring is positioned so that no short-circuiting can occur. Connect battery cable so that engine can be operated while making switch adjustment. Adjust thermostatic switch. NOTE:

A pressure sensing switch is used on most late General Motors models with accumulator-type systems. It performs the same function as thermostatic switch.

CORRECTION WITH CLUTCH CYCLING SWITCH

NOTE:

Switch is non adjustable and is mounted on a Schrader valve fitting. Therefore, no system discharge is required.

1. Stop engine and turn air conditioner off. 2. Detach electrical connector from pressure sensing switch at accumulator. 3. Remove pressure sensing switch, and install a new switch.

LOW R-12 CHARGE GAUGE READINGS Low Side Gauge - Low High Side Gauge - Low OTHER SYMPTOMS Discharge Air - Slightly cool. Sight Glass - Some bubbles.

Fig. 6: Low R-12 Charge Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION 1. Leak test system. 2. Discharge refrigerant from system, using approved refrigerant recovery/recycling equipment, if necessary to replace units or lines. 3. Repair leaks.

4. 5. 6. 7.

Check compressor oil level. System may have lost oil due to leakage. Evacuate system using vacuum pump. Charge system with R-12. Operate system and check performance.

VERY LOW R-12 CHARGE GAUGE READINGS Low Side Gauge - Low High Side Gauge - Low OTHER SYMPTOMS Discharge Air - Warm. Sight Glass - Clear or Oil Streaks. Compressor

Operation may have stopped if system is equipped with a refrigerant pressure sensing switch.

Fig. 7: Very Low R-12 Charge Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION

1. If compressor operation is stopped due to a pressure sensing switch, by-pass switch with jumper wire until testing and correction are complete. 2. Add a partial refrigerant charge (to at least 50 percent system capacity), then make thorough leak test. 3. Discharge refrigerant from system using approved refrigerant recovery/recycling equipment. 4. Check compressor oil level. System may have lost oil due to leakage. 5. Evacuate system using vacuum pump. 6. Charge system with R-12. 7. Operate system and check performance.

ORIFICE TUBE PLUGGED GAUGE READINGS Low Side Gauge - Low High Side Gauge - Low OTHER SYMPTOMS Discharge Air - Slightly cool. Evaporator Inlet Pipe - Sweating or frost build up just ahead of orifice tube. TESTING If evaporator inlet pipe after orifice tube and accumulator surface are warm, orifice tube is plugged.

Fig. 8: Orifice Tube Plugged Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP.

CORRECTION 1. 2. 3. 4.

Evacuate system using vacuum pump. Replace orifice tube. Charge system with R-12. Operate system and check performance.

EXPANSION OR "H" VALVE STUCK CLOSED Low Side Gauge - Low High Side Gauge - Low OTHER SYMPTOMS Discharge Air - Slightly cool. Evaporator Inlet Pipe - Sweating or frost build up. TESTING 1. If evaporator inlet is cool to touch, proceed as follows: a. Set air conditioner for maximum cooling and operate the system. b. Spray liquid R-12 on head of valve or capillary tube (if equipped). Note low side gauge reading. Low side gauge should drop into a vacuum. c. If low side vacuum reading was obtained, warm expansion valve diaphragm chamber with hand, then repeat test step b.). d. If expansion valve test indicates valve operation is satisfactory, clean contact surface of evaporator outlet pipe and temperature sensing bulb. Make sure bulb is securely in contact with pipe. e. If expansion valve test indicates the valve is defective, discharge the system using approved refrigerant recovery/recycling equipment, replace expansion valve, and proceed with correction procedure. 2. If expansion valve inlet shows sweating or frost proceed as follows: a. Discharge system using approved refrigerant recovery/recycling equipment. b. Disconnect inlet line at expansion valve. Remove and inspect screen. c. Clean and replace screen and reconnect inlet line. d. Proceed with correction procedure.

Fig. 9: Expansion or "H" Valve Stuck Closed Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION 1. Evacuate system using vacuum pump. 2. Charge system with R-12. 3. Operate system and check performance.

EXPANSION OR "H" VALVE STUCK OPEN GAUGE READINGS Low Side Gauge - High High Side Gauge - High OTHER SYMPTOMS Discharge Air - Warm Evaporator - Sweating or frost. TESTING Check for expansion valve stuck open, or incorrect mounting of temperature sensing bulb as follows: 1. Set air conditioner for maximum cooling and operate system several minutes. 2. Spray liquid R-12 on head of valve or capillary bulb, and note low side gauge reading. It should drop into a vacuum (if not, a stuck open valve or incorrect bulb mounting is indicated). This test may not be possible on applications where sensing bulb is not accessible.

3. If low side vacuum reading is obtained, warm expansion valve diaphragm chamber with hand, then repeat test.

Fig. 10: Expansion or "H" Valve Stuck Open Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION 1. If expansion valve test indicates valve operation is satisfactory, proceed as follows: a. Clean contact surface of evaporator outlet pipe and temperature sensing bulb, then clamp bulb securely in contact with pipe and recover with proper insulation tape. b. Operate system and check performance. 2. If expansion valve test indicates valve is defective, proceed as follows: a. Discharge system using approved refrigerant recovery/recycling equipment. b. Replace expansion valve, making sure all contacts are clean and secure. c. Evacuate system using vacuum pump, then charge system with R-12. d. Operate system and check performance.

COMPRESSOR MALFUNCTION GAUGE READINGS Low Side Gauge - High.

High Side Gauge - Low. OTHER SYMPTOMS Compressor - Noisy.

Fig. 11: Compressor Malfunction Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION 1. Isolate compressor (if equipped with stem-type service valves) or discharge entire system using approved refrigerant recovery/recycling equipment. 2. Remove compressor cylinder head and inspect compressor. a. Replace reed valve plate assembly if necessary. b. Install cylinder head using NEW gasket. 3. Check compressor oil level. 4. Replace receiver-drier, desiccant or accumulator if: a. System previously opened. b. System operated two or more seasons with present unit. c. Compressor inspection revealed desiccant particles (very fine golden or brown particles). 5. Using vacuum pump, evacuate compressor or entire system (depending on procedure used in step 1). 6. Charge system with R-12. 7. Operate system and check performance.

CONDENSER MALFUNCTION OR R-12 OVERCHARGE GAUGE READINGS

Low Side Gauge - High High Side Gauge - High OTHER SYMPTOMS Discharge Air - Warm. High Side Lines - Very Hot. Sight Glass - Bubbles.

Fig. 12: Condenser Malfunction or R-12 Overcharge Pressure Gauge Indications Courtesy of GENERAL MOTORS CORP. CORRECTION 1. Check electric cooling fan operation.

2. Inspect condenser for clogged air passages, bug screen, or other obstructions preventing airflow through condenser. 3. Inspect condenser mounting for proper radiator clearance. Inspect clutch type fan for proper operation. Inspect radiator pressure cap for correct type and proper operation. NOTE:

After Making Above Corrections. Operate system and check performance. If Condition is Not Corrected perform the following:

4. Inspect system for overcharge of refrigerant and correct as follows: a. Discharge refrigerant, using approved refrigerant recovery/recycling equipment, until stream of bubbles appears in sight glass and both high and low gauge readings drop below normal. b. Add R-12 until bubbles disappear and pressures are normal, then add an additional 1/4-1/2 lb. of refrigerant. 5. Operate system and check performance. If gauge readings are Still Too High: a. Discharge system using approved refrigerant recovery/recycling equipment, and remove and inspect condenser to ensure free passage of refrigerant or replace condenser. b. Replace receiver-drier, desiccant bag or accumulator. c. Evacuate system using vacuum pump. d. Charge system with R-12. e. Operate system and check performance.

ORIFICE TUBE REPLACEMENT REMOVAL 1. Orifice tube may be located at condenser outlet or evaporator. See appropriate ORIFICE TUBE LOCATION & REMOVER/INSTALLER ID (PASSENGER CARS) or ORIFICE TUBE LOCATION & REMOVER/INSTALLER ID (TRUCKS & VANS) table. Discharge refrigerant from system using approved refrigerant recovery/recycling equipment and disconnect liquid line at evaporator or condenser. 2. Remove orifice tube using needle nose pliers or proper orifice tube remover/installer. See appropriate ORIFICE TUBE LOCATION & REMOVER/INSTALLER ID (PASSENGER CARS) or ORIFICE TUBE LOCATION & REMOVER/INSTALLER ID (TRUCKS & VANS) table.

ORIFICE TUBE LOCATION & TOOL IDENTIFICATION 1991 PASSENGER CARS ORIFICE TUBE LOCATION & REMOVER/INSTALLER ID (PASSENGER CARS) (1) Application Orifice Tube Location Orifice Tube Remover/Installer "A" Body Condenser J-26549-C "B" Body Condenser J-26549-E "C" Body Evaporator J-26549-D

"D" Body Evaporator "E" Body Evaproator "F" Body Evaporator "H" Body Condenser "J" Body Condenser "K" Body Evaporator "L" Body Evaporator "N" Body Condenser "W" Body Evaporator "Y" Body Evaporator (1) Body codes are determined by fourth character of VIN code.

J-26549-D J-26549-D J-26549-D J-26549-D J-26549-89 J-26549-D J-26549-D J-26549-89 J-26549-C J-26549-D

ORIFICE TUBE LOCATION & REMOVER/INSTALLER ID (TRUCKS & VANS) (1) Application Orifice Tube Location Orifice Tube Remover/Installer "C" Series Evaporator Not Available "G" Series Evaporator Not Available "K" Series Evaporator Not Available "L" Series Evaporator Not Available "M" Series Evaporator Not Available "P" Series Evaporator Not Available "R" Series Evaporator Not Available "S" Series Evaporator J-26549-D "T" Series Evaporator J-26549-D "U" Series Condenser J-26549-C "V" Series Evaporator Not Available (1) Series codes are determined by fifth character of VIN code. 1. If difficulty is encountered during removal of a plugged or restricted orifice tube, remove as much impacted residue as possible. 2. Using a heat gun, carefully apply heat on inlet pipe. If inlet pipe contains small dimples in the line, apply heat 1/4" away from the dimples. On all applications, use care not to overheat pipe. NOTE:

If system has a pressure switch near orifice tube location, remove pressure switch prior to heating the pipe to avoid switch damage.

3. While heat is being applied, install proper orifice tube remover/installer in orifice tube. Use a turning motion along with a push or pull motion to loosen orifice tube and remove it. INSTALLATION 1. To install orifice tube, coat pipe area with refrigerant. Lubricate new orifice tube and "O" ring with refrigeration oil and insert into inlet pipe.

2. Install orifice tube with shorter screen end first. To complete installation, reverse removal procedure. Evacuate and recharge system. Test system for proper operation.

REFRIGERANT RECOVERY CAUTION: If variation is noted in service procedures, follow the manufacturer's instructions on refrigerant recovery/recycle system. 1. Close both valves on manifold gauge set. Connect manifold gauge set to high and low side service valves. 2. Connect center hose on manifold gauge set to inlet port on Refrigerant Recovery/Recycle System (J38100-B). Start engine. Turn A/C on for approximately 2 minutes. NOTE:

Operating A/C for 2 minutes will warm the refrigerant so refrigerant recovery/recycle system can recover more refrigerant from the system.

3. Shut engine off. Open BOTH valves on manifold gauge set. Open BOTH valves on refrigerant recovery/recycle system storage tank at the same time. 4. Plug refrigerant recovery/recycle system in and turn power switch on. Depress compressor START switch and note that the compressor ON light is activated. 5. The refrigerant recovery/recycle system will shut off when a vacuum reading of 17 in. Hg is obtained on manifold gauge set. Manifold gauge vacuum reading should remain at 17 in. Hg for at least 2 minutes. 6. If reading increases to above zero, refrigerant still remains in the vehicle A/C system. Depress compressor START switch and operate refrigerant recovery/recycle system through another cycle. 7. Once refrigerant is recovered, open accumulator pressure valve on the refrigerant recovery/recycle system for 15 seconds. This will pressurize the oil separator so refrigerant oil can be drained. 8. Open OIL DRAIN valve on the refrigerant recovery/recycle system and drain refrigerant oil into a container. Measure exact amount of oil to be added when system is put back in service.

DISCHARGING A/C SYSTEM NOTE:

Recent findings by the EPA indicate that refrigerant is harmful to the Earth's protective Ozone layer. When discharging refrigerant, avoid allowing refrigerant to enter the atmosphere. Refrigerant recovery/recycle system should be used whenever possible instead of discharging system. Many states now require by law the use of recovery/recycle systems. Check local laws before proceeding.

General Motors does not provide procedures for discharging of A/C system. To discharge system, follow procedures for refrigerant recovery using a recovery/recycle system as outlined under REFRIGERANT RECOVERY .

FLUSHING A/C SYSTEM 1. Manufacturer does not recommend flushing A/C system. If system is contaminated, discharge system

2. 3.

5. 6. 7.

using approved refrigerant recovery/recycling equipment and install a liquid line filter between condenser and evaporator. Filter may be an integral part of the line or line may need to be cut and filter installed (non-integral type). Filters may contain an orifice. See Fig. 13 . Filters with orifice are used when filter is being installed on low pressure side of the orifice tube. Original orifice tube must be removed if filter with orifice is installed. Filter without the orifice must be installed on the high pressure side of the orifice tube. To install liquid line filter, discharge A/C system using approved refrigerant recovery/recycling equipment and remove liquid line. Using a tubing cutter, cut section from liquid line to allow installation of liquid line filter. Clean all burrs and smooth surfaces. Install nut over the line. Install ferrule on line with small end toward the nut. DO NOT install "O" ring at this time. Push line into fitting until it bottoms on filter assembly. Tighten nuts on each joint to 11 ft. lbs. (15 N.m). Disassemble joint assembly. Install new "O" rings, lubricated with refrigeration oil, on the lines. Install filter assembly. Ensure arrow on filter indicates proper flow of refrigerant. Tighten nuts to 11 ft. lbs. (15 N.m). Evacuate system and charge system. Check for leaks.

Fig. 13: Exploded View of Liquid Line Filter & Components Courtesy of GENERAL MOTORS CORP.

CHARGING A/C SYSTEM

NOTE:

DO NOT connect high side gauge hose to high side service port. Perform A/C charging service through low side only.

1. System must be evacuated before charging. With manifold gauge set attached from evacuation procedure, start engine, but DO NOT turn on A/C. With gauges and R-12 drum (inverted for liquid charging) connected from evacuation procedure, open low side gauge valve on manifold gauge set. Allow one pound of R-12 to enter system. 2. When one pound of R-12 has entered system, turn A/C to NORM position with blower on high speed. Continue charging (liquid charging) until proper amount of R-12 has entered system. 3. Close R-12 drum valve and continue running A/C system for 30 seconds to clear lines and gauges. Turn off valve on manifold gauge set. With engine running, disconnect low side hose and install service valve cap at accumulator. Perform leak test procedure.

ALTERNATOR & REGULATOR ELECTRICAL Alternators

DESCRIPTION The CS series alternators are available in 74, 85, 100, 105 and 120-amp output. The alternators use a delta stator, rectifier bridge, and rotor with slip rings and brushes. A built-in regulator incorporates fault detection circuitry. Conventional pulley and cooling fan are used. CS series alternators operate with 2 wire connections and a ground path through the mounting bracket. The first wire connection is the battery positive "BAT" terminal. This terminal must be connected to the battery during operation. The second wire connection is through the indicator or suitable external resistor to the "L" terminal of the regulator. This connection serves to turn the unit on at start-up. Three other regulator terminals, "P", "I" and "S", are provided for optional use. The "P" terminal is connected to the stator and may be connected to a tachometer. The "I" terminal provides an alternate method for turning on the alternator without going through the indicator light or external resistor and is often used in parallel with the "L" terminal connection. The "S" terminal may be used to sense electrical system voltage somewhere else on the vehicle for voltage control. If the "S" terminal is not used, the regulator uses an internal voltage sense for control. No periodic maintenance of CS alternators is necessary. CS144 alternator can be disassembled and repaired. All CS121 and CS130 alternators are non-serviceable and must be replaced as complete assemblies. See the ALTERNATOR SPECIFICATIONS to determine model number and amperage of individual units.

ADJUSTMENTS No adjustment or maintenance is required on alternator assembly. Regulator voltage is preset and no adjustment is possible.

ON-VEHICLE TESTS ALTERNATOR WARNING LIGHT 1. Visually check alternator belt and wiring. On models without charge light, proceed to UNDER OR OVERCHARGED BATTERY . On models with charge light, proceed to step 2). 2. Turn ignition switch to the ON position (engine not running). Charge light should come on. If charge light is not on, disconnect alternator harness connector at alternator. Using a jumper wire, connect one end of jumper wire to alternator harness connector terminal "L". Connect the other end to ground. If charge light comes on, repair or replace alternator. 3. If charge light did not come on in step 2) with jumper wire connected, locate open circuit between grounding lead and ignition switch. Charge light may be open. If charge light was on in step 2), go to next step. 4. Start engine and run at moderate speed. Charge light should go off. If charge light stays on, disconnect alternator wiring connector. If light goes off, repair or replace alternator. If light stays on, check for

grounded wire to alternator wiring connector terminal "L". UNDER OR OVERCHARGED BATTERY 1. If battery is undercharged or overcharged, disconnect alternator wiring connector from alternator. 2. Using a voltmeter, connect positive voltmeter lead to "L" terminal of alternator wiring connector and negative lead to ground. Turn ignition switch to ON position (engine not running). 3. If voltmeter reads zero volts, an open between "L" terminal and battery is indicated. Repair as required. Reconnect alternator wiring connector. 4. Using a voltmeter, connect positive voltmeter lead to positive battery post. Connect negative lead to negative battery post. Start engine and run at moderate speed. If voltage reads more than 16 volts, repair or replace alternator. CURRENT OUTPUT 1. Connect an ammeter in series with positive battery cable. Connect positive voltmeter lead to positive battery post and negative lead to negative battery post. CAUTION: Carbon pile testing is part of this procedure. To avoid explosion, turn carbon pile OFF before connecting it to or disconnecting it from vehicle battery. 2. Connect carbon pile rheostat to battery, ensuring carbon pile rheostat is in the OFF position before connecting to battery. 3. Start engine and reduce speed to idle. Turn on all accessories. Load battery with carbon pile rheostat to obtain maximum amperage. Maintain voltage at 13 volts or more. 4. If ammeter reads within 15 amps of rated output, alternator is okay. If ammeter does not read within 15 amps of rated output, replace alternator. See ALTERNATOR SPECIFICATIONS at the end of this article.

BENCH TESTING ALTERNATOR OUTPUT CAUTION: Carbon pile testing is part of this procedure. To avoid explosion, turn carbon pile OFF before connecting it to or disconnecting it from vehicle battery. 1. Mount alternator on test stand. Be sure ground polarity of alternator and battery are the same. Ensure battery is fully charged. Connect voltmeter, ammeter, carbon pile (in OFF position) and 30-500 ohm resistor between the battery and the terminal "L" of alternator. See Fig. 1 .

Fig. 1: Alternator Bench Test Courtesy of GENERAL MOTORS CORP. 2. Rotate alternator by hand in clockwise direction. Slowly increase alternator speed and observe voltage. If voltage is uncontrolled and increases to more than 16 volts, rotor field is shorted and/or regulator is defective. A shorted rotor field coil can cause regulator to become defective.

3. If voltage is less than 16 volts, increase speed and adjust carbon pile to obtain maximum amperage output. Maintain voltage at 13 volts. If output is within 15 amps of rated output, alternator is okay. If output is not within 15 amps of rated output, repair or replace alternator. See ALTERNATOR SPECIFICATIONS at the end of this article. ROTOR - CS144 ONLY 1. Scribe end frames to facilitate reassembly. Remove through-bolts and separate end frames. Using an ohmmeter, check for grounds. See Fig. 2 . Reading should be very high or infinite. If reading is not as specified, replace rotor.

Fig. 2: CS144 Alternator Rotor Test Courtesy of GENERAL MOTORS CORP. 2. With an ohmmeter, check rotor for shorts and opens. See Fig. 2 . Replace rotor if reading is not 1.7-2.1 ohms at 70Â°F (21.1Â°C).

3. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. See Fig. 5 . Remove retaining pin after tightening through-bolts. NOTE:

Manufacturer recommends using a new bearing whenever end frames are separated.

STATOR - CS144 ONLY 1. Scribe end frames to facilitate reassembly. Remove through-bolts and separate end frames. Remove stator lead attaching nuts and remove stator. Using an ohmmeter, check stator grounds. See Fig. 3 . Connect one ohmmeter probe to one stator lead and the other probe to the stator core.

Fig. 3: CS144 Alternator Stator Test Courtesy of GENERAL MOTORS CORP. 2. Ohmmeter should read infinite. If ohmmeter does not read infinite, replace stator. Repeat test with remaining stator leads. Stator cannot be checked for opens and shorts with ohmmeter. 3. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. See Fig. 5 . Remove retaining pin after tightening through-bolts. NOTE:

Manufacturer recommends using a new bearing whenever end frames are separated.

RECTIFIER BRIDGE - CS144 ONLY 1. Scribe end frames to facilitate reassembly. Remove through-bolts and separate end frames. Connect an ohmmeter from grounded heat sink to one (of the 3) grounded flat metal rectifier bridge terminal connectors and note reading. See Fig. 4 .

Fig. 4: CS144 Alternator Rectifier Bridge Test Courtesy of GENERAL MOTORS CORP. 2. Reverse leads. If both readings are the same, replace rectifier bridge. Repeat test between grounded heat sink and the other 2 flat metal terminal connectors. If reading is the same when leads are reversed at either connection, replace rectifier bridge. 3. Repeat test between insulated heat sink and its 3 flat rectifier bridge metal connectors. Replace rectifier bridge if test reading is the same when leads are reversed at any test connection.

4. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. See Fig. 5 . Remove retaining pin after tightening through-bolts.

Fig. 5: CS144 Brush Removal Courtesy of GENERAL MOTORS CORP.

NOTE:

Manufacturer recommends using a new bearing whenever end frames are separated.

TROUBLE SHOOTING NOTE:

See the TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

OVERHAUL NOTE:

Replacement parts are not available for CS121 and CS130 alternator. If alternator is defective, a new unit must be installed. CS144 alternator may be disassembled for repair.

BRUSHES & REGULATOR OVERHAUL - CS144 1. Scribe end frames to facilitate reassembly. Remove through-bolts and separate end frames. Remove solder from brush connections and remove attaching screws and connectors. Separate regulator and brush holder from end frame. Clean new brushes with soft dry cloth. 2. Put brushes in holder and hold with brush retaining pin. See Fig. 5 . Install brush holder into alternator by reversing removal procedure. To reassemble alternator, reverse disassembly procedure. Remove brush retainer pin after tightening through-bolts. NOTE:

Manufacturer recommends using a new bearing whenever end frames are separated.

DRIVE END BEARING OVERHAUL - CS144 1. Scribe end frames to facilitate reassembly. Remove through-bolts and separate end frames. Remove shaft nut while holding rotor with a hex wrench inserted into shaft end. Push rotor from housing. Remove plate and push bearing out. 2. To insert new bearing, press against outer race and push bearing in until stop is felt. Bearing is double sealed, no added lubricant is required. Assemble retainer and press rotor into end frame. Torque shaft nut to 40-80 ft. lbs. (54-108 N.m). 3. To reassemble alternator, reverse disassembly procedure. Retain brushes with brush retaining pin during reassembly. See Fig. 5 . Remove retaining pin after tightening through-bolts. NOTE:

Manufacturer recommends using a new bearing whenever end frames are separated.

ALTERNATOR SPECIFICATIONS ALTERNATOR SPECIFICATIONS Part Number

Model

Rated Amp Output

1101140 CS130 1101142 CS130 1101143 CS130 1101145 CS130 1101229 CS130 1101231 CS130 1101253 CS130 1101254 CS130 1101264 CS130 1101277 CS130 1101278 CS130 1101310 CS130 1101319 CS121 1101320 CS130 1101321 CS121 1101344 CS130 1101454 CS144 1101461 CS130 1101466 CS130 1101483 CS130 1101646 CS130 1101647 CS130 1101849 CS144 1102614 CS121 1105694 CS130 1105697 CS121 1105698 CS130 (1) On Cavalier, rated output is 100 amps.

100A 85A 100A 120A 85A 100A 85A 100A 105A 85A 100A 105A 74A 74A 74A 105A 120A 100A 100A 74A 105A 105A 120A 80A (1) 85A

74A 85A

ANTENNA - POWER ACCESSORIES & SAFETY EQUIPMENT General Motors Power Antennas

DESCRIPTION & OPERATION DESCRIPTION The automatic power antenna is activated whenever radio and ignition are turned on or off. Major power antenna components are: antenna assembly, lead-in cable, switches, motor and gear housing, gear and spool assembly, mast and tubing, and drive unit. The drive unit is encased in a 2-piece plastic housing with mast and tube assembly attached. See Fig. 1 . OPERATION With ignition switch in ACCESSORY or RUN position and radio turned on, voltage is applied to antenna relay coil. The relay contacts close and battery voltage is supplied through Dark Green wire to antenna motor, driving antenna mast up. The other motor terminal is grounded through the internal antenna motor up switch (Gray wire and relay contacts). At the end of upward mast travel, up switch opens and motor stops. When radio or ignition is turned off, the circuit through antenna relay coil is opened and contacts move to a position which applies battery voltage to White wire. The Dark Green wire is now grounded, reversing the motor polarity. The motor now runs in reverse and drives antenna mast down. Once antenna mast is fully down, internal antenna motor down switch opens and breaks current flow. Both sets of switches are now open.

Fig. 1: Exploded View of Power Antenna Courtesy of GENERAL MOTORS CORP.

TROUBLE SHOOTING ANTENNA DOES NOT RAISE OR LOWER

Check for blown fuse, loose electrical connections on receiver or antenna, bent mast or defective relay. See TESTING in this article. Should mast meet with an obstruction while cycling to full extension, it automatically recycles in 30 seconds and attempts to reach full extension. If obstruction remains, cycling will continue every 30 seconds. If mast is obstructed during downward cycle, mast stops where obstruction occurred. No recycling takes place as in the up cycle. FADING OR WEAK RECEPTION Probable cause is moisture in support tube from condensation or leakage. Remove antenna and disassemble. Clean drive housing or replace as required. EXCESS IGNITION NOISE, ERRATIC AUDIO OR REDUCED CB RECEPTION Check for poor grounding of antenna at mounting or at lead-in system. See GROUND CHECK in this article.

TESTING PRELIMINARY CHECK 1. Unplug antenna lead at back of radio and plug in a known good antenna. Ground the test antenna and keep hands off mast. Check reception in an area away from electrical interference. 2. Tune radio to high and low ends of dial in both AM and FM bands. If reception is okay, a problem exists with antenna and/or lead-in cable. If reception is still poor, radio may be at fault. LEAD-IN CABLE CHECK Broken center conductor of lead-in cable will normally result in no AM and weak FM reception. In cases of continuous reception problems, check lead-in cable with an ohmmeter. See Fig. 2 . When checking resistance, wiggle lead-in tip and cable. If results are not as listed in chart, lead-in cable should be replaced. See LEAD-IN CABLE RESISTANCE table.

Fig. 2: Lead-In Resistance Check Points Courtesy of GENERAL MOTORS CORP. LEAD-IN CABLE RESISTANCE Ohmmeter Test Points Resistance (Ohms) (1) Less Than .2 A&B C&D Less Than .2 A&D Infinite C&B Infinite A&C Infinite B&D Infinite (1) Some long lead-ins have capacitance added in tip and will show about 100,000 ohms. GROUND CHECK 1. Lower antenna mast. Remove escutcheon from fender. Attach alligator clip to upper end of mast to act as antenna. Leave other end of clip unattached. 2. Tune radio to a weak AM station or a station which is received when clip is attached and not received when clip is removed. Remove clip. Ground upper end of mast to fender with very short jumper wire. 3. If station is not received, antenna grounds are good. If station is still present or even stronger, a poor ground or no ground condition exists. 4. Possible ground loss points are: antenna upper mounting (screw loose or paint overspray), coaxial connector at mast not connected or corroded, coaxial connector at radio not tight or corroded or quick

connector corroded. ANTENNA OPERATES BUT WON'T COMPLETELY RAISE OR LOWER TEST 1. If motor operates, pull up on top section of mast. If mast moves freely, plastic drive cable is broken. Replace mast and support tube. If cable is not broken, remove mast and support tube. Check mast sections for binding. 2. If binding exists, eliminate binding or replace mast and support tube. If no binds exist, check drive cable for broken hook. If no breaks exist, replace gear and spool assembly. Refer to, in this article, MAST & CABLE, GEAR & SPOOL ASSEMBLY . ANTENNA DOES NOT LOWER TEST 1. If the motor does not operate, check CLK-CIG fuse in fuse block. If fuse is blown, remove relay and install new fuse. If fuse blows again, repair short in Orange wire. If fuse does not blow, check for short in White wire. If there is no short, replace relay. If White wire is shorted, repair wire. If there is no short, repair motor. 2. If the fuse was good in original check, use test light and check for 12 volts on Orange wire at antenna relay. If light does not glow, repair open in Orange wire. If light glows, check for voltage at White wire on relay. 3. If light does not glow, replace antenna relay. If light glows, check for open in White wire. If no open exists, check for voltage at Dark Green wire. If light glows, check relay connections and ground wire. If both are okay, replace relay. If light does not glow, check for loose connection between relay and connector or connector to antenna. If okay, repair motor. ANTENNA DOES NOT RAISE TEST 1. If motor does not operate, check fuses in fuse block. If radio fuse is blown, repair radio. If CLK-CIG fuse is blown, remove antenna relay, install new fuse and recheck. If CLK-CIG fuse is okay, disconnect 3-wire connector with White wire and install connector with Orange wire at antenna relay. 2. Recheck fuse. If blown, replace relay. If okay, check for short in Gray and Dark Green wires from relay to antenna motor connector and to the antenna assembly. If no short, replace antenna motor. If new fuse blows, repair short in Orange wire from fuse panel to connector. 3. If fuses were okay in original check, turn ignition off. Connect test light to Orange wire at relay connector. If light does not glow, repair open in Orange wire. If light glows, turn ignition and radio on and listen for relay click. 4. If relay does not click, check for open relay ground, open in Pink wire, or bad radio switch. Probe Pink wire with test light. If voltage exists, replace relay. If relay clicked, check for voltage at Dark Green wire in relay connector. If light does not glow, replace relay. 5. If light glows, check for voltage at Gray wire. If light glows, check relay connections and ground wire. If okay, replace relay. If light does not glow at Gray wire, check for open or short in Gray and Dark Green wires. If okay, repair motor.

REMOVAL & INSTALLATION ANTENNA

NOTE:

The following procedure is a general procedure for all vehicles. Not all steps apply to all models.

Removal

1. Disconnect negative battery cable. Remove fender inner splash shield. Remove instrument panel sound absorber. 2. Disconnect antenna lead-in connector from radio and antenna relay. Remove antenna-to-fender attaching retainers. Remove tire and wheel if necessary to gain access under fender. Remove inner fender supports. 3. Remove antenna bracket bolts, or lower antenna attaching screws. On Cadillac models, attach a 4-foot guide wire to top of antenna to help guide mast sections out of housing. On all other models, with all wiring disconnected, gently guide wires and antenna through fender opening. Installation

To install, reverse removal procedure. On Cadillac, use guide wire to guide new antenna into housing. MAST & CABLE, GEAR & SPOOL ASSEMBLY Removal

1. Remove power antenna unit from vehicle. Remove 4 cover-to-housing eyelets. Remove 5 retaining clips. Using a small screwdriver, carefully wedge cover from housing. Clean excess and/or loose sealer from cover and housing. 2. Separate mast and tube assembly from gear housing and unwind cable from gear spool as required to gain access to attaching hook. Unhook end of cable from gear. If replacing gear and spool assembly, slide gear and spool assembly from housing post. NOTE:

Switch, armature or field assembly need not be removed to remove gear and spool assembly.

Installation

1. Extend replacement mast as required until approximately 10" (250 mm) of cable are left exposed. Hook end of cable in gear and route cable in spool. See Fig. 3 . Position mast and tube assembly on housing so rubber drain pipe fits into housing hole and mounting ears are located in housing slots. 2. Push excess drive cable into tube assembly as required to keep cable in gear spool. Position cover on gear and motor housing. Install nuts and bolts which attach mast and tube assembly to housing. Install remaining bolts and nuts and 5 retainer clips.

Fig. 3: Power Antenna Mast & Cable, Gear & Spool Assembly Replacement Courtesy of GENERAL MOTORS CORP.

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

1989-91 ACCESSORIES & SAFETY EQUIPMENT Anti-Theft System - Alarm

DESCRIPTION & OPERATION DESCRIPTION Anti-theft system consists of a controller, protective switches, alarm relay and starter interrupt relay (some models). The controller is located under left side of instrument panel on Bonneville, Electra, Reatta, Toronado and Trefeo. Firebird models are equipped with a 2-part theft deterrent system. First, horn is used as an alarm to deter any forced entry. Second, an engine-start disable Anti-Theft Pass Key System, operates when a method other than the proper ignition key is used to start engine. Separate system checks and diagnostics are used for evaluation of combined theft deterrent system. OPERATION Anti-theft system is "armed" when all windows are closed, ignition key is removed, and doors are locked. When forced entry is attempted, alarm warning system will trip, causing horn to sound intermittently and exterior lights to flash for 3 to 7 minutes. On models with a starter interrupt relay, starter will cease to function. System is "disarmed" by unlocking either front door with key or by turning ignition on.

TROUBLE SHOOTING SYSTEM WILL NOT DISARM Check lock cylinder switches for looseness. Try to disarm system using key in passenger door lock cylinder. If system disarms, check for open circuit in wire leading to lock cylinder in driver's door. SYSTEM WILL NOT DISARM FROM EITHER DOOR Hold lock cylinder in unlock position with door key. Check for open circuit in wire coming from controller. SYSTEM GOES OFF BY ITSELF Check for too close adjustment of door jamb switches. Check jamb switches and ground wires for corrosion. Check lock cylinders, tamper switches and door jamb wires for looseness. Check diodes. SECURITY LIGHT INOPERATIVE Check fuses or bulb. Check wiring to bulb for shorts or open circuit. SECURITY LIGHT GLOWS BUT SYSTEM WILL NOT DISARM Check lock cylinder switches for signs of tampering. Check switches for looseness. Check for frayed or pinched

wires to cylinder or jamb switches. Check jamb switches for proper adjustment. Check circuits external to controller. If all circuits are okay, repair or replace controller and relay. SECURITY LIGHT BLINKS ON & OFF Check switches for looseness. Check wire between door jamb switch and security switch for pinch or fray. Check wire leading to tamper switch. Check door lock switches and wiring.

Fig. 1: Electra Anti-Theft Controller Location Courtesy of GENERAL MOTORS CORP.

Fig. 2: Riviera Anti-Theft Controller Location Courtesy of GENERAL MOTORS CORP.

Fig. 3: Toronado & Trefeo Anti-Theft Controller Location Courtesy of GENERAL MOTORS CORP.

REMOVAL & INSTALLATION NOTE:

Removal and installation procedures are only available for Toronado and Trefeo.

Removal & Installation (Toronado & Trefeo)

1. Remove left side sound absorber and hood release handle assembly. Remove screw attaching theft

deterrent relay/controller bracket at instrument panel. Pull relay/controller bracket down and remove. 2. Remove electrical connectors to relay and controller. Cut plastic tie to remove relay from controller. Remove screws attaching controller to mounting bracket. Remove theft deterrent controller. To install, reverse removal procedure. See Fig. 3 .

WIRING DIAGRAMS For wiring diagrams, refer to appropriate chassis wiring diagram in WIRING DIAGRAMS section.

AUTOMATIC TRANSMISSIONS

APPLICATIONGeneral Motors Corp. - Turbo Hydra-Matic 200-4R Overhaul TRANSMISSION APPLICATION (BUICK) Vehicle Application 1983-84 Electra 4.1L 1983-89 Electra 5.0L 1983-85 Electra 5.7L Estate Wagon 5.0L 1983-89 LeSabre 5.0L 1983-85 LeSabre 4.1L & 5.7L 1983-87 Regal 3.8L 1983-84 Regal 4.1L & 4.3L 1983 Regal 5.7L 1984-87 Regal 5.0L

Transmission 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9

TRANSMISSION APPLICATION (CADILLAC) Vehicle Application 1987-90 Brougham 5.0L 1983-84 DeVille 4.1L & 5.7L 1983-85 Fleetwood 4.1L & 5.7L 1984 Fleetwood 6.0L 1986 Fleetwood 5.0L

Transmission 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9

TRANSMISSION APPLICATION (CHEVROLET) Vehicle Application 1983-90 Caprice 5.0L 1983-85 Caprice 5.7L 1984 El Camino 3.8L & 5.7L 1984-87 El Camino 5.0L 1985-87 El Camino 4.3L 1983-84 Impala 5.0L 1983-85 Impala 5.7L 1984 Monte Carlo 3.8L & 5.7L 1984-88 Monte Carlo 5.0L 1988 Monte Carlo 4.3

Transmission 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9

TRANSMISSION APPLICATION (GMC) Vehicle Application

Transmission

1984 Caballero 3.8L & 5.7L 1984-87 Caballero 5.0L 1985-87 Caballero 4.3L 1986-87 Caballero 4.3L

200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9

TRANSMISSION APPLICATION (OLDSMOBILE) Vehicle Application 1983-90 Custom Cruiser 5.0L 1983-85 Custom Cruiser 5.7L 1983 Cutlass 4.3 1983-88 Cutlass 5.0L 1983-85 Cutlass 5.7L 1984 Cutlass 4.3 1985 Cutlass 3.8 1983-85 Delta 88 5.0L & 5.7L 1983 Ninety-Eight 4.1L 1983-84 Ninety-Eight 5.0L & 5.7L

Transmission 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9

TRANSMISSION APPLICATION (PONTIAC) Vehicle Application 1984-86 Bonneville 5.0L 1984 Bonneville 5.7L 1986 Bonneville 4.3L 1989 Firebird 3.8L 1984 Grand Prix 5.7L 1984-87 Grand Prix 5.0L 1986-87 Grand Prix 4.3L 1983-86 Parisienne 5.0L 1983-85 Parisienne 5.7L 1986 Parisienne 4.3L 1987-89 Safari 5.0L

Transmission 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9 200-4R, MW9

IDENTIFICATION Transmission is identified by the production number, located on an I.D. plate attached to right side (rear) of case, near modulator. Production number consists of a year code, a 2 character model code and a build date code.

DESCRIPTION The Turbo Hydra-Matic 200-4R transmission is a fully automatic unit consisting of 3 major components: 3element torque converter (with a torque converter clutch), compound planetary gear set and an overdrive unit.

Friction elements used in this transmission include 5 multiple-disc clutches, 2 roller clutches and a band. A hydraulic system, pressurized by a variable capacity vane-type pump, provides working pressure required to operate friction elements and automatic controls.

Fig. 1: Cutaway View of Turbo Hydra-Matic 200-4R Transmission Courtesy of GENERAL MOTORS CORP. NOTE:

For information on converter clutch system used in the THM 200-4R, see GENERAL MOTORS TORQUE CONVERTER CLUTCH article.

LUBRICATION See appropriate TRANSMISSION SERVICING - A/T article in the AUTOMATIC TRANS SERVICE section.

ADJUSTMENTS See appropriate TRANSMISSION SERVICING - A/T article in the AUTOMATIC TRANS SERVICE section.

SERVICE (IN VEHICLE) The following components can be removed from transmission without removing transmission from vehicle. For removal and installation procedures for these components, see TRANSMISSION DISASSEMBLY .   

Extension Housing Seal. Governor Assembly. Intermediate Servo Piston Assembly.

                           

Oil Pan and Screen. Control Valve Assembly. Check Balls and Valve Body Spacer Plate and Gaskets. Pressure Regulator Parts. Inside Detent/Selector Lever. Manual Detent Roller and Spring Assembly. Throttle Lever and Bracket Assembly. T.V. Cable and "O" Ring. T.V. Boost Valve and Bushing. Parking Pawl Actuator Rod, Bracket and Pawl. Manual Shaft and Seal. Manual Valve and Link. Rear Seal. 1-2 Accumulator Assembly. 3-4 Accumulator Assembly. Low-Reverse Cup Plug. Reverse Boost Valve and Bushing. Stop Valve. Intermediate Band Anchor Pin. 4-3 Pressure Switch. 4th Clutch Pressure Switch. Speedometer Driven Gear Assembly. Converter Clutch Valve and Spring. Converter Clutch Solenoid. Solenoid Wire Clips. Electrical Connectors. Cooler Fittings. Oil Filter Pipe and "O" Ring.

TROUBLE SHOOTING See TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section. CLUTCH & BAND APPLICATIONS Lever Position "D" Drive First

Elements In Use Overdrive Clutch, Low Roller Clutch & Forward Clutch

Second Third Overdrive "3" Manual 3rd "2" Manual 2nd "1" Low Reverse Neutral/Park

Intermediate Band, Overdrive Clutch & Forward Clutch Overdrive Clutch, Direct Clutch & Forward Clutch Direct Clutch, Low Roller Clutch & 4th Clutch Overrun Clutch, Direct Clutch & Forward Clutch Overrun Clutch, Intermediate Band & Forward Clutch Overrun Clutch, Forward Clutch & Low/Reverse Clutch Overdrive Clutch, Direct Clutch & Low/Reverse Clutch Overdrive Clutch

TESTING LEAKAGE See AUTO TRANS OVERHAUL - TURBO HYDRA-MATIC 400 article. ROAD TEST In Drive

Position selector lever in Drive and accelerate vehicle. A 1-2 and 2-3 shift should occur at all throttle positions (shift points will vary with throttle position). Check part throttle 3-2 downshift at 30 MPH by quickly opening throttle approximately three-fourths. Transmission should downshift 3-2. Check for 3-2 downshifts at 50 MPH, by depressing accelerator fully. In "L2"

Position selector lever in "L2" and accelerate vehicle. A 1-2 shift should occur at all throttle openings (shift point will vary with throttle opening). Check detent 2-1 downshift at 20 MPH. Transmission should downshift 2-1. Downshift From Drive To "L2"

Place selector lever in Drive. Moving at approximately 50 MPH with closed throttle, move selector lever to "L2". Transmission should downshift to 2nd gear. An increase in engine RPM and an engine braking effect should be noticed. In ("L1")

Place selector lever in Low ("1") and accelerate vehicle. No upshift should occur.

Downshift From "L2" To "L1"

At 40 MPH with throttle closed, move selector lever to "1st". A 2-1 downshift should occur at about 40-25 MPH, depending on axle ratio and control valve assembly calibration. The 2-1 downshift at closed throttle will be accompanied by increasing engine RPM and an engine braking effect should be noticed. In Reverse

Place selector lever in Reverse and check for proper reverse operation. HYDRAULIC PRESSURE TESTS Preliminary Checking Procedure

Prior to making control pressure test: check transmission fluid level, check and adjust T.V. cable, check and adjust outside manual linkage. Check engine tune. Install oil pressure gauge to transmission and connect tachometer to engine. CAUTION: When performing T.V. pressure checks, DO NOT sustain engine test speed more than 2 minutes. Minimum T.V. Pressure Check

With T.V. cable adjusted to specifications and brakes applied, check line pressure in selector lever positions and at 1000 RPM. See CONTROL PRESSURE SPECIFICATIONS . Maximum T.V. Pressure Check

With T.V. cable held at in fully extended position and brakes applied, check for correct line pressure in selector lever positions and at 1000 RPM. See CONTROL PRESSURE SPECIFICATIONS . CONTROL PRESSURE SPECIFICATIONS CONTROL PRESSURE SPECIFICATIONS (PARK & NEUTRAL @ 1000 RPM) Series Code MINIMUM T.V. MINIMUM T.V. MAXIMUM T.V. MAXIMUM T.V. 2 Letter psi psi kg/cm kg/cm2 BR 56-64 3.9-4.5 173-198 12.0-13.8 CC, HF, HT 56-64 3.9 4.5 119 134 8.32-9.4 CH, CY 56-64 3.9-4.5 114-129 8.0-9.0 CR 56-64 3.9-4.5 112-126 7.8-8.8 CZ 56-64 3.9-4.5 144-162 10.8-11.3 KC, KJ, KT 56-64 3.9-4.5 116-130 8.1-9.1 KZ 56-64 3.9-4.5 160-183 11.2-12.8 CONTROL PRESSURE SPECIFICATIONS (REVERSE @ 1000 RPM)

Series Code Letter BR CC, HH, HT CH, CY CR CZ KC, KJ, KT KZ

MINIMUM T.V. psi 105-118 105-118 105-118 105-118 105-118 105-118 80-90

MINIMUM T.V. kg/cm2 7.4-8.3 7.4-8.3 7.4-8.3 7.4-8.3 7.4-8.3 7.4-8.3 5.6-6.3

MAXIMUM T.V. psi 322-369 222-250 213-240 208-235 268-301 215-242 226-257

CONTROL PRESSURE SPECIFICATIONS ("D4" & "D3" @ 1000 RPM) Series Code Letter MINIMUM T.V. MINIMUM T.V. MAXIMUM T.V. psi psi kg/cm2 BR 56-64 3.9-4.5 173-198 CC, HH, HT 56-64 3.9-4.5 119-134 CR 56-64 3.9-4.5 112-126 CZ 56-64 3.9-4.5 144-162 KC, KJ, KT 56-64 3.9-4.5 116-130 KZ 56-64 3.9-4.5 160-183 CONTROL PRESSURE SPECIFICATIONS ("D2" & "D1" @ 1000 RPM) Series Code Letter MINIMUM T.V. MINIMUM T.V. MAXIMUM T.V. psi psi kg/cm2 BR, CC, CH CR, 123-138 7.9-8.9 123-138 CY, CZ HH, HT, KC, KJ, KT KZ 114-129 7.9-9.0 114-129

MAXIMUM T.V. kg/cm2 22.5-25.8 15.5-17.5 14.8-16.8 14.5-16.4 18.7-21.0 15.1-17.0 15.8-18.0

MAXIMUM T.V. kg/cm2 12.0-13.8 8.3-9.4 7.8-8.8 10.1-11.3 8.1-9.1 11.2-12.8

MAXIMUM T.V. kg/cm2 7.9-8.9

PRESSURE TEST RESULTS High or Low Pressures         

T.V. cable out of adjustment, binding, unhooked, broken or wrong link. Throttle lever and bracket assembly binding, unhooked or mispositioned. Throttle valve or plunger valve binding. Pressure regulator valve binding. T.V. boost valve binding or wrong valve installed (causing low oil pressure only). Reverse boost valve binding. Manual valve unhooked or mispositioned. Pressure relief valve ball missing or spring damaged. Oil pump slide stuck or slide seal missing or damaged.

7.9-9.0

    

Pump decrease air bleed orifice missing or damaged (causing low oil pressure only). Pump decrease air bleed orifice plugged (causing low oil pressure only). T.V. limit valve binding. Line bias valve binding in open position (causing high oil pressure). Line bias valve binding in closed position (causing low oil pressure).

NOTE:

Control valve assembly spacer plate and case should be closely inspected for corroded orifices and passages.

REMOVAL & INSTALLATION See appropriate TRANSMISSION REMOVAL & INSTALLATION - A/T article. NOTE:

For information on converter clutch system used in the THM 200-4R, see GENERAL MOTORS TORQUE CONVERTER CLUTCH article.

Fig. 2: Turbo Hydra-Matic 200-4R Hydraulic Circuits Diagram Courtesy of GENERAL MOTORS CORP.

TRANSMISSION DISASSEMBLY

INPUT SHAFT END PLAY See AUTO TRANS OVERHAUL - TURBO HYDRA-MATIC 400 article. EXTERNAL PARTS 1. Mount transmission in a holding fixture and remove torque converter. Rotate transmission so that oil pan is facing up. Remove oil pan and gasket. Remove oil filter intake pipe and "O" rings. "O" rings may be located in pump bore. 2. Disconnect wire leads at electrical connector and pressure switches. See Fig. 3 . Using a 3/4" box wrench to compress connector tangs, withdraw electrical connector and "O" ring from case. Remove converter clutch solenoid assembly bolts, clips and solenoid.

Fig. 3: Bottom View of Transmission Case Courtesy of GENERAL MOTORS CORP. 3. Using care not to bend throttle lever link, remove throttle lever and bracket assembly. T.V. exhaust valve lifter and spring may separate from lever and bracket assembly. Remove manual detent roller and spring

assembly, signal (Drive "2") oil pipe retaining clip and oil pipe. 4. Remove 4-3 pressure switch and retaining bolt. Remove remaining bolts attaching valve body to case. Identify bolts for replacement in correct location during reassembly. Hold manual valve in bore and carefully lift control valve assembly from case. Care must be taken as 3 check balls are located on top of spacer plate-to-valve body gasket. Remove check balls. 5. Remove 1-2 accumulator housing. Withdraw spring, gasket, plate and piston from housing. It may be necessary to apply low air pressure (approximately 3 psi) to orifice in accumulator housing passage to remove piston. 6. Remove control valve assembly gaskets and spacer plate from transmission case. Withdraw 3-4 accumulator spring, piston and pin from bore in case. It may be necessary to apply low air pressure (approximately 3 psi) to orifice in case core passage to remove piston. See Fig. 4 .

Fig. 4: View of Case Core Passage Courtesy of GENERAL MOTORS CORP. 7. Remove 9 check balls from the core passages in the case. See Fig. 5 and Fig. 41 . Remove governor cover and gasket from case. Remove governor assembly while rotating output shaft counterclockwise to ease

removal.

Fig. 5: Removing Check Balls From Case Courtesy of GENERAL MOTORS CORP. NOTE:

DO NOT use pliers to remove governor assembly.

8. Pry intermediate servo cover retaining ring from groove in case. Remove servo cover and discard seal ring. Remove servo piston and band apply pin from bore in case. NOTE:

Before continuing with transmission disassembly, check for proper intermediate band apply pin as follows.

Intermediate Band Apply Pin Selection

1. Install Band Apply Pin Selection Gauge (J-25014-2) in intermediate servo bore and retain with servo cover retaining ring, aligning ring with gap at case slot. Install Selection Gauge Tapered Pin (J-25014-1) into gauge. See Fig. 6 .

Fig. 6: Intermediate Band Apply Pin Selection Courtesy of GENERAL MOTORS CORP. 2. Ensure tapered pin end is properly located against band apply lug and band anchor pin is properly located in case and band anchor lug. If band selection tapered pin does not register between high and low limits, look for possible problem with intermediate band, direct clutch housing or transmission case. 3. Install dial indicator and position indicator point on top of selection gauge post. Set indicator to zero. Ensure selection gauge is squarely seated against servo retaining ring and stepped side of tapered pin is aligned with torquing arm of gauge. 4. Using torque wrench, apply 100 INCH Lbs (12 N.m.) to selection gauge torque arm. Slide dial indicator over tapered pin. Read dial indicator and see INTERMEDIATE BAND APPLY PIN SELECTION for proper pin. NOTE:

Dial indicator travel is reversed, making indicator readings backwards. On an indicator that ranges from 0-100, a .020" (.51 mm) travel will read .080" (2.03 mm), a .060" (1.52 mm) travel will read .040" (1.02 mm).

INTERMEDIATE BAND APPLY PIN SELECTION Indicator Reading: In. (mm) 0-.029 (0-.72) .029-.057 (.72-1.44)

Apply Pin I.D. One Groove 2 Grooves

.057-.086 (1.44-2.16) .086-.114 (2.16-2.88)

3 Grooves None

3rd Accumulator Check Valve Replacement

1. Inspect 3rd accumulator check valve for the following conditions: Missing check ball, check ball binding or stuck in tube, oil feed slot in tube missing or restricted, improperly assembled, loose fitting or not fully seated in case. If check valve requires replacement, go to step 2).

Fig. 7: 3rd Accumulator Check Valve Assembly Courtesy of GENERAL MOTORS CORP. 2. Using a No. 4 screw extractor, remove check valve assembly from case by turning and pulling straight out. See Fig. 8 . 3. Install new check valve assembly, small end first, into case. Position oil feed slot in tube so it faces servo. Using a 3/8" diameter metal rod and hammer, drive assembly until it is seated in case hole.

Fig. 8: Removing 3rd Accumulator Check Valve Assembly Courtesy of GENERAL MOTORS CORP. OVERDRIVE UNIT PARTS NOTE:

Prior to removing overdrive unit parts, check overdrive unit end play to determine correct end play thrust washer for use during reassembly.

Overdrive End Play

1. Install Output Shaft Loading Fixture (J-29332) and Support Sleeve (J-25013-1) on output shaft. See Fig. 9 . Turn transmission to vertical position, pump side up.

Fig. 9: Installing Output Shaft Loader Courtesy of GENERAL MOTORS CORP. 2. Remove one pump-to-case bolt and washer and install an 11" long bolt into pump bolt hole. Attach Overdrive End Play Checker (J-25022) and Oil Pump Remover (J-24773-5) to turbine shaft. See Fig. 10 .

Fig. 10: Checking Overdrive Unit End Play Courtesy of GENERAL MOTORS CORP. NOTE:

The following step must be performed to eliminate tolerance difference between turbine shaft snap ring and overdrive carrier.

3. Mount a dial indicator and clamp assembly on long bolt, positioning indicator point cap on top of pump remover. Lift upward on remover with approximately 3 lbs. force and zero indicator while maintaining upward force. 4. With dial indicator zeroed, increase upward force to approximately 20 lbs. (9.1 kg) and read end play on indicator. Overdrive unit end play should be .004-.027" (.10-.69 mm). The selective thrust washer controlling this end play is located between pump cover and overdrive clutch housing. If more or less washer thickness is required to bring end play within specification, select correct washer. See OVERDRIVE UNIT END PLAY WASHER SELECTION . OVERDRIVE UNIT END PLAY WASHER SELECTION Washer Thickness I.D. Number .167-.171" (4.25-4.36 mm) 0 .172-.176" (4.37-4.48 mm) 1

I.D. Color Scarlet White

.177-.180" (4.49-4.60 mm) .181-.185" (4.61-4.72 mm) .186-.190" (4.73-4.84 mm) .191-.195" (4.85-4.96 mm) .196-.200" (4.97-5.08 mm) .201-.204" (5.09-5.20 mm) .205-.209" (5.21-5.32 mm)

2 3 4 5 6 7 8

Brown Grey Yellow Lt. Blue Purple Orange Green

Component Removal

1. If necessary, pry oil pump seal from pump. Remove pump-to-case bolts and washers. Install Oil Pump Remover (J-24773-5) on turbine shaft. See Fig. 10 . Remove oil pump assembly from case. Remove pump-to-case gasket and tanged oil deflector plate located under pump. 2. Remove 4th clutch plate-to-case snap ring. Grasp turbine shaft and lift overdrive assembly and 4th clutch plates from case. Remove clutch plates from overdrive assembly and remaining steel plate from case. 3. Remove overdrive internal gear-to-carrier thrust washer from inside internal gear. Remove internal gear and internal gear-to-support thrust washer from case. 4. Using a spring compressor, compress 4th clutch spring and retainer assembly. Remove support-to-clutch snap ring, spring and retainer. Remove compressor from retainer assembly. Lift 4th clutch piston from case. FRONT UNIT PARTS NOTE:

Prior to removing front unit parts, check front unit end play to determine correct thrust washer to install at reassembly.

Front Unit End Play

1. Push forward clutch shaft downward. Install Forward And Direct Clutch Remover (J-29337) in end of shaft. Mount dial indicator and clamp assembly. See Fig. 11 . Position indicator point on top of clutch remover. NOTE:

Perform this check with output shaft loading fixture and support sleeve in place.

Fig. 11: Checking Front Unit End Play Courtesy of GENERAL MOTORS CORP. 2. Move output shaft upward by turning adjusting screw on output shaft loading fixture. Move shaft upward until White or scribed line on support sleeve begins to disappear. Zero dial indicator. 3. Pull clutch remover upward and read resulting end play on dial indicator. Front unit end play should be .022-.051" (.56-1.30 mm). Selective thrust washer controlling this end play is located between output shaft and forward clutch shaft. If more or less washer thickness is required to bring end play within specification, select proper washer. See FRONT UNIT END PLAY WASHER SELECTION . FRONT UNIT END PLAY WASHER SELECTION Washer Thickness I.D. Number .065-.070" (1.66-1.78 mm) 1 .070-.075" (1.78-1.90 mm) 2 .076-.080" (1.92-2.03 mm) 3 .081-.085" (2.05-2.16 mm) 4 .086-.090" (2.18-2.29 mm) 5 .091-.095" (2.31-2.42 mm) 6 .096-.100" (2.44-2.55 mm) 7 .101-.106" (2.57-2.69 mm) 8 .106-.111" (2.69-2.82 mm) 9 .111-.116" (2.82-2.94 mm) 10 .117-.121" (2.96-3.07 mm) 11

I.D. Color N/A N/A Black Lt. Green Scarlet Purple Brown Orange Yellow Lt. Blue N/A

.122-.126" (3.09-3.20 mm) .127-.131" (3.22-3.33 mm) .132-.136" (3.35-3.46 mm) .137-.141" (3.48-3.59 mm)

12 13 14 15

N/A Pink Green Grey

Component Removal

1. Remove 2 center support bolts. See Fig. 12 . From inside case, remove center support beveled snap ring. Lift center support from case using Slide Hammer (J-7004) and Remover (J-29334). Remove center support/direct clutch thrust washer. NOTE:

Center support/direct clutch thrust washer may be stuck to back of direct clutch.

Fig. 12: Removing Center Support Bolts Courtesy of GENERAL MOTORS CORP. 2. Install Direct And Forward Clutch Remover (J-29337) in end of forward clutch shaft. See Fig. 11 . Pull direct and forward clutch assemblies from case. Separate direct clutch from forward clutch. Remove intermediate band assembly and band anchor pin from case. Remove output shaft-to-forward clutch shaft selective thrust washer.

NOTE:

The direct-to-forward clutch thrust washer may stick to end of direct clutch housing when separating clutch assemblies.

FRONT GEAR PARTS NOTE:

Prior to removing front gear parts, check rear unit end play to determine correct thrust washer to install at transmission reassembly.

Rear Unit End Play

1. Loosen adjusting screw on output shaft loading fixture (installed at overdrive end play check) and push output shaft downward. Install a "C" clamp on case. See Fig. 13 . Mount a dial indicator and extension on "C" clamp.

Fig. 13: Checking Rear Unit End Play Courtesy of GENERAL MOTORS CORP. 2. Position dial indicator extension against end of output shaft and set indicator to zero. Move output shaft upward by turning screw on loading fixture until White or scribed line on support sleeve begins to disappear. Read indicator end play.

3. Rear unit end play should be .004-.025" (.10-.64 mm). Selective thrust washer controlling this end play is located between front internal gear thrust washer and output shaft snap ring. If more or less thrust washer thickness is required to bring end play within specification, select proper washer. See REAR UNIT END PLAY WASHER SELECTION . Remove dial indicator and "C" clamp. REAR UNIT END PLAY WASHER SELECTION Washer Thickness .097-.102" (2.46-2.59 mm) .114-.119" (2.90-3.01 mm) .121-.126" (3.08-3.19 mm) .128-.133" (3.26-3.37 mm) .135-.140" (3.44-3.55 mm) .143-.147" (3.62-3.73 mm) .150-.154" (3.80-3.91 mm) .157-.161" (3.98-4.09 mm) .164-.168" (4.16-4.27 mm) .171-.175" (4.34-4.45 mm)

I.D. Number 0 1 2 3 4 5 6 7 8 9

I.D. Color N/A Orange White Yellow Blue Red Brown Green Black Purple

Component Removal

1. Remove output shaft-to-selective washer snap ring. Lift front internal gear, rear selective washer and thrust washer from case and remove washers from front internal gear.

Fig. 14: Removing Output Shaft Snap Ring Courtesy of GENERAL MOTORS CORP. 2. Remove front carrier assembly and front internal gear-to-front carrier thrust bearing assembly. If it did not come out with front carrier, remove front sun gear and sun gear-to-front carrier thrust bearing assembly. NOTE:

The front sun gear-to-front carrier thrust bearing requires only one race.

3. Remove input drum and rear sun gear. Remove 4-tanged input drum-to-reverse clutch housing thrust washer from rear of drum or front clutch housing.

4. Grind approximately 3/4" from end of a No. 4 screw extractor. Insert screw extractor into low-reverse clutch housing-to-case cup plug. Turn screw extractor 2 or 3 turns and pull out cup plug. Remove lowreverse clutch-to-case beveled snap ring. Lift clutch assembly from case. Remove low-reverse clutch housing-to-case spacer ring. NOTE:

DO NOT reuse low-reverse clutch housing cup plug and seal assembly.

Fig. 15: Removing Low-Reverse Clutch Housing Cup Plug Courtesy of GENERAL MOTORS CORP. REAR GEAR PARTS NOTE:

Governor assembly must be removed before removing rear gear parts.

1. Grasp output shaft and lift out remaining rear unit parts and lay in a horizontal position. Remove roller clutch and rear carrier from output shaft. Remove 4-tanged rear carrier-to-rear internal gear thrust washer from end of carrier or from inside rear internal gear. 2. Pull low-reverse clutch plates from output shaft. Remove rear internal gear-to-rear sun gear thrust bearing assembly from internal gear. Remove internal gear from output shaft. If necessary, remove rear oil seal from transmission case. MANUAL SHAFT & PARKING PAWL PARTS 1. Turn transmission to a horizontal position, oil pan side up. If necessary, remove manual shaft and parking pawl linkage. 2. Remove hex nut securing inside detent lever to manual shaft. Remove parking lock actuator rod and

inside detent lever. Remove manual shaft retaining pin from case and slide shaft out. If damaged, pry manual shaft oil seal from case. 3. Remove parking lock bracket. Remove parking pawl shaft retaining pin. Remove parking pawl cup plug using a No. 4 screw extractor with 3/4" ground from end. Using No. 4 screw extractor, remove parking pawl shaft from case. Remove parking pawl and spring.

Fig. 16: Removing Parking Pawl Cup Plug Courtesy of GENERAL MOTORS CORP. TORQUE CONVERTER NOTE:

The torque converter is a sealed unit and cannot be disassembled for service.

COMPONENT DISASSEMBLY & REASSEMBLY TRANSMISSION CASE Cleaning & Inspection

1. Inspect case assembly for damage, cracks, porosity or interconnected oil passages. Inspect orifice plug in intermediate servo bore. If plug requires replacement, install new plug, orifice end first, flush to slightly below top of plug hole. 2. Inspect case exhaust passages for restrictions. Inspect reverse clutch lugs, governor, intermediate servo bore, speedometer bore and snap ring grooves for damage. Inspect all bolt holes for damage or stripped holes. Inspect case bushing for damage and scoring.

Fig. 17: Front View of Transmission Case Showing Oil Passages Courtesy of GENERAL MOTORS CORP.

Fig. 18: Bottom View of Transmission Case Showing Oil Passages Courtesy of GENERAL MOTORS CORP. REAR GEAR PARTS Cleaning & Inspection

1. Inspect output shaft journals, snap ring groove and splines for wear or damage. Check lubrication passages for damage or obstructions. Check governor drive gear for rough or damaged teeth. 2. Inspect rear internal gear splines, teeth and bearing surface for wear, cracks or damage. Inspect parking pawl lugs for cracks or damage. Thoroughly clean, air dry and inspect rear internal gear-to-rear sun gear thrust bearing assembly for pitted or rough conditions. ROLLER CLUTCH & REAR CARRIER ASSEMBLY Disassembly

Remove roller clutch inner race and lift roller clutch assembly from rear carrier. Remove rear carrier-to-clutch thrust washer (4 tangs) from rear of carrier and roller clutch-to-rear carrier thrust washer from inside carrier.

Cleaning & Inspection

1. Inspect roller clutch race and spline for scoring or wear. Inspect roller clutch bearings, cage and springs for damage or wear. Inspect thrust washers for signs of scoring or excessive wear and check tanged thrust washer for bent tangs.

Fig. 19: Exploded View of Roller Clutch & Rear Carrier Assembly Courtesy of GENERAL MOTORS CORP. 2. Inspect rear carrier for damage to roller clutch cam ramps. Inspect bushing for damage and scoring. Inspect planet pinions for damage, rough bearings or tilt. Check pinion end play using a feeler gauge inserted between carrier and pinion gears. End play should be .009-.024" (.23-.61 mm). Reassembly

1. Position roller clutch-to-carrier thrust washer in rear carrier. Install rollers that may have come out of roller cage by compressing energizing spring with forefinger and inserting roller from outer edge. Install roller clutch into rear carrier.

Fig. 20: Exploded View of Low-Reverse Clutch Assembly Courtesy of GENERAL MOTORS CORP. 2. Install roller clutch race, spline side out, into roller clutch and rotate it into position. Install 4-tanged rear carrier-to-rear internal gear thrust washer. Align tangs into slots of rear carrier and retain with petroleum jelly. LOW-REVERSE CLUTCH Disassembly

Compress low-reverse clutch spring retainer and remove snap ring. Remove waved spring from top of piston. Remove piston from housing. Remove inner and outer seals from piston. Remove clutch apply ring. Lowreverse clutch assembly clutch plates and disc were removed during TRANSMISSION DISASSEMBLY . Cleaning & Inspection

1. Inspect composition, steel and waved clutch plates for signs of wear or burning. Check spring retainer and waved spring for damage or distortion. Inspect clutch housing for damage or plugged feed hole. Inspect clutch housing bushing for damage or scoring. 2. Inspect clutch housing splines and snap ring groove for damage or burrs. Remove burrs with crocus cloth. Inspect clutch piston and apply ring assembly for distortion, cracks or damage. Inspect clutch housing-tocase spacer ring for damage. Reassembly

1. Position clutch apply ring on piston. Install new inner and outer seals on piston with seal lips facing away from apply ring side. Lubricate seals with automatic transmission fluid. Install piston into housing using care not to damage seals. 2. Install waved release spring on clutch piston. Install spring retainer, cupped face up, on top of piston. Compress retainer and install snap ring. REAR SUN GEAR & INPUT DRUM

NOTE:

Rear sun gear and input drum need not be disassembled unless it is worn or defective.

Disassembly

Remove input drum-to-rear sun gear snap ring. Separate sun gear from input drum. Remove tanged thrust washer from drum. Cleaning & Inspection

Inspect rear sun gear for cracks, splits, damaged splines, worn gear or journals and plugged lubrication holes. Inspect sun gear bushing for damage or scoring. Inspect input drum for damage. Inspect 4-tanged input drumto-low and reverse clutch housing thrust washer for scoring or distorted tangs. If damaged, replace sun gear-toinput drum snap ring. Reassembly

Install sun gear into input drum, spline side first and retain with snap ring. Install 4-tanged thrust washer on drum over sun gear end. Align tangs into drum and retain with petroleum jelly.

Fig. 21: Disassembled View of Rear Sun Gear & Input Drum Assembly Courtesy of GENERAL MOTORS CORP. FRONT SUN GEAR

Cleaning & Inspection

Inspect front sun gear splines and teeth for damage or wear. Inspect machined face for pitting, scoring or damage. FRONT CARRIER ASSEMBLY Cleaning & Inspection

1. Inspect front carrier for damage. Check pinions for damage, rough bearings or tilt. Check pinion end play by placing a feeler gauge between pinion gear and carrier housing. End play should be .009-.024" (.23-.61 mm). 2. Inspect front carrier-to-front internal gear thrust bearing assembly for pitted or rough conditions. FRONT INTERNAL GEAR Cleaning & Inspection

Inspect forward clutch hub for worn splines and restricted lubrication holes. Inspect internal gear for cracks, damage and worn gear teeth. Check bushing for damage or scoring. Inspect front internal gear-to-selective thrust washer for scoring or damage. See Fig. 14 . DIRECT CLUTCH ASSEMBLY Disassembly

1. Remove snap ring and lift out clutch backing plate, composition clutch plates and steel clutch plates. Keep clutch plates separated from forward clutch plates. 2. Compress retainer and spring assembly and remove snap ring. Withdraw retainer and spring assembly from clutch housing. Remove release spring guide. Remove piston from housing and remove seals from piston. Remove center seal from housing. NOTE:

DO NOT remove apply ring from clutch piston unless piston or apply ring require replacement.

Fig. 22: Exploded View of Direct Clutch Assembly Courtesy of GENERAL MOTORS CORP. Cleaning & Inspection

1. Inspect clutch plates for wear or signs of burning. Inspect backing plate for scoring or damage. Inspect retainer and release springs for being collapsed. Inspect release spring guide for damage. 2. Inspect clutch piston for distortion, cracks or other damage. Check for free operation of check ball in clutch housing or piston. If damaged, replace check ball. 3. Remove check ball assembly using a 3/8" diameter rod as a punch. Place new check ball in check ball hole. Using same rod, drive check ball down into hole until it bottoms. 4. Inspect direct clutch housing for cracks, wear and open oil passages. Inspect housing snap ring grooves for damage. Inspect direct clutch bushings for damage or scoring. Reassembly

1. If removed, install clutch apply ring on piston. Install new inner and outer seals on piston with lips facing away from clutch apply ring side. Install new center seal on direct clutch housing with lip facing up. Lubricate seals and install piston into housing using care not to damage seals. CAUTION: Use care when installing piston into clutch housing. Large snap ring groove in housing could cut outer piston seal. 2. Install release spring guide with omitted rib over check ball in piston. See Fig. 23 . Install retainer and spring assembly, compress springs and install snap ring.

Fig. 23: Installing Direct Clutch Release Spring Guide Courtesy of GENERAL MOTORS CORP. 3. Oil and install clutch plates into clutch housing. Start with a flat steel and alternate composition and flat steel clutch plates. See DIRECT CLUTCH PLATE USAGE . Install backing plate, micro-finish down. Install clutch pack retaining snap ring. Ensure composition clutch plates turn freely. DIRECT CLUTCH PLATE USAGE Application All Models

Steel 6

Composition 6

FORWARD CLUTCH ASSEMBLY Disassembly

1. If damaged, remove Teflon oil seal rings from forward clutch shaft. Remove forward clutch-to-direct clutch thrust washer. Remove retaining snap ring and withdraw backing plate, composition plates and steel plates from clutch housing and keep them separated from direct clutch plates. 2. Compress retainer and release spring assembly and remove snap ring. Remove retainer and spring assembly from housing. Remove forward clutch piston from housing. Remove inner and outer oil seals from piston. If necessary, remove clutch apply ring from piston.

NOTE:

DO NOT remove clutch apply ring from piston unless apply ring or piston requires replacement.

Cleaning & Inspection

Forward clutch assembly inspection is identical to direct clutch assembly inspection except for the following differences; Replace forward clutch housing cup plug if damaged or missing. Remove plug using a No. 3 screw extractor (grind to fit). Install new cup plug .039" (1 mm) below surface.

Fig. 24: Forward Clutch Housing Courtesy of GENERAL MOTORS CORP.

Fig. 25: Exploded View of Forward Clutch Assembly Courtesy of GENERAL MOTORS CORP. Reassembly

1. If removed, install clutch apply ring on clutch piston. Install new inner and outer seals on clutch piston. Lubricate piston seals and install piston into clutch housing using care to prevent seals from being damaged when installing piston past large snap ring groove in housing. 2. Install release springs and retainer assembly on piston. Compress retainer and install snap ring. Lubricate (ATF) and install clutch plates into housing, starting with waved steel plate and alternating composition plates and flat steel plates. See FORWARD CLUTCH PLATE USAGE . 3. Install backing plate into housing with micro-finish side down. Install clutch pack retaining snap ring and ensure composition clutch plates rotate freely in housing. Install forward-to-direct clutch thrust washer and retain with petroleum jelly. 4. If removed, install new forward clutch shaft oil seal rings. Ensure cut ends are assembled in same relationship as cut and that rings are seated in their groove. Retain with petroleum jelly. FORWARD CLUTCH PLATE USAGE Application All Models

Steel (1) 4

Composition 4

(1) Installed first is one waved steel plate .062" (1.57 mm) thick. Flat steel plates are .077" (1.96 mm)

thick. CENTER SUPPORT Cleaning & Inspection

1. Remove 4th clutch inner and outer seal rings from center support. Check condition of cast iron oil rings. If necessary, remove from center support. 2. Inspect bushings for scoring, wear or galling. Check oil ring grooves and oil rings for nicks or other damage. Apply air to oil passages to ensure passages are open and are not interconnected. 3. Inspect piston sealing surfaces for scratches. Inspect support for cracks or porosity. Inspect support for

burrs or raised edges. If present, remove with fine stone or fine abrasive paper. 4. If removed, install cast iron oil seal rings on center support. Install new inner and outer seal rings on center support with seal lips down. See Fig. 26 . NOTE:

When installing cast iron oil seal rings, ensure ends overlap and interlock. Verify that ends are flush with each other when interlocked and oil seal rings are seated in grooves to prevent damage to ring during assembly of mating parts.

Fig. 26: Location of Cast Iron Seals on Center Support Courtesy of GENERAL MOTORS CORP. 4TH CLUTCH ASSEMBLY NOTE:

The 4th clutch assembly was disassembled during TRANSMISSION DISASSEMBLY.

Cleaning & Inspection

Inspect snap rings for damage. Inspect 4th clutch piston for cracks or damage. Inspect release springs and retainer assembly for distortion or damage. Inspect clutch plates for signs of wear or burring. Inspect plate for scratches or damage. OVERDRIVE INTERNAL GEAR Cleaning & Inspection

Clean and inspect internal gear-to-support thrust washer and overdrive carrier-to-sun gear thrust bearing assembly. Inspect gear, splines, teeth and bearing surface of overdrive gear for wear, cracks or damage. OVERRUN CLUTCH & OVERDRIVE CARRIER ASSEMBLY Disassembly

Remove snap ring and slide turbine shaft from overdrive carrier assembly. Remove carrier from overrun clutch assembly. Remove sun gear from clutch assembly. NOTE:

Reassembly of this unit follows disassembly and reassembly of individual components.

OVERRUN CLUTCH ASSEMBLY Disassembly

1. Remove retaining snap ring and lift backing plate, steel clutch plates and composition clutch plates from overrun clutch housing. Keep clutch plates separated from other plate assemblies. 2. Using snap ring pliers, remove overrun clutch hub snap ring. Lift overdrive roller clutch cam assembly from housing. Separate roller clutch from cam assembly. 3. Remove retainer and wave spring assembly from clutch housing. Remove overrun clutch piston from housing. Remove inner and outer seals from piston.

Fig. 27: Removing Overdrive Roller Clutch Cam Assembly Courtesy of GENERAL MOTORS CORP. Cleaning & Inspection

1. Inspect clutch plates for signs of wear or burning. Inspect roller clutch cam ramps for damage. Check roller bearings, cage and springs of roller clutch for wear or damage. 2. Inspect retainer and wave spring for damage. Inspect clutch piston for distortion, cracks and damage. Inspect housing for cracks, wear and open oil passages. Check clutch housing snap ring groove and bushing for damage or scoring. Reassembly

1. Install new inner and outer seals on piston with seal lips facing away from clutch apply ring side. Lubricate seals and install piston into clutch housing using care not to damage seals. Install overrun clutch waved release spring and spring retainer (cupped face down) on clutch piston. 2. Install roller clutch cam on roller clutch assembly. Locating tangs on roller clutch must set on roller clutch cam. Install roller clutch assembly on overrun clutch hub. Compress spring and retainer assembly by pushing down on roller clutch assembly and install narrow snap ring. 3. Oil and install overrun clutch plate into housing. Start with a flat steel and alternate composition and flat steel plates. See OVERRUN CLUTCH PLATE USAGE . Install backing plate, chamfered side up. Install retaining snap ring. Ensure composition clutch plates rotate freely. OVERRUN CLUTCH PLATE USAGE Application

Flat Steel

Composition

All Models

(1) 2

(1) Plate thickness is .077" (1.96 mm).

OVERDRIVE CARRIER Inspection

1. Inspect locating splines for damage and roller clutch race for scratches and wear. Inspect carrier housing for cracks and wear. 2. Inspect pinions for damage, rough bearings or tilt. Using a feeler gauge, measure pinion end play between pinion and carrier. End play should be .009-.024" (.23-.61 mm). If necessary to disassemble carrier, go to disassembly procedure. Disassembly

1. Remove overdrive carrier snap ring. Using pliers, remove pinion pins. Remove pinions, thrust washers and roller bearings. Inspect pinion pocket thrust faces for burrs. Remove if present. 2. Remove overdrive sun gear-to-overdrive carrier thrust bearing assembly. Thoroughly clean, air dry and closely inspect thrust bearing assembly for pitting or rough condition.

Fig. 28: Assembling Overdrive Carrier Pinions Courtesy of GENERAL MOTORS CORP. Reassembly

1. Install thrust bearing into carrier housing with small diameter race down. Retain bearing in place with petroleum jelly. Install 19 needle bearings into each pinion and hold them in place. Place a bronze and steel thrust washer on each side of pinion so that steel washer is against pinion. Hold washers in place with petroleum jelly. 2. Install a pinion assembly in place in housing and use a pilot shaft to align parts. Push pinion pin into place while rotating pinions from side. Repeat procedure for remaining pinions. Install overdrive carrier snap ring to retain pinion pins. TURBINE SHAFT Cleaning & Inspection

1. Inspect Teflon oil seals on turbine shaft for damage and free fit in grooves. DO NOT remove seal unless replacement is necessary. Inspect snap ring for damage. Check journals and snap ring grooves for wear or damage. 2. Inspect both ends of turbine shaft for open oil passages. Inspect journals for damage. Check for free operation of check ball in end of shaft. If check ball is damaged, go to step 3). 3. Straighten tangs of retainer and check valve assembly capsule in end of shaft. Remove check ball. Using a No. 4 screw extractor, remove check valve retainer from turbine shaft by turning and pulling straight out. 4. Install new check valve assembly, check valve seat first, into turbine shaft. Using a 3/8" diameter rod, drive retainer and check valve assembly until it is 1/8" below top surface of turbine shaft.

Fig. 29: Turbine Shaft Assembly Courtesy of GENERAL MOTORS CORP.

OVERRUN CLUTCH & OVERDRIVE CARRIER ASSEMBLY Reassembly

1. Install overdrive sun gear on overrun clutch hub with groove up. Center clutches in overrun clutch housing. Position overdrive carrier in overrun clutch with pinion side of carrier facing up. It may be necessary to rotate carrier counterclockwise to seat it. 2. Position clutch and carrier assembly (clutch up) over hole in work bench. Install turbine shaft, ring grooved spline first, into carrier assembly. Turn assembly sideways and install NEW turbine shaft snap ring. CAUTION: A new turbine shaft snap ring must be installed as damage to unit may occur if old snap ring is used. PUMP ASSEMBLY Disassembly

1. Remove pump-to-case seal ring. See Fig. 30 . Remove pump cover-to-pump body attaching bolts and separate cover from body. Remove stator shaft-to-overrun selective thrust washer. 2. Push in on T.V. boost valve bushing, compressing pressure regulator spring. Remove retaining snap ring. Release spring tension slowly and remove valve train. 3. Push in on converter clutch stop valve, compressing converter clutch valve spring. Remove snap ring. Release spring tension slowly and remove stop valve and converter clutch valve. Using a punch, remove pressure relief spring retaining pin. Remove relief spring and ball. 4. If replacement of stator shaft and flange assembly is required, remove attaching screws and press stator shaft until it is removed from pump cover bore. 5. Place shop towel over pump slide spring (spring is under high pressure) and using a screwdriver, remove spring from pump body. Remove pump slide, slide-to-wear plate oil seal and back-up "O" ring seal, rotor, rotor guide, 7 vanes and 2 vane rings, pump slide seal support and seal. Remove pivot slide pin and spring. Cleaning & Inspection

1. Inspect pump-to-case seal ring groove in pump body for damage. Inspect stator shaft-to-overrun selective washer for wear and damage. Wash pump body, springs, pump slide, rotor, vanes, vane rings and rotor guide. DO NOT put pump seals in solvent. 2. Inspect pump pocket and pump body for damage or scoring. Check pump body bushing for wear or scoring. Inspect springs for damage or distortion and pump slide for damage, cracks or wear. Check rotor for damage, cracks or wear. Inspect vanes and vane rings for damage, cracks or wear. Inspect pump body face for nicks and overall flatness and open oil passages. 3. Inspect T.V. boost valve, reverse boost valve, stop valve and converter clutch valve for nicks or damage. Check valves for free operation in bushing or cover bore. Inspect all springs for damage or distortion. Inspect stator shaft and flange assembly for damaged splines or bushing. Check stator shaft for damaged or missing orifice cup plug in dowel pin. DO NOT remove cup plug unless damaged.

Fig. 30: Exploded View of Pump Assembly Courtesy of GENERAL MOTORS CORP. 4. Inspect pump cover for open oil passages. Check pump cover face for nicks and overall flatness. Inspect for chips in pressure regulator, pressure relief and converter clutch bores. Inspect cup plugs and orifice plugs in cover and if damaged, replace plugs. Pump Cover Cup Plug Replacement

If cup plug is missing, drive a new plug to 1/32" below top of hole, using a 9/32" diameter rod on 2 smaller plugs, a 5/16" rod on line-to-case cup plug and a 7/16" rod on large plug. Stake top of hole in 2 places, directly opposite each other, to retain plug. Pump Cover Orifice Plug Replacement

If plugs require replacement, place new plug, orifice end first, into plug hole from rough casting side of cover. Drive new plug flush to .100" (2.8 mm) below top of hole, on rough casting side. Stake top of hole in 2 places to retain plug.

Fig. 31: View of Pump Cover & Body Showing Hydraulic Passages Courtesy of GENERAL MOTORS CORP. Reassembly

1. Turn pump body so that pump pocket side is up. Install slide "O" ring and slide-to-wear plate oil seal in slide and retain with petroleum jelly. Install slide into pump pocket with seal side down. Install slide seal support and pump slide seal. Retain with petroleum jelly. Install pivot pin and spring into bore in pump body (opposite pivot pin and spring). 2. Install a vane ring in pump pocket. Install rotor guide in pump rotor. Install rotor into pump pocket. Center and seat rotor on guide so rotor is flush with pump slide. Install 7 vanes into pump. Ensure vane pattern is installed against vane ring. Install top vane ring. Install pump slide spring. 3. If stator shaft and flange assembly was removed from pump cover, install as follows: Align dowel pin of stator shaft with hole in pump cover. Using a press, press stator shaft into cover until fully seated on cover. Install stator shaft and flange assembly attaching bolts. 4. Install all valve trains in reverse order of removal. See Fig. 31 . Assemble pump cover to pump body and install attaching bolts finger tight. Align cover to body using Alignment Strap (J-25015). Tighten attaching bolts. Install pump-to-case seal ring, chamfered side out, making sure seal is not twisted. Install stator shaft-to-overrun clutch selective thrust washer and retain with petroleum jelly. GOVERNOR ASSEMBLY Cleaning & Inspection

1. Inspect governor cover for damage, plugged oil passage, scored or worn bore. Inspect governor driven gear for nicks or damage. If replacement is necessary, remove retaining ring. Slide gear and thrust washer from shaft. NOTE:

Care must be taken after removing driven gear to keep governor in a vertical position to retain governor weight pin in its holding position.

2. Inspect governor shaft seal ring for cuts, damage and free fit in groove. Inspect for free operation of weights. Weights must operate freely and independently of each other. Check spring for damage and correct installation. Check for presence of 2 check balls. Inspect shaft for damage. INTERMEDIATE SERVO ASSEMBLY Disassembly

Using a small screwdriver, remove intermediate pin-to-retainer snap ring. Separate band apply pin, spring and washer from servo pistons.

Fig. 32: Exploded View of Intermediate Servo Courtesy of GENERAL MOTORS CORP. Cleaning & Inspection

Inspect pin oil seal rings for damage and replace if necessary. Inspect pin for damage and fit in case. Inspect inner and outer piston seal rings for damage and free fit in grooves; DO NOT replace unless damaged. Inspect spring for damage and distortion. Reassembly

1. Install retainer on band apply pin. Install snap ring. Install apply pin, retainer end first, through servo pistons. If removed, install new inner and outer piston seal rings, making sure cut ends are assembled in same relationship as cut. Retain with petroleum jelly. 2. Lubricate with petroleum jelly and install new seal ring on intermediate servo cover. Install servo piston into servo cover. CAUTION: Intermediate servo cover seal rings must be well lubricated to prevent damage or cutting of ring. CONTROL VALVE ASSEMBLY NOTE:

As valve trains are removed from each valve body bore, place individual parts

in correct order in relative position to valve body to ease reassembly. Valves, bushings and springs are not interchangeable. Parts must be installed in correct order in proper valve body bore. Disassembly

1. Lay control valve assembly with machined face up and manual valve at upper left corner. If not removed at TRANSMISSION DISASSEMBLY, remove 3 check balls from cored passages of valve body. Remove manual valve from upper left corner bore. CAUTION: Some roll pins in valve body have pressure against them. Hold shop towel over bore while removing pin to prevent possibly losing bore plug or spring. 2. From bore beneath manual valve, remove roll pin and slide out 2-3 throttle valve and 2-3 shift valve train. The 2-3 throttle valve spring and valve may be inside bushing. 3. From next bore down, remove roll pin and withdraw converter clutch valve train. Converter clutch valve spring and converter clutch throttle valve may be inside bushing. On Computer Command Control models, clutch throttle valve and spring have been eliminated. 4. From next bore down, remove outer roll pin and remove 1-2 throttle valve train and low 1st/detent valve. Remove inner roll pin and slide out low 1st/detent valve bushing and 1-2 shift valve. 5. Cover next bore down to prevent loss of spring. Remove outer spring retaining sleeve. Remove bore plug and 4-3 control valve and spring. Remove inner spring retaining sleeve and withdraw low-overrun clutch valve spring and valve. 6. From next bore down, remove roll pin and slide out 3-4 throttle valve train. From last bore down, remove roll pin and bore plug and withdraw accumulator valve train. 7. From upper right corner, remove roll pin and remove line bias valve train. From next bore down, remove roll pin and 3-2 control valve train. 8. From next bore down, remove roll pin. Remove T.V. modulator upshift valve train. From next bore down, remove roll pin and T.V. modulator downshift valve train. 9. Cover next bore down to prevent loss of spring. Remove spring retaining sleeve and withdraw T.V. limit valve train. 10. From last bore, remove outer roll pin. Remove throttle valve bushing, plunger and spring. Remove inner pin as follows: Grind a taper to end of a No. 49 drill. Lightly tap tapered end of drill into roll pin. Pull drill and roll pin out. Remove throttle valve.

Fig. 33: Removing Throttle Valve Inner Roll Pin Courtesy of GENERAL MOTORS CORP. Cleaning & Inspection

1. Wash control valve body, springs, valves and other parts in clean solvent and air dry. Inspect valves for scoring, cracks and free movement in their bores. 2. Inspect bushings for cracks and scored bores. Inspect valve body for cracks, damage or scored bores. Inspect springs for distortion or collapsed coils. Inspect bore plugs for damage.

Fig. 34: Exploded View of Control Valve Assembly Courtesy of GENERAL MOTORS CORP. Reassembly

Reassembly is reverse of disassembly procedure. Reassemble control valve assembly using exploded view as a guide. See Fig. 34 .  



 

Install all flared roll pins (zinc coated) flared end out and from machined face of valve body. Install 2 tapered roll pins (Black finish) that retain throttle valve and throttle valve bushing, tapered end first. Roll pins do not fit flush on rough casting face. Ensure all roll pins are flush at machined face or damage to transmission will occur. Ensure all spring retaining sleeves are installed from machined face and that they are level with or below machined surface. Install all bore plugs with hole out. Install all valve sleeves so that slot in sleeve aligns with roll pin hole in valve body.

TRANSMISSION REASSEMBLY MANUAL SHAFT & PARKING PAWL PARTS 1. Turn transmission to horizontal position with oil pan side up. If removed, install new manual shaft seal with lip facing into case using a 9/16" socket to seat seal. Install parking pawl and spring into case with

tooth toward inside of case and spring under pawl tooth with spring ends toward inside of case. Ensure spring ends locate against case pad. 2. Align parking pawl and spring with case shaft hole. Install parking pawl shaft, tapered end first. Using a 3/8" diameter rod, install new parking pawl cup plug, open end out, past retaining pin hole. Install retaining pin.

Fig. 35: Manual Shaft & Parking Parts Courtesy of GENERAL MOTORS CORP. 3. While holding parking pawl toward center of transmission, install parking lock bracket and tighten attaching bolts. Assemble parking actuator rod on pin side of inside detent lever, locating lever between

actuator rod tangs. Install rod and detent lever into case with detent lever pin toward center of transmission and actuator plunger between parking pawl and parking lock bracket. NOTE:

File any burrs or raised edges off manual shaft that could damage manual shaft seal during installation of shaft.

4. Install manual shaft, small identification ring groove first, through case. Align inside detent lever with flats on shaft. Install detent lever on manual shaft. Install hex nut on manual shaft and tighten. Install manual shaft retaining pin, indexing with large groove on shaft. REAR GEAR PARTS 1. Install rear internal gear, hub end first, onto output shaft. Install rear internal gear-to-rear thrust bearing assembly, inside diameter race against gear, over output shaft and into internal gear. 2. Install roller clutch and rear carrier assembly into rear internal gear. Install output shaft loading fixture and support sleeve into rear of case. See Fig. 9 . Turn case to vertical position, pump end up. Install rear unit parts into case, indexing internal gear parking pawl lugs to pass by parking pawl tooth. 3. Using adjusting screw on output shaft loading fixture, adjust height of rear internal gear parking pawl lugs to align flush with parking pawl tooth.

Fig. 36: Installing Rear Internal Gear & Thrust Bearing Courtesy of GENERAL MOTORS CORP. 4. Oil and install low-reverse clutch plates into case starting with a flat steel plate and alternating composition and flat steel clutch plates. See LOW-REVERSE CLUTCH USAGE . Install waved steel plate on top of last flat steel plate. Install low-reverse clutch housing-to-case spacer ring in case. 5. Install low-reverse clutch housing into case, aligning feed hole in housing with reverse clutch feed passage in case. If clutch housing does not seat past case snap ring groove, install input drum and rear sun gear into case.

6. Rotate sun gear back and forth, tapping lightly with input drum to align roller clutch race with lowreverse clutch hub splines. Remove input drum and rear sun gear assembly. 7. Install low-reverse clutch-to-case snap ring with flat side against clutch (beveled side up). Position snap ring groove on opposite side of parking pawl rod. LOW-REVERSE CLUTCH USAGE Application Steel (1) 7 All Models

Composition 6

(1) Installed last is one waved steel plate .077" (1.96 mm) thick.

NOTE:

It may be necessary to loosen adjusting screw on output shaft loading fixture to install clutch-to-case snap ring.

8. If removed, install new low-reverse clutch housing-to-case cup plug and seal. Use a 3/8" diameter rod to drive cup plug and seal assembly into case until it seats against clutch housing. See Fig. 37 .

Fig. 37: Installing Low-Reverse Clutch Housing Cup Plug & Seal Assembly Courtesy of GENERAL MOTORS CORP.

FRONT GEAR PARTS 1. Install 4-tanged thrust washer on input drum over sun gear end. Align tangs into input drum and retain with petroleum jelly. Install rear sun gear and input drum assembly into case. 2. Install front sun gear into case and input drum with face of gear having identification groove against input drum. Install front sun gear-to-front carrier thrust bearing and race assembly into case with needle bearing against sun gear. 3. Install front carrier-to-front internal gear thrust bearing assembly on carrier with small diameter race against carrier. Install front carrier and thrust bearing assembly into transmission. 4. Install thrust washer on front internal gear and retain with petroleum jelly. Install front internal gear and thrust washer into case. Install rear unit end play selective washer into case with identification number on washer toward front of transmission. Install wide retaining snap ring. See Fig. 14 . NOTE:

At this point, recheck rear unit end play to verify that correct selective washer has been installed. See Rear Unit End Play in TRANSMISSION DISASSEMBLY .

5. Install output shaft-to-forward clutch shaft selective thrust washer into case and position washer. See Fig. 38 .

Fig. 38: Installing Front Selective Washer Courtesy of GENERAL MOTORS CORP. FRONT UNIT PARTS 1. Install intermediate band into case, locating band apply lug and anchor pin lug in case slot. Install band anchor pin. 2. Position direct clutch assembly, clutch plate end up, over hole in work bench. Align teeth of composition plates in direct clutch. Install forward clutch assembly, shaft first, into direct clutch assembly. Hold direct clutch and rotate forward clutch back and forth until fully seated. NOTE:

When forward clutch is fully seated, it will be approximately 5/8" from tang end of direct clutch housing to end of forward clutch drum.

3. Install direct and forward clutch assemblies into case and rotate into position. When assemblies are correctly installed, it will be approximately 4 1/8" from pump face in case to direct clutch housing. 4. Install center support-to-direct clutch thrust washer on center support. Visually align center support with case bolt holes and install center support into case. Install, but DO NOT tighten, center support attaching bolts. Install center support-to-case snap ring with beveled side up. Tighten center support attaching bolts.

NOTE:

At this point, recheck input shaft end play to verify that correct front selective washer has been installed. See INPUT SHAFT END PLAY .

OVERDRIVE UNIT PARTS 1. Install 4th clutch outer and inner seals on center support with lips facing down, apply petroleum jelly to seals. Install 4th clutch piston into case, aligning piston tab with wide case spline. Position return spring and retainer assembly on piston. Compress retainer assembly and install support-to-4th clutch spring snap ring. NOTE:

The 4th clutch inner seal, installed on center support, is identified by a White stripe.

2. Install internal gear-to-support thrust washer into case with tangs down. Install overdrive internal gear, hub end first, on forward clutch shaft. Install overdrive carrier-to-sun gear thrust bearing assembly into overdrive internal gear with large diameter race against carrier. 3. Grasp turbine shaft and lower overrun clutch and overdrive carrier assembly into case and rotate into position. Select proper 4th clutch plates. See FOURTH CLUTCH PLATE USAGE . Oil and install 4th clutch plates into case. See Fig. 39 . Install clutch pack retaining snap ring. Install oil deflector plate into case with tangs facing up. CAUTION: Note installation order of 4th clutch plates. The center has 2 steel plates together and thick plate is on top. Incorrect installation sequence will cause damage.

Fig. 39: 4th Clutch Plate Installation Sequence Courtesy of GENERAL MOTORS CORP. FOURTH CLUTCH PLATE USAGE Application Steel All Models 3

Composition 2

4. Install a new pump-to-case gasket on pump and retain with petroleum jelly. Install 2 alignment pins into pump attaching bolt holes opposite each other. Install pump assembly in case. Install pump attaching bolts with NEW washers. Remove alignment pins and install remaining bolts and washers. Tighten oil pump attaching bolts. NOTE:

At this point, recheck overdrive unit end play to verify that correct overdrive

end play thrust washer has been installed. See Overdrive End Play. EXTERNAL PARTS 1. Remove output shaft loading fixture and support sleeve from rear of transmission case. Turn transmission to horizontal position with oil pan side up. If removed, install new oil seal ring on governor shaft. Install governor assembly into case. Install governor cover and tighten attaching bolts. NOTE:

Ensure governor shaft is piloted in governor cover before tightening cover attaching bolts.

2. With correct band apply pin installed, as determined during transmission disassembly, install intermediate servo assembly into case. Ensure tapered end of apply pin is properly located against band apply lug. Install servo cover retaining ring and align ring gap with end showing in case slot. NOTE:

Intermediate servo cover seal rings must be well lubricated with petroleum jelly to prevent damage or cutting of ring.

3. Lubricate with petroleum jelly and install new "O" rings on case electrical connector. Install electrical connector with lock tabs facing into case, positioning locator tab in notch on side of case. 4. Install a new Teflon seal on 3-4 accumulator piston. Install accumulator pin in case. Install accumulator piston and spring. See Fig. 40 .

Fig. 40: Installing 3-4 Accumulator Assembly Courtesy of GENERAL MOTORS CORP. 5. Install 9 check balls into locations in case. See Fig. 41 . Install 2 valve body alignment pins into opposing bolt holes. Install spacer plate-to-case gasket (marked "C") on case. Install spacer plate. 6. Install valve body assembly-to-spacer plate gasket (marked "VB") on spacer plate. Position 1-2 accumulator plate and gasket in place on case, install accumulator spring on plate. Install a new Teflon seal on 1-2 accumulator piston, install piston in accumulator housing with dome up. Install 1-2 accumulator assembly. Install and tighten 5 attaching bolts in original positions. 7. Position the remaining 3 check balls in valve body. See Fig. 34 . Retain with petroleum jelly. Remove alignment pins. Install valve body assembly making sure to align manual valve with detent lever. NOTE:

It is possible during reassembly to position manual valve too far into valve body and still connect selective lever link to it. This will prevent valve body from fitting properly in case.

Fig. 41: Location of Check Balls in Bottom of Case Courtesy of GENERAL MOTORS CORP.

Fig. 42: Proper Positioning of Manual Valve & Selective Lever Link In Valve Body Courtesy of GENERAL MOTORS CORP. 8. Start 15 of 20 valve body attaching bolts in original positions. DO NOT thread the following bolts at this time: Throttle lever and bracket assembly, manual detent roller and spring assembly, and clip retaining bolts. Install signal oil pipe in valve body assembly. 9. Install manual detent roller and spring assembly, locating tang in valve body and roller on inside detent lever. If removed, install throttle and bracket assembly spring on top of lifter. Install link on throttle. Ensure link is hooked. See Fig. 43 . Install throttle lever and bracket assembly, locating slot in bracket with roll pin. Align lifter through valve body hole and link through T.V. linkage case bore. Install retaining bolt. 10. With locating pipe in hole, install 4-3 pressure switch (on non Computer Command Control models only) and attaching bolt. Install filter intake pipe "O" ring on pipe and coat with petroleum jelly. Install filter in pump bore. Install oil pan using a new gasket and tighten attaching bolts.

Fig. 43: Throttle Lever & Bracket Installation Courtesy of GENERAL MOTORS CORP.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Case-To-Center Support Converter-To-Flywheel Cooler Connector Governor Cover-To-Case Manual Shaft-To-Lever Nut Oil Pan-To-Case Park Lock Bracket-To-Case Pump Body-To-Pump Cover Pump-To-Case Transmission-To-Engine Accumulator Housing-To-Case Pressure Switch Pressure Take Off Plugs

Ft. Lbs. (N.m) 15-20 (20-27) 41-52 (55-70) 26-30 (35-40) 15-20 (20-27) 20-25 (27-34) 10-13 (14-18) 15-20 (20-27) 15-20 (20-27) 15-20 (20-27) 35 (47) INCH Lbs. (N.m) 84-120 (10-14) 60-120 (7-14) 60-120 (7-14)

Solenoid-To-Case Speedometer Retainer-To-Case Stator Shaft-To-Pump Cover Valve Body-To-Case

84-120 (10-14) 84-120 (10-14) 84-120 (10-14) 84-120 (10-14)

1983-93 AUTOMATIC TRANSMISSIONS Hydra-Matic 700-R4/4L60 Overhaul

APPLICATION THM 700-R4/4L60 APPLICATIONS Vehicle Application Buick Electra LeSabre Roadmaster Cadillac Brougham Fleetwood Chevrolet Astro Blazer Camaro Caprice Corvette Cutaway Van El Camino Hi-Cube Van Impala Monte Carlo Passenger Van Sport Van Suburban Pickup S10 & S10 Blazer Suburban GMC Caballero Cutaway Van Jimmy Magnavan Passenger Van Rally Van Safari School Bus

Engine 5.0L 5.0L 5.0L, 5.7L 5.0L, 5.7L 5.7L 2.5L & 4.3L 2.5L, 4.3L, 5.0L, 5.7L & 6.2L 2.5L, 2.8L, 3.1L, 5.0L & 5.7L 4.3L, 4.4L, 5.0L & 5.7L 5.7L 5.7L, 6.2L, 7.4L 4.3L & 5.0L 5.7L, 6.2L, 7.4L 4.3L, 4.4L, 5.0L & 5.7L 4.3L & 5.0L 4.3L, 5.0L, 5.7L, 6.2L, 7.4L 4.3L, 5.0L, 5.7L, 6.2L, 7.4L 5.7L, 6.2L, 7.4L 2.5L, 4.3L, 5.0L, 5.7L, 6.2L, 6.5L, 7.4L 2.0L, 2.2L, 2.5L, 2.8L & 4.3L 5.0L, 5.7L & 6.2L 4.3L & 5.0L 4.3L, 5.7L 5.0L, 5.7L & 6.2L 5.7L, 6.2L, 7.4L 4.1L, 4.3L, 5.0L, 5.7L & 6.2L 4.3L, 5.0L, 5.7L, 6.2L 2.5L & 4.3L 4.3L, 5.7L

Sierra Sonoma Pickup S15 Pickup & Jimmy Suburban Vandura Yukon Oldsmobile Bravada Custom Cruiser Pontiac Bonneville Firebird Grand Prix Parisienne Safari

4.3L, 5.7L, 6.2L, 7.4L 2.5L & 4.3L 2.5L, 4.1L, 4.3L, 5.7L & 6.2L 2.0L, 2.5L, 2.8L & 4.3L 5.0L, 5.7L & 6.2L 4.1L, 4.3L, 5.0L, 5.7L & 6.2L 5.7L 4.3L 5.0L, 5.7L 4.3L & 5.0L 2.5L, 2.8L, 3.1L, 5.0L & 5.7L 4.3L & 5.0L 4.3L, 5.0L & 5.7 5.0L

IDENTIFICATION Turbo Hydra-Matic 4L60 (previously 700-R4) transmission can be identified by a letter code contained in identification number. Identification number is stamped on transmission case above oil pan rail on right rear side. See Fig. 1 . Identification number contains information which must be used when ordering replacement parts.

Fig. 1: Identifying Transmission & Locating Circuit Taps Courtesy of GENERAL MOTORS CORP.

DESCRIPTION

Turbo Hydra-Matic (THM) 4L60 is a fully automatic trans-mission consisting of a 3-element hydraulic torque converter with a Torque Converter Clutch (TCC). Two planetary gear sets, 5 multiple-disc clutches, one sprag clutch, one roller clutch and a band provide friction elements necessary to produce 4 forward speeds, last of which is Overdrive. See Fig. 2 . A hydraulic system, pressurized by a variable capacity vane type pump, provides pressure required to operate friction elements and automatic controls. Transmission contains an auxiliary valve body for smoother Drive and Reverse engagement. Temperature switch may be used to apply TCC to prevent transmission overheating. Temperature switch reduces fluid temperature in Overdrive when TCC is not applied. Temperature switch mounts on valve body and sits in transmission pan fluid. See Fig. 37 . At normal operating temperature or less, switch is open. As fluid in pan heats to 270-286째F (134-140째C), switch closes to allow TCC to apply until fluid in pan cools to 250-268째F (121-131째C). Heat is reduced when TCC is applied and torque multiplication function of converter is bypassed. CAUTION: Ensure transmission contains auxiliary valve body before performing repairs. See Fig. 3 . NOTE:

See AUTO TRANS DIAGNOSIS - GM TORQUE CONVERTER CLUTCH article in AUTOMATIC TRANSMISSIONS for information on converter clutch system used in THM 4L60 transmission.

Fig. 2: Cut-Away View of 4L60 Transmission Courtesy of GENERAL MOTORS CORP.

Fig. 3: Locating Auxiliary Valve Body Courtesy of GENERAL MOTORS CORP.

LUBRICATION & ADJUSTMENTS See appropriate TRANSMISSION SERVICING - A/T article in the AUTOMATIC TRANSMISSION SERVICING section.

ON-VEHICLE SERVICE THROTTLE VALVE CABLE Removal

Remove air cleaner. Disconnect throttle valve cable from throttle linkage. Compress locking tabs. Remove cable from mounting bracket. Raise and support vehicle. Remove cable retaining bolt from transmission. Disconnect cable from transmission. Remove seal. Installation

To install, reverse removal procedure. Install NEW seal. Once cable is fully installed, pull upper end of cable.

Slight resistance should be felt due to return spring. Ensure cable fully returns. Adjust cable. See appropriate TRANSMISSION SERVICING - A/T article in the TRANSMISSION SERVICING section. GOVERNOR ASSEMBLY Removal

Raise and support vehicle. On some models, exhaust system components may require removal and transmission may require lowering to access governor cover. Remove governor cover and "O" ring. Remove governor assembly. Inspection

Inspect governor valve and sleeve for binding and scoring. See Fig. 4 . Ensure weights operate freely. Inspect governor drive gear for damage and loose fit on shaft. Replace governor if necessary. Installation

To install, reverse removal procedure. Install NEW cover seal or gasket. Apply thin coat of Loctite sealant on cover before installation. Ensure cover is fully seated. Ensure fluid level is correct.

Fig. 4: Exploded View of Governor Assembly

Courtesy of GENERAL MOTORS CORP. 2-4 SERVO ASSEMBLY Removal & Installation

1. Raise and support vehicle. On some models, exhaust system, drive shaft and crossmember may require removal and transmission may require lowering to access servo assembly. Install piston compressor (J29714) on 2 oil pan bolts. 2. Compress servo cover, and remove retaining ring. See Fig. 31 . Remove servo cover and "O" ring. Remove 2-4 servo assembly. To install, reverse removal procedure. For servo pin length check, see 2-4 SERVO ASSEMBLY under TRANSMISSION DISASSEMBLY. REAR OIL SEAL Removal

Raise and support vehicle. On some models, exhaust system may require removal to access rear oil seal. Remove drive shaft. Pry oil seal from extension housing. Installation

Coat NEW oil seal O.D. with non-hardening sealer. Using Seal Installer (J-21426), install oil seal into housing. To complete installation, reverse removal procedure. Check fluid level. AUXILIARY VALVE BODY Removal

Raise and support vehicle. Remove transmission oil pan. Remove oil filter and "O" ring. Ensure "O" ring is removed from transmission case. Remove clamp and pressure tube. Remove auxiliary valve body retaining bolts. Remove auxiliary valve body and check ball. See Fig. 5 . Note location of check ball. Installation

Coat check ball with petroleum jelly before installation. Install check ball in auxiliary valve body. To complete installation, reverse removal procedure. Lubricate "O" ring with petroleum jelly. Install new filter and "O" ring. Tighten bolts to specification. See TORQUE SPECIFICATIONS table. Fill transmission with fluid.

Fig. 5: Locating Valve Body Check Balls Courtesy of GENERAL MOTORS CORP. VALVE BODY CAUTION: Note valve body bolt length and location during removal procedure. Transmission case damage may occur if bolts are incorrectly installed. Removal

1. Disconnect throttle valve cable from throttle lever. Raise and support vehicle, and remove transmission oil pan. Remove oil filter and "O" ring. Ensure "O" ring is removed from transmission case. 2. Remove electrical connectors from switches (if required), and tag. Remove auxiliary valve tube to access valve body. Remove valve body bolts. Note length and location of bolts for installation. 3. Note direction of manual valve link. Remove manual valve link from manual valve at valve body. See Fig. 6 . Note direction of throttle valve link. See Fig. 7 . Remove throttle valve bracket and throttle valve link. Remove valve body. Note location of check balls. DO NOT lose balls. See Fig. 5 .

Fig. 6: Installing Manual Valve Link Courtesy of GENERAL MOTORS CORP.

Fig. 7: Installing Throttle Valve Link Courtesy of GENERAL MOTORS CORP. Installation

1. Coat check balls with petroleum jelly. Install check balls in proper locations on separator plate. See Fig. 5 . Install manual valve link. Ensure manual valve link is properly seated in manual valve. See Fig. 6 . Improper positioning may prevent vehicle operation in "D" range. NOTE:

Improper positioning of throttle valve link will result in erratic shift points or high main line oil pressure.

2. Install throttle link. Ensure link is properly positioned with lower hook facing outside of transmission case. See Fig. 7 . Install valve body and retaining bolts. Tighten bolts to specification. To complete installation, reverse removal procedure. 3. Lubricate oil filter "O" ring with ATF before installation. Tighten all bolts to specification. See TORQUE SPECIFICATIONS . Fill transmission with fluid.

TROUBLE SHOOTING NOTE:

For additional trouble shooting, see SERVICE BULLETINS . For clutch and band

application, see CLUTCH & BAND APPLICATION CHART under CLUTCH & BAND APPLICATION. 1ST GEAR ONLY, NO UPSHIFT Check governor assembly. Governor valve sticking. Driven gear loose or damaged. Drive gear retaining pin missing. Nicks or burrs on output shaft, governor sleeve or case bore. Improper support pin length. Governor weights or springs missing, damaged or binding. 1-2 shift valve sticking in valve body. Spacer plate or gaskets damaged or not positioned properly. Case-tovalve body face damaged or not flat. Governor screen restricted or damaged. 2-4 servo assembly restricted or blocked case passages. Nicks or burrs on servo pin or case pin bore. Missing or damaged piston or pin seals. 4th servo piston installed backward. 2-4 band worn or damaged or band anchor pin not engaged. SLIPS IN 1ST Defective forward clutch assembly. Clutch plates worn. Piston porous or damaged. Piston seals missing or damaged. Input housing-to-forward clutch housing "O" ring seal missing or damaged. Damaged housing. Housing retainer and ball assembly damaged or not seating. Input housing and shaft assembly turbine shaft seals missing or damaged. Accumulator valve stuck in valve body. Valve body face not flat, damaged lands, or interconnected passages. Spacer plate or gaskets incorrect, damaged or not positioned properly. Binding or broken T.V. cable. Defective 1-2 accumulator piston assembly. Porosity in piston or cover and pin assembly. Damaged piston ring grooves. Piston seal missing or damaged. Cover gasket missing or damaged. Broken accumulator spring. Improper oil pressure. Torque converter stator roller clutch not holding or 4th servo piston in backward. Damage to low roller clutch lugs or inner ramps. Rollers not free moving, inadequate spring tension or damage to inner splines. Oil passage plugged. Forward clutch accumulator piston seal missing or damaged. Piston out of its bore. Porosity in piston or auxiliary valve body. Abuse valve stuck in auxiliary valve body. HIGH OR LOW 1-2 SHIFT SPEEDS T.V. cable binding, broken or improperly adjusted. Governor assembly valve sticking. Driven gear loose or damaged. Drive gear retaining pin missing. Nicks or burrs on output shaft, governor sleeve or case bore. Improper support pin length. Governor weights or springs missing, damaged or binding. Throttle lever and bracket assembly damaged, binding or not installed properly. T.V. link missing, binding or damaged. Valve body face not flat, T.V. exhaust check ball stuck or T.V. plunger sticking. Oil pump assembly or case face not flat. SLIPPING OR ROUGH 1-2 SHIFT Throttle lever and bracket assembly damaged, not installed properly or T.V. cable broken or binding. Valve body assembly throttle valve sticking. T.V. bushing turned in bore. Defective valve body assembly. 1-2 shift valve train, line bias valve, accumulator valve or T.V. limit valve stuck. Gaskets or spacer plate incorrect, damaged or not installed properly. Body face not flat.

Defective 2-4 servo assembly. Apply pin incorrect length. Servo seals or "O" ring seals missing or damaged. Restricted or missing oil passages. Case servo bore damaged. Defective 2nd accumulator. Porosity in 1-2 accumulator housing or piston. Piston seal or groove damaged. Nicks or burrs in 1-2 accumulator housing. Missing or restricted oil passages or 2-4 band worn or not positioned properly. Oil pump assembly or case faces not flat. SLIPPING, ROUGH OR NO 2-3 SHIFT Internal converter damage. Governor valve sticking. Drive gear retaining pin missing or loose. Governor weights binding. Governor drive gear damaged. Support pin in case incorrect length. Oil pump stator shaft sleeve scored or not located properly. Valve body 2-3 valve train or accumulator valve stuck. Spacer plate or gaskets incorrect, damaged or not positioned properly. Throttle valve or T.V. limit valve stuck. Input housing assembly forward or 3-4 clutch plates worn. Excessive clutch plate travel. Forward or 3-4 piston seals damaged. Porosity in 3-4 clutch housing or piston, or 3-4 piston check ball stuck, damaged or not sealing. Restricted apply passages. Forward clutch piston or 3rd accumulator retainer and ball assembly not seating. Sealing balls loose or missing. 2-4 servo assembly or 2nd apply piston seals missing or damaged. SLIPPING, ROUGH OR NO 3-4 SHIFT Governor weights binding. Governor valve sticking. Drive gear damaged or retaining pin missing or loose. Support pin in case incorrect length. Oil pump assembly faces not flat or pump cover retainer and ball assembly omitted or damaged. Valve body assembly 2-3 valve train, accumulator valve, throttle valve, T.V. limit valve, 1-2 shift valve or 3-2 control valve stuck. Manual valve link bent or damaged. Spacer plate or gaskets incorrect, damaged or not positioned properly. Defective 2-4 servo assembly. Incorrect band apply pin. Servo seals missing or damaged. Porosity in pistons, cover or case. Plugged or missing orifice cup plug. Case 3rd accumulator retainer and ball assembly leaking. Porosity in 3-4 accumulator piston or bore. 3-4 accumulator piston seal or seal grooves damaged. Restricted oil passage. Defective input housing assembly. Forward or 3-4 clutch plates worn, or excessive plate travel. Forward or 3-4 piston seals damaged. Porosity in 3-4 clutch housing or piston. 3-4 piston check ball stuck, damaged or not sealing. Restricted apply passages. Forward clutch piston retainer and ball assembly not seating. 2-4 band worn or not positioned properly. Sealing balls loose or missing. NO "R" OR SLIPS IN "R" Defective input housing assembly. 3-4 apply ring stuck in applied position. Forward clutch not releasing. Turbine shaft seals missing or damaged. Manual valve link disconnected. Defective oil pump assembly. Retainer and ball assembly missing or damaged. Stator shaft seal rings or ring grooves damaged. Stator shaft sleeve scored or damaged. Reverse boost valve stuck, damaged or not assembled properly. Cup plug missing. Restricted oil passage. Faces not flat. Converter clutch apply valve stuck. Defective valve body assembly. 2-3 shift valve stuck. Manual linkage out of adjustment. Spacer plate and gaskets incorrect, damaged or not positioned properly. Defective reverse input clutch assembly. Clutch plate worn. Housing and drum assembly cracked at weld. Clutch plate or return spring assembly retaining ring out of groove. Piston deformed or dished.

Seals damaged or missing. Retainer and ball assembly not sealing. Restricted apply passage. Defective lowreverse clutch. Clutch plates worn or retaining ring not positioned properly. Porosity in piston. Seals damaged. Return spring assembly retaining ring not positioned properly. Case porosity. Case cover plate not tightened properly or gasket missing or damaged. Auxiliary valve body low overrun valve stuck. Cup plug restricted, missing or damaged. NO PART THROTTLE OR DELAYED DOWNSHIFTS T.V. cable loose or not adjusted properly. T. V. bracket assembly bent. Defective 2-4 servo assembly. Servo cover retaining ring missing or not assembled properly. 4th apply piston damaged or not assembled properly. Inner housing damaged or not assembled properly. Governor weights binding or governor valve stuck. Defective valve body assembly. Throttle valve, 3-2 control valve or T.V. modulated downshift valve stuck. T.V. sleeve turned in bore. 4-3 sequence valve body channel blocked. No. 5 check ball missing. NO OVERRUN BRAKING IN MANUAL 3-2-1 T.V. cable loose or not adjusted properly. Defective valve body assembly. 4-3 sequence valve or throttle valve stuck. No. 3 check ball not positioned properly. Spacer plate and gaskets incorrect, damaged or not positioned properly. Defective input clutch assembly. Turbine shaft oil passages plugged or not drilled. Turbine shaft seal rings damaged. Turbine shaft sealing balls loose or missing. Porosity in forward or overrun clutch piston. Overrun piston seals damaged or cut. Overrun piston check ball not sealing. DRIVES (CREEPS) IN NEUTRAL Forward clutch not releasing. Manual valve link disconnected. Converter clutch apply valve stuck in oil pump. Face of transmission case not flat or internal leakage in case. STARTS IN 2ND IN "D" Governor support pin too long or missing or governor valve stuck. Forward sprag clutch assembly installed backward. NO PARK Parking linkage binding, loose, missing or not positioned properly. OIL PRESSURE HIGH OR LOW Perform PRELIMINARY CHECKING PROCEDURE. See CONTROL PRESSURE TEST under TESTING. Oil pressure regulator valve stuck or valve spring damaged. Rotor guide omitted or not assembled properly. Rotor cracked or broken. T.V. or reverse boost valve or sleeve stuck, damaged or not assembled properly. Orifice valve in pressure regulator valve plugged. Sticking slide or excessive rotor clearance. Pressure relief ball not seated or damaged. Pump cover or body has porosity. Incorrect pump cover or pump face not flat. Excessive rotor clearance. Intake pipe restricted by casting flash. Cracks in filter body or intake pipe. "O" ring seal missing, cut or damaged. Incorrect grease used during rebuild procedure. T.V. exhaust ball stuck or damaged. Throttle link, lever and bracket assembly binding, damaged or not assembled properly.

Manual valve scored or damaged. Spacer plate or gaskets incorrect, damaged or not assembled properly. Face not flat. Throttle valve or T.V. limit valve sticking. Modulated downshift valve, line bias valve or 2-3 shift valve stuck. Check balls omitted or not assembled properly. Case-to-valve body face not flat. HIGH OR LOW SHIFT POINTS T.V. cable binding or not adjusted properly. T.V. exhaust ball stuck or damaged. Throttle lever and bracket assembly binding, damaged or not assembled properly. Pressure regulator valve or T.V. boost valve stuck. Pump slide sticking. Throttle valve or plunger sticking. Modulated T.V. upshift or downshift valves, T.V. limit valve or line bias valve sticking. Spacer plate or gaskets damaged, incorrect or not assembled properly. Valve body pad porous or damaged. Governor filter restricted or damaged. 2-4 accumulator has porosity. Servo piston seals damaged. Apply pin damaged or has improper length. 2-4 band burned or anchor pin not engaged. NO CONVERTER CLUTCH APPLY Transmission not supplied 12 volts. Outside electrical connector damaged. Inside electrical connector wiring harness or solenoid damaged. Solenoid wire pinched. Solenoid not grounded. Pressure switches incorrect or damaged. Temperature switch damaged. Converter internal damage. Converter clutch valve stuck or assembled backward, or retaining ring not positioned properly. Pump-to-case gasket not positioned properly. Orifice cup plug restricted or damaged. Solenoid "O" ring seal cut or damaged. Pump-to-body cover high or uneven bolt torque.Turbine shaft "O" ring seal cut or damaged. Turbine shaft retainer and ball assembly restricted or damaged. TCC shift valve or apply valve stuck. Solenoid "O" ring leaking. Solenoid screen is blocked. CONVERTER SHUDDER Torque converter has internal damage. Converter clutch valve stuck. Restricted oil passages. Crack in filter body. Flash restricting filter neck. "O" ring seal cut or damaged.Turbine shaft "O" ring cut or damaged. Turbine shaft retainer and ball assembly restricted or damaged. Low oil pressure. Engine not tuned properly. NO CONVERTER CLUTCH RELEASE Solenoid external ground. Converter internal damage. Converter clutch valve stuck. Converter clutch apply valve stuck in apply position. ECM external ground. RATCHETING NOISE Parking pawl return spring weak, damaged or not assembled properly. OIL LEAKING OUT VENT Chamfer in pump body rotor pocket too large. T.V. limit valve stuck. Fluid level overfilled. Cross leak out of pump body and cover.

VIBRATION IN REVERSE & WHINING NOISE IN PARK Oil pump broken vane rings. FRONT OIL LEAK Torque converter welded seam leaking. Damaged torque converter hub. Damaged front seal. NO REVERSE, SLIPS IN REVERSE, BAD ENGAGEMENT (NO BRAKING OR WEAK BRAKING IN MANUAL LOW) No. 5 check ball missing. Faulty low-reverse clutch. Reverse boost valve sticking. Reverse boost valve installed backward. PUMP BUSHING SPINS OUT, "WALKS" INTO SEAL, OR SEIZES TO CONVERTER HUB Transmission and engine center lines do not match. Excessive crankshaft runout (common on 6.2L). Bent flexplate (drive plate). Excessive converter hub runout. Pump bushing I.D. not centered in pump. Bushing too loose in pump. Not enough hub-to-bushing clearance. SLIP ON 2-3 SHIFT, FALLING OUT OF 3RD, REPEATED 3-4 CLUTCH OR 2-4 BAND FAILURE Leaking No. 7 check ball (direct clutch accumulator check valve located in case, visible through servo). Cracked input shaft. Input shaft sealing rings leaking. Leak at base of input shaft where shaft is pressed into drum. Pump cover bore (sealing ring surface) worn. Servo air bleed cup plug loose or blown out of case. Pumpto-case gasket misaligned or ripped. 3-4 air bleed ball in back of input drum leaking. 3-4 clutch piston seals leaking. Servo release side (large) sealing ring leaking in 2nd gear and dragging 3rd clutch. Band apply pin in case worn. Servo seized in case. Damaged pump. Stator sleeve turned in pump and partly blocking feed passage. Throttle valve sticking, causing delayed 3rd clutch circuit pressure rise during 2-3 shift. DELAYED OR NO FORWARD CLUTCH ENGAGEMENT, SLIPS OR CHATTERS IN 1ST GEAR Leak at forward clutch accumulator (auxiliary valve body) caused by accumulator pin "walking" out of oval hole in cover. NO 4TH GEAR, NO 3-4 UPSHIFT (STAYS IN 3RD, 2ND USUALLY OKAY) Leaking 4th gear piston sealing ring (inside servo cover). Excessive servo clearance allowing 4th piston to "walk" out of cover, leaking 4th apply oil out servo vent hole. Servo vent hole blocked (hole is at pan gasket surface). Leaking 4th signal switch. 3-4 relay valve installed backward. Aluminum disc missing from between 3-4 relay valve and hole pin. Servo feed tunnel cup missing from valve body. 3-4 shift valve stuck. Incorrect spring or spring too stiff at 3-4 shift valve. 3-4 accumulator air bleed cup plug blown out of case. Throttle valve sticks. FALLS OUT OF 4TH GEAR DURING COASTING Low line pressure at idle (weak pressure regulator spring).

BINDS UP ON 3-4 SHIFT (FEELS LIKE BRAKE DRAG) Forward pressure plate installed incorrectly. Too many plates in overrun clutch. Incorrect top steel plate installed in overrun clutch. NO FORWARD OR REVERSE GEARS (LINE PRESSURE READING OKAY) Mismatched converter input shaft or broken turbine hub. BINDS UP IN REVERSE Stator sleeve rotated out of position. Stuck 2-3 shift valve. Servo pin jammed in case. Stuck 3-4 relay or 4-3 sequence valve. NO REVERSE Reverse input drum cracked at weld or seals damaged. NO DRIVE IN DRIVE RANGE Torque converter stator roller clutch not holding. NO DRIVE IN OVERDRIVE RANGE Faulty output sprag. Teeth "hammered" out of forward friction plates. CLUTCH & BAND APPLICATION CLUTCH & BAND APPLICATION CHART Selector Lever Position "D" (Overdrive) First Gear Second Gear Third Gear Overdrive "D" (Drive) First Gear

Second Gear

Elements In Use Forward Clutch, Forward Sprag & Low Roller Clutch Forward Clutch, Forward Sprag & 2-4 Band Forward Clutch, Forward Sprag & 3-4 Clutch Forward Clutch, 2-4 Band & 3-4 Clutch Forward Clutch, Forward Sprag, Low Roller Clutch & Overrun Clutch Forward Clutch, Forward Sprag, Overrun Clutch & 2-4 Band

Third Gear

"2" (Intermediate) First Gear

Second Gear

"1" (Low) First Gear

"R" (Reverse) "N" Or "P" (Neutral Or Park)

Forward Clutch, Forward Sprag, Overrun Clutch & 3-4 Clutch Forward Clutch, Forward Sprag, Low Roller Clutch & Overrun Clutch Forward Clutch, Forward Sprag, Overrun Clutch & 2-4 Band Forward Clutch, Forward Sprag, Low Reverse Clutch, Low Roller Clutch & Overrun Clutch Low Reverse Clutch & Reverse Input Clutch All Clutches & Bands Released Or Ineffective

TESTING ROAD TEST 1. Operate vehicle in Overdrive. Accelerate using steady throttle pressure. Note shift points for 2nd, 3rd, Overdrive and TCC application. TCC application should occur in 3rd or Overdrive. 2. Torque converter clutch will not engage until engine coolant has reached a temperature of 130Â°F (54Â°C). Compare shift points to shift speed charts. See SHIFT SPEED CHARTS. If TCC application is not obtained, see AUTO TRANS DIAGNOSIS - GM TORQUE CONVERTER CLUTCH article in the AUTOMATIC TRANSMISSIONS section. 3. Operate vehicle in Overdrive normally at 40-55 MPH with throttle in half-open position. Ensure TCC releases, and note 3rd gear downshift point. Repeat procedure with wide open throttle. Ensure TCC releases, and note 2nd gear downshift point. 4. Operate vehicle in Overdrive normally at 40-55 MPH. Release accelerator while manually shifting transmission to 3rd gear. Ensure TCC releases and engine braking is felt, and note 3rd gear downshift point. 5. Operate vehicle in Overdrive normally at 40-45 MPH. Release accelerator while manually shifting transmission into 2nd gear. Ensure TCC releases and engine braking is felt, and note 2nd gear downshift point. 6. With transmission in Overdrive, accelerate normally to 25 MPH, allowing vehicle to upshift normally. Release accelerator while manually shifting transmission into 1st gear. Ensure TCC releases and engine braking is felt, and note 1st gear downshift point. 7. With transmission in Overdrive, accelerate to 4th gear with TCC applied. Release accelerator. Lightly apply brakes, and ensure TCC releases and note speed at which downshifts occur. Compare shift points noted to shift speed charts. See SHIFT SPEED CHARTS .

8. Place transmission in 3rd gear with vehicle stopped. Accelerate, and note 1st-2nd and 2nd-3rd shift points. Repeat procedure with transmission in 2nd gear. Note 1st-2nd shift point. Accelerate to 25 MPH. Ensure 2nd-3rd gear upshift does not occur and TCC does not engage. 9. Place transmission in 1st gear with vehicle stopped. Accelerate to 15 MPH. Ensure upshifts do not occur and TCC does not engage. With vehicle stopped, place transmission in Reverse and slowly accelerate to observe reverse gear operation. 10. Compare all shift points to shift speed charts. See SHIFT SPEED CHARTS . If shift points are not within approximate speed listed, see TROUBLE SHOOTING . Control pressure can also be checked. See CONTROL PRESSURE TEST . SHIFT SPEED CHARTS NOTE:

Shift speed charts are not available for 1983 through 1986 models.

Fig. 8: Shift Speed Chart (1987 Models Except Corvette) Courtesy of GENERAL MOTORS CORP.

Fig. 9: Shift Speed Chart (1987 Corvette) Courtesy of GENERAL MOTORS CORP.

Fig. 10: Shift Speed Chart (1988 Car Models) Courtesy of GENERAL MOTORS CORP.

Fig. 11: Shift Speed Chart (1988 Truck Models) Courtesy of GENERAL MOTORS CORP.

Fig. 12: Shift Speed Chart (1989 Models) Courtesy of GENERAL MOTORS CORP.

Fig. 13: Shift Speed Chart ( Models) Courtesy of GENERAL MOTORS CORP.

Fig. 14: Shift Speed Chart (1991 Models) Courtesy of GENERAL MOTORS CORP.

Fig. 15: Shift Speed Chart (1992 Models) Courtesy of GENERAL MOTORS CORP. CONTROL PRESSURE TEST Preliminary Checking Procedure

1. Ensure fluid level is correct and engine is in good operating condition before performing control pressure test. Ensure shift linkage is properly adjusted. See appropriate TRANSMISSION SERVICING - A/T article in the AUTOMATIC TRANSMISSION SERVICING section. 2. Control pressure can be checked to ensure proper throttle valve cable adjustment. If control pressure is not within specification, adjust throttle valve cable before attempting any other corrections. See THROTTLE VALVE CONTROL PRESSURE CHECK. Throttle Valve Control Pressure Check

1. Install pressure gauge on transmission line pressure tap. See Fig. 16 . Install tachometer on engine. Apply parking brake. Ensure engine is at normal operating temperature. 2. Operate engine at 1000 RPM. With gear selector in "P" position, note oil pressure reading. Move gear selector to "D" position, and note oil pressure reading. 3. Oil pressure "D" reading must be equal to "P" reading or must not exceed it by more than 10 psi (.70 kg/cm). Operate engine at 1400 RPM. Oil pressure should increase. Adjust throttle valve cable if pressure does not increase. See appropriate TRANSMISSION SERVICING - A/T article in the AUTOMATIC TRANSMISSION SERVICING section.

Fig. 16: Locating Line Pressure Tap Courtesy of GENERAL MOTORS CORP. CAUTION: DO NOT perform following pressure tests for longer than 2 minutes or transmission damage may occur. Minimum Throttle Valve Pressure Check

1. Ensure throttle valve cable is properly adjusted. Attach pressure gauge to line pressure tap. See Fig. 16 . Apply parking brake and service brakes. 2. Check line pressure as specified. See OIL PRESSURE SPECIFICATION CHARTS . Pressure readings must be within specification. If pressure reading is not within specification, see TROUBLE SHOOTING . Full Throttle Valve Pressure Check

1. Attach pressure gauge to line pressure tap. See Fig. 16 . Apply parking brake and service brakes. Ensure throttle valve cable is secured in fully extended position. 2. Check line pressure as specified. See OIL PRESSURE SPECIFICATION CHARTS . Pressure readings must be within specification. If pressure reading is not within specification, see TROUBLE SHOOTING . Pressure Differential Check

1. Possible leakage in clutch circuits may be determined by checking oil pressure differential between line pressure and 2nd, 3rd and 4th clutches. Attach pressure gauges to line pressure tap and appropriate clutch circuit tap on transmission. 2. Circuit tap for 2nd clutch is located on right rear side of transmission, above pan. Circuit tap for 3rd clutch is located next to 2-4 servo, above 4th clutch circuit tap. See Fig. 1 . Drive vehicle, and note both pressure readings. Pressure differential between line pressure and clutch circuits exceeding 10 psi (0.70 kg/cm2 ) indicates possible leakage in clutch circuit. OIL PRESSURE SPECIFICATION CHARTS

Fig. 17: Oil Pressure Specifications (1983 Models) Courtesy of GENERAL MOTORS CORP.

Fig. 18: Oil Pressure Specifications (1984 Models) Courtesy of GENERAL MOTORS CORP.

Fig. 19: Oil Pressure Specifications (1985 Models) Courtesy of GENERAL MOTORS CORP.

Fig. 20: Oil Pressure Specifications (1986 Car Models) Courtesy of GENERAL MOTORS CORP.

Fig. 21: Oil Pressure Specifications (1986 Truck Models) Courtesy of GENERAL MOTORS CORP.

Fig. 22: Oil Pressure Specifications (1987 Models Except Astro & Safari) Courtesy of GENERAL MOTORS CORP.

Fig. 23: Oil Pressure Specifications (1987 Astro & Safari) Courtesy of GENERAL MOTORS CORP.

Fig. 24: Oil Pressure Specifications (1988 Car Models) Courtesy of GENERAL MOTORS CORP.

Fig. 25: Oil Pressure Specifications (1988 Truck Models) Courtesy of GENERAL MOTORS CORP.

Fig. 26: Oil Pressure Specifications (1989 Models) Courtesy of GENERAL MOTORS CORP.

Fig. 27: Oil Pressure Specifications ( Models) Courtesy of GENERAL MOTORS CORP.

Fig. 28: Oil Pressure Specifications (1991 Models) Courtesy of GENERAL MOTORS CORP.

Fig. 29: Oil Pressure Specifications (1992 Models) Courtesy of GENERAL MOTORS CORP.

TORQUE CONVERTER NOTE:

Torque converter is a sealed unit and must be serviced as complete assembly.

STALL TEST 1. Torque converter whine is usually noticed when vehicle is stopped and transmission is in Reverse or Drive. Whine will increase when engine RPM is increased and will stop when vehicle is moving or when torque converter clutch is applied. Stall test is to ensure whine is coming from torque converter. 2. Start engine, and allow it to reach normal operating temperature. Apply parking and service brakes. Put transmission in Drive. Depress accelerator to approximately 1200 RPM for less than 6 seconds. DO NOT depress accelerator for more than 6 seconds or transmission damage may occur. Torque converter noise will increase under this load. NOTE:

Torque converter whine should not be confused with pump whine, which is usually noticeable in Park, Neutral and all other gear ranges.

STATOR CHECK 1. Torque converter stator roller clutch can either remain locked up at all times or freewheel in both directions. If stator is freewheeling at all times, vehicle tends to have poor acceleration from a stop. Vehicle may act normal at speeds above 30-35 MPH. 2. If poor acceleration is noted, ensure exhaust system is not blocked, engine timing is correct and transmission is in 1st gear when starting from a stop. If stator is locked up at all times, performance from a stop appears normal. Engine RPM and acceleration is limited at high speeds. Engine may overheat from this condition. 3. A visual inspection of torque converter may reveal converter is Blue from overheating. If torque converter has been removed from vehicle, stator roller clutch can be checked by inserting a finger into splined inner race of roller clutch and trying to turn race in both directions. Inner race should turn freely clockwise but should not turn or should be difficult to turn counterclockwise. END PLAY CHECK 1. Inspect torque converter for hub scoring, cracks or weld area cracks before checking end play. Install End Play Checking Tool (J-35138) on torque converter. See Fig. 30 . 2. Note end play of torque converter. End play must be within specification. See TORQUE CONVERTER END PLAY SPECIFICATIONS . Replace torque converter if end play is not within specification or damage to hub area exists. TORQUE CONVERTER END PLAY SPECIFICATIONS Converter Diameter: In. (mm) 9.65 (245.0) 11.73 (298.0)

End Play: In. (mm) .000-.020 (.00-.50) .000-.024 (.00-.61)

Fig. 30: Checking Torque Converter End Play Courtesy of GENERAL MOTORS CORP. CONVERTER FLUSHING Torque converter flushing is not recommended. Replace torque converter if contamination is found during oil cooler flushing procedure. NOTE:

For additional information on Torque Converter Clutch (TCC), see AUTO TRANS DIAGNOSIS - GM TORQUE CONVERTER CLUTCH article in the AUTOMATIC TRANSMISSIONS section.

REMOVAL & INSTALLATION See appropriate TRANSMISSION REMOVAL & INSTALLATION - A/T article in the TRANSMISSION SERVICING section.

TRANSMISSION DISASSEMBLY 2-4 SERVO ASSEMBLY 1. Mount transmission in Holding Fixture (J-8763-02). Remove torque converter. Clean outside of transmission case if necessary. Install Servo Cover Compressor (J-29714) on 2 oil pan bolts. See Fig. 31 . Compress servo cover. Remove retaining ring. Remove servo cover and "O" ring. 2. Remove 2-4 servo assembly. Servo pin length should be checked before disassembling assembly to determine 2-4 band and reverse input drum wear or damage.

Fig. 31: Compressing Servo Cover Courtesy of GENERAL MOTORS CORP. CHECKING SERVO PIN LENGTH 1. Remove 4th apply piston and return spring. See Fig. 32 . Remove retainer ring, washer, apply pin spring and 2nd apply piston pin. Install Piston Compressor (J-22269-01) on 2nd apply piston. See Fig. 33 . 2. Remove retainer ring, cushion spring and spring retainer. Install Band Apply Pin Tool (J-33037) and apply pin. See Fig. 34 . Apply 100 INCH lbs. (11 N.m) torque. Note White line on band apply tool. 3. White line should appear within gauge slot if pin length is correct. If White line does not appear, inspect

2-4 band and reverse input drum for wear and damage during disassembly. 4. Servo pin length must be checked during reassembly. Servo pin is preset and must not be readjusted. See SERVO PIN SPECIFICATIONS under 2-4 BAND & SERVO ASSEMBLY under TRANSMISSION REASSEMBLY.

Fig. 32: Exploded View of 2-4 Servo Assembly Courtesy of GENERAL MOTORS CORP.

Fig. 33: Compressing 2nd Apply Piston Courtesy of GENERAL MOTORS CORP.

Fig. 34: Measuring Servo Pin Length

Courtesy of GENERAL MOTORS CORP. EXTENSION HOUSING 1. Remove governor cover and "O" ring. Remove governor assembly. On models with mechanical speedometers, remove retaining bolt, washer and retainer. Remove speedometer driven gear assembly, driven gear and "O" ring. 2. On models with internal speed sensor, remove retaining bolt and washer. Remove speed sensor assembly and "O" ring. Remove extension housing retaining bolts. Remove extension housing and seal. Remove output shaft sleeve and "O" ring (if equipped). Speed sensor rotor must be removed from output shaft. 3. Install Gear Puller (J-21427-01) and Adapter (J-8433) on rotor. Pull rotor from output shaft. On models with mechanical speedometers, push retaining clip tab. Remove speedometer gear from output shaft. VALVE BODY & AUXILIARY VALVE BODY Remove valve body and auxiliary valve body. See VALVE BODY and AUXILIARY VALVE BODY under ON-VEHICLE SERVICE. Note bolt length and location during removal. Note check ball location for reassembly reference. 1-2 ACCUMULATOR & SPACER PLATES 1. Remove solenoid retaining bolts. Remove solenoid and "O" ring. Remove wiring harness, and note location for reassembly reference. Carefully remove accumulator cover retaining bolts, 1-2 accumulator cover and pin assembly. 2. Remove 1-2 accumulator piston, seal and spring. Remove spacer plate, and note check ball and filter locations. Remove spring, 3-4 accumulator piston and pin. Note spacer plate and gasket locations. See Fig. 35 for check ball and filter locations.

Fig. 35: Locating Check Balls & Filters Courtesy of GENERAL MOTORS CORP. TRANSMISSION END PLAY CHECK NOTE:

Check transmission end play before disassembly. If end play is not within specification, check for damaged components.

1. Position transmission with oil pump facing up. Remove one oil pump retaining bolt and washer, and replace it using an 11" bolt and lock nut. Install Pump Remover/End Play Fixture (J-24773-A) and End Play Adapter (J-25022-A) on end of turbine shaft. See Fig. 36 . 2. Clamp dial indicator on long bolt. Position indicator tip on end play fixture. Zero dial indicator. Pull up on pump remover. Note dial indicator reading. Transmission end play should be .005-.036" (.13-.91 mm). Check for worn components if end play is not within specification.

Fig. 36: Checking Transmission End Play Courtesy of GENERAL MOTORS CORP. OIL PUMP, INPUT CLUTCH & REVERSE CLUTCH 1. Ensure solenoid assembly and oil filter are removed before oil pump removal. Remove oil pump retaining bolts. Using Oil Pump Remover (J-37789-A) and Adapter (J-39119), pull pump assembly free from case. 2. Remove oil pump seal and gasket. Remove reverse input clutch-to-pump thrust washer from pump. Remove reverse and input clutch assembly by lifting out along with turbine shaft. 2-4 BAND & INPUT GEAR SET 1. Remove band anchor pin from case. See Fig. 37 . Remove 2-4 band assembly from case. Remove input sun gear. See Fig. 38 . CAUTION: Output shaft must be held in place when removing input carrier retaining ring.

2. Install Output Shaft Support (J-29837) on output shaft. See Fig. 39 . Remove input carrier to output shaft retaining ring. Remove input carrier. Remove output shaft. Remove input carrier thrust washer from reaction carrier shaft.

Fig. 37: Exploded View of 4L60 Transmission External Components Courtesy of GENERAL MOTORS CORP. LEGEND FOR FIGURE 37 Item No. 1 2 3 4 5 6 7 8

Description Converter Assembly Oil Seal Oil Pump Body Bushing Stator Shaft Bushing Oil Pump Pump Cover-To-Case Gasket Transmission Case Vent Assembly

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

Oil Cooler Pipe Connector Retaining Ring "O" Ring 2-4 Servo Cover 4th Apply Piston Oil Seal Ring Retainer Ring Washer Spring Servo Piston Housing 2nd Apply Piston Servo Cushion Spring Servo Spring Retainer Piston Pin Servo Return Spring Case Plug Electrical Connector Seal Extension Housing Bushing Speedometer Gear Retainer Speedometer Gear Assembly Speedometer Gear Speed Sensor Governor Cover Governor Cap Governor Pin Retaining Pin Driven Gear Plug Screen Retainer & Ball Assembly 3-4 Accumulator Piston 3-4 Accumulator Spring Spacer Plate Check Ball Band Anchor Pin Case Bushing Stator Shaft Bushing Seal Retainer

51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

Solenoid Gasket Carbon Ball Throttle Lever Link Bracket Assembly Valve Body Filter Oil Pan Magnet Solenoid Wire Conduit Detent Spring Clip Temperature Switch Accumulator Cover 1-2 Accumulator Piston 1-2 Accumulator Spring Tube Clamp Oil Tube Ball Auxiliary Valve Body

Fig. 38: Exploded View of 4L60 Transmission Internal Components Courtesy of GENERAL MOTORS CORP. LEGEND FOR FIGURE 38 Item No. 1 2

Description Thrust Washer 2-4 Band

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

Bushing Reverse Input Clutch Housing Piston Seal Spring Assembly Retainer Ring Belleville Plate Clutch Assembly Backing Plate Retaining Ring Bearing Assembly Check Valve "O" Ring Oil Seal Cup Plug Input Shaft Housing Assembly Clutch Boost Spring Assembly Check Ball 3-4 Clutch Apply Ring Retainer & Ball Assembly Forward Clutch Housing Snap Ring Overrun Clutch Assembly Overrun Clutch Hub Sprag Retainer Rings Sprag Assembly Forward Clutch Race Sprag Retainer & Race Forward Clutch Apply Plate Waved Plate Forward Clutch Assembly Clutch Retainer Plate 3-4 Clutch Apply Plate 3-4 Clutch Assembly Input Sun Gear Input Carrier Assembly Input Internal Gear Reaction Carrier Shaft Reaction Sun Gear Shell Reaction Sun Gear Low-Reverse Clutch Race

45 46 47 48 49 50 51 52 53 54 55 56 57 58

Low-Reverse Roller Clutch Support Reaction Carrier Assembly Oil Deflector Low-Reverse Clutch Assembly Spacer Plate Internal Reaction Gear Internal Reaction Gear Support Retainer Spring Output Shaft Rotor Clip Speedometer Drive Gear Output Shaft Sleeve Output Shaft Seal

Fig. 39: Installing Output Shaft Support Courtesy of GENERAL MOTORS CORP. REACTION GEAR SET 1. Remove input internal gear and reaction carrier shaft. Remove reaction sun shell and thrust washer. Remove sun shell-to-clutch race thrust washer. Remove support-to-case retaining ring.

2. Remove spring retainer from low-reverse support. Remove reaction sun gear, low-reverse clutch race, clutch roller, support assembly and reaction carrier assembly. See Fig. 38 . 3. Remove low-reverse clutch assembly. Note locations of components. Remove internal reaction gear and bearing assembly. Remove internal reaction support-to-case bearing assembly. LOW-REVERSE CLUTCH NOTE:

Parking pawl may require removal to access low-reverse clutch.

1. Remove parking lock bracket retaining bolts. Remove lock bracket. Using screw extractor, remove shaft plug. Remove parking pawl shaft, parking pawl and return spring if necessary. 2. Using Clutch Spring Compressor (J-23327), compress low reverse clutch spring retainer. Remove spring retaining ring and low-reverse spring assembly. Remove low-reverse clutch piston by applying air pressure in case apply passage. See Fig. 40 .

Fig. 40: Removing Low-Reverse Clutch Piston Courtesy of GENERAL MOTORS CORP. INNER MANUAL SHAFT LINKAGE Remove manual shaft nut. Remove manual shaft and retainer. Remove parking lock actuator assembly and inner detent lever. Using a screwdriver, remove manual shaft seal from transmission case. 3RD ACCUMULATOR CHECK VALVE

1. Check 3rd accumulator check valve before removing it. DO NOT remove check valve unless it is leaking. Install servo assembly in bore. Install servo cover and retaining ring. See Fig. 31 . Pour clean solvent in bore. Inspect for leaks in transmission case. Replace check valve assembly if it leaks. See Fig. 41 . Remove servo assembly. 2. For check valve removal, install No. 4 screw extractor in check valve assembly. Remove check valve. Ensure bore is free of burrs. Installation tool must be made to ensure proper installation depth is obtained. Using a 3/8" O.D. rod, scribe indicator mark at 1.653" (41.98 mm) from end of rod. Install check valve until scribe mark on rod is flush with case. See Fig. 41 .

Fig. 41: Installing 3rd Accumulator Check Valve Assembly Courtesy of GENERAL MOTORS CORP.

COMPONENT DISASSEMBLY & REASSEMBLY REVERSE INPUT CLUTCH Disassembly

1. Remove retaining ring from reverse input clutch housing. Remove backing plate, steel clutch plates, composition plates and Belleville plate. See Fig. 38 . Note number of clutch plates used. Using Clutch Spring Compressor (J-23327), compress reverse input spring assembly. 2. Remove retaining ring. Remove clutch spring compressor, and remove spring assembly. Remove piston and seals. Thickness of composition plates should be .068-.074" (1.73-1.88 mm). Selective thickness backing plate is also used. Inspection

1. Inspect backing plate and steel clutch plates for damage, distortion, flatness and burred edges. Inspect composition plates for signs of excessive heat and damage to tang areas. 2. Inspect spring retainer for distortion. Check piston for deformation or damage in seal ring area. Inspect clutch housing bushings for wear. Inspect clutch housing for dishing. Replace worn or damaged components as necessary. If components are replaced, ensure replacement components match those previously used. NOTE:

Soak clutch plates in ATF before installation.

Reassembly

1. Lubricate piston seals with ATF. Install seals on piston with seal lips facing away from hub. Install piston in clutch housing. Use small feeler gauge to position seals. Install spring assembly with large opening toward piston. 2. Using clutch spring compressor, compress spring assembly. Install retaining ring. Remove spring compressor. CAUTION: Ensure correct retaining ring is used. Ensure reverse input clutch retaining ring is not interchanged with low-reverse retaining ring. 3. Install Belleville plate. Note number of clutch plates to be installed. Install clutch plates. Install backing plate with chamfered side upward. Install retaining ring. Clearance must be checked to determine proper selective backing plate usage. Apply even pressure to backing plate using fingers. 4. DO NOT apply excessive pressure or Belleville plate will be distorted, resulting in inaccurate measurement. Using feeler gauge, measure clearance between retaining ring and backing plate. Clearance should be 040-.076" (1.02-1.94 mm). Select backing plate to obtain correct clearance. See BACKING PLATE SPECIFICATIONS . BACKING PLATE SPECIFICATIONS Identification

Thickness: In. (mm)

5 6 7 8

.293-.299 (7.44-7.59) .267-.273 (6.78-6.93) .241-.247 (6.12-6.27) .215-.221 (5.46-5.61)

VALVE BODY NOTE:

Valves are held in valve body by pins. Use care when removing pins. Valves may be under spring pressure. Note locations of all components during disassembly for reassembly reference.

Disassembly

1. Remove valve train, and note direction of valve installation. Remove all outside pins by pushing pins through from rough casting side of valve body. See Fig. 42 . 2. Remove blind pins using modified drill bit. Grind taper on end of a 1/16" drill bit. Drive drill bit into pin. Pull drill bit and pin straight out. Remove pressure switches. Note locations of all components. Inspection

1. Clean all components with clean solvent, and dry using compressed air. Ensure all components are placed in sequence for correct reassembly. 2. Inspect valves and sleeves for scoring and cracks. Ensure valves move freely in bores. Inspect valve body for cracks and scored bores. Inspect machined surfaces for damage. Inspect springs for damaged coils. Replace damaged components as necessary. Reassembly

For reassembly, reverse disassembly procedure. Ensure all components are installed in correct location. See Fig. 42 . Ensure pins are fully installed and do not extend into machined areas. Note position of valve lands and bushing passages.

Fig. 42: Exploded View of Valve Body Courtesy of GENERAL MOTORS CORP. LEGEND FOR FIGURE 42 Item No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Description Valve Body Pin Throttle Valve Spring Throttle Valve Plunger Sleeve 3-4 Valve 3-4 Relay Valve Plug Cup Plug 4th Clutch Pressure Switch Throttle Valve Limit Valve Throttle Valve Plug Retainer 1-2 Accumulator Valve Valve Sleeve Line Bias Valve 3-4 Pulse Pressure Switch 3-2 Control Valve

20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

3rd Clutch Pressure Switch Manual Valve T.C.C. Pressure Switch Modulator Downshift Valve Modulator Upshift Valve 3-4 Throttle Valve Sleeve 3-4 Throttle Valve Spring 3-4 Throttle Valve 3-4 Shift Valve 2-3 Shift Valve 2-3 Throttle Valve 2-3 Throttle Valve Spring 2-3 Throttle Valve Sleeve 1-2 Throttle Valve Sleeve 1-2 Throttle Valve Spring 1-2 Throttle Valve 1-2 Shift Valve

AUXILIARY VALVE BODY CAUTION: Note location of all components during disassembly for reassembly reference. Disassembly

1. Auxiliary valve cover is under spring tension. Carefully remove cover retaining bolts. Remove cover and spring. Remove piston and "O" ring. See Fig. 43 . Press low-overrun clutch valve downward. 2. Remove pin, spring and low-overrun valve. Remove pin, abuse valve stop, spring and abuse valve. DO NOT remove orifice plug unless it is damaged.

Fig. 43: Exploded View of Auxiliary Valve Body Courtesy of GENERAL MOTORS CORP. LEGEND FOR FIGURE 43 Item No. 1 2 3 4 5 6 7 8 9 10 11 12

Description Pin Spring Low-Overrun Clutch Valve Auxiliary Valve Body Orifice Plug "O" Ring Piston Cover Abuse Valve Abuse Valve Stop Piston Pin Check Ball

Inspection

1. Clean all components with clean solvent, and dry using compressed air. Inspect piston for cracks and roughness. Inspect valves and piston bore for nicks and scoring. Inspect springs for damaged coils. 2. Ensure valves operate freely in bores. Inspect valve body for damaged or rough machined surfaces. Ensure overrun valve pin is tight in valve body. If pin has come out of valve body, loss or slipping in "D" range may occur or forward and overrun clutches may be burnt. Reassembly

1. Install orifice plug (if removed) using 3/8" diameter rod. Orifice plug must be positioned flush with mounting surface. For reassembly, reverse disassembly procedure. 2. Install NEW "O" ring on piston. Lubricate "O" ring with petroleum jelly. Install piston and spring. Install cover and retaining bolts. Tighten bolts to specification. See TORQUE SPECIFICATIONS . LOW-REVERSE SUPPORT ASSEMBLY CAUTION: Note direction roller clutch is installed in support. Roller clutch must be installed in proper direction to provide lockup of inner race when rotated. Disassembly & Inspection

Remove inner race and retainer ring. Remove roller clutch assembly. Check inner race for damage and surface finish. See Fig. 44 . Inspect roller and springs for damage and distortion. Inspect support for loose cam, cracks and damaged surface finish. Replace damaged components as necessary. Reassembly

1. Install roller clutch assembly in low-reverse support. See Fig. 44 . Place support in case with hub facing downward. Install inner race. Rotate inner race while pushing downward. Use care not to damage roller and springs during installation. 2. Ensure inner race is fully seated. Bottom tangs will be flush with carrier hub when fully seated. Inner race should rotate clockwise and lock counterclockwise with clutch hub downward. Insert support retainer spring into case between case lug and open notch in support.

Fig. 44: Exploded View of Low-Reverse Clutch Assembly Courtesy of GENERAL MOTORS CORP. INPUT CLUTCH & FORWARD CLUTCH HUB ASSEMBLY Disassembly

1. Position input clutch assembly on bench. Remove snap ring retaining 3-4 clutch backing plate. Remove backing plate. Remove 3-4 clutch plates. Note number and locations of components. Remove 3-4 apply plate and clutch ring retainer. See Fig. 38 . 2. Remove forward clutch retainer ring, and remove backing plate. Remove forward clutch sprag assembly and bearing. Remove input housing seal. Remove forward clutch plates. Note number and locations of components. 3. Remove waved and apply plates. Remove overrun clutch plates (2 steel and 2 composition). Using Clutch Spring Compressor (J-23456) and Adapter (J-25018-A), compress overrun clutch spring retainer. 4. Remove retainer ring. Remove compressor, adapter and spring assembly. Remove overrun piston and forward clutch piston. Remove seals from pistons. Note direction of seals. Remove forward clutch housing. Remove 3-4 spring, 3-4 apply ring and piston. Remove "O" ring from input housing. Remove turbine shaft seal rings. 5. Remove forward clutch race. Remove snap ring and overrun clutch hub. Remove sprag retainer and race. Note direction race is installed. Use care not to lose rollers from roller cage. Inspection

1. Inspect sprag assembly for weak or damaged springs and retainers and worn rollers. Inspect overrun clutch hub for spline damage, excessive wear and open oil passages. Inspect retainer and race for spline damage, surface wear and damaged ring grooves. 2. Replace sprag assembly if damaged. Inspect forward clutch race for spline damage, excessive wear and open oil passages. Inspect input shaft and housing for spline damage, wear and open feed passages. 3. Inspect 3 sealing balls located in rear of turbine shaft for tightness. Turbine shaft contains one open lubrication hole. Ensure orifice plug is installed. 4. Inspect check valve located in end of turbine shaft for tightness in shaft. Check ball must move freely. Replace check valve if damaged. Inspect turbine shaft seal areas for roughness and burrs. 5. Inspect check ball located in input housing for free operation. Pour solvent in check ball, and check for leakage. Replace check ball if it leaks. 6. Inspect pistons for wear, damage and porosity. Inspect spring assemblies for damage and distortion. Inspect steel clutch plates for damaged tang ends, high or burned spots, excessive wear and distortion caused by heat. 7. Inspect composition clutch plates for damaged tang ends, burning, flaking and excessive wear. Inspect retainer rings for distortion and damage. Check backing plates for flatness and distortion. Inspect clutch apply rings for distortion and damaged tangs. 8. Inspect forward clutch housing check ball for proper operation (if equipped). Inspect housing for cracks and damage in seal areas. Inspect bearings for excessive wear, flatness, damage and flat rollers. Reassembly

1. If turbine shaft check valve requires replacement, straighten tangs of retainer and remove check ball. Using No. 4 screw extractor, remove check valve. Remove retainer from shaft by turning. 2. Position check valve in turbine shaft. Using a 3/8" diameter rod, drive retainer and check valve assembly into shaft. Check valve must be positioned 1/8" below top surface of turbine shaft. Ensure check ball is loose. 3. For input housing check ball replacement, drive retainer and ball assembly from housing using 1/4" diameter drift. Install NEW check ball assembly using 1/4" drift. Check ball assembly should seat on housing shoulder. Assemble forward clutch sprag assembly. 4. Install sprag assembly in forward clutch race. Notches located in sprag must face upward. See Fig. 45 . Install retainer ring on sprag retainer and race. Retainer ring flange must face away from retainer and race.

Fig. 45: Installing & Checking Clutch Sprag Assembly Courtesy of GENERAL MOTORS CORP. 5. Hold outer race in left hand. Support sprag assembly. Install sprag retainer and race in sprag assembly.

8. 9.

10.

11.

12.

Rotate retainer and race left. Install remaining retainer ring. Install overrun clutch hub. Install snap ring. Check sprag operation. Holding forward clutch race, rotate overrun clutch hub. Overrun clutch hub should turn freely clockwise and lock counterclockwise. See Fig. 45 . If lock operation is not correct, sprag assembly is installed backward. Place input clutch housing with turbine shaft downward. Install 3-4 piston seals with lips facing away from hub. Install 3-4 piston in input housing. Rotate and gently push downward. Ensure piston is fully seated. Measure 3-4 clutch apply ring from end of arm to base area that sets against 3-4 piston. Different size apply rings are used. Install 3-4 clutch apply ring. Install "O" ring in input clutch housing. Install forward clutch housing. Install seals on forward clutch piston with lips facing away from tangs. Install forward clutch piston in forward clutch housing. Install 3-4 spring on 3-4 clutch apply ring. Install forward clutch assembly on3-4 spring assembly. Align forward clutch piston legs with tangs of 3-4 apply ring. Install Seal Protector (J-29883) on input housing. Install 3-4 apply ring and forward clutch assembly in input clutch housing. Hold apply ring tangs while installing. DO NOT allow forward clutch piston to separate from assembly. Ensure assembly is firmly seated. Install Seal Protector (J-29883) on input housing. Install overrun clutch piston with hub facing upward. Remove seal protector. If fully seated, overrun piston should be 3/16" below top of snap ring groove in input housing hub. Install spring assembly on overrun piston. Install Spring Compressor (J-23456) and Adapter (J-25018-A) on spring assembly. Compress springs, and install snap ring. Remove spring compressor. Install input housing seal. NOTE:

Soak clutch plates in ATF before installation. Coat all seals and "O" rings with ATF. Coat thrust washers and bearings with petroleum jelly.

13. Install 4 overrun clutch plates, starting with steel plate. Align wide notches with case lugs. Install remaining clutch plates, alternating steel and composition plates. 14. Install bearing assembly on input clutch hub. Bearing inner race must face input housing hub. Ensure bearing is centered. Align clutch plate tabs. Install forward clutch sprag assembly in input housing. Align overrun clutch hub with clutch plates. 15. Install forward clutch apply plate in input housing. Install waved forward clutch plate. Ensure all plates are aligned with input housing tangs. Starting with steel plate, install clutch plates, alternating steel and composition plates. Install backing plate and retainer ring. 16. Using 2 feeler gauges, measure clearance between backing plate and retainer ring. Clearance should be .030-.063" (.75-1.60 mm). Install correct amount of clutch plates for model application. See FORWARD CLUTCH PLATE SPECIFICATIONS . Install backing plate with chamfered side upward. For backing plate thickness, see FORWARD CLUTCH BACKING PLATE SPECIFICATIONS . Install retainer ring. FORWARD CLUTCH PLATE SPECIFICATIONS Plate Type Quantity Apply 1 Waved Steel 1

Thickness In. (mm) .169 (4.29) .070 (1.78)

Flat Steel Composition Backing

5 5 1

.090 (2.29) .070 (1.78) Selective

FORWARD CLUTCH BACKING PLATE SPECIFICATIONS Identification Thickness In. (mm) A .274-.278 (6.96-7.06) B .251-.255 (6.38-6.48) C .228-.232 (5.79-5.89) D .205-.208 (5.20-5.28) E .180-.185 (4.57-4.70) 17. Install steel plate, composition plate and backing plate in reverse order of disassembly. Install clutch plates and backing plate with chamfered side upward. Install retainer ring. 18. Using feeler gauge, measure clearance between backing plate and first composition plate. Clearance is different depending on transmission model. See 3-4 CLUTCH PLATE SPECIFICATIONS . 19. Select proper backing plate to obtain correct clearance. See 3-4 BACKING PLATE SPECIFICATIONS . Air check all clutches by applying air pressure at feed holes in turbine shaft. 20. During overrun clutch test, air pressure will blow past forward clutch piston seals and exit out forward clutch feed hole in turbine shaft. Turbine shaft seals require sizing and should be installed just before oil pump installation. 3-4 CLUTCH PLATE SPECIFICATIONS Plate Type Stepped Apply Flat Steel (1)

Quantity 1 1

Flat Steel (2)

5 Or 6

.070 (1.78)

Composition (3) Backing (1) Same spline configuration as apply plate.

5 Or 6

.079 (2.01)

Thickness In. (mm) .183 (4.65) .070 (1.78)

Selective

(2) 6 plates on FBM, MBM and SAM models. (3) 5 plates on FBM, MBM and SAM models.

3-4 BACKING PLATE SPECIFICATIONS Identification FBM & SAM Models 5 6 All Others 7

Thickness In. (mm) .251-.259 (6.38-6.58) .218-.226 (5.54-5.74) .186-.194 (4.72-4.93)

.153-.161 (3.89-4.09)

OIL PUMP ASSEMBLY Disassembly

1. Remove reverse input clutch drum-to-pump thrust washer, pump-to-case gasket and pump-to-case oil seal ring from pump assembly. Remove pump cover retaining bolts. Separate pump cover from pump body. CAUTION: Pump slide spring and pressure relief spring rivet are under high pressure. To prevent possible injury, cover springs during removal. 2. Using needle-nose pliers, compress pump slide spring. Remove from pump by pulling straight out. Remove pump vane rings, pump vanes, pump rotor and rotor guide from pump pocket. 3. Remove slide from pump pocket. Remove slide seal and seal support from pump slide. See Fig. 46 . Remove pivot pin and pivot pin spring. Remove seal ring and "O" ring from pump slide. Remove seal retainer and seal from pump body. 4. Check condition of pump bushing. If bushing is in good condition, DO NOT remove it. Push inward on converter clutch valve stop to compress spring. Remove snap ring. Remove valve stop, converter clutch apply valve and springs. 5. Using a small punch, remove pressure relief spring retaining rivet. Remove relief spring and ball. Remove oil screen and "O" ring from pump cover. Using a small screwdriver, compress throttle valve boost valve bushing. Remove snap ring. 6. Remove Throttle Valve (T.V.) boost bushing, throttle valve boost valve and reverse boost valve sleeve. Remove reverse boost valve, pressure regulator valve spring and pressure regulator valve.

Fig. 46: Exploded View of Oil Pump Assembly Courtesy of GENERAL MOTORS CORP. LEGEND FOR FIGURE 46 Item No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Description Rivet Pressure Relief Spring Check Ball Stator Shaft Screw Cover-To-Body Bolt Converter Clutch Spring (Inner) Converter Clutch Spring (Outer) Converter Clutch Valve Valve Stop Snap Ring Pump Slide Spring (Inner) Pump Slide Spring (Outer) Oil Pump Cover Plug Oil Pump Cooler Feed Plug Oil Pump Converter Clutch Signal Plug Retainer & Ball Assembly Auxiliary Accumulator Valve Tube

18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

Rotor Guide Pump Vane Ring Seal Support Pump Slide Seal Bushing Seal Seal Retainer Pump Body Seal Ring "O" Ring Pivot Pin Spring Pivot Pin Pump Slide Vane Rotor Stator Shaft T.V. Boost Bushing T.V. Boost Valve Boost Valve Sleeve Reverse Boost Valve Regulator Valve Spring Pressure Regulator Valve Pump Cover Screen Oil Seal Ring Oil Pump Air Bleed Plug

Inspection

1. Inspect all valves, springs, sleeves and bushings for chips, burrs, distortion and freeness in bores. Check pressure relief ball and spring for damage and distortion, especially after metal contamination. Low main line pressure will exist if ball and spring are damaged. NOTE:

Use compressed air to blow out all passages, especially converter passage between TCC apply valve and stator support shaft. Metal particles commonly get lodged inside passage.

2. Inspect pump cover screen and "O" ring for wear and damage. Clean pump body and cover. Check all bores for obstructions. Inspect mating sides of cover and body for scoring, flatness and damage between channels. Check channels for dirt and damaged passages. Inspect stator shaft and pump body bushings for damage. 3. Inspect rotor and slide for scoring, cracks and damage. Check rotor guide and pump vane rings for excessive wear and damage. Inspect all seals for damage. Measure pump rotor and slide thickness in

undamaged area if replacement is required. Replacement components must be same size as those removed to provide proper end clearance. Reassembly

1. Lay pump body flat on bench, and install rotor into rotor and slide cavity. Lay straight edge over pump body and rotor. Use feeler gauge to check rotor-to-stator (cover) clearance. Specification is .0010.0015" (.025-.038 mm). If pump cover is replaced, ensure reverse input feed hole in stator hub is same diameter as in hub removed. 2. Install "O" ring and seal ring in groove on back side of pump slide. Retain seal ring using petroleum jelly. Install pivot pin and spring in pump body. Install pump slide. Notch in pump slide must align with pivot pin hole and with flat oil seal ring facing downward in pump pocket. Install slide seal and support. 3. Install pump vane ring into pump pocket. Coat rotor guide with petroleum jelly. Install rotor guide on rotor. Install rotor and guide into pump pocket with guide toward pump pocket. Install vanes in rotor. Install vane guide ring. Compress pump slide spring and install into pump pocket. All components must be even with pump body surface. Install "O" ring on pump screen, and install screen in pump cover with seal end last. 4. Using Seal Installer (J-25016), install seal in pump body. Install seal retainer. Install pressure relief check ball and spring in pump cover. Install retaining rivet. Install converter clutch valve springs and converter clutch valve. Install valve stop and snap ring. Install pressure regulator valve and spring in pump cover. See Fig. 46 . 5. Coat T.V. boost valve with petroleum jelly. Install T.V. boost valve in throttle valve bushing. Long area on valve must be positioned in large hole of bushing. Coat reverse boost valve with petroleum jelly. Install reverse boost valve in boost valve sleeve with small end first. Install reverse boost valve sleeve in pump cover. 6. Install T.V. boost valve sleeve in pump cover. Install snap ring. Ensure snap ring is fully seated. Install pump cover on pump body. Install retaining bolts finger tight. Align pump body and cover using Alignment Strap (J-21368). Place bolt through pump-to-case bolt hole. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS . Remove alignment strap. 7. Position NEW pump-to-case gasket on pump, and retain it using petroleum jelly. Install oil seal rings on stator hub. Retain oil seal rings using petroleum jelly. Install NEW pump-to-case oil seal on cover. Ensure seal is not twisted. Coat seal with ATF. Install pump-to-drum thrust washer. Ensure tangs on washer engage with holes in hub. 2-4 SERVO ASSEMBLY Disassembly

1. Remove 4th apply piston and housing from 2nd apply piston assembly. Remove return spring from apply pin. Install Piston Compressor (J-22269-01) on second apply piston. See Fig. 33 . 2. Compress 2nd servo apply piston assembly. Remove retainer ring. Separate 2nd apply piston, spring and retainer. Remove retainer ring, washer and spring from apply pin, and remove pin. Remove all oil seal rings. See Fig. 32 . Inspection

Inspect all pistons for porosity and damage. Check for ring groove damage and servo bore in case for any wear which may cut servo seals. Check all springs and oil seal rings for distortion and damage. Reassembly

Different servo piston housings and 2nd apply pistons are used for different applications. If servo piston housing or 2nd apply piston is replaced, inside dimension of components must be checked. Measure inside of piston housing and 2nd apply piston. Dimension must be same as original. To assemble, reverse disassembly procedure. Coat seals with petroleum jelly before assembly.

CLEANING & INSPECTION TRANSMISSION CASE Cleaning & Inspection

1. Clean case with solvent, and dry using compressed air. Inspect case assembly for damage, cracks and damaged bolt hole threads. Inspect valve body surface for flatness and land damage. Using compressed air, check case oil passages for restrictions and blockage. 2. Inspect case internal clutch plate lugs for damage and wear. Inspect speedometer, servo and accumulator bores for damage. Inspect all snap ring grooves for damage. Inspect governor support pin for proper length. Measure distance from governor cover surface to end of governor support pin. 3. Governor support pin length should be 3.30" (83.8 mm) measured from governor cover surface to end of support pin. Incorrect pin length may result in damaged governor gear. Replace transmission case if damaged. Ensure replacement case contains a ribbed area in valve body area. Rib area must be present for use with auxiliary valve body. CASE ATTACHING PARTS Cleaning & Inspection

1. Clean all components with clean solvent, and dry using compressed air. Inspect 1-2 and 3-4 accumulator components for damage to pistons or housing. Inspect for flatness and condition of accumulator, oil passage plate and gasket. 2. Inspect wiring harness leads and connectors for damage. Inspect coil and all connections for damage. Inspect speedometer gear and clip for tooth damage and distortion. REACTION & INPUT GEAR SETS, LOW-REVERSE CLUTCH & SUPPORT Cleaning & Inspection

1. Clean all components with clean solvent, and dry using compressed air. Inspect reaction and input carriers for pinion gear damage, excessive wear and improper staking of pinion pins. 2. Inspect carrier bearings for heat damage, flatness and roller condition by rotating top thrust washer. Check bearing located inside reaction carrier. Place output shaft sleeve inside reaction carrier and input carrier.

3. Rotate sleeve and note smoothness of bearing operation. Replace carrier assembly if roughness is felt. Check pinion gear end play on reaction and input carriers. 4. Pinion gear end play should be .008-.024" (.20-.61 mm). Replace carrier if pinion gear end play is excessive. Inspect internal reaction gear and support for cracks and damaged splines. Inspect low-reverse clutch plates for wear and signs of excessive heat. 5. Inspect low-reverse clutch piston for roughness or damage in seal ring area. Inspect retainer ring and spring assembly for damage. Inspect sun and internal gears and supports for spline and bushing wear and damage. Replace damaged components as necessary.

TRANSMISSION REASSEMBLY NOTE:

To identify seals, bearings and thrust washers locations, see SEALS, BEARINGS & THRUST WASHERS under TRANSMISSION REASSEMBLY.

LOW-REVERSE CLUTCH 1. Place transmission in a vertical position. Ensure piston is same dimension as that removed if replacement is required. Different thickness pistons are used. Install seals on low-reverse clutch piston. Coat seals with petroleum jelly. Install piston into transmission case. 2. Align piston with notch in bottom of transmission case. Ensure piston is fully seated and parking pawl aligns with opening in piston wall. Install spring assembly with flat side of retainer upward. Using Spring Compressor (J-23327), compress springs past ring groove in case hub. Install retainer ring. 3. Remove spring compressor. Coat bearing assembly with petroleum jelly. Install bearing assembly on case hub with outside bearing race toward case hub. Install internal reaction gear and support. Install bearing assembly onto support with outside bearing race toward support. Install oil deflector (if equipped) and reaction carrier assembly in case. See Fig. 38 . Ensure clutch plates are proper thickness. 4. Install correct number of clutch plates. See LOW-REVERSE CLUTCH PLATE USAGE . Ensure clutch plates align with splines of reaction carrier and case and that steel plates are aligned. Place waved plate on work bench. Install 5 composition plates and 4 steel plates alternately, starting with composition plate. LOW-REVERSE CLUTCH PLATE USAGE Type No. Used Flat Steel 4 Composition 5

Thickness: In. (mm) .069 (1.75) .088 (2.24)

5. Install low-reverse support. Apply light pressure to low-reverse support. DO NOT apply excessive pressure or waved plate will start to flatten, resulting in inaccurate measurement. Measure height of clutch pack from work bench to top of low-reverse support. Using height dimension, determine proper selective spacer plate to be used. See SPACER PLATE SELECTION . SPACER PLATE SELECTION Measured Clutch Pack Height In. (mm) (2)

(1) Plate Thickness In. (mm)

1.136-1.164 (28.85-29.57) .066-.073 (1.67-1.85) 1.107-1.136 (28.12-28.85) .094-.101 (2.39-2.57) 1.079-1.107 (27.41-28.12) .122-.129 (3.10-3.28) (1) Spacer plates are available in select sizes. Plate (8680439) has no identifying marks and is .066-.073" (1.67-1.85 mm) thick. All other plates have same GM part number (8680440) but are different thicknesses and have one of following stamped identifying marks: "0", "4" or "8". (2) Clutch pack height is measured without spacer plate in position. 6. Place spacer plate between waved plate and first composition clutch plate with identification facing upward. Measure overall height of clutch pack. Overall height should be 1.20-1.24" (30.5-31.5 mm). Install clutch pack assembly in transmission case. 7. Install low-reverse support in case with hub downward. Install inner race by pushing downward while rotating until it is fully engaged. Bottom tangs will be flush with hub when fully installed. Install spring retainer in case between case lug and open notch in support. Install low-reverse retainer ring. REACTION & INPUT GEAR SETS 1. Install snap ring on reaction sun gear (if removed). Install sun gear into reaction carrier. Install thrust washer on low-reverse clutch race. Install reaction sun gear shell on reaction sun gear. 2. Install thrust washer on reaction sun gear shell. Ensure thrust washer tangs engage on gear shell. Install input internal gear and reaction carrier shaft in sun gear shell. Carrier shaft splines must engage with reaction carrier. See Fig. 38 . 3. Install thrust washer on reaction carrier shaft. Outer race must face toward reaction carrier shaft. Install output shaft in transmission. Ensure output shaft engages with all components. 4. Install Output Shaft Support (J-29837). Adjust support so output shaft is positioned upward as far as possible. Install input carrier assembly with hub end down on output shaft. Install NEW retainer ring on output shaft. Remove output shaft support. Install input sun gear, indexing gear end with input carrier pinions. REVERSE INPUT ASSEMBLY & INPUT CLUTCH Install selective thrust washer on input housing. Install bearing assembly on selective thrust washer. Inner race (Black) must go toward oil pump. Position reverse input assembly on input clutch assembly. Reverse input clutch plates must align with input clutch hub. Ensure all clutch plates are fully engaged. REVERSE & INPUT CLUTCHES Install reverse and input clutch assemblies in case as an assembly. Align 3-4 clutch plates of input assembly with input internal gear. Assembly is fully seated when reverse housing is just below oil pump face of case. 2-4 BAND & SERVO ASSEMBLY 1. Install 2-4 band in case. Align band anchor pin end with case pin hole. Install band anchor pin in case. Ensure band anchor pin aligns with end of 2-4 band.

2. Install 2-4 servo assembly into case, and index apply pin on band end. Check for proper engagement of apply pin on band end. Recheck 2-4 servo apply pin selection to ensure correct pin is installed. See CHECKING SERVO PIN LENGTH under TRANSMISSION DISASSEMBLY. Different length servo pins are available. See SERVO PIN SPECIFICATIONS . Select proper length servo pin. SERVO PIN SPECIFICATIONS Pin ID 2 Rings 3 Rings Wide Band

Pin Length: In. (mm) 2.61-2.62 (66.3-66.5) 2.67-2.68 (67.8-68.1) 2.72-2.73 (69.1-69.3)

3. Install servo cover and "O" ring. Install Servo Cover Compressor (J-29714), and compress cover. Install cover retaining ring, indexing ring ends with slot in case. SEALS, BEARINGS & THRUST WASHERS NOTE:

To identify seals, bearings and thrust washers locations, see Fig. 47 .

Fig. 47: Exploded View of Seals, Bearings & Thrust Washers Courtesy of GENERAL MOTORS CORP. LEGEND FOR FIGURE 47 Item No. 1 2 3 4 5 6 7 8 9 10 11

Description Reverse Input Clutch Seals 3-4 Clutch Seals Input-To-Forward Housing "O" Ring Forward Clutch Seals Overrun Clutch Seals Low-Reverse Clutch Seals Pump-To-Input Drum Thrust Washer Stator Shaft Bearing Selective Thrust Washer Input Sun Gear Bearing Input Carrier-To-Reaction Shaft Thrust Washer

12 13 14 15

Reaction Shaft-To-Shell Thrust Washer Reaction Shell-To-Shaft Thrust Washer Reaction Carrier-To-Support Bearing Reaction Gear-To-Case Bearing

OIL PUMP ASSEMBLY 1. Turbine shaft seals should be installed just before oil pump installation. Position Seal Installer (J-364181) on input shaft. See Fig. 48 . Adjustment screw in seal installer must be adjusted to obtain correct height for each seal installation. Install 4 turbine shaft seals.

Fig. 48: Installing & Sizing Turbine Shaft Seals Courtesy of GENERAL MOTORS CORP.

2. Turbine shaft seals must be sized using Seal Sizer (J-36418-2A) after installation. Install aligning pins in 2 opposing pump bolt holes in case. Ensure thrust washer is installed on rear of oil pump. Thrust washer can be retained using petroleum jelly. 3. Install pump into case, aligning filter and pressure regulator holes with holes in case. Install retaining bolts. Tighten bolts to specification. See TORQUE SPECIFICATIONS . Place transmission in a horizontal position. 4. Turbine shaft should rotate by hand. If turbine shaft will not rotate, loosen pump retaining bolts and attempt to rotate shaft again. If shaft now turns, reverse and input assemblies have not been indexed properly or some other assembly problem has occurred, such as thrust washer not positioned properly. 5. Transmission end play should be checked. See TRANSMISSION END PLAY CHECK under TRANSMISSION DISASSEMBLY. Transmission end play should be .005-.036" (.13-.91 mm). If transmission end play is not within specification, thrust washer must be changed between oil pump and input housing. 6. Select proper thickness thrust washer. See OIL PUMP THRUST WASHER SPECIFICATIONS . Install thrust washer, and recheck end play. Install torque converter. Ensure converter hub is aligned with oil pump. Install torque converter retaining strap to hold converter. OIL PUMP THRUST WASHER SPECIFICATIONS Identification 67 68 69 70 71 72 73 74

Thickness: In. (mm) .074-.078 (1.88-1.98) .080-.084 (2.03-2.13) .087-.091 (2.21-2.31) .094-.098 (2.39-2.49) .100-.104 (2.54-2.64) .107-.111 (2.72-2.82) .113-.118 (2.87-3.00) .120-.124 (3.05-3.15)

1-2 ACCUMULATOR & SPACER PLATES CAUTION: If spacer plate and gasket replacement is required, ensure NEW spacer plate and gasket are identical as those removed. 1. Install 3-4 accumulator piston pin in case. Install 3-4 piston seal on piston. Install 3-4 accumulator piston on pin. Legs of piston must face valve body. 2. Install 3-4 accumulator spring. Install check balls and oil screens in proper locations. Install special retainer and ball assembly. See Fig. 35 and Fig. 36 for check ball and filter installation locations. Install spacer plate gasket and spacer plate. 3. Install 1-2 accumulator spring, oil seal ring and 1-2 accumulator piston. Install accumulator cover and bolts. Tighten bolts to specification. See TORQUE SPECIFICATIONS . VALVE BODY & AUXILIARY VALVE BODY Install valve body and auxiliary valve body. See VALVE BODY and AUXILIARY VALVE BODY under

ON-VEHICLE SERVICE. EXTENSION HOUSING 1. Install speedometer gear and retaining clip on output shaft. If output shaft has 2 locating holes, use hole nearest yoke on Corvette only. Install "O" ring in output shaft sleeve. 2. Using Seal Installer (J-25016), install output sleeve on output shaft. DO NOT position output sleeve past machined surface of output shaft. Install seal ring on extension housing. 3. Position extension housing on transmission case with speedometer bore on governor side of case. Install retaining bolts. Tighten bolts to specification. Using Seal Installer (J-21426), install oil seal in extension housing. 4. Install speedometer driven gear and fitting assembly. Install retainer and bolt. Tighten bolt to specification. See TORQUE SPECIFICATIONS . Install outside electrical connector and manual shift lever.

SERVICE BULLETINS NO UPSHIFT OR STUCK IN 1ST GEAR 1991 Custom Cruiser, 1991 Bravada & 1991-92 Roadmaster (GM TSB 177113R)

Some Hydra-Matic 4L60 transmissions may experience a no upshift or stuck in 1st gear condition. This condition may be caused by input carrier-to-output shaft retaining ring becoming unseated or retaining ring omitted during assembly. Output shaft is able to move slightly and will cause wear on governor driven gear. Governor driven gear wear may be described as an "apple coring" condition. If governor driven gear is worn, transmission cannot upshift out of 1st gear. Remove governor, and inspect governor driven gear. If "apple coring" condition exists, disassemble transmission to determine if retaining ring is unseated, broken or missing. See Fig. 49 . Install NEW retaining ring as necessary. DO NOT over expand new retaining ring during installation.

Fig. 49: Exploded View Of Input Carrier-To-Output Shaft Assembly Courtesy of GENERAL MOTORS CORP. LEGEND FOR FIGURE 49 Item No. 1 2 3 4 5 6 7 8 9 10

Description 3rd-4th Backing Plate Retaining Ring Bushing Input Sun Gear Output Shaft-To-Input Carrier Retainer Ring Input Carrier Assembly Bearing Input Internal Gear Reaction Carrier Shaft Thrust Washer

NO 3RD OR 4TH GEAR OR SLIPPING IN 3RD OR 4TH GEAR 1991-92 All Models (GM TSB 177119)

Some Hydra-Matic 4L60 transmissions may experience a no 3rd or 4th gear or slipping in 3rd or 4th gear condition. Ensure T.V. cable is adjusted correctly and fluid level is filled to correct level. Check cooler lines to ensure lines are not restricted. Remove transmission pan, and check transmission filter neck seal for proper fit. If seal does not seal properly around filter, air can enter into oil pump and cause low line pressure or aerated fluid. Replace seal if necessary.

If overhaul is performed, disassemble oil pump and inspect pump body bushing for wear. Replace bushing if necessary. A worn bushing can create a large leak in oil pump and lower line pressure, which can cause oil flow to be cut off. If oil pump bore has excessive wear in one area (out-of-round), replace oil pump body. Inspect 3-4 clutch boost springs for signs of polishing on spring tabs. Polishing is caused by 3-4 clutch friction plates rubbing on boost springs. Replace boost springs as necessary. Inspect input housing splines on inside of input housing. If splines show drag marks in middle spline, 3-4 clutch steel plates are binding in housing. New plates with smaller outer diameter are available to correct this condition. See REDESIGNED 3-4 STEEL CLUTCHPLATES under SERVICE BULLETINS. Check 2-4 band for a lube passage. If lube passage does not exist in 2-4 band, install new design 2-4 band with lube passage. Inspect 1-2 and 3-4 accumulator piston and bore for scoring caused by metal particles in transmission. Inspect 3rd accumulator exhaust check ball and retainer (located in case servo bore). Check ball may not seat due to metal particles stuck in bore. This will cause 2-4 band to drag or 3-4 clutch to not fully apply on 2-3 upshift. Ensure 3rd accumulator orifice cup plug (located in case servo bore) is not blocked. If metal particles block orifice, 3rd accumulator will not fill properly due to trapped air in cavity. This can effect 3-4 clutch. Orifice cup plug also lubricates 2-4 band through lube passage. Check 3-4 clutch exhaust check ball and retainer (located in input housing). Check ball helps exhaust 3-4 clutch. If check ball does not seat, 3-4 clutch cannot fully apply. If check ball is stuck in seated position, 3-4 clutch cannot exhaust fully. NO 4TH GEAR, LATE OR FALLS OUT OF 4TH GEAR 1991-92 All Models (ATRA TSB 043)

Ensure T.V. cable and manual linkage is adjusted correctly. Check line pressure at 4th gear transmission tap. If pressure does not exist, go to STEP "A" . If pressure is low, go to STEP "B" . If pressure is normal, go to STEP "C" . STEP "A"

If 4th gear pressure does not exist, check items which could keep transmission from shifting. Check for oversized tires. Oversized tires can reduce governor pressure. Ensure governor is operating correctly. Ensure valve body bolts are tightened to correct specification. Ensure pressure regulator snap ring is installed in its groove. Air check into exhaust hole at 4-3 sequence valve to check 4th apply servo circuit. Air check into exhaust hole at 3-4 shift valve to check 4th gear switch, 4-3 relay and sequence valve for sticking and binding. Check for missing plug at relay valve. Air check governor circuit for leaks, and check for sticking 3-4 shift valve. Check for missing cup plug. Remove valve body, and check for stuck valves, relay valve installed backward or plugs missing from upshift and downshift valves. Ensure gaskets are not covering separator plate holes. Check placement of check balls in case and 3-4 spring tension. STEP "B"

If 4th gear pressure is low, shift occurred but a leak exists in circuit. Remove transmission pan, and air check into exhaust hole at 4-3 sequence valve to check 4th apply servo circuit. Check for valve body leaks. Remove servo, and check for damaged seals, incorrect clearance and assembly errors. Check piston for cracks and pin bore for wear. Check 3-4 accumulator piston for cracks and damaged seal. Check for missing cup plug. STEP "C"

If 4th gear pressure is normal, a mechanical problem exists in transmission. Remove transmission pan, and check servo exhaust hole for blockage by pan gasket or sealant. Air check into 4th gear pressure tap. Air should come out 4-3 sequence exhaust hole, showing a clear circuit. Block 4-3 sequence exhaust hole, and air check again. Servo should apply. Remove servo, and check for stuck servo pin in second gear piston. Check for stripped sun gear shell. Stripped sun gear shell will cause loss of 2nd gear and Reverse. LOSS OF WIDE OPEN THROTTLE 3-4 UPSHIFT WHEN HOT 1991 Caprice 5.7L Police (GM TSB 077155)

Some 1991 Hydra-Matic 4L60 transmissions, models BFM, BPM & YNM with 5.7L engine, may exhibit a loss of wide open throttle 3-4 upshift when hot. When servicing this condition, install new T.V. boost valve and spring into oil pump cover. Install new 3-4 throttle valve, sleeve and spring into valve body. See Fig. 50 . If service is necessary on BFM model transmission, replacement of T.V. boost valve and sleeve in oil pump cover may not be required. Beginning September 24,1991 (Julian Date 267), transmission contains updated boost valve and sleeve. Beginning October 19, (Julian Date 292), BFM model transmission was replaced by BJM model transmission. BJM model transmission contains updated components. BFM, BPM & YNM MODEL TRANSMISSION SERVICE PARTS Description Throttle Boost Valve & Bushing, 3-4 Throttle Valve, Bushing & Sleeve Service Package NOTE:

Part Number 8673948

During high speed pursuit, vehicles should be driven in Overdrive for maximum power train performance. DO NOT install 1991 model transmission in earlier model vehicles. 1991 model transmission is not compatible with earlier model vehicles.

Fig. 50: Installing Throttle Valve & T.V. Boost Valve Assemblies Courtesy of GENERAL MOTORS CORP. REDESIGNED OUTPUT SHAFT & INPUT HOUSING-TO-OUTPUT SHAFT SEAL 1991 All Models (GM TSB 177118)

Due to changes in lube passage locations, Hydra-Matic 4L60 transmission output shafts and input housing-tooutput shaft seals have been redesigned to provide increased oil flow. Beginning January 28, 1991 (Julian Date 028), all transmissions were built using new output shaft and seal. New seal can only be used on new output shaft. If new seal is used on previous model output shaft, seal will block one lube passage. Previous seal can be used on both shaft designs. New output shaft and seal can be used as a set in all 4L60 transmissions manufactured. New output shaft can be identified by lube passage location. New shaft has a lube passage on chamfer at front of output shaft. Lube passage was previously located on shank of output shaft. REDESIGNED 3-4 STEEL CLUTCH PLATES 1991 All Models (GM TSB 077138)

Redesigned 3-4 steel clutch plates have a slightly smaller outer radius. Design lets plates move freely in clutch housing. Beginning July 27,1990 (Julian Date 208), all Hydra-Matic 4L60 transmissions are equipped with new design plates. New clutch plates may be used on any 1989-91 4L60 transmission. 3-4 STEEL CLUTCH PLATES Description 3rd & 4th Plate (Set Of 5 Plates) 3rd & 4th Plate (Single Plate)

Part Number 8678053 8678054

NEW 3-4 CLUTCH FRICTION MATERIAL 1991-92 All Models (GM TSB 177119)

New friction material on 3-4 clutch plates has been installed on limited applications of Hydra-Matic 4L60 transmission. New friction material has increased heat capacity but cannot be used interchangeably with previous friction material. New material was put into production during 1991 model year. Model codes changed as transmissions received new 3-4 clutch plates. New plates cannot be used to service any transmissions except those 1991 models listed. See 1991 TRANSMISSION MODEL LIST . Transmissions used with 5.7L engine were first to contain new plates, beginning in January 1991. NOTE:

DO NOT use new plates in any transmission which is not listed in 1991 TRANSMISSION MODEL LIST . If new plates are used in incorrect application, shift quality will be poor and transmission damage could occur quickly.

1991 TRANSMISSION MODEL LIST New (1) AMM APM CNM CYM

Previous AKM DBM CHM CJM

FYM FUM KWM KRM LHM None RCM RAM RDM WCM YHM YDM (1) New models contain new material. Previous models are early 1991 models which do not contain new material. PEENED SPACER PLATE 1991 All Models (GM TSB 177120)

Some valve body spacer plate peening is acceptable and preferred to help seat check balls. Excessive peening will cause uneven seating of check ball. Inspect spacer plate for raised material on opposite side of check ball seat. If material on opposite side is raised, peening is too severe and spacer plate must be replaced. See Fig. 51 . To verify spacer plate is peening evenly and check ball is sealing correctly, seat check ball on spacer plate. Shine beam of light on opposite side and inspect for light between spacer plate and check ball. Light should not be present. If light is present, check ball is not seated properly and spacer plate must be replaced.

Fig. 51: Checking for Spacer Plate Peening Courtesy of GENERAL MOTORS CORP. NOISE IN SHIFT LEVER 1991 Bravada (GM TSB 167103)

When driving vehicle, a squeak or buzz can be heard in shift lever. Possible cause can be found at connection of transmission shift lever and transmission control lever. Check for loose fitting of control lever to shift lever. A loose control lever can generate a vibration induced noise. To correct this condition, a wave washer should be installed on control lever. A second source of noise is a possible grinding out of shift lever with end of slot in control lever. This condition can be corrected by adding one or 2 flat washers as necessary to end of shift lever that is secured to frame. See Fig. 52 . Shift lever will center in slot in control lever, preventing grinding out condition. When wave and flat washers have been added to control lever, ensure shift linkage is adjusted correctly. Bravada vehicles built after Vehicle Identification Number (VIN) 1GHDT13Z2M2704746 have had new washers installed.

SHIFT LEVER SERVICE PARTS Description Wave Washer Flat Washer

Part Number 4722812 14074908

Fig. 52: Exploded View of Shift Lever Assembly Courtesy of GENERAL MOTORS CORP. VALVE BODY SLEEVE INSTALLATION 1991-92 All Models (ATRA TSB 058)

Valve body sleeves may be installed incorrectly if casting lines on end of sleeve are not within 10 degrees of vertical. Casting lines are visible without removing valve body. If casting lines are not within 10 degrees of vertical, retaining pin is installed into an oil slot, not into retaining groove. See Fig. 53 . NOTE:

Sleeves can be installed incorrectly even if casting lines are within vertical position.

Fig. 53: Locating Valve Sleeve Retaining Groove Courtesy of ATRA. OIL PUMP REMOVAL TOOL 1991-92 Bravada, Custom Cruiser & Firebird (GM TSB 277107)

Due to product changes in 4L60 Hydra-Matic transmission stator shaft, a new tool has been developed to remove oil pump assembly. New tool is an adapter for use with current pump puller. Because groove under stator shaft has been removed, previous tool cannot fit onto new shaft. With transmission removed from vehicle, remove torque converter. Position transmission in an upright position. Remove "O" ring and turbine shaft. Remove oil pump bolts, and install 4L60 adapter by slipping adapter over stator shaft. Install 4L80E pump puller over adapter. Tighten small screw to secure pump puller to adapter. Turn forcing screw to lift oil pump out of case. POSSIBLE BLOWN FUSES ON CIRCUITS 420, 422 OR 446 DUE TO SHORTED TCC WIRING 1989 B, C, D, F, G, K, M, R, S, T, V, & Y Body Vehicles

A breakdown in Torque Converter Clutch (TCC) wiring insulation may cause a short to ground which may affect vehicle's transmission, electrical system and engine performance. Short circuit may cause blown fuse, loss of A/C, ECM failure or instrument cluster failure. Die to electrical design differences, each vehicle line may show unique symptoms. A short in TCC wiring will

usually blow the circuit containing the TCC fuse. The TCC solenoid wiring harness was modified in production as of May 17, 1989 (Julian Date 137) in all 4L60 transmissions. NOTE:

Check vehicle wiring diagram and eliminate any other cause of blown fuses.

Checking Vehicle For Short To Ground

1. Turn off ignition. Unplug TCC wiring harness at transmission. Replace blow fuse. 2. Start engine. Check if short circuit is still present. If so, TCC wiring is probably not the cause. If short circuit is not present, continue with diagnosis. Check TCC Wiring Harness For Short To Ground

1. Turn off ignition. Unplug wiring harness from transmission case. Using self-powered test light or high impedance ohmmeter, check for short circuit between transmission case and terminal "A", and between terminal "D". 2. If short exists, replace TCC solenoid wiring harness. DO NOT attempt to repair wiring. Diagnostic Hints

1. If wire "A" (circuit 420) shorts to ground, check for blown fuse in 12-volt feed circuit. See TCC BATTERY FEED CIRCUIT . NOTE:

TCC BATTERY FEED CIRCUIT does not include all possible fuses. Check vehicle wiring diagram.

TCC BATTERY FEED CIRCUIT Vehicle Type & Body Check For Blown Fuse (Circuit Code 420) Passenger Cars B Gauges D G.A. Trans F Gauges Y Gauges Light Trucks & Vans C/K ECM/Ignition M Gauges R/V Gauges/Idle G Gauges S/T Ignition/Gauges

2. If wire "D" (circuit 422) shorts to ground, 3 different conditions may occur:  TCC may engage if transmission is too hot and there is short in White wire between TCC and TCC switch.  Engine may idle rough. If transmission has 4th gear switch and there is short between ECM and switch, ECM always receives signal that transmission is in 4th gear. This may affect engine performance if spark timing depends on gear position. 3. If wire "B" (circuit 446) shorts to ground, TCC will engage after a 1-2 shift (all except S and T truck with 2.5L engine). DIAGNOSIS INFORMATION FOR POSSIBLE INOPERATIVE TORQUE CONVERTER OR RELATED CONDITION 1985-87 F (2.8L), M, S & T Body Vehicles

1. Causes for possible torque converter failure are as follows:  Broken damper plate rivet (inside the converter)  Broken or loose spring tips  Broken or loose converter pump vanes  Broken converter turbine hub  Damaged seals causing hydraulic leak  Delamination of converter clutch apply plate fiber material 2. Symptoms that a vehicle may exhibit upon or during torque converter operation are as follows:  Shudder and/or vibration during torque converter clutch apply  No upshift due to fiber material sticking valves and/or fiber material and metal particles in filter  No Drive and/or Reverse  Converter sprag inoperative (no torque multiplication)  Noisy converter bearing or excessive end play  Pinging noise (constantly)  Vibration, out of balance, loose vanes (noisy)  Vehicle may exhibit shudder or no TCC apply. Torque converter clutch lining delaminating due to coolant contamination from transmission cooler  Torque converter clutch crowd shudder condition: This condition is caused by a leak in the TCC circuit which could cause excessive slippage and wear away the fiber lining on the TCC apply plate. Possible causes for TCC solenoid "O" ring, valve body gaskets. Worn TCC accumulator piston pin or seal.  TCC apply shudder caused by converter dampener plate not parallel.  A whine noise when shifted into drive that may increase when brake torqued. Torque converter whine is usually noticed when the vehicle is stopped and when the transmission is in Drive or Reverse. The noise will increase when the vehicle is moving and there is no torque multiplication (both halves of the torque converter are turning at the same speed) or when the torque converter clutch is applied. 3. With foot on brake and Gear Selector in Drive, depress accelerator to approximately 1200 RPM for no

more than 6 seconds (Stall Test). A torque converter noise increases under load. NOTE:

This noise should not be confused with pump whine noise which is usually noticeable in Park, Neutral and all other gear ranges. Pump whine will vary with pressure ranges.

4. The torque converter should be replaced under any of the following conditions:  Vehicles have TCC shudder and/or No TCC apply but, only after all Electrical and Hydraulic diagnosis has been made (Converter Clutch material may be glazed)  Evidence of damage to the pump assembly or steel particles in converter  Steel particles are found after flushing the cooler and cooler lines  External leaks in the hub weld area  Converter pilot is broken, damaged or poor fit into crankshaft.  Converter hub is scored or damaged  Internal failure to stator roller clutch  Contamination from engine coolant  Excess end play found after checking converter for end play  Steel particles or clutch lining material found in fluid filter or on magnet when no internal parts in unit are worn or damaged indicating lining material came from converter.  Heavy clutch debris due to overheating (Blue Converter) NEW LOW & REVERSE CLUTCH SUPPORT & SELECTIVE PLATE DIMENSIONS B, C, D, F, G, K, L, M, R, S, T, V & Y Body Vehicles

1. Dimensional change has been made in low and reverse clutch support and its selective plates. Thickness of low and reverse clutch support has increased while thickness of selective plates has decreased. Three selective plates are available. Productions change was initiated as follows:  Low and Reverse Clutch Support November 1, 1989 (Julian Date 305) and Selective Plates February 2, (Julian Date 033). 2. In most cases, new low and reverse clutch assembly will only require fifth reactions plate instead of selective plate. To identify low and reverse clutch support, measure its thickness with a micrometer. 3. The new low and reverse clutch support and selective plates may be used to service a post model year transmission if:  Transmission was built after February 9, 1987 (Julian Date 040) NOTE:

Selective plates are not interchangeable between previous clutch support and new clutch support. If selective plates are installed in the wrong clutch assembly, durability or low and reverse clutch will be reduced.

4. The following is service parts information:

NEW LOW & REVERSE CLUTCH ASSEMBLY Part Name Part No. Selective Plate 8673548 Selective Plate 8673549 Selective Plate 6261120 Clutch Support N/A Low & Reverse Clutch & Support 8673544 Assembly

Dimension: In. (mm) .0459-.0519 (1.168-1.314) .0865-.0922 (2.198-2.344) N/A .3020-.3090 (7.671-7.849) N/A

PREVIOUS LOW & REVERSE CLUTCH ASSEMBLY Part Name Part No. Selective Plate 8667584 Selective Plate 8667585 Clutch Support N/A Low & Reverse Clutch & Support 8663094 Assembly

Dimension: In. (mm) .0939-.1007 (2.386-2.557) .1221-.1288 (3.101-3.272) .2620-.2720 (6.655-6.909) N/A

CLUTCH APPLY PLATES-MATERIAL CHANGED TO POWDERED METAL IN FORWARD & 3-4 CLUTCHES B, C, D, F, G, K, L, M,, S, T, V, & 7 Body Vehicles

The forward and 3-4 clutch apply plates will now be manufactured from powdered metal instead of steel. Production change was as follows: Forward - January 25, (Julian Date 025), 3-4 - January 29, (Julian Date 029) The new powdered metal plates are interchangeable with current steel plates. Part Numbers have changed as listed in 3-4 CLUTCH APPLY PLATE . 3-4 CLUTCH APPLY PLATE Part Number 8663785 8667423 8676059 8676379

Description Apply Plate - Forward Clutch (steel) Apply Plate - 3-4 Clutch (steel) Apply Plate - Forward Clutch (powdered metal) Apply Plate - 3-4 Clutch (powdered metal)

NOISE/VIBRATION WITH TORQUE CONVERTER CLUTCH APPLIED (REPLACE TORQUE CONVERTER K7020) 1989-91 S/T Trucks, 1989-90 C, G, L & M Body Vehicles (4.3L LB4 Engines Only)

The transmission may produce a noise or vibration with the torque converter clutch (TCC) applied. This may happen if the damper spring stops in the torque converter damper bottom out against the damper plate. This may occur in Hydra-Matic 4L60 models that are used with 4.3L LB4 engines.

Date of Production Change

The following dates show which transmissions contain torque converters with damper springs that may bottom out against the spring stops. TORQUE CONVERTER WITH DAMPER SPRINGS Model 9FMM, 9MAM, 9MFM, 9MXM, 9TH, 9TLM 0CAM, 0CAM, 0WAM 0SHM 0TLM 0MJM, 0MNM

Date of Production Some after December 9, 1988 Julian Date 343) All before February 20, Julian Date 051) All before February 20, 1990 Julian Date 051) All before February 14, 1990 Julian Date 045) All before February 2, 1990 Julian Date 033)

Diagnosis

The following information will help you determine if vehicle has a vibration condition caused by damper spring stops bottoming out in the torque converter. ď Ź ď Ź

Gear Range: Drive 4 (overdrive) with TCC engaged Vehicle Speed: Approximately 40-50 MPH with TCC engaged - then step into the throttle slightly

Conditions: 1. Noise, vibration or rattle 2. Low frequency noise that builds up until the floorboards rattle 3. Low growl or driveline grumble Road grades or trailer loads may cause conditions to be more prominent or extended. The condition should disappear when the TCC is disengaged. To eliminate this condition, a Torque Converter Assembly Package (8678979) containing damper springs with a higher spring rate and improved torque capacity has been released for production and service. ERRATIC OR NO UPSHIFT 1989 B, C, E, F, K, M, R, S, T, V & Y Body Vehicles

A Hydra-Matic 4L60 transmission with an erratic or no upshift condition may be due to "Applecoring" or the governor driven gear. "Applecoring" may be caused by nicks and burrs on the governor drive gear. Beginning July 6, 1987 all transmissions were produced with the new governor driven gear and pin package (8663995). REDESIGNED CLUTCH PISTON SEAL 1989 B, C, F, G, K, M, R, S, T & Y Body Vehicles

Beginning February 28, 1989, all 1989 Hydra-Matic 4L60 transmissions have been built using the new short lip

design. Short lip seals are interchangeable with previous seals. All eight seals are available in overhaul kit or in two separate packages. See NEW PISTON SEAL PACKAGES . NEW PISTON SEAL PACKAGES Part Number Description 8642919 3-4 Clutch Piston Inner and Outer Seals, Forward Clutch Piston Inner and Outer Seals, Overrun Clutch Piston Inner and Outer Seals 8657922 Reverse Input Clutch Piston Inner and Outer Seals PROPER SPACER PLATE GASKETS USAGE 1982-89 B, C, F, G, K, M, R, S, T, V & Y Body Vehicles

Two sets of spacer plate gaskets are supplied with each transmission overhaul service kit. One set is for use on model years 1982-86, and the other set for model years 1987-89. The difference between the two sets of gaskets is the addition of holes in 1987 to accommodate an auxiliary valve body. If the incorrect (1982-86) gasket set is used on a 1987-89 model year transmission, with or without an auxiliary valve body, the third clutch exhaust passage will be blocked. This may cause slipping or flaring during a 3-2 shift, a delayed 3-2 downshift, or a burned 3-4 clutch. See PROPER SPACER PLATE GASKET SELECTION . PROPER SPACER PLATE GASKET SELECTION Model Year Part No.: Gasket Set Only 1982-86 8642993 1988-89 8657938

Part No.: Output Kit 8649995 8649995

LOSS OF WIDE OPEN THROTTLE 3-4 UPSHIFT WHEN HOT 1989 B Body (5.7L Police Only)

Some 1989 Hydra-Matic 4L60 YNM Model transmissions, a 5.7L (Police only) may exhibit a loss of wide open throttle 3-4 upshift when hot. Beginning April 24, 1989, all YNM model transmissions were built with a new control valve assembly containing the new 3-4 throttle valve and sleeve. When servicing for a no wide open throttle 3-4 upshift when hot, install the new 3-4 throttle valve and sleeve. The new control valve assembly is also available if it is necessary to replace the control valve assembly complete. See YNM MODEL SERVICE PARTS . YNM MODEL SERVICE PARTS Part Number 8671953 8673413 BINDING OR INOPERATIVE IN REVERSE

Description 9YNM - 3-4 Throttle Valve and Sleeve Service Package 9YNM - Control Valve Assembly Complete

1982-89 B, C, F, G, K, M, R, S, T, V & Y Body Vehicles

When servicing a transmission for a binding in reverse condition, remove the control valve assembly and inspect the 4-3 sequence valve and the 2-3 shift valve. Either valve, if stuck in the upshifted position, will result in a binding condition. To correct this condition, the valve body must be completely disassembled and reconditioned. Inspect the transmission bottom pan for clutch material or burned fluid. Evidence of this will require further transmission diagnosis. Repairs may include complete transmission reconditioning, including disassembly and reconditioning of the transmission pump and possible torque converter replacement. Complete the cleaning of the hydraulic circuit by changing the transmission fluid and filter and flushing the transmission cooler and cooler pipes. CAUTION: Overtorquing the bolts during unit reassembly can cause valve to bind. This condition may become more apparent as the unit warms to operating temperature. Correct bolt torque specifications for control valve assembly are 72-120 INCH lbs. (8-14 N.m). Torquing bolts to minimum specification, 72 INCH lbs. (8 N.m) is recommended. DRIVELINE CLUNK DURING GARAGE SHIFT OR HARD ACCELERATION C Bodies

Vehicles may exhibit a clunking noise during a garage shift or a driveline clunk during hard acceleration. Vehicles may be affected if they were built within the following VIN numbers ranges: ď Ź ď Ź

Chevrolet: 1GCDC14K2LZ100013 - 1GCDC14Z2LZ101290 GMC: 1GTDC14Z1LZ500000 - 1GTDC14KXLZ500368

This condition can be repaired by installing a reinforcement plate in the tailshaft crossover support. To install, remove the nut and washer from the underside of the transmission crossmember. Install reinforcement plate (15567681) onto the bolt that passes through crossmember and replace the washer and nut. Torque the nut 40 ft.lbs. (54 N.m). 2-4 BAND CHANGES 1989 B, C, D, F, G, K, L, M, S, T, V & Y Body Vehicles

A new transmission 2-4 band has changes to the apply and anchor brackets, locating tabs, and the addition of a "lube window". The lube window was added to direct lubricating transmission fluid to the bank friction material while the band is not applied. Structural changes to the apply and anchor brackets increase their durability and the locating tabs were added to aid in assembly. The new band is interchangeable with the previous band and should be used for service whenever possible. As soon as the previous bands are used up, the new bands will become available. See 2-4 BAND ASSEMBLY .

2-4 BAND ASSEMBLY Part Name Band Assembly-2/4

Previous Part Number 8654144

New Part Number 8673175

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Cooler Pipe Connector Detent Spring-To-Valve Body Bolt Extension Housing Bolt Manual Shaft-To-Detent Lever Nut Oil Pump Cover-To-Body Bolt Oil Pump-To-Case Bolt Park Bracket-To-Case Bolt Pressure Plugs 1/4 X 18" Torque Converter-To-Flexplate Bolt Accumulator Cover-To-Case Bolt Auxiliary Valve Body Bolt Oil Pan-To-Case Bolt Oil Passage Cover Bolt Pressure Plugs 1/8 X 27" Pressure Switches Solenoid Bolt Speed Sensor Bolt T.V. Cable Bolt Valve Body-To-Case Bolt (1) (1) Tighten valve body bolts in a spiral pattern starting in center of valve body.

Ft. Lbs. (N.m) 28 (38) 18 (24) 26 (35) 23 (31) 18 (24) 18 (24) 18 (24) 18 (24) 46 (62) INCH Lbs. (N.m) 96 (11.0) 96 (11.0) 96 (11.0) 96 (11.0) 96 (11.0) 96 (11.0) 96 (11.0) 89 (10.0) 75 (8.5) 96 (11.0)

TRANSMISSION REMOVAL & INSTALLATION - A/T TRANSMISSION SERVICING General Motors Auto Transmission Removal & Installation

DESCRIPTION A new system has been developed by Hydra-Matic to "functionally" describe its transmissions and transaxles. The new transmission designations, used throughout this manual, will indicate (in sequence) the number of speeds, type, series and major features (if applicable). Refer to the HYDRA-MATIC PRODUCT DESIGNATIONS tables to reference each new designation. HYDRA-MATIC PRODUCT DESIGNATIONS (AUTOMATIC) Previous Designation THM A-1 THM F-7 THM R-1 THM 125/125C THM 180/180C THM 200-4R

New Designation Hydra-Matic 3T40-A (1) THM F-7

Hydra-Matic 4L30-E Hydra-Matic 3T40 Hydra-Matic 3L30 (1) THM 200-4R

THM 400 THM 440-T4 THM 475 THM 700-R4

Hydra-Matic 3L80 Hydra-Matic 4T60 Hydra-Matic 3L80-HD Hydra-Matic 4L60

(1)

No change in designation. FWD AUTOMATIC TRANSAXLE APPLICATION Model Buick Century Electra LeSabre Park Avenue Reatta Regal Riviera Skylark Cadillac DeVille Eldorado Fleetwood

Body

Transmission(s)

"A" "C" "H" "C" "E" "W" "E" "N"

3T40 & 4T60 4T60 3T40 4T60 4T60 4T60 4T60 3T40

"C" "E" "C"

4T60 4T60 4T60

Seville Chevrolet Beretta Cavalier Celebrity Corsica Lumina Oldsmobile Cutlass Calais Cutlass Ciera Cutlass Cruiser Wagon Cutlass Supreme Delta 88 Ninety-Eight Toronado Trofeo Pontiac Bonneville Grand Am Grand Prix Sunbird Touring Sedan 6000 RWD AUTOMATIC TRANSMISSION APPLICATION Model Buick Electra Wagon Cadillac Brougham Chevrolet Camaro Caprice Corvette Oldsmobile Custom Cruiser Pontiac Firebird

TRANSAXLE REMOVAL & INSTALLATION

"K"

4T60

"L" "J" "A" "L" "W"

3T40 3T40 3T40 & 4T60 3T40 3T40

"N" "A" "A" "W" "H" "C" "E" "E"

3T40 3T40 & 4T60 4T60 4T60 4T60 4T60 4T60 4T60

"H" "N" "W" "J" "C" "A"

4T60 3T40 4T60 3T40 4T60 3T40 & 4T60

Body

Transmission(s)

"B"

200-4R & 4L60

"D"

200-4R

"F" "B" "Y"

4L60 200-4R & 4L60 4L60

"B"

200-4R & 4L60

"F"

200-4R & 4L60

3T40 Removal (All Models)

1. Disconnect negative battery cable. Remove air cleaner and T.V. cable from throttle lever and transaxle. Remove airflow meter and intake duct (if equipped). Remove shift linkage and wiring harness routing clips and straps. 2. On V6 models, remove exhaust crossover bolts at right side manifold, and left side exhaust manifold bolts at cylinder head. Raise and support manifold/crossover assembly. 3. On all models, remove filler tube and install Engine Support Fixture (J-28467-A). Insert a 1/4" x 2" bolt in hole at front right motor mount to maintain driveline alignment. 4. Remove nut securing wiring harness to transaxle. Disconnect all external wiring connectors from transaxle. Disconnect manual shift linkage and remove from bracket. Remove top 2 transaxle-to-engine bolts and upper left transaxle bracket and mount. 5. Remove rubber hose from transaxle to vent pipe. Remove remaining upper engine-to-transaxle bolts. Raise and support vehicle and remove front wheels. Drain transaxle. Remove lower ball joints from control arms. 6. Install Axle Boot Protectors (J-34754). Remove and support axles. Refer to appropriate AXLE SHAFTS article in DRIVE AXLES section for removal procedure. Remove transaxle mounting strut. Remove left stabilizer bar bolt and left stabilizer bar clamp nuts attaching left stabilizer bar to frame. Remove left frame support assembly. 7. On models equipped with 2.0L, remove header pipe at exhaust manifold. On models equipped with 2.8L, remove header pipe and front exhaust manifold. On all models, disconnect speedometer cable and remove starter motor. Remove torque converter cover. Index mark torque converter to flex plate and remove converter mounting bolts. 8. Disconnect oil cooler lines. Remove transaxle-to-engine support bracket. Secure transaxle jack under transaxle and remove remaining engine-to-transaxle bolts. Slide transaxle away from engine and right axle shaft. Lower transaxle from vehicle. Installation (All Models)

To install, reverse removal procedure. Guide right axle shaft into transaxle when raising transaxle to engine. Adjust T.V. and shift cables after installation. Refill transaxle to proper fluid level. See AUTOMATIC TRANSMISSION SERVICING article. 4T60 Removal (All Except "A" Bodies)

1. Disconnect negative battery cable. On models with air injection crossover pipe, remove air cleaner, air injection crossover pipe, air management valve and exhaust crossover pipe. On all others, remove airflow meter. 2. Remove T.V. cable at throttle body and transaxle. Remove shift linkage and vacuum modulator line. Remove neutral safety switch, cruise control and vehicle speed sensor wiring. Remove 3 upper transaxleto-engine mounting bolts. 3. Install Engine Support (J-28467) and raise engine to unload engine mounts. On Eldorado, Toronado and

Seville, remove driveline damper and engine mount. On all vehicles, raise on a hoist and remove front wheels. 4. Remove both lower ball joints from steering knuckle. Install Axle Boot Protectors (J-34754). Using Drive Axle Remover (J-33008), remove drive axle shafts from transaxle. Refer to appropriate AXLE SHAFTS article in DRIVE AXLES section for removal procedure. Secure drive axles aside. NOTE:

If necessary, raise left side of engine 2" to remove left engine mount and left cradle attaching bolts. Ensure engine is lowered back to original position.

5. Remove stabilizer linkage at left side. Remove left splash shield, vacuum pump (if equipped), and disconnect all wiring and hoses. Remove all transaxle-to-cradle bolts. Remove engine-to-left cradle assembly mounting bolts. Support left cradle assembly. Remove right and left cradle attaching bolts and remove left cradle assembly. NOTE:

Whenever cradle assembly is removed or lowered from vehicle, rack and pinion steering assembly must be disconnected from cradle. To prevent damage to intermediate shaft, steering assembly must be supported so it does not "hang" by intermediate shaft.

6. Disconnect oil cooler lines and remove dust cover. Index mark torque converter to flexplate and remove converter mounting bolts. Secure transmission jack under transaxle. Remove remaining transaxle mounting bolts and remove from vehicle. NOTE:

Locate bolt connecting transaxle-to-engine installed from opposite direction. On some models, a 3-foot (socket) extension placed through right wheelhousing will help remove this bolt.

Installation (All Except "A" Bodies)

To install, reverse removal procedure. Guide right axle shaft into transaxle when raising transaxle to engine. Adjust T.V. and shift cables. Refill transaxle to proper fluid level. See AUTOMATIC TRANSMISSION SERVICING article. Removal ("A" Body)

1. Disconnect negative battery cable. Remove air cleaner, wiring and cable routing clips and straps. Remove bolt securing T.V. cable to transaxle. Install Engine Support (J-28467) and relieve weight from mounts. 2. Raise vehicle on a hoist. Drain transaxle fluid. Remove strut shock bracket bolts from transaxle. Remove oil cooler lines from strut bracket and transaxle. 3. Remove left front wheel. Disconnect left front lower ball joint from steering knuckle. Remove brake line bracket at strut. Remove stabilizer bolts from frame and control arm. 4. Remove transaxle-to-engine bolts leaving bolt near starter loosely installed. Remove speedometer cable at upper and lower couplings. Disconnect shift linkage from transmission lever. Remove shifter linkage retaining clip, washer and bracket from transaxle. 5. Remove front and left sections of cradle. Install Axle Boot Protectors (J-34754). Position Axle Shaft

Remover (J-33008) and Slide Hammer (J-2619-01) behind axle shaft cones and pull axle shafts from transaxle. Refer to appropriate AXLE SHAFTS article in DRIVE AXLES section for removal procedure. 6. Remove starter motor and converter shields. Index mark flexplate to torque converter and remove torque converter mounting bolts. Remove 2 transaxle extension bolts from engine-to-transaxle. Remove rear transaxle mount bracket. It may be necessary to raise transaxle to remove bracket. 7. Secure transmission jack under transaxle. Remove 2 braces to right end of transaxle bolts. Remove remaining transaxle-to-engine bolt (located near starter). Slide transaxle away from engine (toward driver's side) and lower transaxle from vehicle. Installation ("A" Body)

To install, reverse removal procedure. Guide right axle shaft into transaxle when raising transaxle to engine. Adjust T.V. cable and shift cable after installation. Refill transaxle to proper level with fluid. See AUTOMATIC TRANSMISSION SERVICING article.

TRANSMISSION REMOVAL & INSTALLATION THM 200-4R & 4L60 Removal (All Models)

1. Disconnect negative battery cable and remove air cleaner. Disconnect upper end of T.V. cable at throttle or carburetor linkage, and remove filler tube. Raise and support vehicle on a hoist. Index mark and remove drive shaft. 2. On Corvette models, remove complete exhaust system and driveline beam. On Corvette convertible, remove upper and lower body braces. Camaro and Firebird, remove torque arm from rear suspension. On Cadillac, remove header pipe at exhaust manifold, catalytic converter, fuel line-to-transmission bracket and transmission-to-engine ground strap bolt. 3. Remove lower floor reinforcement (if equipped). Disconnect speedometer cable. Remove shifter linkage and disconnect all electrical connectors. Remove flexplate cover. Index mark flexplate to torque converter and remove attaching bolts. 4. Remove catalytic converter support bracket and remove crossmember. Support transmission with transmission jack. Lower transmission slightly, disconnect oil cooler lines and remove T.V. cable hold down bolt. 5. Support engine with a screw jack and block of wood. Remove transmission-to-engine bolts. Pull transmission back enough to install Torque Converter Holder (J-21366). Lower transmission from vehicle. Installation (All Models)

1. To install transmission, reverse removal procedures. Observe index marks made during removal and align marks to original positions. 2. Test torque converter for freedom of rotation. Tighten torque converter-to-flexplate bolts finger tight, then tighten to specifications. Adjust shift linkage and T.V. cable as necessary. Fill transmission to proper level with fluid. See AUTOMATIC TRANSMISSION SERVICING article.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application 3T40 & 4T60 Cooler Lines Nut Flexplate-to-Crankshaft Bolt 2.0L 2.3L 2.5L 2.8L 3.3L 3.1L & 3.8L 4.3L, 4.5L & 5.0L Front Cradle Assembly Bolt "J","L" & "N" Bodies All Others Torque Converter-to-Flexplate Bolt "J","L" & "N" Bodies All Others Transaxle-to-Engine Bolt Transaxle-to-Mount Nut THM 200-4R & 4L60 Cooler Lines Nut Crossmember-to-Frame Bolt Flexplate-to-Crankshaft Bolt 2.8L 3.8L 4.3L & 5.0L All Others Torque Converter-to-Flexplate Bolt Transmission-to-Engine Bolt Transmission-to-Mount Bolt (1) Rotate an additional 35 degrees.

Ft. Lbs. (N.m) 16 (22) 52 (70) (1) 30 (22)

55 (75) 35 (47) 61 (83) 61 (83) 74 (100) 65 (88) 74 (100) 35 (47) 46 (62) 55 (75) 40 (54) 16 (22) 41 (56) 35 (47) 61 (83) 74 (100) 60 (81) 46 (62) 35 (47) 35 (47)

TRANSMISSION SERVICING - A/T TRANSMISSION SERVICING General Motors Corp. Automatic Transmission

IDENTIFICATION A new system has been developed by Hydra-Matic to "functionally" describe its transmissions and transaxles. The new transmission designations, used throughout this manual, will indicate (in sequence) the number of speeds, type, series and major features (if applicable). Refer to HYDRA-MATIC PRODUCT DESIGNATIONS to reference each new designation. HYDRA-MATIC PRODUCT DESIGNATION SYSTEM CODES 3 - No. Speeds: T - Type: 40 - Series: 3 T - Transverse Based on 4 L - Longitudinal Relative 5 M - Manual Torque Rating HYDRA-MATIC PRODUCT DESIGNATIONS Previous Designation THM A-1 THM F-7 THM R-1 THM 125/125C THM 180/180C THM 200-4R

New Designation Hydra-Matic 3T40-A THM F-7 Hydra-Matic 4L30-E Hydra-Matic 3T40 Hydra-Matic 3L30 (1) THM 200-4R

THM 400 THM 440-T4 THM 475 THM 700-R4 (1) No change in designation. FWD APPLICATION Model Buick Century Electra LeSabre Park Avenue Reatta Regal Riviera

E - Features: E - Elect. A - AWD HD - Heavy Duty

Hydra-Matic 3L80 Hydra-Matic 4T60 Hydra-Matic 3L80-HD Hydra-Matic 4L60

Body

Transmission(s)

"A" "C" "H" "C" "E" "W" "E"

3T40 & 4T60 4T60 3T40 4T60 4T60 3T40 & 4T60 4T60

Skylark Cadillac DeVille Eldorado Fleetwood Seville Chevrolet Beretta Cavalier Celebrity Corsica Lumina Oldsmobile Cutlass Calais Cutlass Ciera Cutlass Cruiser Cutlass Supreme Delta 88 Ninety-Eight Toronado Trofeo Pontiac Bonneville Grand Am Grand Prix Sunbird Touring Sedan 6000 RWD TRANSMISSION APPLICATION Model Brougham Camaro Caprice Corvette Custom Cruiser Estate Wagon Firebird

LUBRICATION

Body "D" "F" "B" "Y" "B" "B" "F"

"N"

3T40

"C" "E" "C" "K"

4T60 4T60 4T60 4T60

"L" "J" "A" "L" "W"

3T40 3T40 3T40 & 4T60 3T40 3T40

"N" "A" "A" "W" "H" "C" "E" "E"

3T40 3T40 & 4T60 4T60 4T60 4T60 4T60 4T60 4T60

"H" "N" "W" "J" "C" "A"

4T60 3T40 4T60 3T40 4T60 3T40 & 4T60

Transmission(s) 200-4R & 4L60 4L60 200-4R & 4L60 4L60 200-4R & 4L60 200-4R & 4L60 200-4R & 4L60

SERVICE INTERVALS Check transmission fluid level at every engine oil change. Transmission fluid should be changed and filter replaced every 100,000 miles under normal operating conditions. Under continuous extreme operating conditions (trailer towing, heavy city traffic with ambient temperature over 90Â°F/32Â°C or delivery service), fluid and filter should be changed every 15,000 miles. CHECKING FLUID LEVEL CAUTION: DO NOT overfill transmission. One pint of fluid will raise level from the "ADD 1 PT. OR .5L" mark to the "FULL HOT" mark on dipstick when transmission is hot. 1. Start engine and operate vehicle for at least 15 minutes or until reaching operating temperature. With engine at curb idle, vehicle on level ground, move gear selector lever through all ranges ending in the "P" position. 2. Remove transmission dipstick, wipe clean and fully reinsert into filler tube. Remove again and inspect fluid level. Fluid level should be between the "ADD 1 PT. OR .5L" mark and the "FULL HOT" mark on dipstick. CAUTION: If vehicle has been driven for an extended period of time at high speeds, in city traffic, hot weather, or if vehicle has been pulling a trailer, an accurate fluid level reading cannot be made until ATF has cooled about 30 minutes after vehicle has been parked. RECOMMENDED FLUID Use only Dexron-II Automatic Transmission Fluid (ATF) or equivalent. FLUID CAPACITY NOTE:

Quantities listed are approximate. Correct fluid level should be determined by mark on dipstick rather than by amount of fluid added.

TRANSMISSION REFILL CAPACITIES Transmission 3T40 THM 200-4R 4T60 4L60

Refill Qts. (L) 4.0 (3.78) 3.5 (3.25) 6.0 (5.67) 5.0 (4.73)

Total Qts. (L) 6.0-6.9 (5.67-6.52) 11.0 (10.40) 10.0-11.0 (9.46-10.40) 11.5 (10.88)

DRAINING & REFILLING 1. With vehicle raised and large drain pan placed under transmission oil pan, remove front and side

4. 5.

transmission oil pan bolts only. Loosen rear pan bolts about 4 turns each. Carefully pry pan loose with screwdriver, allowing fluid to drain. Remove remaining bolts and remove oil pan. Discard old pan gasket. Remove filter and "O" ring or sleeve type seal. Remove any remaining gasket material left on transmission case. Thoroughly clean pan, magnet and screen with solvent and dry with compressed air. Paper type filters should be replaced. Install new "O" ring on pick-up tube or new sleeve into pick-up tube recess. Lubricate with clean oil before installation. Install filter assembly into pick-up tube recess. Install oil pan using new gasket and tighten pan bolts to specification. Add required amount of fluid to transmission through filler tube. Start engine with gear selector lever in the "P" position and parking brake applied. Engage transmission in each gear ending in the "P" position. Check fluid level with vehicle warm and add fluid if necessary. DO NOT overfill.

TORQUE SPECIFICATIONS (OIL PAN BOLTS) Transmission 3T40 THM 200-4R 4T60 4L60

INCH Lbs. (N.m) 97 (11) 97 (11) 115 (13) 177 (20)

ADJUSTMENTS THROTTLE VALVE (T.V.) CABLE "N" Body (2.3L Quad 4)

1. Rotate T.V. cable adjuster body (at transaxle) 90 degrees. Pull cable conduit out until slider mechanism hits stop. See Fig. 1 . 2. Rotate adjuster body back to original position. Using a torque wrench and socket, rotate T.V. cable adjuster hex nut until 75 INCH lbs. (8.5 N.m) is reached. Road test vehicle.

Fig. 1: Throttle Valve (T.V.) Cable On "N" Body (2.3L Quad 4) Courtesy of GENERAL MOTORS CORP. "A" Body (2.5L)

1. Ensure T.V. cable is in full, nonadjusted position. Ensure T.V. cable operates smoothly and connected at transaxle.

2. Accelerator cable must be installed when adjusting T.V. cable. Rotate idler pulley (cam) counterclockwise to 65 INCH lbs. (7 N.m) to place cable in adjusted position. See Fig. 2 .

Fig. 2: Adjusting Throttle Cable On "A" Body (2.5L) Courtesy of GENERAL MOTORS CORP. All Other Models

1. Engine must be off. Depress metal readjust tab on cable adjuster (located at cable support bracket on engine) and hold it in this position. 2. Move cable housing slider (away from throttle lever) until it stops and is completely against fitting. Release readjust tab. See Fig. 3 . 3. Rotate throttle lever (by hand) to its full throttle position. Slider must move (ratchet) toward lever when lever is rotated to its full throttle position. Check cable for sticking and binding.

Fig. 3: Self-Adjusting Throttle Valve Cable Courtesy of GENERAL MOTORS CORP. GEAR SHIFT LINKAGE Gear Shift Linkage Basic Adjustment Information

1. Linkage should be adjusted so that engine cannot be started in any position except Park or Neutral. If linkage is improperly adjusted, an internal hydraulic leak could occur causing internal clutch and/or band failure. 2. With selector lever in the "P" position, transmission parking pawl should engage rear/reaction internal gear lugs or output ring gear lugs. Pointer on indicator quadrant should line up properly with range indicators in all ranges. Column Shift Rod (RWD)

1. Position steering column gear selector lever in the Neutral gate notch. Loosen clamp screw from below vehicle and place transmission lever in Neutral. See Fig. 4 . 2. Hold clamp flush against equalizer lever. Tighten clamp screw finger tight, then tighten to 21 ft. lbs. (28 N.m) without applying tension on either equalizer lever or selector rod. Ensure there is no tension on either equalizer lever or selector rod after adjustment is complete. See Fig. 4 .

Fig. 4: Column Shift Rod (RWD Models) Courtesy of GENERAL MOTORS CORP. Floor Shift Cable "B" & "D" Bodies (RWD)

1. Place gear selector lever in the "P" position. Raise and support vehicle. Ensure transmission is fully engaged in Park by rotating drive shaft until parking pawl engages preventing rotation of shaft. 2. Loosen cable adjusting nut on transmission lever to allow pin to slide freely. With gear selector lever and transmission lever both in Park position, tighten cable adjusting nut to 15 ft. lbs. (20 N.m). See Fig. 5 .

Fig. 5: Floor Shift Cable "B" & "D" Bodies (RWD) Courtesy of GENERAL MOTORS CORP. Floor Shift Cable "F" & "Y" Bodies (RWD)

Place gear selector lever in the "N" position. Raise and support vehicle. Loosen cable adjusting nut at transmission lever. See Fig. 6 . Ensure that transmission lever is in the Neutral position by rotating it clockwise to Park detent, then back (counterclockwise) 2 detents to Neutral. Tighten cable adjusting nut to 15 ft. lbs. (20 N.m). NOTE:

Lever must be held out of Park when tightening nut.

Fig. 6: Floor Shift Cable "F" & "Y" Bodies (RWD) Courtesy of GENERAL MOTORS CORP. Except Self-Adjusting Cable Type (FWD)

1. Place gear selector lever in the "N" position. Loosen cable adjusting nut at transaxle lever. See Fig. 7 . 2. Ensure that transaxle lever is in the Neutral detent. Tighten cable adjusting nut. Lever MUST be held out of Park when tightening nut. DO NOT use impact tools on nut.

Fig. 7: Typical Floor Shift Linkage (FWD) Courtesy of GENERAL MOTORS CORP. NOTE:

Self-adjusting shift cable is commonly used on "A," "C," "H," "N" and "W" body styles.

Self-Adjusting Cable (FWD)

Place gear selector lever in the "N" position. Lift up lock button on cable adjuster at transaxle mounting bracket. See Fig. 8 . Place transaxle lever in Neutral detent. Push down on lock button.

Fig. 8: Self-Adjusting Cable (FWD) Courtesy of GENERAL MOTORS CORP. PARK/LOCK CONTROL CABLE Floor Shift Models

1. With gear selector lever in the Park position and ignition key in LOCK position, gear selector lever should not be able to be moved to other gear positions. Ignition key should be removable from column.

2. With key in RUN position and gear selector lever in the Neutral position, ensure key cannot be turned to LOCK position. If system does not perform as described in steps 1) and 2), go to step 3) for adjustment procedure. 3. If key cannot be removed in Park position, snap connector lock button to up position. Move cable connector nose rearward until key can be removed from ignition. See Fig. 9 -Fig. 11 . Snap lock button down.

Fig. 9: Park/Lock Control Cable (Corvette) Courtesy of GENERAL MOTORS CORP.

Fig. 10: Park/Lock Control Cable On "J" & "N" Bodies Courtesy of GENERAL MOTORS CORP.

Fig. 11: Park/Lock Control Cable On "A" & "W" Bodies Courtesy of GENERAL MOTORS CORP. NEUTRAL SAFETY SWITCH RWD Models ("B" & "D" Bodies)

Column shift models use a mechanical interference-type neutral start system. A wedge-shaped finger, attached to the ignition switch actuator rod, blocks movement of ignition switch to the "Start" position in all gear selector positions except park or neutral. RWD Models ("F" & "Y" Bodies)

1. Disconnect negative battery cable. Remove gear selector knob. Remove center console cover. Place gear selector lever in the "N" position. If old switch is being readjusted, go to step 2). If new switch is being installed, go to step 4). 2. Align tang on switch with tang slot on shift control. See Fig. 12 . Loosen switch mounting nuts. Rotate switch to align service adjustment hole with carrier tang hole. 3. Insert a .094" (2.34 mm) wire gauge into adjustment hole in top of switch. Rotate switch until pin drops to depth of .59" (15 mm). Tighten mounting nuts to 26 INCH lbs. (3 N.m). Vehicle should only start in Park or Neutral. 4. If new switch if being installed, insert switch tang in slot on shift control. Tighten mounting nuts to 26 INCH lbs. (3 N.m). 5. If holes do not align with shift control, ensure gear selector lever is in the "N" position. DO NOT rotate switch. Switch is pinned in Neutral. NOTE:

If new switch has been rotated and was pin broken during installation, use adjustment procedure in step 2).

6. If holes align with shift control, move gear selector lever out of Neutral position to shear plastic pin.

Fig. 12: Adjusting Neutral Safety & Back-Up Light Switch On "F" & "Y" Bodies Courtesy of GENERAL MOTORS CORP. FWD MODELS 1. There are 2 different neutral safety/back-up light switches used on FWD models. See Fig. 13 . To adjust switch, place gear selector lever in the "N" position. 2. Ensure shift cable is adjusted correctly and transaxle lever is in Neutral position. Loosen switch attaching screws. Rotate switch on shifter assembly to align adjustment hole with carrier tang hole. 3. Insert a 3/32" (2.4 mm) wire gauge about 5/8" into switch holes. Tighten attaching screws. Remove wire gauge. New switches may have plastic pin installed in hole. Plastic pin is designed to shear off during shift lever operation.

Fig. 13: Neutral Safety Switches (FWD) Courtesy of GENERAL MOTORS CORP. TORQUE CONVERTER CLUTCH BRAKE SWITCH The torque converter clutch brake switch must be adjusted to prevent vehicle stalling at idle due to the clutch remaining applied. Ensure brake pedal is fully released. Adjust plunger to just touch brake pedal lever. VISCOUS CONVERTER CLUTCH THERMISTOR SWITCH Cadillac

Some models with 4T60 transaxle are equipped with a thermistor switch that senses transaxle fluid temperature. This information is sent to the ECM to determine Viscous Converter Clutch (VCC) operation. The ECM engages VCC when fluid temperature is 200°F (93°C) or less, provided all other conditions have been met. If fluid temperature is higher than specified, ECM will not allow VCC engagement until vehicle speed is approximately 36 MPH.

SPECIFICATIONS

OIL PAN GASKET IDENTIFICATION

Fig. 14: Hydra-Matic THM 200-4R Oil Pan Gasket Courtesy of GENERAL MOTORS CORP.

Fig. 15: Hydra-Matic 3T40 (THM 125C) Oil Pan Gasket Courtesy of GENERAL MOTORS CORP.

Fig. 16: Hydra-Matic 4L60 (THM 700-R4) Oil Pan Gasket Courtesy of GENERAL MOTORS CORP.

Fig. 17: Hydra-Matic 4T60 (THM 440-T4) Oil Pan Gasket Courtesy of GENERAL MOTORS CORP.

GENERAL INFORMATION Trouble Shooting - Basic Procedures

* PLEASE READ THIS FIRST * NOTE:

This is GENERAL information. This article is not intended to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.

ACCESSORIES & ELECTRICAL CHARGING SYSTEM TROUBLE SHOOTING NOTE:

NOTE:

BASIC CHARGING SYSTEM TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Vehicle Will Not Start Dead battery

Loose or corroded battery connections Ignition circuit or switch malfunction Alternator Light Stays On With Engine Running Loose or worn alternator drive belt

Loose alternator wiring connections

CORRECTION Check battery cells, alternator belt tension and alternator output Check all charging system connections Check and replace as necessary Check alternator drive tension and condition, See Belt Adjustment in TUNE-UP article in the TUNE-UP section Check all charging system connections

Short in alternator light wiring

Defective alternator stator or diodes Defective regulator Alternator Light Stays Off With Ignition Switch ON Blown fuse Defective alternator Defective indicator light bulb or socket

Alternator Light Stays OFF With Ignition Switch ON Short in alternator wiring Defective rectifier bridge Lights or Fuses Burn Out Frequently Defective alternator wiring Defective regulator Defective battery Ammeter Gauge Shows Discharge Loose or worn drive belt

Defective wiring Defective alternator or regulator

Defective ammeter, or improper ammeter wiring connection

Noisy Alternator Loose drive pulley

See Indicator Warning Lights in STANDARD INSTRUMENTS in the ACCESSORIES & EQUIPMENT section See Bench Tests in ALTERNATOR article See Regulator Check in ALTERNATOR article See WIRING DIAGRAMS See Testing in ALTERNATOR article See Indicator Warning Lights in STANDARD INSTRUMENTS in the ACCESSORIES & EQUIPMENT section See On-Vehicle Tests in ALTERNATOR article See Bench Tests in ALTERNATOR article See On-Vehicle Tests in ALTERNATOR article See Regulator Check in ALTERNATOR article Check and replace as necessary Check alternator drive belt tension and condition. See Belt Adjustment in TUNE-UP article in the TUNE-UP section Check all wires and wire connections See Bench Tests and OnVehicle Tests in ALTERNATOR article See Testing in STANDARD INSTRUMENTS in the ACCESSORIES & EQUIPMENT section Tighten drive pulley attaching nut

Loose mounting bolts Worn or dirty bearings Defective diodes or stator Battery Does Stay Charged Loose or worn drive belt

Loose or corroded battery connections Loose alternator connections Defective alternator or battery

Add-on electrical accessories exceeding alternator capacity Battery Overcharged-Uses Too Much Water Defective battery Defective alternator Excessive alternator voltage

Tighten all alternator mounting bolts See Bearing Replacement ALTERNATOR article See Bench Test in ALTERNATOR article Check alternator drive belt tension and condition. See Belt Adjustment in appropriate TUNE-UP article in the TUNEUP section Check all charging system connections Check all charging system connections See On-Vehicle Tests and Bench Tests in ALTERNATOR article Install larger alternator Check alternator output and repair as necessary See On-Vehicle Test and Bench Tests in ALTERNATOR article Check alternator output and repair as necessary

IGNITION SYSTEM TROUBLE SHOOTING NOTE:

Fig. 1: Ignition Secondary Trouble Shooting Chart

Fig. 2: Ignition Primary Trouble Shooting Chart STARTER TROUBLE SHOOTING NOTE:

BASIC STARTER TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Starter Fails to Operate Dead battery or bad connections between starter and battery

Ignition switch faulty or misadjusted Open circuit between starter switch ignition terminal on starter relay Starter relay or starter defective Open solenoid pull-in wire Starter Does Not Operate and Headlights Dim Weak battery or dead cell Loose or corroded battery connections Internal ground in starter windings Grounded starter fields Armature rubbing on pole Starter Turns but Engine Does Not Rotate Starter clutch slipping Broken clutch housing Pinion shaft rusted or dry Engine basic timing incorrect Broken teeth on engine flywheel Starter Will Not Crank Engine Faulty overrunning clutch Broken clutch housing Broken flywheel teeth

CORRECTION Check battery charge and all wires and connections to starter Adjust or replace ignition switch Check and repair wires and connections as necessary See Testing in STARTER article Testing in STARTER article Charge or replace battery as necessary Check that battery connections are clean and tight See Testing in STARTER article See Testing in STARTERS See STARTER article shoes See STARTER article See STARTER article See STARTER article See Ignition Timing in TUNEUP article Replace flywheel and check for starter pinion gear damage See STARTER article See STARTER article Replace flywheel and check

Armature shaft sheared or reduction gear teeth stripped Weak battery Faulty solenoid Poor grounds Ignition switch faulty or misadjusted Starter Cranks Engine Slowly Battery weak or defective Engine overheated Engine oil too heavy Poor battery-to-starter connections Current draw too low or too high Bent armature, loose pole shoes screws or worn bearing Burned solenoid contacts Faulty starter Starter Engages Engine Only Momentarily Engine timing too far advanced Overrunning clutch not engaging properly Broken starter clutch Broken teeth on engine flywheel Weak drive assembly thrust spring Weak hold-in coil Starter Drive Will Not Engage Defective point assembly Poor point assembly ground Defective pull-in coil Starter Relay Does Not Close Dead battery

for starter pinion gear damage See STARTER article Charge or replace battery as necessary See On-Vehicle Tests in STARTER article Check all ground connections for tight and clean connections Adjust or replace ignition switch as necessary Charge or replace battery as necessary See ENGINE COOLING SYSTEM article Check that proper viscosity oil is used Check that all between battery and starter are clean and tight See Bench Tests in STARTER article See STARTER article Replace solenoid Replace starter See Ignition Timing in TUNEUP article Replace overrunning clutch. See STARTER article See STARTER article Replace flywheel and check starter pinion gear for damage See STARTER article See Bench Tests in STARTER article See Testing in STARTER article See Testing in STARTER article Replace starter solenoid Charge or replace battery as

Faulty wiring Neutral safety switch faulty Starter relay faulty Starter Drive Will Not Disengage Starter motor loose on mountings Worn drive end bushing Damaged engine flywheel teeth Drive yolk return spring broken or missing Faulty ignition switch Insufficient clearance between winding leads to solenoid terminal and main contact in solenoid Starter clutch not disengaging Ignition starter switch Starter Relay Operates but Solenoid Does Not Faulty solenoid switch, switch connections or relay

Broken lead or loose soldered connections Solenoid Plunger Vibrates When Switch is Engaged Weak battery Solenoid contacts corroded Faulty wiring Broken connections inside switch cover Open hold-in wire Low Current Draw Worn brushes or weak brush springs

necessary Check all wiring and connections leading to relay Replace neutral safety switch Replace starter relay Tighten starter attach bolts See STARTER article Replace flywheel and starter pinion gear for damage Replace return spring Replace ignition switch Replace starter solenoid Replace starter clutch Replace ignition switch contacts sticking Check all wiring between relay and solenoid or replace relay or solenoid as necessary Repair wire or wire connections as necessary Charge or replace battery as necessary Clean contacts or replace solenoid Check all wiring leading to solenoid Repair connections or replace solenoid solenoid

Replace brushes or brush springs as necessary High Pitched Whine During Cranking Before Engine Fires but Engine Fires and Cranks Normally Distance too great between starter pinion and flywheel Align starter or check that correct starter and flywheel are being used High Pitched Whine After Engine Fires With Key released. Engine Fires and Cranks Normally Distance too small between starter pinion and flywheel Flywheel runout contributes to the intermittent nature

AIR CONDITIONING & HEAT AIR CONDITIONING TROUBLE SHOOTING WARNING: This is GENERAL information. This article is not intended to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing. BASIC AIR CONDITIONING TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE Compressor Not Working Compressor clutch circuit open. ..... Compressor clutch coil inoperative. ..... Poor clutch ground connection. ..... Fan belts loose. ..... Thermostatic switch inoperative. ..... Thermostatic switch not adjusted. ..... Ambient temperature switch open. ..... Superheat fuse blown. Excessive Noise or Vibration Missing or loose mounting bolts. ..... Bad idler pulley bearings. ..... Fan belts not tightened correctly. ..... Compressor clutch contacting body. ..... Excessive system pressure. ..... Compressor oil level low. ..... Damaged clutch bearings. ..... Damaged reed valves. ..... Damaged compressor. Insufficient or No Cooling; Expansion valve inoperative. Compressor Working ..... Heater control valve stuck open. ..... Low system pressure. ..... Blocked condenser fins. ..... Blocked evaporator fins. ..... Vacuum system leak. ..... Vacuum motors inoperative. ..... Control cables improperly adjusted. ..... Restricted air inlet. ..... Mode doors binding. ..... Blower motor inoperative.

.....

Temperature above system capacity.

HEATER SYSTEM TROUBLE SHOOTING NOTE:

This is GENERAL information. This article is not intended to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble Shooting information is to provide a list of common causes to problem symptoms. For model-specific Trouble Shooting, refer to DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing.

BASIC HEATER SYSTEM TROUBLE SHOOTING CHART CONDITION Insufficient, Erratic, or No Heat ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... ..... Too Much Heat ..... ..... ..... Air Flow Changes During Acceleration ..... Air From Defroster At All Times ..... ..... Blower Does Not Operate Correctly ..... ..... ..... ..... ..... .....

POSSIBLE CAUSE Low Coolant Level Incorrect thermostat. Restricted coolant flow through core. Heater hoses plugged. Misadjusted control cable. Sticking heater control valve. Vacuum hose leaking. Vacuum hose blocked. Vacuum motors inoperative. Blocked air inlet. Inoperative heater blower motor. Oil residue on heater core fins. Dirt on heater core fins. Improperly adjusted cables. Sticking heater control valve. No vacuum to heater control valve. Temperature door stuck open. Vacuum system leak. Bad check valve or reservoir. Vacuum system leak. Improperly adjusted control cables. Inoperative vacuum motor. Blown fuse. Blower motor windings open. Resistors burned out. Motor ground connection loose. Wiring harness connections loose. Blower motor switch inoperative. Blower relay inoperative.

..... .....

Fan binding or foreign object in housing. Fan blades broken or bent.

BRAKES BRAKE SYSTEM TROUBLE SHOOTING NOTE:

BRAKE SYSTEM TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Brakes Pull Left or Right Incorrect tire pressure Front end out of alignment Mismatched tires Restricted brake lines or hoses Loose or malfunctioning caliper Bent shoe or oily linings Malfunctioning rear brakes Loose suspension parts Noises Without Brakes Applied Front linings worn out Dust or oil on drums or rotors Noises With Brakes Applied Insulator on outboard shoe damaged Incorrect pads or linings Brake Rough, Chatters or Pulsates Excessive lateral runout Parallelism not to specifications Wheel bearings not adjusted Rear drums out-of-round Disc pad reversed, steel against rotor Excessive Pedal Effort Malfunctioning power unit

CORRECTION Inflate tires to proper pressure See WHEEL ALIGNMENT Check tires sizes Check hose routing See DISC BRAKES or BRAKE SYSTEM See DRUM BRAKES or BRAKE SYSTEM See DRUM, DISC BRAKES or BRAKE SYSTEM See SUSPENSION Replace linings See DRUM, DISC BRAKES or BRAKE SYSTEM See DISC BRAKES or BRAKE SYSTEM Replace pads or linings Check rotor runout Reface or replace rotor See SUSPENSION Reface or replace drums Remove and reinstall pad See POWER BRAKES or

Partial system failure Worn disc pad or lining Caliper piston stuck or sluggish Master cylinder piston stuck Brake fade due to incorrect pads for linings Linings or pads glazed Worn drums Excessive Pedal Travel Partial brake system failure Insufficient fluid in master cylinder Air trapped in system Rear brakes not adjusted

Bent shoe or lining Plugged master cylinder cap Improper brake fluid Pedal Travel Decreasing Compensating port plugged Swollen cup in master cylinder Master cylinder piston not returning Weak shoe retracting springs Wheel cylinder piston sticking Dragging Brakes Master cylinder pistons not returning Restricted brake lines or hoses Incorrect parking brake adjustment Parking Brake cables frozen

BRAKE SYSTEM Check fluid and pipes Replace pad or lining See DISC BRAKES or BRAKE SYSTEM See MASTER CYLINDERS or BRAKE SYSTEM Replace pads or linings Replace pads or linings Reface or replace drums Check fluid and pipes See MASTER CYLINDERS or BRAKE SYSTEM See BRAKE BLEEDING or BRAKE SYSTEM See Adjustments in DRUM BRAKES or BRAKE SYSTEM See DRUM BRAKES or BRAKE SYSTEM See MASTER CYLINDERS or BRAKE SYSTEM Replace brake fluid See MASTER CYLINDERS or BRAKE SYSTEM See MASTER CYLINDERS or BRAKE SYSTEM See MASTER CYLINDERS or BRAKE SYSTEM See DRUM BRAKES BRAKE SYSTEM See DRUM BRAKES or BRAKE SYSTEM See MASTER CYLINDERS BRAKE SYSTEM Check line routing See DRUM BRAKES BRAKE SYSTEM See DRUM BRAKES BRAKE SYSTEM

Incorrect installation of inboard disc pad Power booster output rod too long Brake pedal not returning freely Brakes Grab or Uneven Braking Action Malfunction of combination valve Malfunction of power brake unit Binding brake pedal Pulsation or Roughness Uneven pad wear caused by caliper Uneven rotor wear Drums out-of-round

Remove and replace correctly See POWER BRAKE UNITS BRAKE SYSTEM See DISC, DRUM BRAKES BRAKE SYSTEM See CONTROL VALVE or BRAKE SYSTEM See POWER BRAKE UNITS or BRAKE SYSTEM See DISC, DRUM BRAKES or BRAKE SYSTEM See DISC BRAKES or BRAKE SYSTEM See DISC BRAKES or BRAKE SYSTEM Reface or replace drums

ENGINE MECHANICAL COOLING SYSTEM TROUBLE SHOOTING NOTE:

COOLING SYSTEM TROUBLE SHOOTING CONDITION & POSSIBLE CAUSE Overheating Coolant Leak A/C Condenser Fins Clogged Radiator Fins Clogged Thermostat Stuck Closed Clogged Cooling System Passages Water Pump Malfunction Fan Clutch Malfunction Retarded Ignition Timing Cooling Fan Malfunction Cooling Fan Motor Malfunction Cooling Fan Relay Malfunction

CORRECTION Fill/Pressure Test System Remove/Clean Condenser Remove/Clean Radiator Replace Thermostat Clean/Flush Cooling System Replace Water Pump Replace Fan Clutch Reset Ignition Timing Test Cooling Fan/Circuit Test Fan Motor Test Fan Relay

Faulty Radiator Cap Broken/Slipping Fan Belt Restricted Exhaust Corrosion Impurities In Coolant Coolant Leakage Damaged hose Leaky Water Pump Damaged Radiator Seam Leaky Thermostat Cover Cylinder Head Problem Leaky Freeze Plugs Recovery System Inoperative Loose and/or Defective Radiator Cap Overflow Tube Clogged and/or Leaking Recovery Bottle Vent Restricted No Heater Core Flow Collapsed Heater Hose Plugged Heater Core Faulty Heater Valve

Replace Radiator Cap Replace Fan Belt Repair Exhaust System Clean/Flush System Replace Hose Replace Water Pump Replace/Repair Radiator Replace Thermostat Cover Check Head/Head Gasket Replace Freeze Plugs Replace Radiator Cap Repair Tube Clean Vent Replace Heater Hose Clean/Replace Heater Core Replace Heater Valve

GASOLINE ENGINE - MECHANICAL TROUBLE SHOOTING NOTE:

BASIC GASOLINE ENGINE - MECHANICAL TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE CORRECTION Engine Lopes At Idle Intake manifold-to-head leaks Replace manifold gasket, See ENGINES Blown head gasket Replace head gasket, See ENGINES Worn timing gears, chain or sprocket Replace gears, chain or sprocket Worn camshaft lobes Replace camshaft, See ENGINES Overheated engine Check cooling system, See COOLING Blocked crankcase vent valve Remove restriction

Leaking EGR valve Faulty fuel pump Engine Has Low Power Leaking fuel pump Excessive piston-to-bore clearance Sticking valves or weak valve springs Incorrect valve timing Worn camshaft lobes Blown head gasket Clutch slipping Engine overheating Auto. Trans. pressure regulator valve faulty Auto. Trans. fluid level too low Improper vacuum diverter valve operation Vacuum leaks Leaking piston rings Faulty High Speed Operation Low fuel pump volume Leaking valves or worn Incorrect valve timing Intake manifold restricted Worn distributor shaft Faulty Acceleration Improper fuel pump stroke Incorrect ignition timing Leaking valves

Repair leak and/or replace valve Replace fuel pump Repair leak and/or replace fuel pump Install larger pistons, See ENGINES Check valve train components, See ENGINES Reset valve timing, See ENGINES Replace camshaft, See ENGINES Replace head gasket. See ENGINES. Adjust pedal and/or replace components, See ENGINES Check cooling system, See COOLING Replace pressure regulator valve Add fluid as necessary Replace vacuum diverter valve Inspect vacuum system and repair as required Replace piston rings, See ENGINES Replace fuel pump Replace valves and/or springs, See ENGINES Reset valve timing,See ENGINES Remove restriction Replace distributor Remove pump and reset pump stroke Reset ignition timing, See TUNE-UP Replace valves, See ENGINES

Worn fuel pump diaphragm or piston Intake Backfire Improper ignition timing Faulty accelerator pump discharge Improper choke operation Defective EGR valve Fuel mixture too lean Choke valve initial clearance too large Exhaust Backfire Vacuum leak Faulty vacuum diverter valve Faulty choke operation Exhaust system leak Engine Detonation Ignition timing too far advanced Faulty ignition system Spark plugs loose or faulty Fuel delivery system clogged EGR valve inoperative PCV system inoperative Vacuum leaks Excessive combustion chamber deposits Leaking, sticking or broken valves External Oil Leakage Fuel pump improperly seated or worn gasket Oil pan gasket broken or pan bent Timing chain cover gasket broken Rear main oil seal worn

Replace diaphragm or piston Reset ignition timing, See TUNE-UP Replace accelerator pump Check choke and adjust as required Replace EGR valve Reset air/fuel mixture, See TUNE-UP Reset choke valve initial clearance Inspect and repair vacuum system Replace vacuum diverter valve Check choke and adjust as required repair exhaust system leak Reset ignition timing, See TUNE-UP Check ignition timing, See TUNE-UP Retighten or replace plugs Inspect lines, pump and filter for clog Replace EGR valve Inspect and/or replace hoses or valve Check vacuum system and repair leaks Remove built-up deposits Inspect and/or replace valves Remove pump, replace gasket and seat properly Straighten pan and replace gasket Replace timing chain cover gasket Replace rear main oil seal

Oil pan drain plug not seated properly Camshaft bearing drain hole blocked Oil pressure sending switch leaking Excessive Oil Consumption Worn valve stems or guides Valve "O" ring seals damaged Plugged oil drain back holes Improper PCV valve operation Engine oil level too high Engine oil too thin Valve stem oil deflectors damaged Incorrect piston rings Piston ring gaps not staggered Insufficient piston ring tension Piston ring grooves or oil return Piston rings sticking in grooves Piston ring grooves excessively worn Compression rings installed upside down Worn or scored cylinder walls Mismatched oil ring expander and rail Intake gasket dowels too long Excessive main or connecting rod bearing clearance No Oil Pressure Low oil level Oil pressure sender or gauge broken Oil pump malfunction Oil pressure relief valve sticking Oil pump passages blocked

Remove and reinstall drain plug Remove restriction Remove and reinstall sending switch Replace stems or guides, See ENGINES Replace "O" ring seals, See ENGINES Remove restrictions Replace PCV valve Remove excess oil Replace thicker oil Replace oil deflectors Replace piston rings, See ENGINES Reinstall piston rings, See ENGINES Replace rings, See ENGINES slots clogged Replace piston rings, See ENGINES Replace piston rings, See ENGINES Replace piston and rings, See ENGINES Replace compression rings correctly, See ENGINES Rebore cylinders or replace block Replace oil ring expander and rail, See ENGINES Replace intake gasket dowels Replace main or connecting rod bearings, See ENGINES Add oil to proper level Replace sender or gauge Remove and overhaul oil pump, See ENGINES Remove and reinstall valve Overhaul oil pump, See ENGINES

Oil pickup screen or tube blocked Loose oil inlet tube Loose camshaft bearings Internal leakage at oil passages Low Oil Pressure Low engine oil level Engine oil too thin Excessive oil pump clearance Oil pickup tube or screen blocked Main, rod or cam bearing clearance excessive High Oil Pressure Improper grade of oil Oil pressure relief valve stuck closed Oil pressure sender or gauge faulty Noisy Main Bearings Inadequate oil supply Excessive main bearing clearance Excessive crankshaft end play Loose flywheel or torque converter Loose or damaged vibration damper Crankshaft journals out-of-round Excessive belt tension Noisy Connecting Rods Excessive bearing clearance or missing bearing Crankshaft rod journal out-of-round Misaligned connecting rod or cap Incorrectly tightened rod bolts Noisy Pistons and Rings Excessive piston-to-bore clearance Bore tapered or out-of-round

Remove restriction Tighten oil inlet tube Replace camshaft bearings, See ENGINES Replace block or cylinder head Add oil to proper level Remove and replace with thicker oil Reduce oil pump clearance, See ENGINES Remove restrictions Replace bearing to reduce clearance, See ENGINES Replace with proper oil Eliminate binding Replace sender or gauge Check oil delivery to main bearings Replace main bearings, See ENGINES Replace crankshaft, See ENGINES Tighten attaching bolts Tighten or replace vibration damper Re-grind crankshaft journals Loosen belt tension Replace bearing, See ENGINES Re-grind crankshaft journal Remove rod or cap and realign Remove and re-tighten rod bolts Install larger pistons, See ENGINES Rebore block

Piston ring broken Piston pin loose or seized Connecting rods misaligned Ring side clearance too loose or tight Carbon build-up on piston Noisy Valve Train Worn or bent push rods Worn rocker arms or bridged pivots Dirt or chips in valve lifters Excessive valve lifter leak-down Valve lifter face worn Broken or cocked valve springs Too much valve stem-to-guide clearance Valve bent Loose rocker arms Excessive valve seat run-out Missing valve lock Excessively worn camshaft lobes Plugged valve lifter oil holes Faulty valve lifter check ball Rocker arm nut installed upside down Valve lifter incorrect for engine Faulty push rod seat or lifter plunger Noisy Valves Improper valve lash Worn or dirty valve lifters Worn valve guides

Replace piston rings, See ENGINES Replace piston pin, See ENGINES Realign connecting rods Replace with larger or smaller rings Remove carbon Replace push rods, See ENGINES Replace push rods, See ENGINES Remove lifters and remove dirt/chips Replace valve lifters, See ENGINES Replace valve lifters, See ENGINES Replace or reposition springs Replace valve guides, See ENGINES Replace valve, See ENGINES Retighten rocker arms, See ENGINES Reface valve seats, See ENGINES Install new valve lock Replace camshaft, See ENGINES Eliminate restriction or replace lifter Replace lifter check ball, See ENGINES Remove and reinstall correctly Remove and replace valve lifters Replace plunger or push rod Re-adjust valve lash, See ENGINES Clean and/or replace lifters Replace valve guides, See ENGINES

Excessive valve seat or face run-out Worn camshaft lobes Loose rocker arm studs Bent push rods Broken valve springs Burned,Sticking or Broken Valves Weak valve springs or warped valves Improper lifter clearance Worn guides or improper guide clearance Out-of-round valve seats or improper seat width Gum deposits on valve stems, seats or guide Improper spark timing Broken Pistons/Rings Undersize pistons Wrong piston rings Out-of-round cylinder bore Improper connecting rod alignment Excessively worn ring grooves Improperly assembled piston pins Insufficient ring gap clearance Engine overheating Incorrect ignition timing Excessive Exhaust Noise Leaks at manifold to head, or to pipe Exhaust manifold cracked or broken

ENGINE PERFORMANCE

Reface seats or valve face Replace camshaft, See ENGINES Re-tighten rocker arm studs, See ENGINES Replace push rods, See ENGINES Replace valve springs, See ENGINES Replace valves and/or springs, See ENGINES Re-adjust clearance or replace lifters Replace valve guides, See ENGINES Re-grind valve seats Remove deposits Re-adjust spark timing Replace with larger pistons, See ENGINES Replace with correct rings, See ENGINES Re-bore cylinder bore Remove and realign connecting rods Replace pistons, See ENGINES Re-assemble pin-to-piston, See ENGINES Install new rings, See ENGINES Check cooling system Re-adjust ignition timing, See TUNE-UP Replace manifold or pipe gasket Replace exhaust manifold, See ENGINES

CARBURETOR TROUBLE SHOOTING: NOTE:

BASIC COLD START SYMPTOMS TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Engine Won't Start Choke not closing Choke linkage bent Engine Starts, Then Dies Choke vacuum kick setting too wide Fast idle RPM too low Fast idle cam index incorrect Vacuum leak Low fuel pump outlet Low carburetor fuel level Engine Quits Under Load Choke vacuum kick setting incorrect Fast idle cam index incorrect Incorrect hot fast idle speed RPM Engine Starts, Runs Up, Then Idles, Slowly With Black Smoke Choke vacuum kick set too narrow Fast idle cam index incorrect Hot fast idle RPM too low

BASIC HOT START SYMPTOMS TROUBLE SHOOTING CHART

CORRECTION Check choke operation, see FUEL SYSTEMS Check linkage, see FUEL SYSTEM Check setting and adjust see, FUEL SYSTEMS Reset RPM to specification, see TUNE-UP Reset fast idle cam index, see FUEL SYSTEMS Inspect vacuum system for leaks Repair or replace pump, see FUEL SYSTEMS Check float setting see FUEL SYSTEM Reset vacuum kick setting,see FUEL SYSTEMS Reset fast idle cam index, see FUEL SYSTEM Reset fast idle RPM, see TUNE-UP

Reset vacuum kick, see FUEL SYSTEMS Reset fast idle cam index, see FUEL SYSTEMS Reset fast idle RPM, see TUNE-UP

CONDITION & POSSIBLE CAUSE Engine Won't Start Engine flooded

CORRECTION Allow fuel to evaporate

BASIC COLD ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE CORRECTION Engine Stalls in Gear Choke vacuum kick setting incorrect Reset choke vacuum kick, see FUEL SYSTEMS Fast idle RPM incorrect Reset fast idle RPM, see TUNE-UP Fast idle cam index incorrect Reset fast idle cam see FUEL SYSTEMS Acceleration Sag or Stall Defective choke control switch Replace choke control switch Choke vacuum kick setting incorrect Reset choke vacuum kick see, FUEL SYSTEMS Float level incorrect (too low) Adjust float level, FUEL SYSTEMS Accelerator pump defective Repair or replace pump see FUEL SYSTEMS Secondary throttles not closed Inspect lockout adjustment, see FUEL SYSTEMS Sag or Stall After Warmup Defective choke control switch Replace choke control switch, see FUEL SYSTEMS Defective accelerator pump Replace pump, see FUEL SYSTEMS Float level incorrect (too low) Adjust float level, see FUEL SYSTEMS Backfiring & Black Smoke Plugged heat crossover system Remove restriction BASIC WARM ENGINE DRIVEABILITY SYMPTOMS TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE CORRECTION Hesitation With Small Amount of Gas Pedal Movement Vacuum leak Inspect vacuum lines Accelerator pump weak or inoperable Replace pump, see FUEL SYSTEMS Float level setting too low Reset float level, see,FUEL SYSTEMS Metering rods sticking or binding Inspect and/or replace rods, see FUEL SYSTEMS

Carburetor idle or transfer system plugged Frozen or binding heated air inlet Hesitation With Heavy Gas Pedal Movement Defective accelerator pump Metering rod carrier sticking or binding Large vacuum leak Float level setting too low Defective fuel pump, lines or filter Air door setting incorrect

Inspect system and remove restriction Inspect heated air door for binding Replace pump, see FUEL SYSTEMS Remove restriction Inspect vacuum system and repair leak Reset float level, see FUEL SYSTEMS Inspect pump, lines and filter Adjust air door setting, see FUEL

DIESEL ENGINE TROUBLE SHOOTING NOTE:

NOTE:

Diesel engines mechanical diagnosis is the same as gasoline engines for items such as noisy valves, bearings, pistons, etc. The following trouble shooting covers only items pertaining to diesel engines.

BASIC DIESEL ENGINE TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Engine Won't Crank Bad battery connections or dead batteries Bad starter connections or bad starter Engine Cranks Slowly, Won't Start Bad battery connections or dead batteries Engine oil too heavy Engine Cranks Normally, But Will Not Start Glow plugs not functioning Glow plug control not functioning

CORRECTION Check connections and/or replace batteries Check connections and/or replace starter Check connections and/or replace batteries Replace engine oil Check glow plug system, see FUEL SYSTEMS Check controller, see FUEL SYSTEMS

Fuel not injected into cylinders No fuel to injection pump Fuel filter blocked Fuel tank filter blocked Fuel pump not operating Fuel return system blocked No voltage to fuel solenoid Incorrect or contaminated fuel Incorrect injection pump timing Low compression Injection pump malfunction Engine Starts, Won't Idle Incorrect slow idle adjustment Fast idle solenoid malfunctioning Fuel return system blocked Glow plugs go off too soon Injection pump timing incorrect No fuel to injection pump Incorrect or contaminated fuel Low compression Injection pump malfunction Fuel solenoid closes in RUN position Engines Starts/Idles Rough W/out Smoke or Noise Incorrect slow idle adjustment Injection line fuel leaks Fuel return system blocked Air in fuel system Incorrect or contaminated fuel

Check fuel injectors, see FUEL SYSTEMS Check fuel delivery system Replace fuel filter Replace fuel tank filter Check pump operation and/or replace pump Inspect system and remove restriction Check solenoid and connections Replace fuel Re-adjust pump timing, see FUEL SYSTEMS Check valves, pistons, rings, see ENGINES Inspect and/or replace injection pump Reset idle adjustment, see TUNE-UP Check solenoid and connections Check system and remove restrictions See glow plug diagnosis in FUEL SYSTEMS Reset pump timing, see FUEL SYSTEMS Check fuel delivery system Replace fuel Check valves, piston, rings, see ENGINES Replace injection pump, see FUEL SYSTEMS Check solenoid and connections Reset slow idle, see TUNE-UP Check lines and connections Check lines and connections Bleed air from system Replace fuel

Injector nozzle malfunction

Check nozzles, see FUEL SYSTEMS Engines Starts and Idles Rough W/out Smoke or Noise, But Clears After Warm-Up Injection pump timing incorrect Reset pump timing, see FUEL SYSTEMS Engine not fully broken in Put more miles on engine Air in system Bleed air from system Injector nozzle malfunction Check nozzles, see FUEL SYSTEMS Engine Idles Correctly, Misfires Above Idle Blocked fuel filter Replace fuel filter Injection pump timing incorrect Reset pump timing, see FUEL SYSTEMS Incorrect or contaminated fuel Replace fuel Engine Won't Return To Idle Fast idle adjustment incorrect Reset fast idle, see TUNE-UP Internal injection pump malfunction Replace injection pump, see FUEL SYSTEMS External linkage binding Check linkage and remove binding Fuel Leaks On Ground Loose or broken fuel line Check lines and connections Internal injection pump seal leak Replace injection pump, see FUEL SYSTEMS Cylinder Knocking Noise Injector nozzles sticking open Test injectors, see FUEL SYSTEMS Very low nozzle opening pressure Test injectors and/or replace Loss of Engine Power Restricted air intake Remove restriction EGR valve malfunction Replace EGR valve Blocked or damaged exhaust system Remove restriction and/or replace components Blocked fuel tank filter Replace filter Restricted fuel filter Remove restriction and/or replace filter Block vent in gas cap Remove restriction and/or replace cap Tank-to-injection pump fuel supply blocked Check fuel lines and connections Blocked fuel return system Remove restriction Incorrect or contaminated fuel Replace fuel Blocked injector nozzles Check nozzle for blockage, see

Low compression Loud Engine Noise With Black Smoke Basic timing incorrect EGR valve malfunction Internal injection pump malfunction Incorrect injector pump housing pressure Engine Overheating Cooling system leaks Belt slipping or damaged Thermostat stuck closed

Head gasket leaking Oil Light on at Idle Low oil pump pressure Oil cooler or line restricted Engine Won't Shut Off Injector pump fuel solenoid does not return fuel valve to OFF position VACUUM PUMP DIAGNOSIS CONDITION & POSSIBLE CAUSE Excessive Noise Loose pump-to-drive assembly screws Loose tube on pump assembly Valves not functioning properly Oil Leakage Loose end plug Bad seal crimp

FUEL SYSTEMS Check valves, rings, pistons, see ENGINES Reset timing, see FUEL SYSTEMS Replace EGR valve Replace injection pump, see FUEL SYSTEMS Check pressure, see FUEL SYSTEMS Check cooling system and repair leaks Check tension and/or replace belt Remove and replace thermostat, see ENGINE COOLING Replace head gasket Check oil pump operation, see ENGINES Remove restriction and/or replace cooler Remove and check solenoid and replace if needed

CORRECTION Tighten screws Tighten tube Replace valves Tighten end plug Remove and re-crimp seal

FUEL INJECTION TROUBLE SHOOTING NOTE:

This is GENERAL information. This article is not intended to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble

No distributor reference pulses Open coolant temperature sensor circuit Shorted W.O.T. switch in T.P.S. Defective ECM Fuel tank residual pressure valve leaks Hard Starting Disconnected hot air tube to air cleaner Defective Idle Air Control (IAC) valve Shorted, open or misadjusted T.P.S. EGR valve open Poor Oxygen sensor signal Incorrect mixture from PCV system Poor High Speed Operation Low fuel pump volume Poor MAP sensor signal Poor Oxygen sensor signal

CORRECTION Test valve and circuit Check vacuum and electrical connections Test fuel for water or alcohol Test relay and wiring Charge and test battery Test pressure regulator and fuel pump, check for restricted lines and filters Repair ignition system as necessary Test sensor and wiring Disconnect W.O.T. switch, engine should start Replace ECM Test for fuel pressure drop after shut down Reconnect tube and test control valve Test valve operation and circuit Test and adjust or replace T.P.S. Test EGR valve and control circuit Test for shorted or circuit Test PCV for flow, check sealing of oil filter cap Faulty pump or restricted fuel lines or filters Test MAP sensor, vacuum hose and wiring Test for shorted or open sensor or circuit

Open coolant temperature sensor circuit Faulty ignition operation

Contaminated fuel Intermittent ECM ground Restricted air cleaner Restricted exhaust system Poor MAF sensor signal Poor VSS signal

Ping or Knock on Acceleration Poor Knock sensor signal Poor Baro sensor signal Improper ignition timing

Check for engine overheating problems

NOTE:

Test sensor and wiring Check wires for cracks or poor connections, test secondary voltage with oscilloscope Test fuel for water or alcohol Test ECM ground connection for resistance Replace air cleaner Test for exhaust manifold back pressure Check leakage between sensor and manifold If tester for ALCL hook-up is available check that VSS reading matches speedometer Test for shorted or open sensor or circuit Test for shorted or open sensor or circuit See VEHICLE EMISSION CONTROL LABEL (where applicable) Low coolant, loose belts or electric cooling fan inoperative

For additional electronic fuel injection trouble shooting information, see the appropriate article in the ENGINE PERFORMANCE section (not all vehicles have Computer Engine Control articles). Information is provided there for diagnosing fuel system problems on vehicles with electronic fuel injection.

IGNITION SYSTEM TROUBLE SHOOTING NOTE:

Fig. 3: Ignition Secondary Trouble Shooting Chart

Fig. 4: Ignition Primary Trouble Shooting Chart STARTER TROUBLE SHOOTING NOTE:

BASIC STARTER TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Starter Fails to Operate Dead battery or bad connections between starter and battery

Internal ground in starter windings Grounded starter fields Armature rubbing on pole shoes Starter Turns but Engine Does Not Rotate Starter clutch slipping Broken clutch housing Pinion shaft rusted or dry Engine basic timing incorrect Broken teeth on engine flywheel

Starter Will Not Crank Engine

CORRECTION Check battery charge and all wires and connections to starter Adjust or replace ignition switch Check and repair wires and connections as necessary See Testing in STARTER article See Testing in STARTER article Charge or replace battery as necessary Check that battery connections are clean and tight See Testing in STARTER article See Testing in STARTERS See STARTER article See STARTER article See STARTER article See STARTER article See Ignition Timing in TUNE-UP article Replace flywheel and check for starter pinion gear damage

Faulty overrunning clutch Broken clutch housing Broken flywheel teeth

Armature shaft sheared or reduction gear teeth stripped Weak battery Faulty solenoid Poor grounds

Ignition switch faulty or misadjusted Starter Cranks Engine Slowly Battery weak or defective Engine overheated Engine oil too heavy Poor battery-to-starter connections

Current draw too low or too high Bent armature, loose pole shoes screws or worn bearings Burned solenoid contacts Faulty starter Starter Engages Engine Only Momentarily Engine timing too far advanced Overrunning clutch not engaging properly Broken starter clutch Broken teeth on engine flywheel

Weak drive assembly thrust spring Weak hold-in coil Starter Drive Will Not Engage Defective point assembly

See STARTER article See STARTER article Replace flywheel and check for starter pinion gear damage See STARTER article Charge or replace battery as necessary See On-Vehicle Tests in STARTER article Check all ground connections for tight and clean connections Adjust or replace ignition switch as necessary Charge or replace battery as necessary See ENGINE COOLING SYSTEM article Check that proper viscosity oil is used Check that all between battery and starter are clean and tight See Bench Tests in STARTER article See STARTER article Replace solenoid Replace starter See Ignition Timing in TUNE-UP article Replace overrunning clutch. See STARTER article See STARTER article Replace flywheel and check starter pinion gear for damage See STARTER article See Bench Tests in STARTER article See Testing in STARTER

Poor point assembly ground Defective pull-in coil Starter Relay Does Not Close Dead battery Faulty wiring Neutral safety switch faulty Starter relay faulty Starter Drive Will Not Disengage Starter motor loose on mountings Worn drive end bushing Damaged engine flywheel teeth Drive yolk return spring broken or missing Faulty ignition switch Insufficient clearance between winding leads to solenoid terminal and main contact in solenoid Starter clutch not disengaging Ignition starter switch contacts sticking Starter Relay Operates but Solenoid Does Not Faulty solenoid switch, switch connections or relay

article See Testing in STARTER article Replace starter solenoid Charge or replace battery as necessary Check all wiring and connections leading to relay Replace neutral safety switch Replace starter relay Tighten starter attach bolts See STARTER article Replace flywheel and starter pinion gear for damage Replace return spring Replace ignition switch Replace starter solenoid Replace starter clutch Replace ignition switch Check all wiring between relay and solenoid or replace relay or solenoid as necessary Repair wire or wire connections as necessary Charge or replace battery as necessary Clean contacts or replace solenoid Check all wiring leading to solenoid Repair connections or replace solenoid Replace solenoid

correct starter and flywheel are being used High Pitched Whine After Engine Fires With Key released. Engine Fires and Cranks Normally Distance too small between starter pinion and flywheel Flywheel runout contributes to the intermittent nature TUNE-UP TROUBLE SHOOTING - GAS ENGINE VEHICLES NOTE:

BASIC SPARK PLUG TROUBLE SHOOTING CHARTS CONDITION & POSSIBLE CAUSE Normal Spark Plug Condition Light Tan or Gray deposits Electrode not burned or fouled Gap tolerance not changed Cold Fouling or Carbon Deposits Overrich air/fuel mixture

Faulty choke

Clogged air filter Incorrect idle speed or dirty carburetor Faulty ignition wires Prolonged operation at idle Sticking valves or worn valve guide seals Wet Fouling or Oil Deposits Worn rings and pistons Excessive cylinder wear Excessive valve guide clearance Gap Bridged Deposits in combustion chamber becoming fused to electrode Blistered Electrode Engine overheating

CORRECTION No Action No Action No Action Adjust air/fuel mixture, see ENGINE PERFORMANCE section Replace choke assembly, see ENGINE PERFORMANCE section Clean and/or replace air filter Reset idle speed and/ or clean carburetor Replace ignition wiring Shut engine off during long idle Check valve train Install new rings and pistons Rebore or replace block Worn or loose bearing Clean combustion chamber of deposits Check cooling system

Wrong type of fuel Loose spark plugs Over-advanced ignition timing

Replace with correct fuel Retighten spark plugs Reset ignition timing see ENGINE PERFORMANCE

Pre-Ignition or Melted Electrodes Incorrect type of fuel Incorrect ignition timing

Replace with correct fuel Reset ignition timing see ENGINE PERFORMANCE Replace valves Check cooling system Replace with correct spark plug, see ENGINE PERFORMANCE

Burned valves Engine Overheating Wrong type of spark plug, too hot

Chipped Insulators Severe detonation Improper gapping procedure Rust Colored Deposits Additives in unleaded fuel Water In Combustion Chamber Blown head gasket or cracked head

NOTE:

Check for over-advanced timing or combustion Re-gap spark plugs Try different fuel brand Repair or replace head or head gasket

Before diagnosing an electronic ignition system, ensure that all wiring is connected properly between distributor, wiring connector and spark plugs. Ignition problem will show up either as: Engine Will Not Start or Engine Runs Rough.

BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS CONDITION & POSSIBLE CAUSE Engine Won't Start Open circuit between distributor and bulkhead connector Open circuit between bulkhead connector and ignition switch Open circuit between ignition switch and starter solenoid Engine Runs Rough Fuel lines leaking or clogged Initial timing incorrect Centrifugal advance malfunction Defective spark plugs or wiring Component Failure Spark arc-over on cap, rotor or coil

CORRECTION Repair circuit Repair circuit Repair circuit Tighten fitting, remove restriction Reset ignition timing see ENGINE PERFORMANCE Repair distributor advance Replace plugs or plug wiring Replace cap, rotor or or coil

Defective pick-up coil Defective ignition coil Defective vacuum unit Defective control module

Replace pick-up coil Replace ignition coil Replace vacuum unit Replace control module

BASIC ELECTRONIC IGNITION TROUBLE SHOOTING CHARTS - USING OSCILLOSCOPE PATTERNS CONDITION & POSSIBLE CAUSE CORRECTION Firing Voltage Lines are the Same, but Abnormally High Retarded ignition timing Reset ignition timing, see ENGINE PERFORMANCE section Fuel mixture too lean Readjust carburetor, see ENGINE PERFORMANCE High resistance in coil wire Replace coil wire Corrosion in coil tower terminal Clean and/or replace coil Corrosion in distributor coil terminal Clean and/or replace distributor cap Firing Voltage Lines are the Same but Abnormally Low Fuel mixture too rich Readjust carburetor, see ENGINE PERFORMANCE Breaks in coil wire causing arcing Replace coil wire Cracked coil tower causing arcing Replace coil Low coil output Replace coil Low engine compression Determine cause and repair One or More, But Not All Firing Voltage Lines are Higher Than Others Carburetor idle mixture not balanced Readjust carburetor, see ENGINE PERFORMANCE EGR valve stuck open Clean and/or replace valve High resistance in spark plug wires Replace spark plug wires Cracked or broken spark plug insulator Replace spark plugs Intake vacuum leak Repair leak Defective spark plugs Replace spark plugs Corroded spark plug terminals Replace spark plugs One or More, But Not All Firing Voltage Lines Are Lower Than Others Curb idle mixture not balanced Readjust carburetor, see ENGINE PERFORMANCE Breaks in plug wires Replace plug wires causing arcing Cracked coil tower causing arcing Replace coil Low compression Determine cause and repair Defective spark plugs Replace spark plugs

Corroded spark plugs Cylinders Not Firing Cracked distributor cap terminals Shorted spark plug wire Mechanical problem in engine Defective spark plugs Spark plugs fouled BASIC DRIVEABILITY PROBLEMS TROUBLE SHOOTING CONDITION & POSSIBLE CAUSE Hard Starting Binding carburetor linkage Binding choke linkage Binding choke piston Restricted choke vacuum Worn or dirty needle valve and seat Float sticking

Incorrect choke adjustment Defective coil Improper spark plug gap Incorrect ignition timing Detonation Over-advanced ignition timing Defective spark plugs Fuel lines clogged EGR system malfunction PCV system malfunction Vacuum leaks Loose fan belts

Restricted airflow Vacuum advance malfunction Dieseling Binding carburetor linkage

Replace spark plugs Replace distributor cap Determine cause and repair Determine cause and repair Replace spark plugs Replace spark plugs

CORRECTION Eliminate binding Eliminate binding Eliminate binding Check vacuum lines for blockage Clean carburetor, see ENGINE PERFORMANCE Readjust or replace float see the ENGINE PERFORMANCE section Reset choke adjustment see ENGINE PERFORMANCE Replace coil Regap spark plugs Reset ignition timing see ENGINE PERFORMANCE Reset ignition timing see ENGINE PERFORMANCE Replace spark plugs Clean fuel lines Check and repair EGR system Repair PCV system Check and repair vacuum system Tighten or replace fan belts, see ENGINE PERFORMANCE Remove restriction Check distributor operation Eliminate binding

Binding throttle linkage Binding choke linkage or fast idle cam Defective idle solenoid Improper base idle speed Incorrect ignition timing Incorrect idle mixture setting Faulty Acceleration Incorrect ignition timing Engine cold and choke too lean Defective spark plugs Defective coil Faulty Low Speed Operation Clogged idle transfer slots Restricted idle air bleeds and passages Clogged air cleaner Defective spark plugs Defective ignition wires Defective distributor cap Faulty High Speed Operation Incorrect ignition timing Defective distributor centrifugal advance Defective distributor vacuum advance Incorrect spark plugs or plug gap Faulty choke operation Clogged vacuum passages Improper size or clogged main jet Restricted air cleaner Defective distributor cap, rotor or coil Misfire at All Speeds

Eliminate blinding Eliminate binding Replace idle solenoid see ENGINE PERFORMANCE Reset idle speed, see see ENGINE PERFORMANCE Reset ignition timing see ENGINE PERFORMANCE Reset idle mixture, see ENGINE PERFORMANCE Reset ignition timing see ENGINE PERFORMANCE Adjust choke and allow engine to warm-up Replace spark plugs Replace coil Clean idle transfer slots, see FUEL Disassemble and clean carburetor, see FUEL Replace air filter Replace spark plugs Replace ignition wire see ENGINE PERFORMANCE Replace distributor cap Reset ignition timing see ENGINE PERFORMANCE Replace advance mechanism Replace advance unit Check gap and/or replace spark plugs Check choke and repair as required Remove restrictions Check jet size and clean, see FUEL Check filter and replace as necessary Replace cap, rotor or coil

Defective spark plugs Defective spark plug wires Defective distributor cap, rotor, or coil Cracked or broken vacuum hoses Vacuum leaks Fuel lines clogged Hesitation Cracked or broken vacuum Vacuum leaks Binding carburetor linkage Binding throttle linkage Binding choke linkage or fast idle cam Improper float setting Cracked or broken ignition wires Rough Idle, Missing or Stalling Incorrect curb idle or fast idle speed Incorrect basic timing Improper idle mixture adjustment Improper feedback system operation Incorrect spark plug gap Moisture in ignition components Loose or broken ignition wires Damaged distributor cap or or rotor Faulty ignition coil Fuel filter clogged or worn Damaged idle mixture screw Improper fast idle cam adjustment

Improper EGR valve operation Faulty PCV valve air flow Choke binding or improper choke setting Vacuum leak Improper float bowl fuel level

Replace spark plugs Replace spark plug wires Replace cap, rotor, or coil Replace vacuum hoses Repair vacuum leaks Remove restriction Replace vacuum hoses hoses Repair Vacuum leaks Eliminate binding Eliminate binding Eliminate binding Readjust float setting, see FUEL Replace ignition wires Reset idle speed, see see ENGINE PERFORMANCE Reset ignition timing see ENGINE PERFORMANCE Reset idle mixture, see ENGINE PERFORMANCE Check feedback system see ENGINE PERFORMANCE Reset spark plug gap, see ENGINE PERFORMANCE Dry components Replace ignition wires Replace distributor cap or rotor Replace ignition coil Replace fuel filter Replace idle mixture screw, see FUEL Reset fast idle cam adjustment, see TUNE- see ENGINE PERFORMANCE Replace EGR valve Replace PCV valve Reset choke or eliminate binding Repair vacuum leak Reset float adjustment, see

Clogged air bleed or idle passages Clogged or worn air cleaner filter Faulty choke vacuum diaphragm Exhaust manifold heat valve inoperative Improper distributor spark advance Leaking valves or valve components Improper carburetor mounting Excessive play in distributor shaft Loose or corroded wiring connections Engine Surges Improper PCV valve airflow Vacuum leaks Clogged air bleeds EGR valve malfunction Restricted air cleaner filter Cracked or broken vacuum hoses Cracked or broken ignition wires Vacuum advance malfunction Defective or fouled spark plugs Ping or Spark Knock Incorrect ignition timing Distributor centrifugal or vacuum advance malfunction Carburetor setting too lean Vacuum leak EGR valve malfunction Poor Gasoline Mileage Cracked or broken vacuum Vacuum leaks Defective ignition wires Incorrect choke setting Defective vacuum advance Defective spark plugs Binding carburetor power piston

FUEL Clean carburetor passages, see FUEL Replace air filter Replace diaphragm, see ENGINE PERFORMANCE Replace heat valve Check distributor operation Check and repair valvetrain Remove and remount carburetor Replace distributor Repair or replace as required Replace PCV valve Repair vacuum leaks Remove restriction Replace EGR valve Replace air filter Replace vacuum hoses Replace ignition wires Check unit and replace as necessary Replace spark plugs Reset ignition timing see ENGINE PERFORMANCE Check operation and replace as necessary Readjust mixture setting, see ENGINE PERFORMANCE Eliminate vacuum leak Replace EGR valve Replace vacuum hoses hoses Repair vacuum leaks Replace wires Readjust setting, see ENGINE PERFORMANCE Replace vacuum advance Replace spark plugs Eliminate binding

Dirt in carburetor jets Incorrect float adjustment Defective power valve Incorrect idle speed Engine Stalls Improper float level Leaking needle valve and seat Vacuum leaks

Clean and/or replace jets Readjust float setting, see FUEL Replace power valve, see ENGINE PERFORMANCE Readjust idle speed Readjust float level Replace needle valve and seat Eliminate vacuum leaks

VACUUM PUMP - DIESEL TROUBLE SHOOTING NOTE:

NOTE:

VACUUM PUMP (DIESEL) TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Excessive Noise Loose pump-to-drive assembly screws Loose tube on pump assembly Valves not functioning properly Oil Leakage Loose end plug Bad seal crimp

CORRECTION Tighten screws Tighten tube Replace valves Tighten end plug Remove and re-crimp seal

MANUAL TRANSMISSION MANUAL TRANSMISSION TROUBLE SHOOTING NOTE:

MANUAL TRANSMISSION/TRANSAXLE TROUBLE SHOOTING Condition Possible Cause Noisy In Forward Gears Low gear oil level, Loose bell housing bolts, Worn bearings or gears Clunk On Deceleration (FWD Only) Loose engine mounts, Worn inboard CV joints, Worn differential pinion shaft, Side gear hub counterbore in case worn oversize Gear Clash When Shifting Forward Gears Clutch Out Of Adjustment, Shift linkage damaged or out of adjustment, Gears or synchronizers damaged, Low gear oil level Transmission Noisy When Moving (RWD Only) Worn rear outputshaft bearing Quiet In Neutral With Clutch Engaged Gear Rattle Worn bearings, Wrong gear oil, Low gear oil, Worn gears Steady Ticking At Idle (Increases With RPM) Broken tooth on gear Gear Clash When Shifting Forward Gears Worn or broken synchronizers Loud Whine In Reverse Normal condition (1) Noise When Stepping On Clutch Ticking Or Screeching As Clutch Is Engaged

Bad release bearing, Worn pilot bearing Faulty release bearing, Uneven pressure plate fingers Click Or Snap When Clutch Is Engaged Worn clutch fork, Worn or broken front bearing retainer Transmission Shifts Hard Clutch not releasing, Shift mechanism binding, Clutch installed backwards Will Not Shift Into One Gear, Shifts Into All Others Bent shift fork, Worn detent balls Locked Into Gear, Cannot Shift Clutch adjustment, Worn detent balls Transmission Jumps Out Of Gear Pilot bearing worn, Bent shift fork, Worn gear teeth or face, Excessive gear train end play, Worn synchronizers, Missing detent ball spring, Shift mechanism worn or out of adjustment, Engine or transmission mount bolts loose or out of adjustment, Transmission not aligned Shift Lever Rattle Worn shift lever or detents, Worn shift forks, Worn synchronizers sleeve Shift Lever Hops Under Acceleration Worn engine or transmission mounts (1) Most units use spur cut gears in reverse and are noisy

POWERTRAIN CLUTCH TROUBLE SHOOTING NOTE:

This is GENERAL information. This article is not intended to be specific to any unique situation or individual vehicle configuration. The purpose of this Trouble

Shooting information is to provide a list of common causes to problem symptoms. For model-specific Trouble Shooting, refer to SUBJECT, DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing. BASIC CLUTCH TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Chattering or Grabbing Incorrect clutch adjustment Oil, grease or glaze on facings Loose "U" joint flange Worn input shaft spline Binding pressure plate Binding release lever Binding clutch disc hub Unequal pressure plate contact Loose/bent clutch disc Incorrect transmission alignment Worn pressure plate, disc or flywheel Broken or weak pressure springs Sticking clutch pedal Incorrect clutch disc facing Engine loose in chassis Failure to Release Oil or grease on clutch facings Incorrect release lever or pedal adjustment Worn or broken clutch facings Bent clutch disc or pressure plate Clutch disc hub binding on input shaft Binding pilot bearing Sticking release bearing sleeve Binding clutch cable Defective clutch master Defective clutch slave Air in hydraulic system Rattling Weak or broken release lever spring Damaged pressure plate

CORRECTION Adjust clutch Disassemble and clean or replace See DRIVE AXLES article Replace input shaft Replace pressure plate See CLUTCH article Replace clutch disc Replace worn/misaligned components Replace clutch disc Realign transmission Replace damaged components Replace pressure plate Lubricate clutch pedal & linkage Replace clutch disc Tighten all mounting bolts Clean or replace clutch clutch disc See CLUTCH article Replace clutch disc Replace damaged components Clean or replace clutch disc and/or input shaft Replace pilot bearing Replace release bearing and/or sleeve See CLUTCH article Replace master cylinder Replace slave cylinder Bleed hydraulic system Replace spring and check alignment Replace pressure plate

Broken clutch return spring Worn splines on clutch disc or input shaft Worn clutch release bearing Dry or worn pilot bearing Unequal release lever contact Incorrect pedal free play Warped or damaged clutch disc Slipping Pressure springs worn or Oily, greasy or worn facings Incorrect clutch alignment Warped clutch disc or pressure plate Binding release levers or clutch pedal Squeaking Worn or damaged release Dry or worn pilot or release bearing Pilot bearing turning in crankshaft Worn input shaft bearing Incorrect transmission alignment Dry release fork between pivot Heavy and/or Stiff Pedal Sticking release bearing sleeve Dry or binding clutch pedal hub Floor mat interference with pedal Dry or binding ball/fork pivots Faulty clutch cable Noisy Clutch Pedal Faulty interlock switch Self-adjuster ratchet noise Speed control interlock switch Clutch Pedal Sticks Down Binding clutch cable Springs weak in pressure plate Binding in clutch linkage Noisy Dry release bearing

Replace return spring Replace clutch disc and/or input shaft Replace release bearing Lubricate or replace pilot bearing Align or replace release lever Adjust free play Replace damaged components Release pressure plate Clean or replace clutch disc Realign clutch assembly Replace damaged components Lubricate and/or replace release components Replace release bearing Lubricate or replace assembly Replace pilot bearing and/or crankshaft Replace bearing and seal Realign transmission Lubricate release fork and pivot Replace release bearing and/or sleeve Lubricate and align components Lay mat flat in proper area Lubricate and align components Replace clutch cable Replace interlock switch Lubricate or replace self-adjuster Lubricate or replace interlock switch See CLUTCH article Replace pressure plate Lubricate and free linkage Lubricate or replace release bearing

Dry or worn pilot bearing Worn input shaft bearing Transmission Click Weak springs in pressure Release fork loose on ball stud Oil on clutch disc damper Broken spring in slave cylinder

Lubricate or replace bearing Replace bearing Replace pressure plate plate Replace release fork and/or ball stud Replace clutch disc Replace slave cylinder

DRIVE AXLE - NOISE DIAGNOSIS Unrelated Noises

Some driveline trouble symptoms are also common to the engine, transmission, wheel bearings, tires, and other parts of the vehicle. Ensure cause of trouble actually is in the drive axle before adjusting, repairing, or replacing any of its parts. Non-Drive Axle Noises

A few conditions can sound just like drive axle noise and have to be considered in pre-diagnosis. The 4 most common noises are exhaust, tires, CV/universal joints and wheel trim rings. In certain conditions, the pitch of the exhaust gases may e gear whine. At other times, it may be mistaken for a wheel bearing rumble. Tires, especially radial and snow, can have a high-pitched tread whine or roar, similar to gear noise. Also, some non-standard tires with an unusual tread construction may emit a roar or whine. Defective CV/universal joints may cause clicking noises or excessive driveline play that can be improperly diagnosed as drive axle problems. Trim and moldings also can cause a whistling or whining noise. Ensure none of these components are causing the noise before disassembling the drive axle. Gear Noise

A "howling" or "whining" noise from the ring and pinion gear can be caused by an improper gear pattern, gear damage, or improper bearing preload. It can occur at various speeds and driving conditions, or it can be continuous. Before disassembling axle to diagnose and correct gear ke sure that tires, exhaust, and vehicle trim have been checked as possible causes. Chuckle

This is a particular rattling noise that sounds like a stick against the spokes of a spinning bicycle wheel. It occurs while decelerating from 40 MPH and usually can be heard until vehicle comes to a complete stop. The

frequency varies with the speed of the vehicle. A chuckle that occurs on the driving phase is usually caused ive clearance due to differential gear wear, or by a damaged tooth on the coast side of the pinion or ring gear. Even a very small tooth nick or a ridge on the edge of a gear tooth is enough the cause the noise. This condition can be corrected simply by cleaning the gear tooth nick or ridge with a small grinding wheel. If either gear is damaged or scored badly, the gear set must be replaced. If metal has broken loose, the carrier and housing must be cleaned to remove particles that could cause damage. Knock

This is very similar to a chuckle, though it may be louder, and occur on acceleration or deceleration. Knock can be caused by a gear tooth that is damaged on the drive side of the ring and pinion gears. Ring gear bolts that are hitting the carrier casting can cause knock. Knock can also be due to excessive end play in the axle shafts. Clunk

Clunk is a metallic noise heard when an automatic transmission is engaged in Reverse or Drive, or when throttle is applied or released. It is caused by backlash somewhere in the driveline, but not necessarily in the axle. To determine whether driveline clunk is caused by the axle, check the total axle backlash as follows: 1. Raise vehicle on a frame or twinpost hoist so that drive wheels are free. Clamp a bar between axle companion flange and a part of the frame or body so that flange cannot move. 2. On conventional drive axles, lock the left wheel to keep it from turning. On all models, turn the right wheel slowly until it is felt to be in Drive condition. Hold a chalk marker on side of tire about 12" from center of wheel. Turn wheel in the opposite direction until it is again felt to be in Drive condition. 3. Measure the length of the chalk mark, which is the total axle backlash. If backlash is one inch or less, drive axle is not the source of clunk noise. Bearing Whine

Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by malfunctioning pinion bearings. Pinion bearings operate at drive shaft speed. Roller wheel bearings may whine in a similar manner if they run completely dry of lubricant. Bearing noise will occur at all driving speeds. This distinguishes it from gear whine, which usually comes and goes as speed changes. Bearing Rumble

Bearing rumble sounds like marbles being tumbled. It is usually caused by a malfunctioning wheel bearing. The lower pitch is because the wheel bearing turns at only about 1/3 of drive shaft speed. Chatter On Turns

This is a condition where the entire front or rear of vehicle vibrates when vehicle is moving. The vibration is plainly felt as well as heard. Extra differential thrust washers installed during axle repair can cause a condition of partial lock-up that creates this chatter.

Axle Shaft Noise

Axle shaft noise is similar to gear noise and pinion bearing whine. Axle shaft bearing noise will normally distinguish itself from gear noise by occurring in all driving modes (Drive, cruise, coast and float), and will persist with transmission in Neutral while vehicle is moving at problem speed. If vehicle displays this noise condition, remove suspect parts, replace wheel seals and install a new set of bearings. Re-evaluate vehicle for noise before removing any internal components. Vibration

Vibration is a high-frequency trembling, shaking or grinding condition (felt or heard) that may be constant or variable in level and can occur during the total operating speed range of the vehicle. The types of vibrations that can be felt in the vehicle can d into 3 main groups:   

Vibrations of various unbalanced rotating parts of the vehicle. Resonance vibrations of the body and frame structures caused by rotating of unbalanced parts. Tip-in moans of resonance vibrations from stressed engine or exhaust system mounts or driveline flexing modes.

DRIVE AXLE - RWD TROUBLE SHOOTING NOTE:

DRIVE AXLE (RWD) TROUBLE SHOOTING CONDITION & POSSIBLE CAUSE Knocking or Clunking Differential Side Gear Clearance Worn Pinion Shaft Axle Shaft End Play Missing Gear Teeth Wrong Axle Backlash Misaligned Driveline Clinking During Engagement Side Gear Clearance Ring and Pinion Backlash Worn/Loose Pinion Shaft

CORRECTION Check Clearance Replace Pinion Shaft Check End Play Check Differential/Replace Gear Check Backlash Realign Driveline Check Clearance Check Backlash Replace Shaft/Bearing

Bad "U" Joint Sticking Slip Yoke Broken Rear Axle Mount Loose Drive Shaft Flange Click/Chatter On Turns Differential Side Gear Clearance Wrong Turn On Plates (1) Wrong Differential Lubricant (1) Knock Or Click Flat Spot on Rear Wheel Bearing Low Vibration At All Speeds Faulty Wheel Bearing Faulty "U" Joint Faulty Drive Shaft Faulty Companion Flange Faulty Slip Yoke Flange (1) Limited slip differential only.

Replace "U" Joint Lube Slip Yoke Replace Mount Check Flange Check Clearance Replace Clutch Plates Change Lubricant Replace Wheel Bearing Replace Wheel Bearing Replace "U" Joint Balance Drive Shaft Replace Flange Replace Flange

FWD AXLE SHAFTS & CV JOINTS TROUBLE SHOOTING NOTE:

BASIC FWD AXLE SHAFTS & CV JOINTS TROUBLE SHOOTING CHART CONDITION POSSIBLE CAUSE Grease Leaks CV boot torn or cracked Clicking Noise on Cornering Damaged outer CV Clunk Noise on Acceleration Damaged inner CV Vibration or Shudder on Acceleration Sticking, damaged or worn CV Misalignment or spring height

STEERING & SUSPENSION MANUAL STEERING GEAR TROUBLE SHOOTING NOTE:

DIAGNOSTIC, or TESTING articles available in the section(s) you are accessing. BASIC MANUAL STEERING GEAR TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE CORRECTION Rattle or Chucking Noise in Rack and Pinion Rack and pinion mounting bracket loose Tighten all mounting bolts Lack of/or incorrect lubricant Correct as necessary Steering gear mounting bolts loose Tighten all mounting bolts Excessive Play Front wheel bearing improperly adjusted See FRONT SUSPENSION article Loose or worn steering linkage See STEERING LINKAGE article Loose or worn steering gear shift See MANUAL STEERING GEAR article Steering arm loose on gear shaft See MANUAL STEERING GEAR article Steering gear housing bolts loose Tighten all mounting bolts Steering gear adjustment too loose See MANUAL STEERING GEAR article Steering arms loose on knuckles Tighten and check steering linkage Rack and pinion mounting loose Tighten all mounting bolts Rack and pinion out of adjustment See adjustment in STEERING article Tie rod end loose Tighten and check steering linkage Excessive Pitman shaft-to-ball nut lash Repair as necessary Poor Returnability Lack of lubricant in ball joint or linkage Lubricate and service systems Binding in linkage or ball joints See STEERING LINKAGE and SUSPENSION article Improper front end alignment See WHEEL ALIGNMENT article Improper tire pressure Inflate to proper pressure Tie rod binding Inflate to proper pressure Shaft seal rubbing shaft See STEERING COLUMN article Excessive Vertical Motion Improper tire pressure Inflate to proper pressure Tires, wheels or rotors out of balance Balance tires then check wheels and rotors Worn or faulty shock absorbers Check and replace if necessary

Loose tie rod ends or steering Loose or worn wheel bearings Steering Pulls to One Side Improper tire pressure Front tires are different sizes Wheel bearings not adjusted properly Bent or broken suspension components Improper wheel alignment Brakes dragging Instability Low or uneven tire pressure Loose or worn wheel bearings Loose or worn idler arm bushing Loose or worn strut bushings Incorrect front wheel alignment Steering gear not centered Springs or shock Improper cross shaft

Tighten or replace if necessary See SUSPENSION article Inflate to proper pressure Rotate or replace if necessary See FRONT SUSPENSION article See FRONT SUSPENSION article See WHEEL ALIGNMENT article See BRAKES article Inflate to proper pressure See FRONT SUSPENSION article See FRONT SUSPENSION article See FRONT SUSPENSION article See WHEEL ALIGNMENT article See MANUAL STEERING GEARS article Check and replace if necessary See MANUAL STEERING GEARS article

POWER STEERING TROUBLE SHOOTING NOTE:

BASIC POWER STEERING TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Rattle or Chucking Noise Pressure hoses touching engine parts Loose Pitman shaft Tie rods ends or Pitman arm loose Rack and pinion mounts loose

CORRECTION Adjust to proper clearance Adjust or replace if necessary Tighten and check system Tighten all mounting bolts

Free play in worm gear Loose sector shaft or thrust bearing adjustment Free play in pot coupling Worn shaft serrations Growl in Steering Pump Excessive pressure in hoses Scored pressure plates Scored thrust plates or rotor Extreme wear of cam ring Rattle in Steering Pump Vanes not installed Vanes sticking in rotor Swish noise in Pump Defective flow control valve Groan in Steering Pump Air in fluid Poor pressure hose connection Squawk When Turning Damper "O" ring on valve spool cut Moan or Whine in Pump Pump shaft bearing scored Air in fluid or fluid level low Hose or column grounded Cover "O" ring missing or damaged Valve cover baffle missing or damaged Interference of components in pump

See POWER STEERING GEAR article See POWER STEERING GEAR See STEERING COLUMN article See STEERING COLUMN article Restricted hoses, see POWER STEERING GEAR article See POWER STEERING GEAR article See POWER STEERING GEAR article See POWER STEERING GEAR article See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article Tighten and check, replace if necessary See POWER STEERING PUMP article Replace bearing and fluid See POWER STEERING PUMP article Check and replace if necessary See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING

Loose or poor bracket alignment Hissing When Parking Internal leakage in steering gear Chirp in Steering Pump Loose or worn power steering belt Buzzing When Not Steering Noisy pump Free play in steering shaft bearing Bearing loose on shaft serrations Clicking Noise in Pump Pump slippers too long Broken slipper springs Excessive wear or nicked rotors Damaged cam contour Poor Return of Wheel Wheel rubbing against turn signal Flange rubbing steering gear adjuster Tight or frozen steering shaft bearing Steering gear out of adjustment Sticking or plugged spool valve Improper front end alignment Wheel bearings worn or loose Ties rods or ball joints binding Intermediate shaft joints binding Kinked pressure hoses Loose housing head spanner nut

PUMP article Correct or replace if necessary Check valved assembly first Adjust or replace if necessary See POWER STEERING PUMP article See STEERING COLUMN article See STEERING COLUMN article See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article See STEERING COLUMN SWITCHES article See STEERING COLUMN article See STEERING COLUMN article See POWER STEERING GEAR article See POWER STEERING PUMP article See WHEEL ALIGNMENT article See FRONT SUSPENSION article Check and replace if necessary See STEERING COLUMN article Correct or replace if necessary See POWER STEERING GEAR article

Damaged valve lever

See POWER STEERING GEAR article Sector shaft adjusted too tight See ADJUSTMENTS in POWER STEERING GEAR article Worm thrust bearing adjusted too tight See ADJUSTMENTS in POWER STEERING GEAR article Reaction ring sticking in cylinder See POWER STEERING GEAR article Reaction ring sticking in housing head See POWER STEERING GEAR article Steering pump internal leakage See POWER STEERING PUMP article Steering gear-to-column misalignment See STEERING COLUMN article Lack of lubrication in linkage Service front suspension Lack of lubrication in ball joints Service front suspension Increased Effort When Turning Wheel Fast Foaming, Milky Power Steering Fluid, Low Fluid Level or Low Pressure High internal pump leakage See POWER STEERING PUMP article Power steering pump belt slipping Adjust or replace if necessary Low fluid level Check and fill to proper level Engine idle speed to low Adjust to correct setting Air in pump fluid system See POWER STEERING PUMP article Pump output low See POWER STEERING PUMP article Steering gear malfunctioning See POWER STEERING GEAR article Wheel Surges or Jerks Low fluid level Check and fill to proper level Loose fan belt Adjust or replace if necessary Insufficient pump pressure See POWER STEERING PUMP article Sticky flow control valve See POWER STEERING PUMP article Linkage hitting oil pan at full turn Replace bent components Kick Back or Free Play Air in pump fluid system See POWER STEERING PUMP article Worn poppet valve in steering gear See POWER STEERING PUMP article

Excessive over center lash Thrust bearing out of adjustment Free play in pot coupling Steering gear coupling loose on shaft Steering disc mounting bolts loose Coupling loose on worm shaft Improper sector shaft adjustment Excessive worm piston side play Damaged valve lever Universal joint loose Defective rotary valve No Power When Parking Sticking flow control valve Insufficient pump pressure output Excessive internal pump leakage Excessive internal gear leakage Flange rubs against gear adjust plug Loose pump belt Low fluid level Engine idle too low Steering gear-to-column misaligned No Power, Left Turn Left turn reaction seal "O" ring worn Left turn reaction seal damaged/missing

See POWER STEERING GEAR article See POWER STEERING GEAR article See POWER STEERING PUMP article See POWER STEERING PUMP article Tighten or replace if necessary Tighten or replace if necessary See POWER STEERING GEAR article See POWER STEERING GEAR article See POWER STEERING GEAR article Tighten or replace if necessary See POWER STEERING GEAR article See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article See STEERING COLUMN article Adjust or replace if necessary Check and add proper amount of fluid Adjust to correct setting See STEERING COLUMN article See POWER STEERING GEAR article See POWER STEERING GEAR article

Cylinder head "O" ring damaged No Power, Right Turns Column pot coupling bottomed Right turn reaction seal "O" ring worn Right turn reaction seal damaged Internal leakage through piston end plug Internal leakage through side plugs Lack of Effort in Turning Left and/or right reaction seal sticking in cylinder head Wanders to One Side Front end alignment incorrect Unbalanced steering gear valve Low Pressure Due to Steering Pump Flow control valve stuck or inoperative Pressure plate not flat against cam ring Extreme wear of cam ring Scored plate, thrust plate or rotor Vanes not installed properly Vanes sticking in rotor slots Cracked/broken thrust or pressure plate

See POWER STEERING PUMP article See STEERING COLUMN article See POWER STEERING GEAR article See POWER STEERING GEAR article See POWER STEERING GEAR article See POWER STEERING GEAR article Replace, see POWER STEERING GEAR article See WHEEL ALIGNMENT article See POWER STEERING GEAR article See POWER STEERING PUMP article See POWER STEERING PUMP article Replace and check adjustments See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article See POWER STEERING PUMP article

STEERING COLUMN TROUBLE SHOOTING NOTE:

BASIC STEERING COLUMN TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Noise in Steering Coupling pulled apart Column not correctly aligned Broken lower joint Horn contact ring not Bearing not lubricated Shaft snap ring not properly seated Plastic spherical joint not lubricated Shroud or housing loose Lock plate retaining ring not seated Loose sight shield High Steering Shaft Effort Column assembly misaligned Improperly installed dust shield Tight steering universal joint High Shift Effort Column is out of alignment Improperly installed dust shield Seals or bearings not lubricated Mounting bracket screws too long Burrs on shift tube Lower bowl bearing assembled wrong Shift tube bent or broken Improper adjustment of shift levers Improper Trans. Shifting Sheared shift tube joint Sheared lower shaft lever Improper shift lever adjustment

CORRECTION See STEERING COLUMNS article See STEERING COLUMNS article Replace joint See STEERING COLUMN article See STEERING COLUMN article Reseat or replace snap ring See STEERING COLUMN article Tighten holding screws See STEERING COLUMN article Tighten holding screws See STEERING COLUMN article Adjust or replace See STEERING COLUMN article See STEERING COLUMN article Adjust or replace See STEERING COLUMNS article Replace with new shorter screws Remove burrs or replace tube See STEERING COLUMN article Replace as necessary See STEERING COLUMN article Replace as necessary Replace as necessary See STEERING COLUMN

Improper gate plate adjustment Excess Play in Column Instrument panel bracket bolts loose Broken weld nut on jacket Instrument bracket capsule sheared Column bracket/jacket bolts loose Steering Locks in Gear Release lever mechanism

article See STEERING COLUMN article Tighten bolts and check bracket See STEERING COLUMN article See STEERING COLUMN article Tighten bolts and check bracket See STEERING COLUMN article

SUSPENSION TROUBLE SHOOTING NOTE:

BASIC SUSPENSION TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Front End Noise Loose or worn wheel Worn shocks or shock mountings Worn struts or strut mountings Loose or worn lower control arm Loose steering gear-to-frame bolts Worn control arm bushings Ball joints not lubricated

Front Wheel Shake, Shimmy, or Vibration Tires or wheels out of balance Incorrect wheel alignment Drive shaft unbalanced Loose or worn wheel bearings

CORRECTION See Wheel Bearing Adjustment in SUSPENSION Replace struts or strut mountings Replace struts or strut mountings See SUSPENSION See STEERING See SUSPENSION Lubricate ball joints & see Ball Joint Checking in SUSPENSION Check tire balance See WHEEL ALIGNMENT Check drive shaft balance See WHEEL ALIGNMENT

Loose or worn tie rod ends Worn upper ball joints Worn shock absorbers Worn strut bushings Car Pulls to One Side Mismatched or uneven tires Broken or sagging springs Loose or worn strut bushings Improper wheel alignment Improper rear axle alignment Power steering gear unbalanced Front brakes dragging Abnormal Tire Wear Unbalanced tires Sagging or broken springs Incorrect front end alignment Faulty shock absorbers Scuffed Tires Toe-In incorrect Suspension arm bent or twisted Springs Bottom or Sag Bent or broken springs Leaking or worn shock absorbers Frame misalignment Spring Noises Loose "U" Bolts Loose or worn bushings Worn or missing interliners Shock Absorber Noise Loose shock mountings Worn bushings Air in system Undercoating on shocks Car Leans or Sways on Corners Loose stabilizer bar Faulty shocks or mountings Broken or sagging springs Shock Absorbers Leaking Worn seals or reservoir tube crimped

See SUSPENSION See Ball Joint Checking in SUSPENSION Replace shock absorbers Replace strut bushings Check tire condition See SUSPENSION See SUSPENSION See WHEEL ALIGNMENT Check rear axle alignment See STEERING See BRAKES Check tire balance & rotation See SUSPENSION See WHEEL ALIGNMENT Replace chock absorbers See WHEEL ALIGNMENT See appropriate SUSPENSION article See SUSPENSION Replace shock absorbers Check frame for damage See SUSPENSION See SUSPENSION See SUSPENSION Check & tighten mountings Replace bushings Bleed air from system Remove undercoating See SUSPENSION Replace shocks or mountings See SUSPENSION See SUSPENSION

Broken Springs Loose "U" bolts Inoperative shock absorbers

See SUSPENSION Replace shock absorbers

WHEEL ALIGNMENT TROUBLE SHOOTING NOTE:

BASIC WHEEL ALIGNMENT TROUBLE SHOOTING CHART CONDITION & POSSIBLE CAUSE Premature Tire Wear Improper tire inflation Front alignment out of tolerance

Suspension components worn Steering system components worn Improper standing height Uneven or sagging springs Bent wheel Improper torsion bar adjustment Loose or worn wheel bearings Worn or defective shock Tires out of balance Pulls to One Side Improper tire inflation Brake dragging Mismatched tires Broken or sagging spring Broken torsion bar Power steering valve not centered Front alignment out of tolerance Defective wheel bearing Uneven sway bar links Frame bent Steering system bushing worn

CORRECTION Check tire pressure See ALIGNMENT SPECS in WHEEL ALIGNMENT section See SUSPENSION section See STEERING section See WHEEL ALIGNMENT See SUSPENSION section See WHEEL ALIGNMENT See SUSPENSION section See WHEEL BEARING ADJ. in SUSPENSION section Replace shock absorbers Check tire balance Check tire pressure See BRAKE section See WHEEL ALIGNMENT See SUSPENSION section See SUSPENSION section See STEERING section See WHEEL ALIGNMENT section See WHEEL BEARINGS in SUSPENSION section See SUSPENSION section Check for frame damage See STEERING section

Hard Steering Idler arm bushing too tight Ball joint tight or seized Steering linkage too tight Power steering fluid low Power steering drive belt loose Power steering pump defective Steering gear out of adjustment Incorrect wheel alignment Damaged steering gear Damaged suspension Bent steering knuckle or supports Vehicle "Wanders" Strut rod or control arm bushing worn Loose or worn wheel bearings Improper tire inflation Stabilizer bar missing or defective Wheel alignment out of tolerance Broken spring Defective shock absorber Worn steering & suspension components Front End Shimmy Tire out of balance/round Excessive wheel runout Insufficient or improper caster Worn suspension or steering components Defective shock absorbers Wheel bearings worn or loose Power steering reaction Bracket loose Steering gear box (rack) mounting loose Steering gear adjustment loose Worn spherical joints Toe-In Not Adjustable Lower control arm bent Frame bent Camber Not Adjustable

See STEERING LINKAGE in STEERING section See SUSPENSION section See STEERING LINKAGE in STEERING section Add proper amount of fluid See STEERING section See STEERING section See STEERING section See WHEEL ALIGNMENT See STEERING section See SUSPENSION section See SUSPENSION section See SUSPENSION section See WHEEL BEARINGS in SUSPENSION section Check tire pressure See SUSPENSION section See Adjustment in WHEEL ALIGNMENT section See SUSPENSION section Replace shock absorbers See SUSPENSION section Check tire balance See WHEEL ALIGNMENT See WHEEL ALIGNMENT section See SUSPENSION section Replace shock absorber See WHEEL BEARING ADJ. in SUSPENSION section See STEERING section See STEERING section See STEERING section See SUSPENSION section See SUSPENSION section Check frame for damage

Control arm bent Frame bent Hub & bearing not seated properly

See SUSPENSION section Check frame for damage See SUSPENSION section

BRAKE SYSTEM BRAKES General Motors - D Body Brake System

PRECAUTIONS ANTI-LOCK BRAKE SAFETY PRECAUTIONS WARNING: Failure to depressurize ABS before repairing brake system could lead to physical injury.  

 



 

NEVER open a bleeder valve or loosen a hydraulic line while ABS is pressurized. NEVER disconnect or reconnect any electrical connectors while ignition is on. Damage to ABS control unit may result. ONLY use specially designed brake hoses/lines on ABS equipped vehicles. DO NOT tap on speed sensor components (sensor, sensor rings). Speed rings must be pressed into hubs, NOT hammered into hubs. Striking these components can cause demagnetization or polarization, affecting the accuracy of the speed signal returning to the ABS control unit. DO NOT mix tire sizes. Increasing the width, as long as tires remain close to the original diameter, is acceptable. Rolling diameter must be identical for all 4 tires. Some manufacturers recommend tires of the same brand, style and type. Failure to follow this precaution may cause inaccurate wheel speed readings. DO NOT contaminate speed sensor components with grease. Only use recommended coating, when system calls for an anti-corrosion coating. When speed sensor components have been removed, ALWAYS check sensor-to-ring air gaps when applicable. These specifications can be found in each appropriate article. ONLY use recommended brake fluids. DO NOT use silicone brake fluids in an ABS equipped vehicle. When installing transmitting devices (CB's, telephones, etc.) on ABS equipped vehicles, DO NOT locate the antenna near the ABS control unit (or any control unit). Disconnect all on-board computers, when using electric welding equipment. DO NOT expose the ABS control unit to prolonged periods of high heat (185°F/85°C for 2 hours is generally considered a maximum limit).

DESCRIPTION ANTI-LOCK BRAKE SYSTEM The Bosch 2U Anti-Lock Brake System (ABS) is designed to prevent wheel lock-up during heavy braking. This provides improved driver control by reducing the distance required to stop vehicle. Major component parts of system include the following: Electronic Brake Control Module (EBCM), 3 wheel speed sensors, 2 dash-mounted warning indicators, Overvoltage Protection (OVP) relay and hydraulic modulator assembly. The hydraulic modulator assembly, also known as a hydraulic unit, houses electric pump motor and solenoid valves.

AUTO ADJUSTER (DRUM BRAKE) Automatic adjusters operate only when brakes are applied as car is moving in reverse. The link, which holds top of actuating lever stationary, forces lever to pivot on secondary shoe. This pivoting action forces pawl downward against tooth on adjuster screw. If the lining-to-drum clearance is correct, the downward movement will stop before adjusting screw is turned. If clearance is too wide, secondary shoe will move outward. This allows pawl to move down enough to turn adjuster screw one notch. This brings lining-to-drum clearance back to correct specifications. If adjuster screw is frozen or clearance is too great, an override device will prevent adjuster movement. This will prevent biding of automatic adjuster linkage. NOTE:

Some models use an adjuster pawl with a separate blade to contact star wheel. This system does not use an override spring.

BRAKE BOOSTER The Delco Moraine Tandem Diaphragm power brake unit is mounted on firewall and connected directly to brake pedal. A combination of vacuum and atmospheric pressure is used to provide power assist. Power cylinder houses power piston assembly, which contains primary and secondary diaphragms, pistons, floating control valve, reaction piston and disc. DISC BRAKES Caliper is a single casting with 1 large piston inboard of disc rotor. It is mounted on the steering knuckle or a support bracket attached to front suspension. Brake rotors are cast iron with ventilation fins separating the 2 braking surfaces. Some models use a groove machined in the braking surfaces to help control brake noise. Disc brake pads are stamped steel with riveted linings. Most models use a wear sensor, a piece of spring steel riveted to the rear edge of inner or outer brake shoe. The sensor produces a high pitched squeal when lining needs replacement. DRUM BRAKES Brakes are hydraulic single anchor and use Bendix type shoes. Anchor pins for brake shoes are fixed to backing plate and are non-adjustable. Automatic system is made up of a link, actuating lever, pawl and pawl spring. Pawl spring is mounted on secondary brake shoe. System uses an override pivot plate and spring to protect against binding linkage. NOTE:

Some models use an adjuster pawl with a separate blade to contact star wheel. This system does not use the override spring.

MASTER CYLINDER The Delco Quick Take-Up master cylinder is a 2 piece unit with cast aluminum master cylinder body and plastic fluid reservoir. It is designed for use with systems utilizing low drag calipers.

This master cylinder includes a quick take-up valve. This valve delivers a large volume of fluid, at low pressure, upon initial application of brakes. The fluid quickly displaces retracted calipers, placing brake linings in contact with brake rotors.

BLEEDING HYDRAULIC BRAKE BLEEDING WARNING: ABS systems are under high pressure under normal operating conditions. Before opening the fluid reservoir or before servicing any component of an ABS system, it is mandatory that system pressure be discharged. To discharge system, turn ignition off and pump brake pedal a minimum of 20-25 times using full pedal strokes. When a definite increase in pedal effort is felt, pump pedal 2 more times. Hydraulic system bleeding is necessary any time air has been introduced into system. Bleed brakes at all 4 wheels if master cylinder lines have been disconnected or master cylinder has run dry. Bleeding may be done either by using pressure bleeding equipment or by manually pumping brake pedal and using bleeder tubes. SERVICING METERING VALVE 1. On disc brake equipped vehicles, the metering section of the combination valve must be deactivated before bleeding. 2. To hold the metering valve open to pressure bleed the front brakes, the valve stem must be pushed in or pulled out. Loosen front mounting bolt and install tool (J-35856) on the combination valve. Stem should be fully extended or depressed. See Fig. 1 .

Fig. 1: Deactivating Metering Valve for Bleeding (Typical) BENCH BLEEDING MASTER CYLINDER NOTE:

Bleed tubes must have a residual pressure check valve installed to keep tubes from siphoning brake fluid.

1. Clamp master cylinder in vise by mounting flange. Install and tighten threaded end of bleed tubes in outlet ports of master cylinder with opposite end of bleeder tube in reservoirs. Fill reservoirs with clean brake fluid so that bleed tube ends are submerged in brake fluid. See Fig. 2 .

Fig. 2: Bleeding Master Cylinder With Bleeding Tubes Installed 2. Slowly compress and release piston assemblies until bubbles cease to appear in brake fluid. Remove tubes and plug master cylinder outlets to keep fluid from draining. MANUAL BLEEDING NOTE:

Before bleeding system, exhaust all vacuum from power unit by depressing brake pedal several times. Bleed master cylinder if equipped with bleed screws, then bleed wheel cylinders or calipers in sequence.

1. Depressurize ABS system. Fill master cylinder. Install bleeder hose to first bleeder valve to be serviced. Bleeding sequence is RR, LR, RF, LF. Place other end of hose in clean glass jar partially filled with clean brake fluid so end of hose is submerged in fluid. 2. Depress brake pedal slowly through its full travel. Open bleeder valve 3/4-1 turn. Close bleeder valve. Release pedal. Repeat procedure until flow of fluid shows no signs of air bubbles. NOTE:

Check fluid level in master cylinder frequently during bleeding to insure air does not enter system.

PRESSURE BLEEDING NOTE:

1. Depressurize ABS system. Clean master cylinder cap and surrounding area, then remove cap. With pressure tank at least 1/3 full, connect to master cylinder using adapters. See Fig. 3 . Attach bleeder hose to first bleeder valve to be serviced. Bleeding sequence is RR, LR, RF, LF. Place other end of hose in clean glass jar partially filled with clean brake fluid so end of hose is submerged in fluid. 2. Open release valve on pressure bleeder. Unscrew valve 3/4-1 turn noting fluid flow. When fluid flowing from cylinder to cup is free of bubbles, close bleeder valve securely. Bleed remaining cylinders in correct sequence and in same manner. Remove tool from combination valve.

Fig. 3: Pressure Bleeder Installation (Typical) BLEEDING PRESSURES PRESSURE BLEEDING SPECIFICATIONS Application All Models

Psi (kg/cm2 ) 20-25 (1.40-1.75)

BLEEDING SEQUENCE BLEEDING SEQUENCE Application

Sequence

All Models

RR, LR, RF, LF

ADJUSTMENTS DISC BRAKE Disc brakes are self-adjusting. Caliper piston seals are designed to retract pistons just enough to allow brake lining to lightly brush disc without any drag. Sliding caliper design compensates for any lining wear. DRUM BRAKE SHOE NOTE:

Adjustment should only be required after relining or replacing shoes, or if length of adjusting screw is changed.

1. Raise vehicle and remove wheels and drums. Check to make certain that parking brake cable and linkage, including levers on rear secondary shoes, are free. Measure brake drum inside diameter using inside caliper portion of tool (J-21177). 2. Adjust brake shoes to dimension obtained on outside caliper portion of tool (J-21177). See Fig. 4 . Check brake fluid level in both master cylinder reservoirs. Add fluid if necessary. Adjust parking brake.

Fig. 4: Adjusting Brake Shoe Clearance (Through Backing Plate) 3. Install drums and wheel. Tighten wheel mounting nuts. Lower vehicle. Drive car alternately forward and backward, applying brakes moderately in each direction. FRONT WHEEL BEARING 1. Install wheel on vehicle. Remove dust cap and cotter pin. Tighten spindle nut to 12 ft. lbs. (16 N.m) while spinning wheel by hand. Back off nut until just loose, then tighten by hand until snug. 2. Back off enough to insert new cotter pin (about 1/2 hex flat or 1/12 turn). Adjustment should provide .001-.005" (.03-.13 mm) end play. Install dust cap. MASTER CYLINDER PUSH ROD NOTE:

Use the following procedure to measure how far the booster piston rod protrudes from booster when vacuum is applied to booster. Piston rod is not adjjustable. If piston rod protrusion is out of limits, rod must replaced with an adjustable service rod.

1. Booster does not have to be installed to perform procedure. Apply 25 in. Hg vacuum or the MAXIMUM available engine vacuum to booster. Position Piston Rod Gauge (J-37839) over piston rod. See Fig. 5 . One side of gauge measures minimum rod lenght. The other side measures maximum rod lenght. 2. If piston rod lenght does not fall between maximum and minimum dimensions, disassemble booster. See OVERHAUL . Replace piston rod with an adjustable service piston rod (with self-locking screw) to make adjustment.

Fig. 5: Gauging Piston Push Rod Courtesy of GENERAL MOTORS CORP. PARKING BRAKE

NOTE:

When rear drum brakes are serviced, the parking brake linkage cable at the equalizer must always be readjusted to prevent possible burn out of rear brakes.

1. Lubricate parking brake linkage at equalizer and cable stud, and ensure free movement of cables. Apply parking brake pedal exactly 6 ratchet clicks. 2. Raise and support vehicle. Tighten adjuster until the right rear wheel can just be turned rearward with two hands but cannot be turned forward. 3. Release parking brake. Wheels should turn freely in either direction without drag.

SERVICING ROTOR SERVICING Lateral Runout

Adjust wheel bearings until all end play is eliminated. Attach a dial indicator to front suspension so pointer contacts face of rotor about 1 inch from edge. Set gauge to zero, then turn rotor through one complete revolution. See Fig. 6 . Check gauge reading with specifications for maximum runout.

Fig. 6: Checking Rotor Lateral Runout Parallelism

Check thickness of rotor at 4 or more points around edge of rotor. Make all measurements the same distance from edge. If thickness varies more than specified, refinish or replace rotor.

CLEANING & INSPECTION DISC PAD INSPECTION

Inspect linings every 6,000 miles or 12 months, or whenever wheels are removed. Check both ends of inboard and outboard linings for wear. Replace any that are worn to within .032" (.81 mm) of rivets on either end of lining. DRUM BRAKE CLEANING Clean all parts except the brake lining and the brake drums with brake cleaning solvent. To remove brake fluid contamination, clean all parts except the brake lining with denatured alcohol. Contaminated brake lining must be replaced. DRUM BRAKE INSPECTION 1. Pull back the wheel cylinder dust boots and check for evidence of leakage. If evidence of leakage is noted, the cylinder should be disassembled, inspected and overhauled. 2. Polish the brake support plate ledges with fine emery cloth and inspect them for grooves that could restrict shoe movement. If grooves exist after polishing, the support plate must be replaced. Inspect lining wear pattern. If wear across the width of the lining is uneven, the drums should be checked for distortion, the shoes for correct positioning, and the support plate for distortion. 3. Inspect all springs for evidence of overheating and fractures. Self-adjusting cables should be inspected for kinks, fraying, or elongation of the eyelet. Inspect adjuster screws for freedom of rotation, and adjuster lever for wear and distortion. 4. Replace defective brake parts.

REMOVAL & INSTALLATION BRAKE BOOSTER Removal

1. Without disconnecting hydraulic lines, remove master cylinder from power unit and position to one side. On Delco-Moraine models equipped with pipe distribution and switch mounting bolt, remove bolt before moving master cylinder away from power unit. CAUTION: Do not bend or kink hydraulic lines.

2. Disconnect vacuum hose from check valve on front of power unit. Disconnect push rod from brake pedal. CAUTION: Do not force push rod to the side when disconnecting.

3. Remove nuts mounting power unit to firewall and remove power unit. Installation

Reverse removal procedure and tighten mounting nuts to 15 ft. lbs. (21 N.m). Check stop light and cruise control (if equipped) switch adjustments. DISC CALIPERS & PADS NOTE:

Relining should be done in complete sets only.

Removal

1. Depressurize ABS system. Remove and discard 2/3 of brake fluid in master cylinder reservoir to prevent overflow during servicing. 2. Raise vehicle and remove front wheels. Position a "C" clamp on caliper. Place solid side of clamp against inside of caliper and screw end of clamp against outboard shoe. 3. Tighten clamp until caliper moves away from vehicle. When caliper moves enough, push piston to bottom on its bore. This will allow shoes to back off from rotor surface. 4. Remove "C" clamp. Unbolt caliper from steering knuckle or support bracket. If removing caliper for overhaul, remove brake hose inlet fitting. 5. Remove caliper and support with a wire so brake hose will not be damaged. Remove shoes and shoe support spring from cavity in piston. Remove sleeves from inboard ears of caliper and rubber bushings from all caliper ears. Installation

1. Using silicone lubricant, coat and install new sleeves and rubber bushings in caliper ears. Attach shoe support spring to inboard shoe. Ensure that shoe is installed in caliper with wear sensor to rear of vehicle. Shoe should be flush against piston. 2. Position outboard shoe in caliper. Engage tab at bottom of shoe with caliper cutout and shoe ears with caliper ears at top of shoe. Place caliper over rotor, aligning caliper ears with mounting holes. 3. Start bolts or pins through inboard caliper ears and mounting bracket. Make sure bolts or pins pass under retaining ears of inboard shoes. 4. Push bolts or pins through caliper to engage hole in outboard shoe and ears of caliper. Thread bolts into mounting bracket and tighten to 38 ft. lbs. (51 N.m). Measure clearance between caliper housing and bracket stops. If necessary, file ends of bracket stops to provide proper clearance. See Fig. 7 .

Fig. 7: Measuring Caliper Housing to Bracket Clearance Courtesy of GENERAL MOTORS CORP. 5. Install brake hose inlet fitting (if removed) and tighten bolt to 32 ft. lbs. (44 N.m). Add brake fluid to fill master cylinder to within 1/8" of top. Bleed brake system if necessary. Pump brake pedal to seat shoes against rotor. 6. Use pliers to clinch upper ears of outboard shoe against caliper. See Fig. 8 . Make sure ears are flat against caliper with no clearance.

Fig. 8: Clinching Tabs on Outboard Shoe DISC ROTOR Raise and support vehicle. Remove wheel, then remove and support caliper. Remove grease cup, cotter pin and nut, then remove rotor. To install brake rotor, reverse removal procedure. DRUM BRAKE SHOE & LINING REPLACEMENT NOTE:

Mark position of springs and star adjusters as they are removed, for installation in original position.

Removal

1. Release parking brake and loosen parking brake cable at equalizer. If necessary, back off brake adjustment before removing brake drums. Remove return springs. Remove brake shoe hold down springs and cups. Lift up on parking brake actuator lever and remove actuator link. Remove actuator lever and

return spring. 2. Separate brake shoes from wheel cylinder connecting links. Remove parking brake strut and spring. Disconnect parking brake cable. Remove brake shoes, spring and adjusting screw from backing plate. Detach spring and screw from brake shoes. Remove parking brake lever from secondary shoe.

Fig. 9: Exploded View of Rear Drum Brake Assembly Installation

1. Lubricate fulcrum end of parking brake lever and attach to secondary shoe. Connect adjusting screw spring, then place screw in position. Ensure that star is aligned with adjusting hole. Lubricate surfaces where shoe and parking brake cable contact backing plate. Position shoes and insert into wheel cylinder links. 2. Connect cable to parking brake lever and install strut and spring between lever and primary shoe. Install actuator, actuator return spring and actuating link. Replace brake drums and wheels. Adjust parking brake and brake shoes. Check for proper operation of brakes before moving vehicle. MASTER CYLINDER Removal

Depressurize ABS system. Disconnect switch wire (if equipped) and all hydraulic lines. Remove cylinder mounting nuts and remove cylinder. Installation

To install, reverse removal procedure. Tighten mounting nuts to 15 ft. lbs. (21 N.m). Fill master cylinder to proper level. Bleed brake system.

REAR WHEEL CYLINDER Removal

Depressurize ABS system. Remove brake shoes. Disconnect inlet tube line and remove 2 screws holding wheel cylinder to backing plate. Remove wheel cylinder. Installation (Bolt Type Retainer)

To install, replace wheel cylinder in position and install screws. Tighten screws to 13 ft. lbs. (18 N.m). Connect inlet tube line and tighten line nut to 18 ft. lbs. (24 N.m).

OVERHAUL BRAKE BOOSTER Disassembly

1. Remove pushrod boot, silencer, front housing seal, grommet and vacuum check valve. 2. Scribe a mark on front and rear housings for reassembly reference. Scribe and unstake staked tabs. Install booster in Holding Fixture (J-23456). See Fig. 10 .

Fig. 10: Unlocking & Locking Booster Courtesy of GENERAL MOTORS CORP. 3. Tighten fixture handscrew just enough to allow for housing rotation. Turn fixture handle counterclockwise until tabs on front housing are moved to unlocked position. 4. Remove power piston group, power piston return spring, and power piston bearing. Remove piston rod, reaction retainer and power head silencer. 5. Grasp assembly at outside edge of divider and diaphragms. Hold with pushrod down against a hard surface. Use a slight force or impact to dislodge diaphragm retainer. 6. Remove primary diaphragm, primary support plate, secondary power piston bearing, housing divider, secondary support plate and diaphragm and power piston assembly. Cleaning & Inspection

Clean all plastic, metal and rubber parts in denatured alcohol. Blow out all passages, orifices and valve holes. Air dry all parts. Slight rust on housing may be cleaned with crocus or emery cloth. Do not reinstall any rubber parts with cuts, nicks or distortion. If in doubt, replace the part.

NOTE:

Prior to installation of rubber, plastic, and metal friction parts, lubricate with silicone lube.

Reassembly

1. Place power piston on bench with push rod end up. Install Assembly Cone (J-28458) over push rod end of piston. Lubricate inside diameter of secondary diaphragm with silicon lubricant and fit in secondary support plate. 2. Install secondary diaphragm and support plate over power piston and push down until it bottoms. Lubricate inside diameter of secondary power piston bearing. Install bearing in housing divider with flat surface of bearing on the same side as 6 raised lugs on divider.

Fig. 11: Exploded View of Delco-Moraine Tandem Diaphragm Booster

Fig. 12: Installing Secondary Diaphragm & Support Plate 3. Hold divider so that formed flange faces up. Press divider down over assembly cone and onto power piston to rest against secondary diaphragm. Lubricate inside diameter of primary diaphragm and install in primary support plate. Remove assembly cone from power piston, place primary support plate and diaphragm assembly over power piston and push down until it bottoms. 4. Place diaphragm retainer over power piston and onto diaphragm. Install Assembly Cone (J-28458) over power piston onto diaphragm retainer and strike with hammer until retainer is locked on neck of power piston. Remove assembly cone. 5. Install reaction retainer, piston rod and power head silencer. Place primary power piston bearing in rear housing center hole. Lubricate with silicone lubricant on inner diameter. Install rear housing in Holding Fixture (J-23456). Attach power piston assembly to rear housing. 6. Install power piston return spring over reaction retainer. Install front housing and align scribe marks. Tighten fixture handscrew just enough to allow for housing rotation. Rotate housing until tabs are fully

seated. Stake 2 housing tabs into sockets at 2 new locations 180Â° apart. Do not stake tabs that have previously been staked. 7. Lubricate inside and outside diameters of grommet and front housing seal. Install seal, grommet, vacuum check valve, silencer and push rod boot. DISC CALIPER Disassembly

1. Clean exterior of caliper with denatured alcohol and place on a clean work surface. Remove brake shoe and discard copper gasket. Drain fluid from caliper. WARNING: DO NOT attempt to catch or protect piston with fingers while applying compressed air. Injury may result. Always use eye protection when performing this step. 2. Using clean shop towels to pad interior of caliper, apply just enough clean compressed air to caliper inlet so piston will ease out of bore. 3. Using a screwdriver, pry boot out of caliper. Pry piston and seal from caliper using a piece of wood or plastic. DO NOT use a metal tool as bore may be damaged requiring caliper replacement. Remove bleeder valve from caliper.

Fig. 13: Exploded View of Single Piston Caliper Courtesy of GENERAL MOTORS CORP. Cleaning & Inspection

1. Replace boot, piston seal, rubber bushings and sleeves each time caliper is overhauled. 2. Clean all parts in denatured alcohol. Dry parts using clean dry compressed air. Lubricated shop air will ruin rubber parts upon contact at reassembly. 3. Check mounting bolts for corrosion, breaks in plating or other damage. Replace bolts if damaged in any way. DO NOT attempt to wire brush or clean them. 4. Check outside diameter of piston for scoring, nicks, corrosion, or worn and damaged plating. If surface defects are visible, replace piston. DO NOT attempt to refinish with abrasives. 5. Check piston bore in caliper for scratches or other damage. Minor scratches or corrosion may be polished clean with crocus or emery cloth. Thoroughly clean bore after polishing. Replace caliper if corrosion is not easily cleaned. Reassembly

1. Lubricate bore in caliper and new piston seal with clean brake fluid. Position seal in caliper bore groove. Lubricate piston with clean brake fluid. Assemble new boot into groove in piston with fold facing open end of piston. 2. Insert piston into caliper bore using care not to unseat seal. Do not force piston to bottom of bore. Position outer diameter of boot in caliper counterbore. Seat boot using dust boot installer. 3. Check boot installation to make sure retaining ring moulded into boot is not bent and that boot is installed completely below caliper face. Install brake hose, using a new copper gasket. NOTE:

After caliper has been overhauled and installed, it must be bled.

DRUM BRAKE SHOE & LINING REPLACEMENT See DRUM BRAKE SHOE & LINING REPLACEMENT under REMOVAL & INSTALLATION. MASTER CYLINDER Disassembly

1. Remove reservoir cover and diaphragm. Discard any brake fluid in reservoir. Depress primary piston and remove lock ring. Apply compressed air at forward brake line hole while plugging rear hole. Pistons will be forced out of bore. 2. Remove spring retainer and seals from secondary piston. Discard seals. Clamp master cylinder in vise by mounting ear and pry off reservoir. 3. Do not attempt to remove take-up valve from master cylinder as it is not serviceable. Remove reservoir grommets and discard.

Fig. 14: Exploded View of Quick Take-Up Master Cylinder

Inspection

Inspect cylinder bore for scoring or corrosion. If signs of corrosion are evident, master cylinder must be replaced. Under no circumstances should abrasive materials be used on cylinder bore. Reassembly

1. Lubricate new reservoir grommets with silicone brake lube and press into master cylinder. Make sure grommets are properly seated. Lay reservoir on flat, hard surface. 2. Rock master cylinder body onto reservoir until completely seated. Lubricate new piston seals and install on secondary piston, with lip of seals towards ends of piston. Install spring retainer. 3. Install secondary piston spring and secondary piston assembly in master cylinder. Lubricate primary piston seals with clean brake fluid. 4. Install primary piston in master cylinder. Depress piston and install lock ring. Fit diaphragm in reservoir cover and install cover. WHEEL CYLINDER Disassembly

With wheel cylinder removed from vehicle, remove rubber boots from ends of cylinder. Remove piston, piston return spring, cups and bleeder screw. Inspect cylinder bore for scoring or corrosion. Replace wheel cylinder if corrosion cannot be removed with crocus cloth or if bore is scored. Rinse with brake fluid.

Fig. 15: Exploded View of the Wheel Cylinder Assembly Reassembly

Install bleeder screw. Lubricate cylinder bore with brake fluid and install piston cup in 1 end of cylinder with lip toward center and install piston with flat side toward cup. Install rubber boot into end of cylinder. Install spring and expander assembly into opposite end. Install remaining cup, piston and rubber boot.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Booster Mounting Nuts Brake Hose-to-Caliper Brake Line-to-Master Cylinder Caliper-to-Mounting Bracket Master Cylinder-to-Power Unit Wheel Cylinder Line Nuts Wheel Cylinder Mounting Screws

Ft. Lbs. (N.m) 15 (21) 32 (44) 24 (32) 38 (51) 15 (21) 18 (24) 13 (18)

WHEEL LUG NUT TORQUE SPECIFICATIONS Application Sedan Wagon & Heavy Duty Police

Ft. Lbs. (N.m) 81 (110) 103 (140)

DISC & DRUM BRAKE SPECIFICATIONS BRAKE SPECIFICATIONS Application Front Rotors Disc Diameter Lateral Runout Parallelism Original Thickness Minimum Refinish Thickness Discard Thickness Rear Drums Drum Diameter Drum Width Maximum Drum Refinish Diameter Discard Diameter Brake Cylinder Diameter Master Cylinder Diameter

In. (mm) 12.00 (305) .004 (.10) .0005 (.013) 1.032 (26.2) .972 (24.68) .965 (24.5) 11.00 (279.4) 2.00 (50.8) 11.060 (280.92) 11.090 (281.69) 1.000 (25.4) 1.125 (28.57)

ENGINE COOLING FAN ENGINE COOLING General Motors Corp. Flex-Blade & Variable Speed Cooling Fans

DESCRIPTION The flex-blade fan assembly is designed to allow blades to flex as engine RPM increases. Blade pitch decreases as RPM increases, thereby saving power and decreasing noise level. Keep fan belt adjusted to proper tension as necessary. See Fig. 1. Many air conditioned models use a thermostatically controlled fluid fan and torque control clutch. Thermal control drive is a silicone-filled coupling connecting fan to a fan pulley, and is operated by an internal control valve. The control valve is operated by a temperature sensitive bimetallic coil (or strip) and controls flow of silicone through the clutch. See Fig. 2. During periods of operation when radiator discharge air temperature is low, fan clutch speeds are slowed, decreasing fan speed and increasing engine warm-up. High radiator discharge air temperature causes bimetallic coil or strip to allow a greater flow of silicone to enter clutch. This increases drag between driven member and driving member, resulting in a higher fan speed and increased cooling.

Fig. 1: Typical Flex-Blade Fan Courtesy of GENERAL MOTORS CORP.

Fig. 2: Typical Thermostatically Controlled Fan Assembly Courtesy of GENERAL MOTORS CORP.

TESTING THERMOSTATICALLY CONTROLLED FAN ASSEMBLY 1. In cases of engine overheating or insufficient air conditioning, start with a cool engine to ensure complete fan clutch disengagement. Cover radiator grille to induce high engine temperature. 2. Start engine and operate at 2000 RPM. Turn on air conditioning (if equipped). When radiator discharge air temperature gets hot, a fan roar will be noticed when fan clutch engages. NOTE:

It takes approximately 5-10 minutes for temperature to become hot enough to allow engagement of fan clutch. While operating engine under this condition, observe temperature light or gauge to prevent overheating. If car overheats, remove cover from radiator grille.

3. When clutch engages, remove radiator grille cover and turn A/C off to assist in engine cooling. After several minutes fan clutch should disengage. This can be determined by a reduction in fan speed and roar. If fan clutch fails to function as described, it should be replaced.

COOLING SYSTEM SPECIFICATIONS ENGINE COOLING General Motors Corp. Cooling System Specifications

DESCRIPTION THERMOSTAT Most thermostats are thermal wax pellet type. As coolant temperatures rise, the wax begins to expand. This expansion overcomes spring tension, allowing the thermostat to open. Some thermostats also have a bleed hole to allow a small amount of circulation and help eliminate air locks. PRESSURE CAP Modern cooling systems use a closed system type cap. This system allows for coolant expansion during engine operation. As coolant expands and builds pressure, some coolant is permitted to bleed past the cap into the overflow tank. When the engine cools and coolant contracts, the cap allows coolant in the overflow tank to siphon back into the system. The pressure cap also increases pressure in the cooling system. The increased pressure raises the boiling point. One pound of pressure raises the boiling point approximately 10Â°F. COOLANT MIXTURE Engine coolant must be mixed with water to a specified percentage. A 100 percent coolant mixture could cause system overheating or premature system failure. The percentage of coolant to water can vary depending on climate condition, but a 50/50 mixture is a standard percentage. MAINTENANCE Periodic maintenance is necessary for extended cooling system and engine life. Because engine and cooling systems are made of different metals, electrolysis begins to destroy the metals. Changing the coolant at scheduled maintenance periods reduces electrolysis and removes sediment. Replace coolant every 24 months or 30,000 miles. NOTE:

Approximate capacity figures are listed. Capacities may slightly vary.

COOLING SYSTEM SPECIFICATIONS Application Coolant Capacity "A" Body 2.5L 3.1L 3.3L "B" Body

Specification

9.9 Qts. 9.6L 13.0 Qts. (12.3L) 12.9 Qts. (12.2L)

5.0L (VIN E) (1)

18.0 Qts. 17.0L)

5.0L (VIN Y) (1) 5.7L "C" Body 3.8L 4.5L "D" Body 5.0L 5.7L "E" Body 3.8L 4.5L "F" Body 3.1L 5.0L (VIN E & F) 5.7L "H" Body 3.8L "J" Body 2.0L (VIN K & M) 2.2L 3.1L "K" Body 4.5L "L" Body 2.2L 2.3L 3.1L "N" Body

15.2 Qts. (14.4L) 16.5 Qts. (15.6L) 13.0 Qts. (12.3L) 13.2 Qts. (12.5L) 15.2 Qts. (14.4L) 16.5 Qts. (15.6L) 13.0 Qts. (12.3L) 13.2 Qts. (12.5L) 13.0 Qts. (12.3L) 18.0 Qts. (17.0L) 16.5 Qts. (15.6L) 13.0 Qts. (12.3L) 8.5 Qts. (8.0L) 8.5 Qts. (8.0L) 13.0 Qts. (12.3L) 13.2 Qts. (12.5L) 8.5 Qts. (8.0L) 8.0 Qts. (7.6L) 13.0 Qts. (12.3L)

2.3L (VIN A) (1)

8.0 Qts. (7.6L)

2.3L (VIN D) (1) 2.5L 3.3L "W" Body

9.2 Qts. (8.7L) 7.8 Qts. (7.4L) 12.9 Qts. (12.2L)

2.3L (VIN A) (1)

8.0 Qts. (7.6L)

2.3L (VIN D) (1) 2.5L 3.1L (VIN T & V) "Y" Body 5.7L

9.2 Qts. (8.7L) 9.9 Qts. (9.4L) 13.0 Qts. (12.3L) 16.5 Qts. (15.6L)

Pressure Cap Thermostat (1) Refers to VIN engine code.

15 psi 195°F (91°C)

GENERAL MOTORS PASSENGER CAR DESIGNATIONS Body Designation Model "A" Body Celebrity, Century, Cutlass Ciera, Cutlass Cruiser Wagon, 6000 "B" Body Caprice, Custom Cruiser, Estate Wagon "C" Body DeVille, Electra, Fleetwood, Ninety-Eight, Park Avenue, Touring Sedan "D" Body Brougham "E" Body Eldorado, Reatta, Riviera, Toronado, Trofeo "F" Body Camaro, Firebird "H" Body Bonneville, Delta 88, LeSabre "J" Body Cavalier, Sunbird "K" Body Seville "L" Body Beretta, Corsica "N" Body Cutlass Calais, Grand Am, Skylark "W" Body Cutlass Supreme, Grand Prix, Lumina, Regal "Y" Body Corvette DRAINING AND FILLING COOLING SYSTEM CAUTION: To avoid being burned by hot water and steam, do not remove the radiator cap while the engine is at normal operating temperature. The cooling system will release scalding fluid and steam under pressure if the cap is removed while the engine and radiator are still hot. 1. Remove the radiator cap while the engine is cool. To remove the radiator cap do the following:  Rotate cap counterclockwise to detent, do not press down while rotating.  Ensure that there is no residual pressure in the cooling system.  After all pressure is relived from the cooling system, press down on the cap while continuing to rotate counterclockwise. 2. Open radiator drain valve and air bleed vent on thermostat housing and bypass pipe. Allow system to drain completely, then close the radiator drain valve tightly. 3. Remove coolant recovery reservoir with clean water, drain and reinstall. Fill the cooling system through the radiator neck until full. Close all bleed vents tightly and install radiator cap.

CRUISE CONTROL SYSTEM ACCESSORIES & EQUIPMENT General Motors Cruise Control System - Cadillac

DESCRIPTION & OPERATION DESCRIPTION The cruise control system uses vacuum to actuate a throttle power unit or servo. Servo moves throttle when its diaphragm is subject to varying amounts of vacuum. Vacuum to servo is constantly modulated in response to commands from Electronic Control Module (ECM) or cruise control electronic controller. The ECM or cruise control electronic controller receives data from the engagement, instrument panel switches, electric brake release switch and speed sensor. A 2-position switch, located on instrument panel, and engagement switches on turn signal lever or steering wheel switches control system operations. There are 2 methods for brake release of cruise control: an electric brake release switch and a vacuum valve. Both switches are mounted on brake pedal. Both switches vent servo diaphragm vacuum to atmosphere. Components used in cruise control system vary depending on vehicle model. See OPERATION in this article as a guide to determine component application of vehicle being serviced. Controls are on the turn signal lever. CRUISE CONTROL MODULE OPERATION Cruise control module receives signals from cruise engagement switch, instrument panel switch, electric brake release switch, servo position sensor and speed sensor circuit. Cruise control module processes this information and transmits command signals to vacuum and vent valves in the servo to control vehicle speed. SPEED SENSOR CIRCUIT OPERATION Speed sensor is located behind speedometer cluster. It provides a signal corresponding with vehicle speed to the control system. A speed sensor circuit wire harness connects speed sensor to a buffer amplifier, located behind left side of instrument panel. A buffered speed signal is sent to the electronic controller via instrument panel wiring harness and cruise control wiring harness. The speed sensor consists of a Light Emitting Diode (LED) and photo transistor enclosed in one housing. Photo transistor generates an electrical signal corresponding to vehicle speed when exposed to reflected light from LED. SERVO UNIT OPERATION Servo operates throttle in response to signals from ECM or electronic controller. The servo uses a vacuum operated diaphragm. A normally open solenoid valve vents the diaphragm chamber to atmosphere. A normally closed solenoid valve connects diaphragm chamber to vacuum source. INSTRUMENT PANEL SWITCH OPERATION

The instrument panel switch must be on for system to operate. An Amber light will be on when system may be engaged. Vehicle may enter cruise control mode at any speed over 25 MPH. When system is engaged, a Green light will illuminate next to the word ENGAGED or AUTO. SET/COAST BUTTON SWITCH OPERATION If SET/COAST button switch is depressed as ignition is turned on, an ECM 067 test code will be set and cruise control will remain inoperative until ignition switch is cycled. RESUME/ACCEL (R/A) SWITCH OPERATION If R/A switch is held in ACCEL position while ignition is turned on, ECM 067 test code will be set and cruise control will remain inoperative until ignition switch is cycled.

ADJUSTMENT BRAKE RELEASE SWITCH/VACUUM RELEASE VALVE ADJUSTMENT 1. Check adjustment of electric brake release switch and vacuum release valve by measuring brake pedal travel distance. Cruise control switch contacts should open at .137-.492" (3.48-12.29 mm) of brake pedal travel, measured at center line of brake pedal pad. Nominal actuation of stoplight switch contact is .177" (4.49 mm) after cruise control contacts open. 2. Vacuum release valve assembly should open at 1.06-1.30" (26.9-33.0 mm) of brake pedal travel, measured at center line of brake pedal pad.

TROUBLE SHOOTING Faulty operation can be caused by one or more mechanical, electrical and/or vacuum problems. Before performing diagnosis, make a visual inspection for disconnected or damaged wiring. Check for pinched, cracked, plugged, loose or disconnected vacuum hoses. Ensure linkage is not binding or misadjusted. Repair or adjust as necessary.

SYSTEM TESTING NOTE:

For trouble code testing information, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE section.

ROAD TEST 1. With instrument panel control switch off, drive vehicle at 50 MPH. Depress and release engagement push button at end of turn signal lever. System should remain inoperative. 2. Turn instrument panel switch on. Amber indicator light should be on. Engage system by momentarily pushing turn signal engagement push button and releasing at 50 MPH. Remove foot from accelerator. Green light should be on and vehicle should maintain 50 MPH with foot off accelerator. 3. Push slide switch and hold. Vehicle should accelerate at a controlled rate. Release switch at

approximately 55 MPH. Speed should remain steady at 55 MPH. Depress brake pedal about 1/2". If Green light goes off, electric brake switch is okay and vehicle speed should decrease. 4. Allow vehicle to decrease to approximately 45 MPH. Momentarily push slide switch and release. Vehicle should accelerate to 55 MPH at a controlled rate and Green light should be on. 5. Push and hold engagement button. Green light should go off. Coast to 50 MPH and release button to engage system at 50 MPH. Green light should be on and vehicle should maintain speed. 6. Check "tap-up" feature by actuating slide switch for less than a second. Vehicle should increase speed by approximately one MPH. Tap switch a couple more times to check incremental speed increases. ELECTRIC BRAKE RELEASE SWITCH TEST On-Vehicle

1. Turn ignition and instrument panel switches on. Connect test light or voltmeter to ground. Probe Brown wire (Brougham) or Purple wire (all others) at brake switch connector with test light or voltmeter. 2. If test light is on or voltmeter shows 12 volts, system is okay. If test light is not on or 12 volts do not exist, probe adjacent terminal. If test light is on or 12 volts exist, adjust or replace switch as necessary. If test light is not on or 12 volts do not exist, repair wiring to switch. INSTRUMENT PANEL & ENGAGEMENT SWITCHES TEST On-Vehicle

1. Turn ignition on. Connect test light or voltmeter to ground. Probe the 3 terminals of turn signal lever cruise control harness connector, first with instrument panel switch off and then on. 2. There should be no power to any terminal with switch off. With switch on, there should be no power to Blue and Gray wire terminals. There should be power to Brown wire center terminal. The Amber indicator light should also be on. 3. Probe Gray wire terminal and depress SET/COAST switch. Power should be present. Probe Blue terminal and depress RESUME/ACCEL switch. Power should be present. Replace turn signal lever switch if power does not exist. AMBER (ON) LIGHT INOPERATIVE TEST 1. Turn ignition on. Turn instrument panel switch on. If Amber light is not on, check bulb and replace if necessary. If bulb is okay, check for open ground wire, open connector, inoperative switch, blown fuse or defective printed circuit. 2. Turn instrument panel switch off. If Amber light is on, check for shorted leads and/or defective switch. GREEN (CRUISE) LIGHT INOPERATIVE TEST 1. Perform road test. If road test indicates cruise control system functions properly and Green light is inoperative, check bulb and replace as necessary. If bulb is okay, check for open in Pink wire between switch and controller connector and for defective controller module. 2. With instrument panel switch on and ignition on, ground Pink wire in controller. Green light should be on. If Green light is on but not during road test, replace controller module.

3. If Green light remains on when system is not controlling speed, check for short in harness between switch and controller module. If no short is present, replace controller module. SYSTEM DIAGNOSIS 1. If "tap-up" and "tap-down" functions are the only system faults, replace cruise control module. Check resistance between grounds on cruise control servo and cruise control switch. If resistance is greater than 0.1 ohm, clean and tighten grounds and negative battery cable. If system ground is suspected, install a ground strap between engine block and bulkhead. 2. If using a digital multimeter for testing, see Fig. 2 . If using a cruise control quick checker for testing, see Fig. 3 . For symptom checking of cruise control, see Fig. 1 . For connector identification, see Fig. 5 .

Fig. 1: Symptom Chart Courtesy of GENERAL MOTORS CORP.

Fig. 2: Digital Multimeter Diagnostic Chart Courtesy of GENERAL MOTORS CORP.

Fig. 3: Cruise Control Quick Checker Chart Courtesy of GENERAL MOTORS CORP.

Fig. 4: Wiring, Harness Connectors & Vacuum System Diagnostic Chart Courtesy of GENERAL MOTORS CORP.

Fig. 5: Harness Connector Identification Courtesy of GENERAL MOTORS CORP. VEHICLE SPEED SENSOR DIAGNOSIS Use the VEHICLE SPEED SENSOR diagnostic chart "for the vehicle speed sensor system. See Fig. 6 .

Fig. 6: Vehicle Speed Sensor Diagnostic Chart Courtesy of GENERAL MOTORS CORP.

REMOVAL & INSTALLATION SERVO UNIT Disconnect electrical connector and vacuum hoses from servo unit. Remove servo cable from servo unit and remove servo unit. Install servo unit and tighten nuts to 12 INCH lbs. (1.4 N.m). Install servo unit cable, vacuum hoses and electrical connector. CRUISE CONTROL CABLE 1. Ensure engine is off. Remove retaining clips from each end of cruise control cable. Remove accelerator cable and cruise control cable from throttle lever. Separate accelerator cable and cruise control cable. Carefully remove cable without disrupting throttle valve cable, spark plug wires and accelerator cable. 2. Route cruise control cable under spark plug wires, throttle valve cable and accelerator cable. Retract idle speed motor until throttle lever is clear of plunger. Attach cruise control cable and accelerator cable to throttle lever. Attach cruise control cable to servo unit, using hole in servo to achieve minimum cable slack. ELECTRIC BRAKE RELEASE SWITCH/VACUUM RELEASE VALVE Removal

Remove left panel. Disconnect electrical connector and vacuum hose (if equipped) from valve. Remove

attaching screw. Remove valve or switch from dash bracket. Installation

1. Hold brake pedal depressed and install switch or valve assembly into retainer. Switch or valve should bottom on retainer. Note that an audible click can be heard as threaded portion of switch is pushed through retainer. 2. Slowly pull brake pedal fully rearward against pedal stop, moving switch or valve assembly rearward. On vehicles equipped with anti-lock brakes, release brake pedal and allow it to come to rest. 3. Release brake pedal and pull back again to assure proper adjustment of switch or valve. On vehicles equipped with anti-lock brakes, slowly push switch or valve further into retainer until plunger is seated against brake pedal bracket. Visually check for proper seat. 4. On all models, to complete installation, reverse removal procedure. Adjust brake release switch. Refer to, under ADJUSTMENTS, BRAKE RELEASE SWITCH/VACUUM RELEASE VALVE ADJUSTMENT in this article. SET/COAST BUTTON SWITCH NOTE:

SET/COAST button switch or illumination bulbs cannot be replaced separately. CAUTION: Air bag system may need to be deactivated prior to removing horn pad for switch assembly service. See AIR BAG TESTING article in this section.

Fig. 7: Exploded View of Steering Wheel Cruise Control Courtesy of GENERAL MOTORS CORP. VEHICLE SPEED SENSOR Disconnect wiring harness connector from vehicle speed sensor. Remove vehicle speed sensor retainer clip. Pull vehicle speed sensor from governor housing. Remove driven gear and seal. To install, reverse removal procedure. SPEED SENSOR BUFFER AMPLIFIER Disconnect negative battery cable. Remove speedometer cluster. Remove clip retaining strap holding speed sensor buffer amplifier. Disconnect electrical connector and remove speed sensor buffer amplifier. To install, reverse removal procedure.

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

DEFOGGER - REAR WINDOW ACCESSORIES & EQUIPMENT General Motors Rear Window Defogger

DESCRIPTION The heated rear window defogger uses a heating grid baked to the inside of the rear window. Window heat is controlled by a control switch and a timer/relay. The timer/relay is located in the accessory relay panel. When defogger is operating, indicator light will glow to show system is on. Current feed to defogger is through a circuit breaker and power to control switch is through a fuse in the fuse block.

OPERATION Voltage is applied to the rear defogger through the defogger relay. With the ignition switch in RUN position, voltage is applied to one side of defogger relay coil. When rear defogger ON/OFF switch is activated, a ground signal is sent from heater-A/C control to the Central Control Module (CCM). Upon receiving this ground signal, and only if the engine is running, the CCM then energizes the defogger relay by grounding the other side of the defogger relay coil. When energized, the normally open contacts in the defogger relay close, applying voltage to heat the rear defogger. The CCM will energize the defogger relay for 10 minutes during the first activation of the rear defogger after ignition on, engine running, and for 5 minutes each additional activation. This timing process will reset at each ignition cycle.

TROUBLE SHOOTING Before performing system test, check the following:    

Check the SEATS circuit breaker by operating seats and power door locks. Check body fuse by operating courtesy lights. Check ignition fuse by operating back-up lights. Check fuse to gauges by observing fuel gauge operation. If components appear to be in good condition, proceed to GRID TEST, SYSTEM TEST, and the appropriate component TESTS A:, B:, C:, D: or E: (as applicable).

TESTING GRID TEST 1. Start engine and turn rear defogger control switch on. Using a test light connected to ground, lightly touch each grid line. If test light shows full brilliance at both ends of all grid lines, check for loose ground wire. Test light brilliance will gradually change as test light probe is moved from left bus bar to right bus bar. 2. Contact each grid line a few inches on either side of glass center line to eliminate the possibility of missing a break in grid line. If a problem on a grid line is detected, place test light probe on that grid line at left bus bar and move probe toward right bus bar until light goes out. This will indicate a break in continuity of grid line. See Fig. 1 .

Fig. 1: Grid Brilliance Test Patterns Courtesy of GENERAL MOTORS CORP.

SYSTEM TEST "D" BODY (BROUGHAM) Circuit Operation

The rear defogger uses a heating grid baked to inside of rear window. With the ignition switch in RUN position, voltage is applied to the following: ď Ź

ď Ź

Through the A/C fuse and defogger relay coil to the Electronic Climate Control (ECC) head and ECC programmer. Through the RR DEFOG fuse and defogger relay contacts to the defoggers.

When the rear defogger button on the ECC head is pressed, the ECC programmer grounds the DK BLU wire from the defogger relay coil. This energizes the defogger relay, closing the defogger relay's contacts, applying voltage from the RR DEFOG fuse to the rear defogger and the left and right mirror defoggers. The ECC head also controls the timing of the defogger circuit. After approximately 10 minutes, the ECC head timer breaks the defogger relay coil's path to ground. The defogger relay is de-energized, the contacts open and voltage is no longer applied to the defoggers. If the rear defogger button is pressed again, the defoggers will operate in 5-minute cycles. The ECC head timer can be reset by turning the ignition off and then on. Once reset, the defoggers will again operate for 10 minutes. Testing

1. Check RR DEFOG fuse with a fuse tester. Check A/C fuse by operating A/C controls. Check the STOP/HAZ fuse by pressing the brake pedal and noting brake light operation. 2. If the rear defogger operates, but the left and right mirror defoggers do not operate, check the defogger inline fuse. Check that the defogger relay is securely inserted into accessory relay panel position "D".

Fig. 2: Brougham System Diagnosis Courtesy of GENERAL MOTORS CORP.

Fig. 3: Brougham System Diagnosis (Cont.) Courtesy of GENERAL MOTORS CORP.

GENERAL INFORMATION Diagnostic Connector (DLC) Locations

DOMESTIC CARS CHRYSLER GROUP LLC NOTE:

This table provides a quick reference for self-diagnostic connector locations, when available from manufacturer, that ARE NOT located at the lower left side of the dash, as mandated in 1996 by the Federal government.

CHRYSLER GROUP LLC - DOMESTIC CARS Application Acclaim 1989-90 1991-92

Connector Location

Under Left Side Of Dash On Left Front Fender Panel, Near Shock Tower 1993-94 Near Battery 1995 Behind Left Side Of Dash, Near Fuse Block Aries, Caravelle, Dynasty, E Class, Executive Sedan, LeBaron Sedan, New Yorker, Reliant, Town & Country, 400 & 600 1984-85 On Left Fender Apron, Behind Battery (2.2L Only) 1986-87 On Front Of Right Shock Tower (2.2L & 2.5L Only) 1988-89 On Left Fenderwell Under Left Side Of Dash 1991-92 On Left Front Fender Panel, Near Shock Tower 1993 (Except New Yorker) Near Battery 1993 (New Yorker) On Left Fender Panel Near PCM Under Center Of Dash, Near Center Avenger (1995-00) Console Breeze, Cirrus & Stratus (1995) Left Of Steering Column, On BCM Charger, Horizon, Omni, Rampage, Scamp & Turismo 1985-89 2.2L Carbureted On Left Fender Apron 2.2L Turbo On Front Of Right Shock Tower Concorde, Intrepid, LHS, New Yorker, Vision & 300M 1993-95 Behind Left Side Of Dash 1996-97 Under Left Side Of Dash, Near Center

Console Daytona 1984-87 1988-89 1990-92 1993 Dynasty 1990 1991-93 Fifth Avenue 1990 1991-93 Horizon & Omni (1989-90) Imperial 1981-83 1990 1991-93 LeBaron Coupe & Convertible 1985-87 1988-89 1990-92 1993 1994 1995 Lancer 1985-87 1988-89 Laser 1990-94 1995 Monaco & Premier 1990 1991-92

On Front Of Right Shock Tower On Left Fenderwell On Left Front Fender Panel, Near Shock Tower On Left Front Inner Fender Or Under Steering Column Under Left Side Of Dash On Left Fender Panel, Near SBEC/PCM Under Left Side Of Dash On Left Fender Panel Near SBEC/PCM Under Left Side Of Dash CCC Connector Left Of Air Cleaner Under Left Side Of Dash On Left Fender Panel Near SBEC/PCM On Right Front Shock Tower On Left Fenderwell On Left Front Fender Panel, Near Shock Tower On Left Front Inner Fender Or Under Steering Column Near Battery Behind Left Side Of Dash, Near Fuse Block On Right Front Shock Tower On Left Fenderwell Above Left Kick Panel, Near Fuse Block Under Left Side Of Dash, Near Center Console On Right Front Fender Panel On Left Fender Panel, Next To SBEC Under Headlight Switch, Under Left Side

Neon (1995) Shadow 1985-87 1988 1989

Of Dash

1990 1991-92 1993-94 Spirit & Sundance 1985-87 1989-90 1991-92 1993-94 1995 Talon 1990-94

On Right Front Shock Tower On Left Fenderwell Under Dash, To Right Of Steering Column On Left Fender Front Panel, Near SBEC On Left Front Fender Panel, Near Shock Tower Near Battery On Right Front Shock Tower Under Left Side Of Dash On Left Front Fender Panel, Near Shock Tower Near Battery Behind Left Side Of Dash, Near Fuse Block Above Left Kick Panel, Near Fuse Block Under Left Side Of Dash, Near Center Console

1995-98

FORD MOTOR CO. NOTE:

FORD MOTOR CO. - DOMESTIC CARS Application Bobcat & Pinto Capri 1980-85 1986 Continental 1984-89 1990-91

Connector Location On Center Of Right Fender Apron On Center Of Left Front Fender Apron On Left Rear Corner Of Engine Compartment On Right Rear Corner Of Engine Compartment On Right Rear Corner Of Firewall, On Electronic Assembly Cover

1992 1993-94 Contour & Mystique 1995 Cougar & Thunderbird 1982-90 1991 1992 1993 1994 1995 3.8L 4.6L 1996 Crown Victoria, Grand Marquis & Lincoln Town Car 1983 & 1987 1985-86 & 1988-90 1992 1993-94 Escort, EXP, Lynx & Tracer 1985-90 1991 1992 1993-95 LTD & Marquis 1983 1984-86 Mark VII 1984-87 1988-90 1991

On Right Fender Apron VIP Connectors (2) On Right Rear Of Engine Compartment, On PCM Cover On Left Rear Corner Of Engine Compartment On Left Fender Apron On Rear Of Right Front Fender Panel Front Of Right Shock Tower 2 Connectors In Right Rear Corner Of Engine Compartment On Right Side Of Engine Compartment & Below Glove Box On Right Side Of Engine Compartment & Below Glove Box Behind Right Side Of Dash, Below Glove Box Lower Right Side Of Dash, Below Glove Box On Right Fender Apron On Left Fender Apron On Left Front Fender Panel On Top Of Left Front Wheelwell On Right Fender Apron Near Firewall On Left Rear Of Engine Compartment On Right Rear Of Engine Compartment, Near Cowl On Left Side Of Firewall On Left Fender Apron On Left Rear Corner Of Engine Compartment On Right Rear Corner Of Engine Compartment Front Of Right Fender Apron On Right Side Of Engine Compartment, Near Thermactor Solenoids

Mark VIII 1993-96 Mustang 1980-85 1986-91

On Top Of Left Wheelwell On Center Of Left Front Fender Apron On Left Rear Corner Of Engine Compartment On Left Shock Tower, Near Ignition Coil 2 Connectors On Right Front Strut Tower Behind Right Front Strut Tower & Right Of Steering Column

1992 1993 1994-95 Probe 1991-92 1993 1994-95 Sable & Taurus 1986-87 (3.0L Only) 1988-90 2.5L 3.0L 1991 1992 1993-95 Tempo & Topaz 1984-92 1993-94

On Left Rear Corner Of Engine Compartment DLC - Behind Left Side Of Dash; STI Connector - On Left Inner Fender Panel On Left Front Inner Fender Panel Near Alternator On Engine Harness Near PCV Hose On Right Rear Corner Of Engine Compartment On Right Rear Corner Of Engine Compartment, On ECA Cover On Right Rear Corner Of Engine Compartment, Below MAP Sensor Right Rear Of Engine Compartment On Right Rear Corner Of Engine Compartment In Engine Compartment, On Left Strut Tower

GENERAL MOTORS NOTE:

GENERAL MOTORS - DOMESTIC CARS Application

Connector Location

Allante

Bonneville (1980-81) Brougham (1987-92) Camaro & Firebird (1980) Caprice Classic 1980-81 1982-88 Catalina Cavalier (1982-88) Cimarron Century Corvette (1980-83) Custom Cruiser 1980-81 1982-88 DeVille (1981-88)

Delta 88 Eldorado (1981-88)

Electra (1980-81) Estate Wagon Fiero Firenza Fleetwood (1981-88)

Fleetwood Brougham Impala (1982-88) LeMans

Enter Diagnostic Mode By Pressing OFF & WARM Buttons On Instrument Panel ECU Connector On Upper Right Kick Panel Bottom Center Of Instrument Panel Diagnostic Ground Lead Connector On Right Shroud Above ECM ECU Connector On Upper Right Kick Panel Under Center Of Instrument Panel ECU Connector On Upper Right Kick Panel On Side Of Fuse Block On Side Of Fuse Block Under Left Of Dash Ashtray In Center Console, Under Ashtray ECU Connector On Upper Right Kick Panel Under Center Of Instrument Panel Enter Diagnostic Mode By Pressing OFF & WARMER Buttons On Instrument Panel ECU Connector On Upper Right Kick Panel Enter Diagnostic Mode By Pressing OFF & WARMER Buttons On Instrument Panel ECU Connector On Upper Right Kick Panel ECU Connector On Upper Right Kick Panel Under Ashtray Or Cigar Lighter Panel Within Center Console On Side Of Fuse Block Enter Diagnostic Mode By Pressing OFF & WARMER Buttons On Instrument Panel On Bottom Center Of Dash, Near Ashtray Under Center Of Instrument Panel ECM Connector On Right Kick Panel

LeSabre (1980-81) LeSabre Wagon (1982-88) Monza Ninety-Eight (1980-81) Nova Parisienne Reatta 1988-92 (MFI)

1991-93 Riviera 1980-85 (Carbureted) 1986-92 (MFI)

Safari Seville (1981-88)

Skyhawk Starfire Sunbird Toronado 1980-85 (Carbureted) 1986-92 (MFI)

Trofeo 1988-92 (MFI)

1991-93 2000

DOMESTIC LIGHT TRUCKS & VANS CHRYSLER GROUP LLC

Or Under Left Side Of Dash ECU Connector On Upper Right Kick Panel Under Center Of Instrument Panel Under Right Side Of Dash ECU Connector On Upper Right Kick Pane Behind Right Strut Tower Under Center Of Instrument Panel Enter Diagnostic Mode By Pressing OFF & WARM Buttons On Instrument Panel Above Parking Brake Pedal Under Left Or Center Of Dash Enter Diagnostic Mode By Pressing OFF & WARM Buttons On Instrument Panel Under Center Of Instrument Panel Enter Diagnostic Mode By Pressing OFF & WARMER Buttons On Instrument Panel Under Right Side Of Dash Under Right Side Of Dash On Side Of Fuse Block, Under Right Side Of Dash Under Left Or Center Of Dash Enter Diagnostic Mode By Pressing OFF & WARM Buttons On Instrument Panel Enter Diagnostic Mode By Pressing OFF & WARM Buttons On Instrument Panel Above Parking Brake Pedal On Side Of Fuse Block

NOTE:

CHRYSLER GROUP LLC - DOMESTIC LIGHT TRUCKS & VANS Application Connector Location Caravan, Grand Caravan, Grand Voyager, Mini Ram Van, Town & Country, & Voyager 1984-92 On Left Side Fender Apron 1993 On Left Fender Front Fender Panel, Near SBEC 1994-95 On Wiring Harness, On Center Of Firewall Dakota 1987-88 On Right Side Fender Apron 1989 On Left Side Of Firewall 1990-92 On Right Side Of Firewall 1993-95 On Right Rear Corner Of Engine Compartment Jeep Cherokee (1992-95) On Left Front Fender Apron, Behind Air Cleaner Comanche On Left Front Fender Apron, Behind Air Cleaner Grand Cherokee & Wagoneer 1993-95 PCM On Right Rear Of Engine Compartment, Near PCM TCM Behind Left Side Of Instrument Panel Wrangler (1992-95) On Left Side Of Firewall, Near PCM Pickup & Ramcharger 1985-90 On Left Side Of Firewall 1991-93 On Left Front Fender Panel, Next To SBEC/PCM 1995 Pickup On Right Side Of Firewall Ram Wagon & Van 1985-90 On Left Side Of Firewall 1991-95 On Center Of Firewall, Near SBEC/PCM FORD MOTOR CO. NOTE:

This table provides a quick reference for self-diagnostic connector locations, when available from manufacturer, that ARE NOT located at the lower left side

of the dash, as mandated in 1996 by the Federal government. FORD MOTOR CO. - DOMESTIC LIGHT TRUCKS & VANS Application Connector Location Aerostar 1986-90 On Left Front Fender 1991 Near Starter Relay 1992 On Left Front Inner Fender Panel 1993-95 On Left Side Of Firewall Bronco 1982-85 6-Cylinder On Left Front Fender V8 On Right Inner Fender Panel 1986-87 On Right Front Fender, Near Starter Relay 1988-92 On Left Fender Apron 1993-95 2 Connectors In Left Rear Of Engine Compartment, On Bracket 1996Below Glove Box Bronco II 1983-85 On Right Front Inner Fender Panel (2.3L Only) 1986-90 On Right Front Fender Apron Excursion Behind Center Of Dash Explorer & Mountaineer (1991-94) On Right Rear Of Engine Compartment, Near A/C-Heater Blower Pickup 1982-85 6-Cylinder On Left Front Fender V8 On Right Inner Fender Panel 1986-87 On Right Front Fender, Near Starter Relay 1988-92 On Left Fender Apron 1993-95 2 Connectors In Left Rear Of Engine Compartment, On Bracket 1996Below Center Of Instrument Panel Pickup (F250 Heavy Duty & F350) Under Right Side Of Dash Ranger 1983-85 On Right Front Inner Fender Panel (2.3L Only) 1986-90 On Right Front Fender Apron 1991 Behind Engine Compartment

Fuse/Relay Block On Left Front Inner Fender Panel On Rear Of Engine Compartment Fuse/Relay Block

1992 1993-95 Van 1986-92 1993-95

On Right Fender Apron On Left Front Corner Of Engine Compartment

1996 5.8L (49 State, Over 8600 GVW) & 7.5L (Except Calif.) All Others 1997-98 Diesel All Others Villager (1993)

On Left Front Corner Of Engine Compartment Under Left Side Of Dash Under Left Side Of Dash Left Front Corner Of Engine Compartment On Left Side Of Engine Compartment, Below Coolant Reservoir

GENERAL MOTORS NOTE:

GENERAL MOTORS - DOMESTIC LIGHT TRUCKS & VANS Application Astro & Safari Van (1986-87) "S" & "T" Series Blazer, Bravada, Envoy, Jimmy, Pickup & Sonoma 1982-85 1.9L 2.0L & 2.8L 2.5L 1986-87 Van ("G" Series) (1982-87)

Connector Location Under Left Corner Of Cowl

Under Left Side Of Dash, Behind ECM Under Ashtray Under Left Side Of Dash Under Ashtray Under Driver's Seat

IMPORTED CARS & TRUCKS ACURA NOTE:

This table provides a quick reference for self-diagnostic connector locations, when available from manufacturer, that ARE NOT located at the lower left side

of the dash, as mandated in 1996 by the Federal government. ACURA - IMPORTED CARS & TRUCKS Application Integra 1991-93 1994-97 1998-02 Legend 1991-93

Connector Location Behind Right Kick Panel Behind Glove Compartment Behind Right Side Of Center Console Under Right Side Of Dash, Above PGM-FI ECU/PCM Behind Glove Compartment Under Glove Compartment Behind Lower Left Corner Of Dash, Behind Cover

1994-95 NSX (1997-01) SLX Vigor 1992-93

Under Right Side Of Dash, Near Center Console Behind Glove Compartment In Front Of Shift Lever, Behind Ashtray In Front Of Shift Lever, Behind Ashtray In Front Of Shift Lever, Behind Ashtray In Front Of Shift Lever, Behind Ashtray

1994 2.2CL & 2.3CL 2.5TL 3.0CL 3.2TL & 3.5RL AUDI NOTE:

AUDI - IMPORTED CARS & TRUCKS Application A4 1996 1997-01 (1.8L Turbo) 1997-99 (2.8L V6) 1997-

Connector Location Next To Rear Ashtray Behind Cover, Under Left Side Of Steering Column Under Cover, Next To Rear Ashtray Under Left Side Of Dash, Behind Cover

A6 1995

Under Ashtray, In Front Storage Compartment Of Center Console

1996-97

Under Cover, Next To Parking Brake Handle

Cabriolet 1994-96 1997-98 Coupe GT, 4000S & 4000S Quattro 80 90 1988-92 1993 1994-95 100 1989-91 1992-94 5000CS Quattro, 5000CS Turbo & 5000S

In Fuse/Relay Block, On Left Side Of Dash Under Ashtray, At Rear Of Center Console In Fuse Socket, On Fuel Pump Relay In Fuse Socket, On Fuel Pump Relay In Fuse Socket, On Fuel Pump Relay In Main Fuse/Relay Block, On Plenum Tray In Fuse/Relay Block, On Left Side Of Dash Under Left Side Of Dash In Auxiliary Relay Station No. 1, On Left Rear Of Engine Compartment In Fuse Socket, On Fuel Pump Relay

BENTLEY NOTE:

BENTLEY - IMPORTED CARS & TRUCKS Application 1996-00 All Models 2001-04 Arnage 2001Azure Convertible Continental

Connector Location In Glove Compartment Below Left Side Of Dash In Glove Compartment In Glove Compartment

BMW NOTE:

BMW - IMPORTED CARS & TRUCKS Application Z3 Z4 & Z8 318 & 325 1991 1992-95 1996 330 524t 525i & 535i 1990-91 (Black 20-Pin Connector) 1992-95 528e 635CSi 735i 1986-87 1988-92 740 & 750 740i & 740iL (1993-01) 745Li 750iL

Connector Location Behind Cover, On Right Side Of Center Console Under Left Side Of Dash, Left Of Steering Column, Behind Cover On Bracket, Above Thermostat Housing On Right Rear Of Engine Compartment Under Left Side Of Dash, Behind Panel Labeled OBD Behind Cover, Under Left Side of Dash Above Hood & Trunk Releases On Top Rear Of Engine Left Rear Corner Of Engine Compartment Outside Of Engine Compartment Fuse/Relay Block On Intake Manifold Bracket, Behind Thermostat Housing On Bracket, Next To Fuse/Relay Block On Bracket, On Top Of Engine On Right Side Of Engine Compartment, On Shock Tower Under Left Side Of Dash, Behind Panel Labeled OBD Behind Cover On Lower Left Corner Of A/C Control Panel In Left Side Kickpanel, Behind Cover Labeled OBD Behind Cover On Lower Left Corner Of A/C Control Panel

DAIHATSU NOTE:

DAIHATSU - IMPORTED CARS & TRUCKS Application Charade

Connector Location At Upper Section Of Transmission

Rocky

On Right Front Fender Panel

CHRYSLER GROUP LLC NOTE:

CHRYSLER GROUP LLC - IMPORTED CARS & TRUCKS Application Colt & Summit 1986-87 1988 1989-98 Colt Vista 1987 1988-89 1990-96 Conquest & Starion Expo Medallion Pickup Ram-50 Sigma Stealth 1991-98 1999 Summit Wagon Vista Wagon

Connector Location Above Inside Of Glove Compartment On Left Rear Corner Of Engine Compartment Under Left Side Of Dash, Near Fuse/Relay Block Behind Glove Compartment Under Left Side Of Dash, Near Hood Release Handle Under Right Side Of Dash Behind Glove Compartment Under Left Side Of Dash, Near Fuse/Relay Block On Left Side Of Firewall Under Left Side Of Dash, Near Fuse/Relay Block Under Left Side Of Dash, Near Fuse/Relay Block In Glove Compartment Under Left Side Of Dash, On Fuse/Relay Block Under Left Side Of Dash, Left Of Center Console Under Right Side Of Dash Under Right Side Of Dash

FERRARI FERRARI - IMPORTED CARS & TRUCKS Application

Connector Location

All Models 1996-

Behind Left Side Of Dash

FORD MOTOR CO. NOTE:

FORD MOTOR CO. - IMPORTED CARS & TRUCKS Application Aspire 1994-95 1996-97 Capri 1991

Connector Location On Left Rear Corner Of Engine Compartment Under Left Side Of Dash Behind Right Side Of Dash, Behind Glove Compartment

1992 1.3L

On Left Rear Corner Of Engine Compartment On Right Rear Corner Of Engine Compartment On Right Rear Corner Of Engine Compartment

1.6L 1993-94 Festiva 1992-93 1.3L

On Left Rear Corner Of Engine Compartment On Right Rear Corner Of Engine Compartment On Right Front Fender Apron, Near Battery On Right Rear Corner Of Engine Compartment On Left Rear Corner Of Engine Compartment

1.6L Merkur XR4Ti Scorpio Tracer

GENERAL MOTORS NOTE:

GENERAL MOTORS & GEO - IMPORTED CARS & TRUCKS Application Connector Location LeMans Behind Right Kick Panel, Above ECM Metro 1989-95 Under Left Side Of Dash, Near Fuse Block 1996 Under Right Side Of Dash, Near Center Console 1997-01 Under Left Side Of Dash Prizm & Prizm LSi 1989-95 On Left Front Strut Tower 1996-02 Under Left Side Of Dash Spectrum Under Right Side Of Dash, Above A/CHeater Blower Motor Sprint On Left Front Shock Tower, Near Battery Storm 1990-91 Behind Right Side Of Dash, Above A/C-Heater Blower Motor 1992-93 Behind Right Kick Panel Tracker 1989-95 Under Left Side Of Dash, Near Fuse Block 1996 In Engine Compartment, Near MAP Sensor 1997Under Left Side Of Dash HONDA NOTE:

HONDA - IMPORTED CARS & TRUCKS Application Accord 1990-95 1996-97 Civic (1992-95) Civic Del Sol 1992-95

Connector Location Behind Right Side Of Dash, Above Kick Panel Behind Ashtray In Center Console Behind Right Side Of Dash, Near PGM-FI ECM Behind Right Side Of Dash, Near

PGM-FI ECM Under Removable Cover On Right Side Of Center Console Behind Passenger Side Of Center Console

1996-97 CR-V Element 2003-11 Insight (2010-11) Odyssey 1995 1996-98 Passport (1995) Prelude 1992-95 1996

Above Gas Pedal, Below Fuse Block Below Left-of-Center Of Dash Behind Right Side Of Dash, Above Kick Panel Behind Passenger Side Of Center Console Behind Left Kick Panel Behind Center Console Under Beverage Holder In Center Console Under Removable Cover On Right Side Of Center Console Behind Right Side Of Center Console

1997-02 S2000 HYUNDAI NOTE:

HYUNDAI - IMPORTED CARS & TRUCKS Application Accent (1995) Sonata 1989 1990 W/Passive Seat Belt Restraints W/O Passive Seat Belt Restraints

Connector Location In Coin Box Under Left Side Of Dash, In Fuse Block In Fuse Block On Lower Left Of Steering Column

INFINITI NOTE:

This table provides a quick reference for self-diagnostic connector locations, when available from manufacturer, that ARE NOT located at the lower left side

of the dash, as mandated in 1996 by the Federal government. INFINITI - IMPORTED CARS & TRUCKS Application G20 (1993-95) I30 (1995) J30 1993 1994-95 1996-98 M30

Connector Location In ECCS Control Unit, Behind Center Console Beside Fuse Box Under Left Side Of Dash In ECM, Behind Right Kick Panel Under Left Side Of Dash Under Left Side Of Dash, Near Fuse Block

Q45 1990-93

Under Left Side Of Dash, Near Fuse Block In ECM, Behind Right Kick Panel

1994-95 ISUZU NOTE:

ISUZU - IMPORTED CARS & TRUCKS Application Amigo & Pickup 1986-89 1990-95 1998-00 Hombre Impulse 1986-89 1990-92 1993-95 I-Mark Oasis Rodeo 1991-95 1996-

Connector Location Under Left Side Of Dash Behind Left Kick Panel, Near ECM Lower Left Corner Of Dash, Behind Small Cover Under Lower Left Side Of Dash, Behind Cover Under Left Side Of Dash, Above ECU Behind Right Kick Panel Behind Left Kick Panel, Near ECM Behind Right Side Of Dash, Above A/CHeater Blower Motor Behind Right Side Of Center Console Behind Left Kick Panel Lower Left Side Of Dash, Behind

Stylus Trooper & Trooper II 1986 1987-91 1992 DOHC SOHC 1993-95 1996-02 VehiCROSS

Small Cover Behind Right Kick Panel Under Left Side Of Dash Under Center Console Behind Center Of Dash, Right Of Steering Column Under Left Side Of Dash Under Left Side Of Dash, Right Of Steering Column Lower Left Side Of Dash, Behind Small Cover Under Left Side Of Dash

JAGUAR NOTE:

JAGUAR - IMPORTED CARS & TRUCKS Application XJR (1995-97) XJS 1992 1993-94 1995-96 XJ6 1992 1993-94 1995-97 XJ12

Connector Location Near Center Console On Left Rear Trunk Wheel Arch, Behind Trim Panel Under Battery Tray, On Right Front Of Luggage Compartment Near Center Console On Left Rear Of Engine Compartment Under Battery Tray, On Right Front Of Luggage Compartment Under Left Side Of Dash, Near Center Console Near Center Console

KIA NOTE:

This table provides a quick reference for self-diagnostic connector locations, when available from manufacturer, that ARE NOT located at the lower left side

of the dash, as mandated in 1996 by the Federal government. KIA - IMPORTED CARS & TRUCKS Application Sephia 1994 1995 & 1996 1.6L 2.0L Sportage 1994 1995 & 1996 1.6L 2.0L

Connector Location On Center Of Firewall Under Center Of Dash, Mounted On Floorboard Under Right Side Of Dash, Near Kick Panel On Center Of Firewall Under Center Of Dash, Mounted On Floorboard Under Right Side Of Dash, Near Kick Panel

LAND ROVER NOTE:

LAND ROVER - IMPORTED CARS & TRUCKS Application Defender 90 Range Rover

Connector Location Behind Fuse Cover, In Center Of Console Under Right Side Of Dash, In Footwell

LEXUS NOTE:

LEXUS - IMPORTED CARS & TRUCKS Application ES Series 1990-91 DLC Total Diagnostic Communication Link Connector 1992-94

Connector Location

Near Left Shock Tower Under Left Side Of Dash

DLC No. 1 DLC No. 2 & 3 1995-97 GS Series 1990-95 DLC No. 1 DLC No. 2 1996-00 LS Series 1990-94 DLC No. 1 DLC No. 2 1995-00 SC Series 1992-95 DLC No. 1 DLC No. 2 & 3 1996-00

On Bracket, Behind Right Front Strut Tower Under Left Side Of Dash In Fuse Box At Lower Left Of Dash

On Bracket, On Top Of Engine Under Left Side Of Dash In Fuse Box At Lower Left Of Dash

On Bracket, Behind Right Front Strut Tower Under Left Side Of Dash In Fuse Box At Lower Left Of Dash

MAZDA NOTE:

MAZDA - IMPORTED CARS & TRUCKS Application B-Series 1987-88 1989-93 Engine Control Check Connector (Black 6-Pin) Trouble Codes Connector (Green 1-Pin) 1994-95 Miata (1990-95) MPV (1989-95) Engine Control Unit (Green 6-Pin & 1-Pin Connectors) MX-3

Connector Location On Right Front Fender Apron Near Windshield Washer Motor Near Black 6-Pin Connector (Engine Control) On Right Front Fender Panel On Left Rear Of Engine Compartment, Near Master Cylinder On Left Side Of Engine Compartment, Near Inner Fender Panel Mounted On Bracket, On Left Front Strut Tower

MX-6 & 626 1988 1989

Behind Left Front Shock Tower On Left Front Corner Of Engine Compartment At ECU Connector Terminal On Left Rear Corner Of Engine Compartment On Side Of Fuse/Relay Block, Near Battery On Left Front Fender Apron

1990-91 1992 1993 1994-95 Navajo 1991-93

On Right Rear Corner Of Engine Compartment On Right Front Fender Panel

1994-95 Protege 1987-89

On Passenger's Footwell (Left Foot Area) On Left Side Of Firewall, Near Wiper Motor

1990-95 RX7 1986-88 (3 Check Connectors) 1989-91 (Green 6-Pin Connector) 1993-95 323 1986-88 1989 (Green 6-Pin & Green 1-Pin Connectors) 1990-95 929 1989 1990-91 (Green 6-Pin Connector) 1992-93 1994-95

At Left & Right Corners Of Engine Compartment Behind Ignition Coil On Bracket, On Left Front Strut Tower Front Left Of Engine Compartment, Near Ignition Coil On Left Side Of Firewall On Left Side Of Firewall, Near Wiper Motor Near Air Cleaner In Left Front Corner Of Engine Compartment Mounted On Air Cleaner Housing On Left Front Strut Tower

MERCEDES-BENZ NOTE:

MERCEDES-BENZ - IMPORTED CARS & TRUCKS Application C-Class (1994) E-Class 1994-97 G-Class ML-Class S-Class 140 Platform (1994-99) 190 Series 1986-87 1988-93 All Models California (OBD) 1994 260E 1987 1988-89 All Models California (OBD) 300 Series 1986-87 1988-92 All Models California (OBD) 1993 Except 300E 300E 1994-95 (All Models) 400 & 500 Series

Connector Location On Right Rear Of Engine Compartment On Right Rear Of Engine Compartment Under Left Side Of Dash, Behind Cover Under Left Side Of Dash, Behind Cover On Right Rear Of Engine Compartment On Left Rear Of Engine Compartment In Engine Compartment, On Left Front Fender On Right Side Of Firewall, Near Battery On Right Rear Of Engine Compartment On Left Front Fender Apron, Next To Ignition Control Module In Engine Compartment, On Left Front Fender On Right Side Of Firewall, Near Battery On Left Front Fender Apron, Next To Ignition Control Module In Engine Compartment, On Left Front Fender On Right Side Of Firewall, Near Battery Left Fender Apron Right Rear Corner Of Engine Compartment On Right Rear Of Engine Compartment

1993 12-Pin Connector 38-Pin (Impulse Readout) 1994-95 420SEL & 560 Series (Except 2.2L) 1986-89 All Models California (OBD) 1990-91 560 Series (2.2L)

On Rear Of Left Front Inner Fender Panel In Module Box, On Right Rear Of Engine Compartment On Right Rear Of Engine Compartment

In Engine Compartment, On Left Front Fender On Right Side Of Firewall, Near Battery In Engine Compartment, On Left Front Fender On Lower Left Side Of Engine Connector

MITSUBISHI NOTE:

MITSUBISHI - IMPORTED CARS & TRUCKS Application Diamante (1992-98) Expo Montero 1986-88 1989-91 Pickup Raider 1987-88 1989 3000GT 1991-98 1999

Connector Location Under Left Side Of Dash, Near Fuse/Relay Block Under Left Side Of Dash, Near Fuse/Relay Block Left Rear Corner Of Engine Compartment Behind Glove Compartment Under Left Side Of Dash, Near Fuse/Relay Block Left Rear Corner Of Engine Compartment Behind Glove Compartment Under Left Side Of Dash, On Fuse/Relay Block Under Left Side Of Dash, Left Of Center Console

NISSAN NOTE:

NISSAN - IMPORTED CARS & TRUCKS Application Altima 1993-94 1995-96 Maxima 1989-94 1995-96 NX & Sentra

Connector Location On Driver-Side Of Center Console, Above Accelerator Pedal Below Fuse Box Under Left Side Of Dash Below Fuse Box Under Left Side Of Dash, Near Fuse Block

Pulsar NX 1986 1987 Quest (1993-95) CONSULT Tester Connector Self-Test Connector Stanza Van 200SX (1995-96) 240SX 1991-94 1995-96 300ZX (1990)

Above Right Side Of Dash, Below Wiper Motor Above Steering Column On Driver-Side Of Center Console, Above Accelerator Pedal Located Near Starter Below Center Of Dash, Near Center Console On Right Side Of Engine Compartment, Behind Fuel Filter Below Fuse Box Under Left Side Of Dash, Below Fuse Block In Glove Box Near Parking Brake

PEUGEOT NOTE:

PEUGEOT - IMPORTED CARS & TRUCKS

Application 505 Series

Connector Location On Lower Left Side Of Engine Connector

PORSCHE NOTE:

PORSCHE - IMPORTED CARS & TRUCKS Application 911 Series 1992-95 1996 928S 944 Series

Connector Location In Passenger's Footwell Left Side Of Center Console Top Front Of Engine On Left Side Of Engine Compartment

RENAULT NOTE:

RENAULT - IMPORTED CARS & TRUCKS Application Sportwagon Engine Diagnostic Fuel Injection Diagnostic

Connector Location On Center Of Firewall Right Rear Of Engine Compartment, Behind Airflow Meter

ROLLS-ROYCE NOTE:

ROLLS-ROYCE - IMPORTED CARS & TRUCKS Application All Models 1996-00 2001SAAB

Connector Location In Glove Compartment Under Left Side Of Dash

NOTE:

SAAB - IMPORTED CARS & TRUCKS Application 900 Series 1986-90 1991-93 1994 Convertible Hatchback All Others 9000 Series 1990 1991-92 1993 1994-95

Connector Location In Front Of Fuse/Relay Panel Under Back Seat, On Right Side Under Rear Seat Under Steering Column Under Right Front Seat On Left Side Of Engine Compartment Under Passenger's Seat On Left Of Firewall Under Right Front Seat

SUBARU NOTE:

SUBARU - IMPORTED CARS & TRUCKS Application Brat, Coupe, Hatchback, Sedan & Wagon 1987 Read Memory Connector Test Mode Connector MFI Sequential MFI 1988-89 Forester Justy 1987-88 Read Memory Connector (Factory) Test Mode Connector

Connector Location

Under Left Side Of Dash, Next To MFI/SMFI Control Unit On Left Side Of Dash, Next To MFI Control Unit On Left Side Of Firewall On Left Side Of Dash, Next To ECU Under Left Side of Dash, Behind Cover

On Right Front Fender, Near Strut Tower On Driver-Side Kick Panel Or ECU

1989-95 Read Memory Connector (Factory) Test Mode Connector Legacy 1990-94 Check Connector (Black Connector) Diagnostic Connector (Black 4-Pin Connector) Read Memory Connector (Black Connector) Select Monitor Connector (Yellow Connector) Test Mode Connector (Green Connector) 1995Loyale 1990-91 MFI (5-Pin Connector) SMFI (Yellow 9-Pin & Black 13-Pin Connectors) 1992-95 Diagnostic Check Connector (Yellow 9-Pin & Black 13-Pin Connectors) Diagnostic Read-Memory Connector (2-Single Wire Connectors) Outback & Outback Sport SVX 1992-96 1997

Under Left Side Of Dash On Driver-Side Kick Panel Or ECU

Behind Right Side Of Steering Column, Near Heater Case Behind Right Side Of Steering Column, Near Heater Case Behind Knee Panel, Right Of Steering Column Behind Right Side Of Steering Column, Near Heater Case Behind Knee Panel, Right Of Steering Column Under Left Side Of Dash, Behind Cover

In Front Of ECU Near Brake Booster Behind Brake Booster Behind Left Front Strut Tower Under Center Of Dash Under Left Side Of Dash Right Of Steering Column, On Center Console

SUZUKI NOTE:

SUZUKI - IMPORTED CARS & TRUCKS Application Esteem (1995) Samurai 1986-90

Connector Location Near Battery Under Right Side Of Dash, Behind Glove Compartment

1991-92 1993-95

On Right Side Of Firewall Under Left Side Of Dash, In Fuse Block

Sidekick & X90 1989-91 1992-93 ALDL Connector Engine Connector 1994-96 Swift 1989-91

Under Left Side Of Dash, In Fuse Block Under Left Side Of Dash Under Left Side Of Dash, Near Fuse Block In Engine Compartment, Near Battery Under Left Side Of Dash, In Fuse Block

1992 ALDL Connector Diagnostic Test Terminal 1993-95

Under Left Side Of Dash In Fuse Block Under Left Side Of Dash, In Fuse Block

TOYOTA NOTE:

TOYOTA - IMPORTED CARS & TRUCKS Application Camry 1983-90 1991 1992-95 4-Cylinder V6 Celica 1983-84 1985-95 Celica Supra Corolla Front Wheel Drive 1987

Connector Location Next To Brake Master Cylinder Near Left Front Shock Tower Near Wiper Motor Under Left Side Of Dash Next To Battery Behind Left Front Shock Tower Rear Of Battery, Near Relay Panel (2-Pin Connector)

Side Of Left Front Shock Tower (2-

1988-94 Rear Wheel Drive 1985-86 1987 Cressida 1988-93 Check Connector Total Diagnostic Communication Link Connector Land Cruiser (1988-94) MR2 1986-90 1992-95 Paseo (1992-95) Pickup 1984-86 1987-90 1992-94 Previa 1992-93 1994 Except Supercharged Supercharged 1995-97 RAV4 Starlet 1981-82 1983-84 Supra 1986-90 1991-92 1993-94 DLC No. 1

Pin Connector) Behind Left Front Shock Tower Side Of Right Front Shock Tower (2-Pin Connector) Right Rear Corner Of Engine Compartment

On Left Front Shock Tower Under Left Side Of Dash Near Wiper Motor Near Airflow Meter On Right Rear Of Engine Compartment, Near MAP Sensor On Side Of Engine Compartment Fuse/Relay Block No. 2, Near Battery Near Ignition Coil, Near Master Cylinder (2-Pin Connector) Right Front Inner Fender Panel, Near Relay Block On Side Of Engine Compartment Fuse/Relay Block No. 2, Near Battery Under Front Of Driver's Seat Under Center Console, Near Parking Brake Lever Under Cover, On Top Center Of Instrument Panel On Top Center Of Instrument Panel Under Dash, Near Center Console On Instrument Panel Fuse Block, On Top Of Dash Right Rear Of Engine Compartment Rear Of Battery, Near Relay Panel On Left Front Shock Tower On Right Side Of Firewall

DLC No. 2 Tacoma & T100 1993 1994-95 Except OBD-II DLC

OBD-II DLC Tercel 1987-90 1991-94 1995-98 Van 4Runner 1985-86

Under Left Side Of Dash, Near Kick Panel On Side Of Engine Compartment Fuse/Relay Block No. 2, Near Battery On Side Of Engine Compartment Fuse/Relay Block No. 2, Near Battery Under Left Side Of Dash In Engine Compartment, Next To Master Cylinder On Side Of Engine Compartment Fuse/Relay Block No. 2, Near Battery Near Steering Column Near Airflow Meter Near Ignition Coil, Next To Master Cylinder (2-Pin Connector) On Side Of Engine Compartment Fuse/Relay Block No. 2, Near Battery

1987-95

VOLKSWAGEN NOTE:

VOLKSWAGEN - IMPORTED CARS & TRUCKS Application Cabrio 1996 1997-02 Corrado Fox Golf 1993 1994 1998-03

Connector Location In Center Console, Below Tachometer On Center Dash, Behind Panel Near Ashtray Under Center Console Trim Plate Under Center Console, Near Shift Lever On Center Of Dash, Below A/CHeater Control Knobs Under Center Console In Center Console

Golf III 2.0L 1995-96 1997-98

Below A/C-Heater Control Panel On Center Dash, Behind Panel Adjacent To Ashtray

GTI 1993

On Center Of Dash, Below A/CHeater Control Knobs Under Center Console On Center Dash, Behind Panel Adjacent To Ashtray

1994 GTI 2.8L Jetta 1993

On Center Of Dash, Below A/CHeater Control Knobs Under Center Console

1994 Jetta III 2.0L 1995-96 1997-98 Jetta/Jetta III 2.8L New Beetle Passat 1992-94

Below A/C-Heater Control Panel On Center Dash, Behind Panel Adjacent To Ashtray On Center Dash, Behind Panel Adjacent To Ashtray Lower Part of Dash, In Front Of Shift Lever Under Center Console, Forward Of Shift Lever On Center Dash, Behind Panel Near Ashtray

1995-97 Toureg 2004-2007

In the cover of the drivers side footwell, to right of engine hood release lever

VOLVO NOTE:

VOLVO - IMPORTED CARS & TRUCKS Application C30 C70

Connector Location Under Left Center Of Dash Behind Cover, Below Parking Brake Lever

S40 S70 S90 V40 V70 (1997-00) V90 240 1986-92 1993 740 & 760 1986-92 Ignition System Fuel Injection (1990-92 Only) 780 850 1993 1994-95 Non-Turbo Turbo 1996-97 940 1991-93 Ignition System Fuel Injection 1994-95 960 1992-95 1996 1997

Under Left Center Of Dash Behind Cover, Below Parking Brake Lever Behind Cover, Below Parking Brake Lever Under Left Center Of Dash Behind Cover Below Parking Brake Lever Behind Cover, Below Parking Brake Lever Left Rear Corner Of Engine Compartment Behind Left Front Strut Tower

On Left Front Fender Apron Left Rear Corner Of Engine Compartment On Left Front Fender, Behind Air Cleaner Housing On Center Console, Forward Of Shift Lever & Near ECM On Right Front Strut Tower Behind Cover, Forward Of Shift Lever Behind Cover, Forward Of Shift Lever

On Left Front Fender Apron Left Rear Corner Of Engine Compartment Behind Left Front Strut Tower On Left Front Strut Tower In Center Console, To Right Of Parking Brake Lever Behind Cover, Forward Of Shift Lever

DOOR LOCKS - POWER ACCESSORIES & SAFETY EQUIPMENT General Motors Power Door Locks

DESCRIPTION & OPERATION DESCRIPTION The power door lock system is actuated by a control switch on each front door. Each door lock motor has an internal circuit breaker, which can take up to 3 minutes to reset. The automatic door lock system uses an Automatic Door Lock (ADL) controller, decoder module, lock and unlock relay, automatic door lock diode, gear selector switch lock relay, motor lock actuator relay, back-up light switch, right front door lock cylinder key switch, drive switch and a seat sensor switch. Some models may not use all these components. OPERATION Doors lock automatically when ignition switch is at RUN, BULB TEST or START position and transmission is placed in any mode other than Park. Doors unlock automatically when ignition switch is at RUN, BULB TEST or START position and transmission is placed in Park.

TROUBLE SHOOTING DOOR LOCKS INOPERATIVE & FUSE BLOWN NOTE:

Trouble shooting procedures apply to vehicle's without automatic door locks.

Replace fuse. If fuse blows immediately, check for short in Orange/Black wire between fuse and door lock switches. If fuse blows when switch is moved to LOCK position, check Blue wire between relay and switches. If fuse blows when switch is moved to UNLOCK position, check Black wire. If system still does not operate, check for open circuit in Orange, Light Blue or Black wires. DOOR LOCKS INOPERATIVE & FUSE GOOD Check Orange/Black wire at relay for power. If there is no power, check circuit breaker and feed wire. Place test light at Light Blue wire and press switch to lock. If light goes off, check for open in Orange, Light Blue or Black wires. Move test light to Gray wire and switch to lock. If test light goes out, check relay ground. Move test light to Tan wire and switch to unlock. If test light goes out, replace relay. If test light stays on, check for open in Tan or Gray wires. ONLY ONE SWITCH OPERATES LOCKS Check for loose wiring connections. Test Orange wire for power at switch. If there is no power, check for open in Orange wire. Test Blue wire at switch with switch in LOCK position. If there is no power, replace switch. If there is power, check for open circuit in Blue or Black wires.

DOORS UNLOCK BUT WILL NOT LOCK Check for power at Tan wire on relay with switch in LOCK position. If there is no power, check for open in Blue wire between relay and body harness. If there is power, replace relay. DOORS LOCK BUT WILL NOT UNLOCK Check for power at Black wire on relay with switch in LOCK position. If there is no power, check for open in Blue wire between relay and body harness. If there is power, replace relay. ONE DOOR LOCK DOES NOT OPERATE Check for loose connection or short in circuit. If both leads to motor are okay, replace motor. LOCKS INOPERATIVE, RELAY CLICKS Check Light Blue and Black wires between switch and relay. DOOR LOCKS INOPERATIVE OR LOCKS PULSATE & RELAY CHATTERS WHEN SWITCH IS ACTIVATED Ensure Gray and Tan wires are making contact between relay and lock actuator motor.

TESTING PRELIMINARY CHECKS 1. 2. 3. 4.

Before performing SYSTEM CHECK, check seats circuit breaker by operating seats. Check body fuse by operating courtesy lights. Check ignition fuse by operating back-up lights. Check ground by operating left hand power seat. If at least one power door lock motor operates, check suspect power door lock motor(s), wires to motor (s), and connections. Repair/replace as necessary. 5. Repair any power door lock symptoms before trouble shooting any automatic door lock problems. AUTOMATIC DOOR LOCK SYSTEM CHECK Action Ignition In RUN & All Doors Closed. Move Selector From PARK Shift To PARK Open LH Door & Shift From Park Lock & Close All Doors. Insert Key In LH Front Door Lock Turn & Hold Key In UNLOCK Position. (Repeat In RH front door lock cylinder) AUTOMATIC DOOR LOCK SYMPTOM

Normal Result All Doors Lock All Doors Unlock Doors Do Not Lock All Doors Unlock

Symptom Automatic Lock Or Unlock Features Do Not Function " " No Automatic Door Lock No Automatic Door Unlock Neither Lock Cylinder Works

For Diagnosis, Go To: TEST A TEST B TEST C TEST B TEST C (1) Check Wiring (1) Check Wiring

Theft Deterrent Disarms From Door Lock Cylinders

(1) Check Light Green wire between theft deterrent module and automatic door lock controller for open.

If wiring is okay, replace controller. TEST A - AUTOMATIC DOOR LOCK MODULE POWER & GROUND TEST Measure voltage at Automatic Door Lock Module Connector (connected) with ignition switch in RUN. If all voltages are correct, go to TEST B - LOCK CIRCUIT (TABLE 1 OF 3) . TEST A - DOOR LOCK MODULE Measure Between Terminal No. 3 (Orange) & Ground

Correct Voltage Battery

For Diagnosis (1)

6 (Pink/Black) & Ground

Battery

(2)

6 (Pink/Black) & 8 (Black)

Battery

(3)

(1) Check/repair Orange wire for an open. (2) Check/repair Pink/Black wire for an open. (3) Check/repair Black wire for an open.

TEST B - LOCK CIRCUIT TEST 1. Enter BCM diagnostics and select Input Test B105. If all results are correct go to TEST B - LOCK CIRCUIT (TABLE 2 OF 3) . TEST B - LOCK CIRCUIT (TABLE 1 OF 3) Action BCM Displays For Diagnosis (1) Close All Doors HI Open Left Door

(2)

Close Left Door

(1)

Open Right Door

(2)

Close Right Door

(1)

(1) Check for shorted door jam switch or a short to ground in

the White wires. (2) Check for an open in the door jam switch or door jam switch wiring. 2. Measure voltage at Automatic Door Lock Module Connector (disconnected) with ignition switch in RUN and all doors closed. If results are correct, go to TEST B - LOCK CIRCUIT (TABLE 3 OF 3) . If all results are correct, check/repair Light Blue wire for an open. TEST B - LOCK CIRCUIT (TABLE 2 OF 3) Measure Between Correct Voltage For Diagnosis (1) 1 (White) & Ground Battery (1) Check White wire for an open between connector Pin C1

and ADL module. 3. Connect TEST LAMP at Automatic Door Lock Module Connector (connected) with the ignition switch in RUN, gear selector in REVERSE and all doors closed and unlocked. TEST B - LOCK CIRCUIT (TABLE 3 OF 3) Connect Between 7 (Gray) & Ground In PARK Position " 4 (Lt. Blue) & GND (3) (1) Check transaxle position switch adjustment.

Correct Result

For Diagnosis

Lamp Does Not Light Lamp Lights

(1)

Lamp Flashes Once

(4)

(2)

(2) Check Gray wire and transaxle position switch. (3) Observe Test Lamp While Moving From PARK Position (4) Check connector terminal. If connector terminal is okay, replace Automatic Door Lock Module.

TEST C - UNLOCK CIRCUIT TEST Connect test lamp at Automatic Door Lock Module Connector (connected) with ignition switch in RUN, gear selector in PARK. If all results are correct, check/repair Black wire for an open. TEST C - UNLOCK CIRCUIT Connect Between 7 (Gray) & Ground 7 (Gray) & Ground (2)

Correct Result Lamp Lights Lamp Does Not Light

Lamp flashes once 2 (Black) & Ground (2) (1) Check Gray wire and transaxle position switch.

Diagnosis (1) (3) (4)

(2) Observe Light While Moving Into PARK (3) Check transaxle position switch adjustment. (4) Check connector terminal. If connector terminal is okay, replace Automatic Door Lock Module.

REMOVAL & INSTALLATION MOTOR 1. Raise window and remove trim panel. Detach insulator pad (if equipped) and inner panel water deflector. Punch out actuator attaching rivet center pin. Drill rivets with 1/4" bit. Disconnect rod and wire harness. Remove actuator through access hole. 2. On rear doors, remove window regulator lower adjusting screw and bracket (if necessary). Move regulator outward, allowing actuator to slide out. To install, reverse removal procedure. Attach actuator motor to door panel using 1/4" x 20 screws and "U" nuts. RELAY Relay is located in either one of the following locations: Behind right kick panel, behind right-hand side of instrument panel on relay bracket or in glove compartment. Disconnect wiring and remove mounting bolts to remove relay. To install, reverse removal procedure.

WIRING DIAGRAMS See appropriate wiring diagram in WIRING DIAGRAMS.

DRIVE AXLE - INTEGRAL Drive Axles - Integral Housing Differentials

AXLE RATIO & IDENTIFICATION Rear axle identification information is stamped on forward side of left or right axle tube on all models except Cadillac. On Cadillac, an identification code is stamped on rear of right axle tube 3" (76 mm) from differential housing or backside of right caliper support plate. AXLE RATIO IDENTIFICATION Ratio 2.41:1 2.56:1 2.73:1 2.93:1 3.08:1 3.23:1 3.27:1 3.42:1 3.45:1

Code 2AJ, 2BJ 6GA, 6GM, 6GS 6GB, 6GT, 6GN, 6HP, 6HT 8YA, 8YH 6HB, 6HF, 6HK, 8DA, 8DB, 8LL, 2ZC, 8LM, 8NC 6HJ, 6HQ, 8YG 8YM 9EQ 6HL, 8YG, 8YM 9ER

Fig. 1: Axle Ratio Code Locations Courtesy of GENERAL MOTORS CORP.

DESCRIPTION

Drive axle is a semi-floating hypoid gear type axle with integral housing. Centerline of pinion is set below centerline of ring gear. A removable steel cover, bolted to rear of housing, permits servicing differential case without removing axle assembly from vehicle. NOTE:

Some models are equipped with positive traction differentials. For testing and overhaul procedures for these units, see DRIVE AXLE - POSITIVE TRACTION article in this section.

REMOVAL & INSTALLATION AXLE SHAFTS & BEARINGS Removal (Except Borg-Warner)

1. Raise and support vehicle. Remove rear wheels and brake drums (or disc calipers and rotors). Drain lubricant from differential by removing cover. 2. Remove pinion shaft lock screw and pinion shaft. Push axle shaft toward center of vehicle and remove "C" lock from inner end of shaft. Carefully remove axle shaft from housing. 3. Insert Bearing and Seal Remover (J-22813-01) into bore. Position remover behind bearing so tangs engage bearing outer race. Using a slide hammer, remove bearing and seal. Discard bearings and seals. Installation (Except Borg-Warner)

1. Lubricate bearings with gear oil. Using Bearing Installer (J-23765 or J-23690) and Handle (J-8092), install bearing. Bearing is properly seated when installer bottoms against bore. 2. Lubricate seal with gear oil. Position seal on Seal Installer (J-23771 on 7 1/2" and 7 5/8" or J-21128 on 8 1/2" axles). Drive seal until flush with axle tube. 3. To complete installation, reverse removal procedure. Pull axle shaft outward after installing "C" lock to seat lock in counterbore of axle side gear. Install pinion shaft and lock screw. Removal (Borg-Warner 7 3/4" Ring Gear)

1. Raise and support vehicle. Remove rear wheels. Remove calipers and support from frame. Remove dust shield and outer bearing retainer. Attach Axle Shaft Remover (J-21579) to axle shaft. Using slide hammer, remove axle shaft and bearing. 2. Mount axle shaft in soft-jawed vise. Using a chisel, split inner bearing retainer and remove from shaft. Using a bearing remover, press bearing and seal off axle shaft. Discard bearing, retainer and seal. Installation (Borg-Warner 7 3/4" Ring Gear)

1. Place outer bearing retainer on axle shaft. Position oil seal on shaft with spring side facing in. Lightly lubricate seal with grease. NOTE:

Right axle shaft seal has Black band and left axle shaft seal has Gold band.

2. Position bearing and inner retainer on shaft with outer chamfer of retainer facing bearing. Using Axle Bearing/Retainer Installer (J-8853-01), press bearing and retainer on until completely seated. 3. To complete installation, reverse removal procedure. Ensure axle shaft splines are fully engaged before rotating axle shafts to verify correct spline alignment.

Fig. 2: Exploded View of Integral Rear Axle Assembly Courtesy of GENERAL MOTORS CORP. COMPANION FLANGE & OIL SEAL Removal

1. Raise and support vehicle. Scribe an alignment mark on drive shaft, companion flange, pinion and pinion nut for reassembly. Remove drive shaft. 2. Using an INCH lb. torque wrench, measure and record pinion bearing preload. Remove pinion nut and washer. Using a puller, remove companion flange. See Fig. 3 . Pry seal out of housing.

Fig. 3: Removing Companion Flange Courtesy of GENERAL MOTORS CORP. Installation

1. Pack seal lip of new seal with lithium based extreme pressure grease. On Camaro and Firebird models, drive seal flush, or recessed up to .010" (.25 mm) from edge of housing. On other models, drive seal into housing until seated against shoulder. On all models, install companion flange, washer and pinion nut. 2. Tighten pinion nut until all end play is removed. Continue tightening nut up to 1/16 turn beyond alignment mark made at disassembly, checking to make sure original preload is not exceeded by more than 3-5 INCH lbs. (.3-.6 N.m). Install drive shaft. NOTE:

If preload specification is exceeded, a new collapsible spacer must be installed and nut retightened until correct preload is obtained.

REAR AXLE ASSEMBLY Removal

1. Raise vehicle and support at frame. Place supports under rear axle assembly. Disconnect shock absorbers from axle. Disconnect level control switch link (if equipped). On Camaro and Firebird, remove left track bar mounting bolt. 2. On all models, remove tires. Loosen parking brake cable adjuster nut. Remove parking brake cables from adjuster and body clips. Remove track bar and stabilizer bar links from axle and body. 3. Scribe alignment mark on companion flange and drive shaft for installation reference. Remove drive shaft

and support out of way. Remove brake line junction block bolt from axle. Disconnect brake lines from junction block and wheel cylinders/calipers. WARNING: Use care when removing springs. Uncontrolled expansion of coil springs could cause bodily injury or damage to vehicle. 4. Disconnect brake line from axle mounting clips. Remove or clear brake lines away from axle assembly. Disconnect upper control arms from axle assembly. Lower axle and remove springs. 5. Disconnect lower control arms and torque arm from axle (if equipped). Remove brake drums and backing plates, or calipers and rotors, and support out of way. Remove axle shafts. Carefully lower axle and remove from vehicle. Installation

To install, reverse removal procedure. Use care when installing axle shafts to avoid damaging seals. Use a NEW cover gasket when installing cover. Refill axle housing with proper lubricant. Bleed and adjust brakes.

OVERHAUL NOTE:

For positive traction differential overhaul procedures, see DRIVE AXLE POSITIVE TRACTION article in this section.

DISASSEMBLY 1. Remove axle shafts. Check ring and pinion gear backlash and pinion bearing preload. This will indicate gear or bearing wear or an error in backlash or preload setting. 2. Mark differential bearing caps and housing for reassembly reference. Remove caps and pry differential case from housing. Remove bearing cups and shims. Keep each set with proper bearing cap for reassembly. 3. Remove differential pinion shaft, gears, and side gears with thrust washers. Keep them in order for reassembly. Remove ring gear bolts (left-hand threads) and tap gear from case using soft drift and hammer. 4. Remove pinion nut and companion flange. Remove pinion shaft and front bearing. If necessary, remove pinion bearing cups from housing using a brass drift. Press pinion shaft out of rear bearing and note thickness of pinion depth shim pack. REASSEMBLY Pinion Depth Adjustment

1. Drive pinion rear bearing shim thickness must be determined whenever a new axle housing, ring and pinion set, or pinion bearings and races are installed. Depth of mesh is determined using Pinion Setting Gauge Set (J-21777-B). NOTE:

Checking procedure for different axle sizes is the same, however, tool

component combinations vary between axles. 2. If removed, lubricate and install pinion bearings into races. Install lubricated pinion bearings. Position gauge plate and rear pinion bearing pilot on preload stud. Install assembly through rear pinion bearing, front pinion bearing and front pinion bearing pilot. See Fig. 4 . 3. Install hex nut until snug. Rotate bearings to ensure proper seating. Hold preload stud stationary with a wrench on flats. Tighten hex nut until 20 INCH lbs. (2.3 N.m) is required to rotate bearings.

Fig. 4: Installing Pinion Depth Gauge Set (J-21777-B) Courtesy of GENERAL MOTORS CORP. 4. Mount side bearing gauging discs on ends of arbor. Place arbor into carrier making sure discs are properly seated. Install side bearing caps and bolts. Tighten bolts to avoid movement. 5. Position dial indicator on mounting post of arbor with contact button resting on top surface of plunger. Preload dial indicator one-half revolution and tighten. Place plunger onto gauging area of gauge plate. 6. Rock plunger rod slowly back and forth across gauging area until dial indicator reads greatest deflection. Set indicator to zero. Repeat rocking action several times to verify setting. Once zero reading is obtained, remove plunger from gauging area. 7. Dial indicator will now read required pinion shim thickness for a "nominal pinion". Record this reading. Check drive pinion for painted or stamped markings on pinion stem or a stamped code number on small end of pinion gear. See Fig. 5 .

Fig. 5: Pinion Marking Locations Courtesy of GENERAL MOTORS CORP. 8. If marking is found to be a positive number, subtract that many thousandths from indicator reading. If marking is a negative number, add that many thousandths to indicator reading. This will be the thickness of rear pinion bearing shim pack. 9. If no markings are found on pinion, use dial indicator reading as shim thickness. Remove bearing caps and gauging tools from housing. Place selected shim pack on drive pinion. Using a press, install lubricated pinion bearing on pinion shaft. Case Reassembly

1. Install ring gear on case with NEW bolts. Alternately tighten bolts to pull ring gear into position on case. Place side gear thrust washers over side gear hubs. 2. Install assemblies into case in their original position. Install pinions and thrust washers into case. Install pinion shaft and lock bolt. Using installing tools, install side bearings onto differential case. Differential Shim Selection

1. Measure thickness of original side bearing preload shims. Select a standard .17" (4.3 mm) service spacer and service shims with a total thickness slightly less than original shims. Standard service shims are steel and are available from .040-.082" (1.02-2.08 mm). Production shims are cast iron and available from .210-.272" (5.33-6.91 mm). NOTE:

Do not attempt to reuse production shims because they may break when

tapped into position. 2. Install differential case in housing. Install spacer between each bearing cup and housing with chamfered edge of spacer against housing. Install left bearing cap loosely so that differential case is free to move. With left bearing race and spacer against housing, install both left and right service shims between right bearing race and service spacer. 3. Insert progressively larger feeler gauges between right service spacer and shim pack until a slight drag is felt. Total thickness of required shim pack is equal to feeler gauge thickness plus shim thickness used in step 1). Remove differential case, shims and spacers from axle housing. Pinion Installation & Preload Adjustment

1. Install a NEW collapsible spacer over pinion stem. Position pinion in housing. While holding pinion forward, carefully drive front pinion bearing onto pinion shaft until a few threads are exposed. NOTE:

Conventional spacer is used on 7 1/2", 7 3/4" and 8 1/2" axles. New inverted type spacer is used on 7 5/8" axle.

2. Install new oil seal, companion flange, washer and nut. Tighten nut until end play is removed. Rotate pinion several times to seat bearings. 3. Check preload using an INCH lb. torque wrench. Continue tightening nut and checking preload until correct preload is obtained. DO NOT overtighten. See AXLE ASSEMBLY SPECIFICATIONS table. CAUTION: If preload is exceeded, a new collapsible spacer must be installed and nut retightened until proper preload is obtained. Ring & Pinion Gear Backlash

1. With pinion depth set and pinion installed, place differential case and ring gear assembly into axle housing. Select 2 shims with a combined thickness equal to that of service shims and feeler gauge used in shim selection procedure. Install shims and spacers between bearing cups and housing. Install differential bearing caps and tighten cap bolts. 2. Rotate differential case several times to seat bearings. Check backlash using a dial indicator. Increase or decrease shim size where necessary to correct backlash reading. See Fig. 6 . Recheck backlash at 4 points equally spaced around ring gear. Ensure that variation between points does not exceed .002" (.05 mm).

Fig. 6: Adjusting Backlash Courtesy of GENERAL MOTORS CORP. Differential Bearing Preload

1. Remove differential bearing caps and increase left and right shim sizes .004" (.10 mm). Gentle tapping may be necessary to install second shim. Make sure shims are seated and differential turns freely. 2. Using gear marking compound, check gear tooth contact pattern to verify proper assembly and adjustment. Complete necessary settings and install axle shafts. Install differential cover and fill with lubricant. DRIVE AXLE CAPACITIES Application 7 1/2" & 7 5/8" Ring Gear 7 3/4" Ring Gear 8 1/2" Ring Gear AXLE ASSEMBLY SPECIFICATIONS Application Specification

Pts. (L) 3.5 (1.7) 4 (1.9) 4.25 (2.0)

Pinion Bearing Preload (1) Cadillac New 20-25 INCH lbs. (2.3-2.8 Bearings N.m) Used 10-15 INCH lbs. (1.1-1.7 Bearings N.m) Borg-Warner 7 3/4" New 12-25 INCH lbs. (1.4-2.8) Bearings Used 5-12 INCH lbs. (0.6-1.4) Bearings All Others New 24-32 INCH lbs. (2.7-3.6 Bearings N.m) Used 9-12 INCH lbs. (1.0-1.4 N.m) Bearings Ring Gear .005-.009" (.13-.23 mm) Backlash (2) Slip Fit Plus .008" (.20 mm) Side Bearing Preload (1) Measured with new seal without ring gear installed. (2) Add .004" (.10 mm) to each side to preload bearings.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Bearing Cap Bolt Borg-Warner All Others Housing Cover Bolts Pinion Shaft Bolts Rear Universal Joint Nuts Ring Gear-to-Case Bolt Borg-Warner All Others

Ft. Lbs. (N.m) 40 (54) 55 (75) 20-27 (27-36) 20 (27) 16 (22) 101 (137) 89 (127)

DRIVE AXLE - POSITIVE TRACTION Drive Axles - Positive Traction Differentials

IDENTIFICATION The differential can be identified as a positive traction unit by raising vehicle and rotating one rear wheel. With transmission in Neutral, both rear wheels will rotate in same direction if vehicle is equipped with a positive traction differential. The axle may also be identified by axle code. The axle code is stamped on front of right rear axle tube. See Fig. 1 . The axle ratio, ring gear diameter and differential type is contained in axle code. Using axle model code, gear ratio may be determined. Refer to the AXLE RATIO IDENTIFICATION table.

Fig. 1: General Motors Axle Identification Courtesy of GENERAL MOTORS CORP. AXLE RATIO IDENTIFICATION Axle Ratio

Axle Code

7 1/2" Ring Gear (1) 2.56:1

6GA

2.73:1

6GB

7 5/8" Ring Gear (1) 2.73:1 3.08:1 3.23:1 7 3/4" Ring Gear (2) 3.27:1 3.45:1 8 1/2" Ring Gear (1) 2.93:1 3.08:1 3.23:1 3.42:1 (1) Auburn differential assembly.

6HE & 6HT 6HF & 6HB 6HQ & 6HJ 9EQ 9ER 8YH 8DA, 8NC & 8ZA 8YM 8ZD

(2) Borg-Warner differential assembly.

DESCRIPTION Positive traction type differential directs a majority of driving force to the wheel with best traction. This is accomplished by 2 spring-loaded thrust plates pressing against the differential side gears, seated in tapered brake cones. The brake cones fit into a tapered recess in each end of differential cases. Outward pressure of thrust plate assembly forces brake cones against recesses, providing resistance to normal differential action. Thrust plate spring load is calibrated to permit some slippage under variable torque conditions. All models equipped with positive traction, except Camaro and Firebird, use Auburn type differential units. Camaro and Firebird models can use either Borg-Warner or Auburn differential units. Models equipped with Borg-Warner differential use rear disc brakes, while Auburn differential come with rear drum brakes. The Borg-Warner unit is serviceable. The Auburn unit is not serviceable and must be replaced as a unit.

LUBRICATION Fill differential with General Motors (1052271) 80W or 80W-90 GL-5 gear lubricant. See LUBRICATION CAPACITIES table for approximate capacity. LUBRICATION CAPACITIES Application 7 1/2" & 7 5/8" Ring Gear 7 3/4" Ring Gear

Pts. (L) 3.50 (1.6) 4 (1.9)

8 1/2" Ring Gear

4.25 (2.0)

TESTING BORG-WARNER DIFFERENTIAL 1. Place transmission in Park. Raise rear of vehicle until both wheels are off ground. Remove rear wheel. Attach Axle Shaft Puller (J-21579) and Adapter (J-619-01) to axle shaft flange. Install 1/2" coarse-thread bolt into adapter. See Fig. 2 . 2. With opposite wheel held from turning, attach torque wrench to adapter and measure torque required to rotate opposite wheel assembly. If torque reading is less than 35 ft. lbs. (48 N.m), disassemble and repair differential case.

Fig. 2: Testing Differential In Vehicle Courtesy of GENERAL MOTORS CORP. AUBURN DIFFERENTIAL 1. Place transmission in Park. Raise rear of vehicle until both wheels are off ground. Remove rear wheel. Attach Adapter (J-2619-01) to axle shaft flange. Install 1/2" coarse-thread bolt into adapter. Attach torque wrench to adapter. See Fig. 2 . 2. Measure torque required to rotate opposite wheel assembly. The reading should be 125-225 ft. lbs. (169305 N.m). Lower vehicle so that one wheel is on ground. Place transmission in Neutral. 3. Check torque to rotate remaining wheel. Reading should be 44-66 ft. lbs. (60-89 N.m) for Camaro and Firebird and 45-110 ft. lbs. (61-149 N.m) for all other models. Replace differential assembly if not within specifications.

REMOVAL & INSTALLATION DIFFERENTIAL ASSEMBLY CAUTION: To prevent misalignment of splines in opposite cone and gear assembly, DO NOT rotate axle after differential and first axle shaft are installed in axle housing. Removal

1. Remove axle shafts. Check ring and pinion gear backlash and pinion bearing preload. This will indicate gear or bearing wear or an error in backlash or preload setting. 2. Mark differential bearing caps and housing for reassembly reference. Remove caps and pry differential case from housing. Remove bearing cups and shims. Keep each set with proper bearing cap for reassembly. 3. Remove differential pinion shaft, gears, and side gears with thrust washers. Keep them in order for reassembly. Remove ring gear bolts (left-hand threads) and tap gear from case using soft drift and hammer. 4. Remove pinion nut and companion flange. Remove pinion shaft and front bearing. If necessary, remove pinion bearing cups from housing using a brass drift. Press pinion shaft out of rear bearing and note thickness of pinion depth shim pack. Pinion Depth Adjustment

Checking procedure for different axle sizes is the same, however, tool component combinations vary between axles.

2. If removed, lubricate and install pinion bearings into races. Install lubricated pinion bearings. Position gauge plate and rear pinion bearing pilot on preload stud. Install assembly through rear pinion bearing, front pinion bearing and front pinion bearing pilot. See Fig. 3 . 3. Install hex nut until snug. Rotate bearings to ensure proper seating. Hold preload stud stationary with a wrench on flats. Tighten hex nut until 20 INCH lbs. (2.3 N.m) is required to rotate bearings.

Fig. 3: Installing Pinion Depth Gauge Set (J-21777-B) Courtesy of GENERAL MOTORS CORP. 4. Mount side bearing gauging discs on ends of arbor. Place arbor into carrier making sure discs are properly seated. Install side bearing caps and bolts. Tighten bolts to avoid movement. 5. Position dial indicator on mounting post of arbor with contact button resting on top surface of plunger. Preload dial indicator one-half revolution and tighten. Place plunger onto gauging area of gauge plate. 6. Rock plunger rod slowly back and forth across gauging area until dial indicator reads greatest deflection. Set indicator to zero. Repeat rocking action several times to verify setting. Once zero reading is obtained, remove plunger from gauging area. 7. Dial indicator will now read required pinion shim thickness for a "nominal pinion". Record this reading. Check drive pinion for painted or stamped markings on pinion stem or a stamped code number on small end of pinion gear. See Fig. 4 .

Fig. 4: Pinion Marking Locations Courtesy of GENERAL MOTORS CORP. 8. If marking is found to be a positive number, subtract that many thousandths from indicator reading. If marking is a negative number, add that many thousandths to indicator reading. This will be the thickness of rear pinion bearing shim pack. 9. If no markings are found on pinion, use dial indicator reading as shim thickness. Remove bearing caps and gauging tools from housing. Place selected shim pack on drive pinion. Using a press, install lubricated pinion bearing on pinion shaft. Case Reassembly

Do not attempt to reuse production shims because they may break when

Conventional spacer is used on 7 1/2", 7 3/4" and 8 1/2" axles. New inverted type spacer is used on 7 5/8" axle.

1. With pinion depth set and pinion installed, place differential case and ring gear assembly into axle housing. Select 2 shims with a combined thickness equal to that of service shims and feeler gauge used in shim selection procedure. Install shims and spacers between bearing cups and housing. Install differential bearing caps and tighten cap bolts. 2. Rotate differential case several times to seat bearings. Check backlash using a dial indicator. Increase or decrease shim size where necessary to correct backlash reading. See Fig. 5 . Recheck backlash at 4 points equally spaced around ring gear. Ensure that variation between points does not exceed .002" (.05 mm).

Fig. 5: Adjusting Backlash Courtesy of GENERAL MOTORS CORP. Differential Bearing Preload

Pts. (L) 3.5 (1.7) 4 (1.9) 4.25 (2.0)

Specification

Ring Gear Backlash Side Bearing Preload

.005-.009" (.13-.23 mm) (2) Slip Fit Plus .008" (.20 mm)

INCH lbs. (N.m.) Pinion Bearing Preload (1) Cadillac New Bearings Used Bearings Borg-Warner 7 3/4" New Bearings Used Bearings All Others New Bearings Used Bearings (1) Measured with new seal without ring gear installed.

20-25 (2.3-2.8) 10-15 (1.1-1.7) 12-25 (1.4-2.8) 5-12 (0.6-1.4) 24-32 (2.7-3.6) 9-12 (1.0-1.4)

(2) Add .004" (.10 mm) to each side to preload bearings.

OVERHAUL AUBURN NOTE:

The Auburn differential units are serviced as a complete assembly only.

BORG-WARNER Disassembly

1. Remove ring gear bolts (left-hand threads). Tap ring gear from differential case with soft-faced hammer. Mark differential case halves for reassembly reference. Remove retaining bolts alternately a small amount from differential case to relieve spring tension. 2. Separate differential case halves. Remove pinion shaft, pinion gears, thrust washers, side gears and side gear shims. Remove spring plates, and compression springs. Discard compression springs. Install new springs during reassembly. 3. Mark brake cones and side gear shims (if equipped) for reassembly reference. Brake cones and side gear shims must be installed in the original location during reassembly. Using bearing puller, remove differential bearings if replacement is required. Inspection

Inspect all gears for damaged teeth. Check brake cone seats for smoothness. Inspect brake cones for scoring or damage. If the brake cone or differential case is damaged, replace brake cones and differential case as a unit.

Fig. 6: Exploded View of 4-Pinion Gear Borg-Warner Differential Courtesy of GENERAL MOTORS CORP. Reassembly

1. Install brake cones in the differential case. Measure the distance from differential case mating surface to flat surface on brake cone when it is fully seated. This determines brake cone shim. See BRAKE CONE SHIM table. BRAKE CONE SHIM Distance Measured In. (mm) 1.155-1.162 (29.34-29.51) 1.163-1.167 (29.54-29.64) 1.168-1.172 (29.67-29.77)

Shim Size In. (mm) No shim required .005 (.13) .010 (.25)

2. Lubricate pinion thrust washers, pinion bores and differential pinion shaft with axle lubricant. Install pinion gears and thrust washers on the pinion shaft. Install proper brake cone shim and side gear in the cap half of the differential case. 3. Brake cone must be installed in proper location. Apply mixture of molybdenum disulfide and rear axle lubricant to the face of both side gears. Install spring plate on the side gear with convex side facing flange half of differential case. 4. Install pinion shaft, pinion gears and thrust washers into cap half of the differential case. Ensure pinions mesh with side gear. Install new concentric thrust springs through center of pinion shaft. Install remaining spring plate and springs. 5. Install side gear shim (if required). Install remaining brake cone on spring plate. Install flange half of differential case while aligning oil channels. Install 2 bolts 180 degrees apart and finger tighten. 6. Use axle shaft to align side gear and brake cone splines. Place "C" clamp on axle shaft so 3" (76 mm)

extends beyond "C" clamp. Install differential assembly onto axle shaft splines, flanged half first. 7. Install other axle shaft through cap side of differential case, aligning the side gear and brake cone splines. Install remaining bolts. Tighten to specification. See TORQUE SPECIFICATIONS table. Install side bearings and ring gear (if removed).

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Axle Shaft Retainer Nuts Bearing Cap Bolts Auburn Borg-Warner Differential Case Bolts Pinion Shaft Lock Bolt Rear Cover Bolts Ring Gear Bolts (1) Auburn Borg-Warner (1) Always use new ring gear bolts.

Ft. Lbs. (N.m) 35 (46) 55 (75) 40 (52) 29 (38) 20 (27) 21 (28) 89 (120) 101 (137)

DRIVE BELT ROUTING ENGINE COOLING SYSTEMS General Motors Drive Belt Routing

DESCRIPTION Many manufacturers are using a single ("serpentine" or "V" ribbed) belt system to drive components normally requiring multiple "V" belts. The serpentine belt system incorporates a tensioner which makes it possible to rigidly mount belt-driven components previously requiring individual adjustment. The serpentine belt tensioner controls belt tension over a wide range of belt lengths. The tensioner cannot compensate for extreme belt lengths. Poor tension control or possible tensioner damage can result from excessive length belts.

SERPENTINE BELT ROUTING Install belt on crankshaft and belt-driven components as shown. Adjust tensioner. See Fig. 3-Fig. 13 . INSPECTION Check belt for fraying. If fraying is noticed, ensure both belt and tensioner are aligned properly. See Fig. 1. Automatic tensioners have a belt-wear indicator. See Fig. 2. If tensioner reaches its travel limit, indicated by marks on tensioner, belt should be replaced. If a whining or grinding noise is heard from tensioner or idler pulley, check for possible bearing failure. Belts must be properly adjusted at all times. Loose belts will result in slippage which may cause a noise complaint or improper accessory operation. Overtightening belts can place severe load on bearings. Serpentine Belt Alignment

Fig. 1: Serpentine Belt Alignment Courtesy of GENERAL MOTORS CORP. Serpentine Belt Tensioner Indicators

Fig. 2: Serpentine Belt Tensioner Indicators Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (Sunbird 2.0L)

Fig. 3: Sunbird 2.0L (With A/C) Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (2.2L & 2.5L)

Fig. 4: 2.2L & 2.5L (Without A/C) Courtesy of GENERAL MOTORS CORP.

Fig. 5: 2.2L & 2.5L (With A/C) Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (2.3L)

Fig. 6: 2.3L (With A/C) Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (3.1L)

Fig. 7: 3.1L (With A/C) Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (3.1L Camaro/Firebird)

Fig. 8: 3.1L Camaro/Firebird (With A/C) Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (3.3L & 3.8L)

Fig. 9: 3.3L & 3.8L (With A/C) Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (4.5L)

Fig. 10: 4.5L (With A/C) Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (5.0L & 5.7L Brougham, Camaro & Firebird)

Fig. 11: 5.0L & 5.7L Brougham, Camaro & Firebird Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (5.0L & 5.7L Except Brougham, Camaro & Firebird)

Fig. 12: 5.0L & 5.7L Except Brougham, Camaro & Firebird Courtesy of GENERAL MOTORS CORP. Serpentine Belt Routing (5.7L Corvette)

Fig. 13: 5.7L Corvette (With A/C) Courtesy of GENERAL MOTORS CORP.

DRIVE SHAFT ALIGNMENT Drive Shaft Alignment

DESCRIPTION Proper universal joint angle should be used to provide smooth operation. Front and rear universal joint angles should be checked with vehicle at proper riding height and gas tank full. Rear universal joint angle can be adjusted by shimming transmission mount or repositioning pinion nose.

CHECKING & ADJUSTING CHECKING 1. Ensure vehicle is at proper riding height with full tank of gasoline. Riding height is measured from top of axle tube to bottom of frame. Vehicle should be bounced and allowed to return to normal riding height prior to measuring. Riding height must be correct. See UNIVERSAL JOINT ANGLE & RIDING HEIGHT SPECIFICATIONS table. See Fig. 1 . 2. If riding height is not within specification, on models with electronic suspension, the height sensor must be adjusted. See HEIGHT SENSOR under ADJUSTING in this article. On models without electronic suspension, add weight to trunk to obtain correct riding height. 3. With vehicle level and supported at axles, measure universal joint angles. Clean all bearing caps and install Inclinometer (J-23498 or J-23489-A) and Adapter on rear drive shaft bearing cap. See Fig. 2 . Bearing cap must be straight up and down. Center bubble in sight glass and record reading. 4. Remove inclinometer, rotate drive shaft 90 degrees and install inclinometer on drive yoke bearing cap. Measure angle and subtract smaller reading from larger reading to determine rear universal joint angle. 5. Attach Inclinometer Adapter (J-23498-20) to front drive shaft bearing cap. See Fig. 3 . Attach inclinometer to adapter and repeat procedure used on rear universal joint to obtain front universal joint angle.

Fig. 1: Checking Riding Height Courtesy of GENERAL MOTORS CORP.

Fig. 2: Measuring Rear Universal Joint Angle Courtesy of GENERAL MOTORS CORP.

Fig. 3: Measuring Front Universal Joint Angle Courtesy of GENERAL MOTORS CORP. ADJUSTING CAUTION: Link must be attached to metal height sensor arm during adjustment.

Height Sensor (Brougham, Custom Cruiser & Estate Wagon)

With link attached to metal arm, loosen metal arm-to-height sensor plastic arm retaining nut. See Fig. 4 . To increase riding height, move plastic arm upward. To decrease riding height, move plastic arm downward. Tighten retaining nut.

Fig. 4: Adjusting Height Sensor Courtesy of GENERAL MOTORS CORP. Transmission Shimming

Adding one shim at transmission mount will decrease front universal joint angle 1/2 degree and increase rear angle 1/4 degree. Removing one shim will increase front angle 1/2 degree and decrease rear angle 1/4 degree. NOTE:

Production bolt is 10 mm x 35 mm (1.5 thread pitch). When using 2 or more shims, a 10 mm x 50 mm bolt should be used.

Repositioning Pinion Nose

Suspension bracket bolt hole tolerances will permit adjustment of rear universal joint angle. Loosen all rear suspension control arm bolts. Reposition pinion nose up or down and tighten all bolts. Control Arm Change (Caprice, Custom Cruiser & Estate Wagon)

Rear universal joint angle corrections within +/- 2 degrees may be obtained using different length control arms. Front universal joint angle corrections within +/- 1/3 degree may be obtained by using different length control arms. UNIVERSAL JOINT ANGLE & RIDING HEIGHT SPECIFICATIONS Application Brougham Camaro & Firebird Caprice

Height (2)

4 11/16" (119 mm)

Front Joint (1) 2.0째 1.1째

Rear Joint 2.0째 1.5째

7.5" Axle (3) 6 1/4" (159 mm)

1.75°

2.5°

(3) 6 1/8" (155 mm)

1.75°

2.5°

1.75°

2°

8.5" Axle Custom Cruiser & Estate Wagon (1) Angles may be +/- 1/2 degree.

6 1/8" (155 mm)

(2) Rear riding height is 4.80-5.59" (121.9-141.9 mm) on models with electronic suspension or 5.15-

5.98" (130.8-151.8 mm) on models without electronic suspension. Riding height must not vary more than .35" (8.9 mm) from each side. (3) Riding height is +/- 1/4" (6 mm).

P - EGR FUNCTION TESTING -95 ENGINE PERFORMANCE General Motors Corp. EGR Function Testing

EGR FUNCTION TESTING PORTED EGR VALVE 1. Turn ignition off. Disconnect EGR vacuum hose at vacuum signal tube. Connect a hand-held vacuum pump to vacuum signal tube and apply 10 in. Hg. EGR diaphragm plate should move up and remain up for at least 20 seconds. 2. If diaphragm moves up and holds for 20 seconds, diaphragm is operating properly. If diaphragm does not hold vacuum, EGR valve is defective. Place transmission in Park or Neutral and start engine. 3. With engine running at normal operating temperature, push up on diaphragm. Engine RPM should decrease. If RPM decreases, EGR valve is functioning properly. Connect vacuum gauge to EGR valve vacuum supply hose. Raise engine speed to 2000 RPM and ensure adequate vacuum supply to EGR valve exists. NEGATIVE BACKPRESSURE EGR VALVE 1. EGR negative backpressure valve may be identified by letter "N" in last position of EGR part number. With engine off, disconnect EGR valve vacuum signal hose. Connect vacuum pump to vacuum signal tube and apply 10 in. Hg. 2. EGR diaphragm should move up and remain up for 20 seconds. If diaphragm does not stay up for 20 seconds, EGR valve is defective. Using an assistant, again apply 10 in. Hg to signal tube. Have assistant immediately try to start engine. Observe diaphragm for movement. 3. If diaphragm moves to a seated position (valve closed) during cranking and initial starting, EGR valve is functioning properly. If diaphragm does not move, clean or replace EGR valve. POSITIVE BACKPRESSURE EGR VALVE 1. EGR positive backpressure valve may be identified by the letter "P" in the last position of the EGR part number. To test EGR valve, place transmission in Park or Neutral. 2. Set parking brake and block drive wheels. Connect tachometer. With engine running at normal operating temperature, increase engine speed to 2000 RPM. 3. Disconnect vacuum hose from EGR valve and plug hose. EGR valve diaphragm should move down and engine RPM should increase. NOTE:

On some engines with ECM-controlled EGR control solenoid, EGR vacuum is locked out in Park/Neutral and EGR control solenoid must be by-passed.

4. Reconnect vacuum hose. Diaphragm should move up and engine RPM should decrease. A slight vibration of diaphragm plate may be noticed in backpressure EGR valves. 5. If engine RPM changes and EGR diaphragm moves, EGR valve is functioning correctly. If engine RPM does not change and diaphragm does not move, remove EGR valve and apply 10 in. Hg to EGR vacuum

signal tube. EGR valve should not open. 6. If EGR valve opens, replace EGR valve. With vacuum still applied, direct a stream of air (15 psi maximum) into valve seat. EGR valve should open completely. 7. If air is not available, connect a section of hose over EGR valve seat. Connect a vacuum pump to signal tube. With thumb plugging intake port of EGR valve, operate vacuum pump while alternately blowing and pausing. 8. With vacuum present at signal tube, EGR valve should open while pressure is applied and should close when no vacuum is present. DIGITAL EGR VALVE - -3.1L, 3.4L & 3.8L NOTE:

A Tech 1 scan tester or a tester capable of cycling ECM output devices may also be used to perform EGR function test.

1. Turn engine off. Disconnect EGR valve electrical connector. Start engine and allow engine to idle. Using a 12-volt power source and a fused jumper wire, apply voltage to terminal "D" of EGR valve. See Fig. 1 . NOTE:

EGR valve wire colors may vary.

2. Using a jumper wire with one end connected to a good ground, alternately touch remaining end of jumper wire to EGR valve terminals "A", "B", and then "C". Engine RPM should change as each EGR valve terminal is contacted. If engine RPM changes, EGR valve is functioning correctly. 3. If engine RPM does not change, check for restriction in EGR supply tube or plugged EGR valve orifice. If EGR valve is not restricted or plugged, EGR valve is defective.

Fig. 1: Digital EGR Valve Circuit (1988-92 3.1L, 3.4L & 3.8L) Courtesy of GENERAL MOTORS CORP. DIGITAL EGR VALVE - -2.3L "W" BODY VIN D

1. Turn engine off. Disconnect EGR valve electrical connector. Start engine, and allow it to idle. Using a 12-volt power source and a fused jumper wire, apply voltage to terminal "B" of EGR valve. See Fig. 2 . Using a jumper wire with one end connected to a good ground, alternately touch remaining end of jumper wire to EGR valve terminal "A" and then to terminal "C". 2. Engine RPM should change as each EGR valve terminal is contacted. If engine RPM changes, EGR valve is functioning correctly. If engine RPM does not change, check for restriction in EGR supply tube or plugged EGR valve orifice. If EGR valve is not restricted or plugged, EGR valve is defective.

Fig. 2: Digital EGR Valve Circuit (1990-91 2.3L "W" Body VIN D) Courtesy of GENERAL MOTORS CORP. INTEGRATED ELECTRONIC EGR VALVE - 1990 1. Turn engine off. Connect vacuum pump to EGR valve. Apply vacuum and observe EGR valve. EGR valve should not move. If valve moves, check vent filter for restriction. Replace EGR valve if necessary. 2. Turn ignition on and repeat step 1). When applying vacuum, EGR valve should not move. If EGR valve moves, system is malfunctioning. DIGITAL EGR VALVE - 1993-94 3.1L, 3.4L & 3.8L (VIN 1) Start engine. Using Tech 1 scan tester or a tester capable of cycling ECM output devices, select miscellaneous tests. With engine idling, RPM should drop and engine should idle rough as each solenoid is energized. If system operates as specified, EGR valve is functioning correctly.

ELECTRICAL COMPONENT LOCATOR ELECTRICAL COMPONENT LOCATIONS General Motors Corp. - Electrical Components

BUZZERS, RELAYS & TIMERS BUZZERS, RELAYS & TIMERS LOCATION Component A/C Cut-Out Relay Defogger Relay ELC Relay Fuel Pump Relay View Fuel Pump Relay Location Hazard Flasher Relay Horn Relay Illuminated Entry Timer Lock Enable Relay Overvoltage Protection Relay Park/Neutral Relay Power Antenna Relay Power Door Lock Relay Starter Interrupt Relay Early Production Late Production Theft Deterrent Relay Turn Signal Flasher Relay

Location On center of firewall, to the right of wiper motor. At position "D" on accessory relay panel. At position "J" on accessory relay panel. See Fig. 1 . On right side fenderwell. See Fig. 2 . On right side fenderwell. See Fig. 1 . Under left side of dash, on lower right corner of fuse block. See Fig. 3 . At position "B" on accessory relay panel. See Fig. 1 . Behind left side of dash, to left of steering column. Taped to automatic door lock controller. Under glove box. At position "F" on accessory relay panel. See Fig. 1 . At position "A" on accessory relay panel. See Fig. 1 . Behind passenger side kick panel. Above steering column, taped to wiring harness. In accessory relay panel. See Fig. 1 . Under left side of dash, on or near theft deterrent controller. Behind dash, on bracket to right of steering column.

CIRCUIT PROTECTION DEVICES CIRCUIT PROTECTION DEVICES LOCATION Component Defogger In-Line Fuse ECM Fuse View

Location Under left side of dash, near fuse block. On accessory relay panel. See Fig. 2 .

ECM Fuse Location Fuel Pump Fuse View Fuel Pump Fuse Location Fuse Block View (5.0L) Fuse Block View (5.7L) Fuse Block Fusible Links 5.0L 5.7L Horn Circuit Breaker In-Line Fuses Theft Deterrent A B Luggage Compartment Pull-Down Injector Fuse Power Seat Circuit Breaker Power Window/Sun Roof/Luggage Compartment Release Circuit Breaker

On accessory relay panel. See Fig. 1 . On accessory relay panel. See Fig. 2 . On accessory relay panel. See Fig. 1 . Under left side of dash, to left of steering column. See Fig. 4 . Under left side of dash, to left of steering column. See Fig. 2 . Under left side of dash, to left of steering column. See Fig. 3 . At junction block, on left fender panel. At junction block, on right fender panel. In lower right side of fuse block. See Fig. 3 .

Under dash, to right of steering column. Under dash, to left of steering column. At center of luggage compartment lid. On accessory relay panel. See Fig. 1 . On each seat motor. In fuse block. See Fig. 3 .

CONTROL UNITS CONTROL UNITS LOCATION Component Audio Alarm Module Automatic Door Lock Controller Brake Control Module Cruise Control Module Elect. Climate Control Power Module Elect. Climate Control Programmer Electronic Control Module (ECM) 5.0L Engine 5.7L Engine Electronic Spark Control Module "SERVICE ENGINE SOON" Light Driver Module Theft Deterrent Controller

Location Under right side of dash, to left of radio. Behind right kick panel, near glove box. Behind right side of instrument panel under glove box. Behind center of dash, under radio. On top of evaporator. Behind glove box. Under right side of dash, near glove box. See Fig. 4 . Under right side of dash, near glove box. See Fig. 2 . At right rear of engine. See Fig. 2 . Behind center of dash. See Fig. 4 . On right side of brake pedal support.

Twilight Sentinel Module

Under left side of dash, near light switch assembly. See Fig. 5 .

SENDING UNITS & SENSORS SENDING UNITS & SENSORS LOCATION Component A/C Temperature Sensor Coolant Temperature Sensor 5.0L Engine 5.7L Engine Elect. Level Control Height Sensor In-Car Temperature Sensor Knock Sensor 5.0L Engine 5.7L Engine Oil Press. Sending Unit/Switch 5.0L 5.7L Outside Temperature Sensor Oxygen Sensor 5.0L Engine 5.7L Engine Manifold Absolute Pressure Sensor 5.0L Engine 5.7L Engine Manifold Air Temp. Sensor Throttle Position Sensor (TPS) 5.0L Engine - View 5.0L Engine - Location 5.7L Engine Vehicle Speed Sensor

Location In A/C line, near evaporator case. At left center of intake manifold. See Fig. 6. At front center of intake manifold. See Fig. 2. On rear crossmember. In right side of dash, near radio. In lower left side of engine block. See Fig. 4. In lower right rear of engine block. See Fig. 2 . On front left top of engine. At lower left rear of engine. On radiator support, behind radiator center grille. In exhaust manifold. See Fig. 4 . In exhaust manifold. See Fig. 2 . Behind distributor. See Fig. 4 . Behind distributor. See Fig. 2 . On right rear of engine. See Fig. 2 . On carburetor. See Fig. 4 . On carburetor. See Fig. 6 . On throttle body. See Fig. 2 . On rear of transmission.

MOTORS MOTORS LOCATION Component

Location

A/C-Heater Blower Motor Elect. Level Control Compressor Fuel Filler Door Motor Idle Air Control (IAC) Motor Luggage Compartment Lid Pull-Down Motor Power Antenna Motor Power Door Lock Motor Power Seat Motor Power Window Motors Sun Roof Motor Wiper/Washer Motor Assembly

On right rear side of firewall. On front side of left front wheelwell. In left rear corner of luggage compartment. On throttle body. See Fig. 2 . Near latch, at center of luggage compartment lid. In right front fender panel, behind wheelwell. In rear of each door. Below front portion of front seats. In lower portion of each door. In center of windshield header area. On left side of firewall.

SOLENOIDS & SOLENOID VALVES SOLENOIDS & SOLENOID VALVES LOCATION Component AIR Converter Solenoid AIR Diverter Solenoid AIR Port Solenoid AIR Switching Solenoid Anti-Diesel Solenoid Canister Purge Solenoid 5.0L Engine - View 5.0L Engine - Location 5.7L Engine EGR Vacuum Solenoid 5.0L Engine - View 5.0L Engine - Location 5.7L Engine Idle Load Compensator Solenoid (5.0L) View Idle Load Compensator Solenoid (5.0L) Location Trunk Lid Release Solenoid Mixture Control Solenoid (5.0L) Rear Vacuum Break Solenoid (5.0L) View Rear Vacuum Break Solenoid (5.0L) Location

Location At center of right valve cover. See Fig. 2 . At front of right valve cover. See Fig. 4 . At center of right valve cover. See Fig. 2 . At front of right valve cover. See Fig. 4 . Above left valve cover. See Fig. 4 . On front center of engine. See Fig. 4 . On front center of engine. See Fig. 6 . At left front corner of engine compartment. See Fig. 2 . At rear of left valve cover. See Fig. 4 . At rear of left valve cover. See Fig. 6 . At rear of right valve cover. See Fig. 2 . At center of left valve cover. See Fig. 4 . At center of left valve cover. See Fig. 6 . At rear center of luggage compartment lid. On front right side of carburetor. See Fig. 6 . At rear of left valve cover. See Fig. 4 . At rear of left valve cover. See Fig. 6 .

SWITCHES SWITCHES LOCATION Component

Location

A/C Low Pressure Switch A/C Pressure Cycling Switch (5.0L) Brake Pressure Switch Coolant Temperature Switch Gear Selector Switch Trunk Lid Release Switch Trunk Lid Tamper Switch Oil Pressure Switch 5.0L Engine 5.7L Engine Parking Brake Switch Power Steering Pressure Switch Seat Belt Switch Stop Light Switch TCC Brake Switch Washer Fluid Level Switch

In A/C compressor assembly. At plenum, at right side of firewall. On vacuum booster. On top front left side of engine. On upper base of steering column. In glove box, on left side. At rear center of luggage compartment lid. At front center of intake manifold. See Fig. 6 . At lower left rear of engine. See Fig. 2 . On top of parking brake assembly. On left front of engine compartment, near pump. See Fig. 2 . Part of driver's seat belt assembly. On brake pedal support. On bracket, above brake pedal. In windshield washer reservoir.

MISCELLANEOUS MISCELLANEOUS LOCATION Component Accessory Relay Panel A/C Compressor Clutch Diode Opera Light Inverter Test Connectors ALDL Diagnostic Connector 5.0L Engine 5.7L Engine Dwell Meter (5.0L) Electronic Level Control Fuel Pump Set Timing Connector Theft Deterrent Diodes Twilight Sentinel Photocell

Location To left of steering column. In connector, at compressor. Inside each opera light.

Under center of dash, near ashtray. See Fig. 4 . Under center of dash, near ashtray. See Fig. 2 . Top left front of engine, taped to harness. See Fig. 6 . On left side of firewall, left of power brake unit. On right side of engine compartment, near shock tower. See Fig. 2 . On right side of engine compartment, near shock tower. See Fig. 2 . In diode module, above fuse block. In corner of left speaker grille. See Fig. 5 .

Vehicle Speed Sensor Buffer

Behind dash, below glove box.

COMPONENT LOCATION GRAPHICS NOTE:

Figures may show multiple component locations. Refer to appropriate table for proper figure references.

Fig. 1: Component Locations (1 Of 6)

Fig. 2: Component Locations (2 Of 6)

Fig. 3: Component Locations (3 Of 6)

Fig. 4: Component Locations (4 Of 6)

Fig. 5: Component Locations (5 Of 6)

Fig. 6: Component Locations (6 Of 6)

EMISSION CONTROL VISUAL INSPECTION PROCEDURES GENERAL INFORMATION Emission Control Visual Inspection Procedures

* PLEASE READ THIS FIRST * NOTE:

This article is provided for general information only. Not all information applies to all makes and models. For more complete information, see appropriate article (s) in the ENGINE PERFORMANCE Section.

EMISSION CONTROL LABELS NOTE:

The vehicle manufacturer's emission control label, also known as the underhood tune-up label or Vehicle's Underhood Emission Control System (VECI) label, is located in the engine compartment. Information regarding year model of vehicle, engine size, number of cylinders, emission equipment or type, engine tune-up specifications, whether vehicle was manufactured for sale in California or is a Federal vehicle, vacuum hose routing schematic, etc., can be found on this label. See Fig. 1. In addition to the VECI label, some emission control inspection and maintenance programs may require an additional label to be affixed to the vehicle in special circumstances. For example, in California, a Bureau Of Automotive Repair (BAR) engine label may be affixed to the left door post. A BAR engine label is only used when the vehicle has an engine change, approved modification or is a Specially Constructed (SPCN) or an acceptable Gray market vehicle. Check your state's emission control inspection and maintenance laws to determine if a similar label is used.

Fig. 1: Typical Emission Control Label Courtesy of GENERAL MOTORS CORP.

EMISSION CONTROL VISUAL INSPECTION

NOTE:

The following emission control visual inspection procedures should be used as a guide only. When performing a visual inspection, always follow your state's recommended inspection procedures.

A visual inspection is made to determine if any required emission control devices are missing, modified or disconnected. Missing, modified or disconnected systems must be made fully operational before a vehicle can be certified. POSITIVE CRANKCASE VENTILATION (PCV) NOTE:

PCV controls the flow of crankcase fumes into the intake manifold while preventing gases and flames from traveling in the opposite direction. PCV is either an open or closed system. See Fig. 2. Ensure PCV system is installed as required. Verify valve, required hoses, connections, flame arresters, etc., are present, routed properly and in serviceable condition.

Fig. 2: Typical Open & Closed Type PCV System THERMOSTATIC AIR CLEANER (TAC) NOTE:

The TAC supplies warm air to air intake during cold engine operation. This system is active during cold engine warm-up only. Under all other operating conditions, air cleaner function is the same as any non-thermostatic unit. Ensure required exhaust shroud, hot air duct, vacuum hoses and air cleaner components are present and installed properly. See Fig. 3. Ensure any required thermostatic vacuum switches are in place and vacuum hoses are installed and in serviceable condition. Also ensure air cleaner lid is installed right side up. Check for oversized air filter elements and for additional holes in the air cleaner housing.

Fig. 3: Typical Thermostatic Air Cleaner System FUEL EVAPORATIVE SYSTEM (EVAP) NOTE:

The EVAP system allows for proper fuel system ventilation while preventing fuel vapors from reaching the atmosphere. This means that vapors must be caught and stored while the engine is off, which is when most fuel evaporation occurs. When the engine is started, these fuel vapors can be removed from storage and burned. In most systems, storage is provided by an activated charcoal (or carbon) canister. See Fig. 4. On a few early systems, charcoal canisters are not used. Instead, fuel vapors are vented into the PCV system and stored inside the crankcase.

The main components of a fuel evaporation system are a sealed fuel tank, a liquid-vapor separator and vent lines to a vapor-storing canister filled with activated charcoal. The filler cap is normally not vented to the atmosphere, but is fitted with a valve to allow both pressure and vacuum relief. Although a few variations do exist between manufacturers, basic operation is the same for all systems. Check for presence of vapor storage canister or crankcase storage connections when required. Ensure required hoses, solenoids, etc., are present and connected properly. Check for proper type fuel tank cap. Check for any nonOEM or auxiliary fuel tanks for compliance and the required number of evaporation canisters.

Fig. 4: Typical Fuel Evaporative System CATALYTIC CONVERTERS Oxidation Catalyst (OC)

NOTE:

This type of converter is the most common. It may use pellets or monolith medium, depending upon application. See Fig. 5. Platinum and palladium (or platinum alone) are used as catalyst in this type of converter. Visually check for presence of catalytic converter(s). Check for external damage such as severe dents, removed or damaged heat shields, etc. Also check for pellets or pieces of converter in the tailpipe.

Fig. 5: Typical Oxidation Catalytic Converter (Pellet Type) Shown; Typical Three-Way Catalytic Converter Is Similar Courtesy of GENERAL MOTORS CORP. Three-Way Catalyst (TWC)

NOTE:

This type of converter is nearly identical to a conventional converter with the exception of the catalyst. See Fig. 5. The TWC converter uses rhodium, with or without platinum, as its catalyst. Rhodium helps reduce NOx emissions, as well as HC and CO. Visually check for presence of catalytic converter(s). Also check for presence of any required air supply system for the oxidizing section of the converter. Check for external damage such as severe dents, removed or damaged heat shields, etc. Check for pellets or pieces of converter in the tailpipe. Three-Way Catalyst + Oxidation Catalyst (TWC + OC)

NOTE:

This system contains a TWC converter and an OC converter in a common housing, separated by a small air space. See Fig. 6. The 2 catalysts are referred to as catalyst beds. Exhaust gases pass through the TWC first. The TWC bed performs the same function as it would as a separate device, reducing all 3 emissions. As exhaust gases leave the bed, they pass through the air space and into the second (OC) converter catalyst bed. Visually check for presence of catalytic converter(s). Check for external damage such as severe dents, removed or damaged heat shields, etc. Check for pellets or pieces of converter in the tailpipe.

Fig. 6: Typical Three-Way + Oxidation Catalytic Converter Courtesy of GENERAL MOTORS CORP. FILL PIPE RESTRICTOR (FR) NOTE:

A fuel tank fill pipe restrictor is used to prohibit the introduction of leaded fuel into the fuel tank. Unleaded gasoline pump dispensers have a smaller diameter nozzle to fit fuel tank of vehicle requiring the use of unleaded fuel (vehicles equipped with catalytic converter). Visually inspect fill pipe restrictor(s) for tampering, i.e., restrictor is oversize or the flapper is non-functional. If vehicle is equipped with an auxiliary fuel tank, ensure auxiliary fuel tank is also equipped with a fill pipe restrictor. EXHAUST GAS RECIRCULATION (EGR) SYSTEM Single Diaphragm EGR Valve

NOTE:

This type uses a single diaphragm connected to the valve by a shaft. Diaphragm is spring-loaded to keep valve closed in the absence of vacuum. As throttle valves open and engine speed increases, vacuum is applied to the EGR vacuum diaphragm, opening the EGR valve. This vacuum signal comes from a ported vacuum source. Variations in the vacuum signal control the amount of exhaust gas that is recirculated. See Fig. 7.

Verify EGR valve is present and not modified or purposely damaged. Ensure thermal vacuum switches, pressure transducers, speed switches, etc., (if applicable) are not by-passed or modified. Ensure vacuum hose(s) to EGR valve is not plugged.

Fig. 7: Typical Single Diaphragm EGR Valve Courtesy of GENERAL MOTORS CORP. Dual Diaphragm EGR Valve

NOTE:

This type uses 2 diaphragms with different effective areas and 2 vacuum sources. Although similar to the single diaphragm type, the second diaphragm is added below the upper diaphragm and is rigidly attached to the valve seat. See Fig. 8. These diaphragms form a vacuum chamber which is connected to manifold vacuum. During highway cruising when manifold vacuum is high in the center chamber, manifold vacuum tends to pull the valve closed. However, the vacuum signal applied to the top side of the upper diaphragm overcomes the downward spring force and the manifold vacuum pull, due to the diaphragm's larger piston. This regulates the amount of EGR. When manifold vacuum is low during acceleration, the higher vacuum signal opens the valve, permitting more EGR. When manifold vacuum is high during highway cruising, the valve is only partially opened, reducing the amount of EGR.

Fig. 8: Typical Dual Diaphragm EGR Valve Courtesy of GENERAL MOTORS CORP. Positive Backpressure EGR (BP/EGR) Valve

NOTE:

This type uses both engine vacuum and exhaust backpressure to control the amount of EGR. It provides more recirculation during heavy engine loads than the single diaphragm EGR valve. A small diaphragm-controlled valve inside EGR valve acts as a pressure regulator. The control valve gets an exhaust backpressure signal through the hollow valve shaft. This exhaust backpressure exerts a force on bottom

of control valve diaphragm. The diaphragm plate contains 6 bleed holes to bleed air into the vacuum chamber when backpressure valve is in open position. See Fig. 9. Verify EGR valve is present and not modified or purposely damaged. Ensure thermal vacuum switches, pressure transducers, speed switches, etc., (if applicable) are not by-passed or modified. Ensure vacuum hose(s) to EGR valve is not plugged.

Fig. 9: Typical Positive Backpressure EGR Valve Courtesy of GENERAL MOTORS CORP. Negative Backpressure EGR (BP/EGR) Valve

NOTE:

This type has the same function as the positive BP/EGR valve except valve is designed to open with a negative exhaust backpressure. The control valve spring in the transducer is placed on the bottom side of the diaphragm. See Fig. 10. When ported vacuum is applied to the main vacuum chamber, partially opening the valve, the vacuum signal from the manifold side (reduced by exhaust backpressure) is transmitted to the hollow stem of the valve. See Fig. 10. This enables the signal to act on the diaphragm, providing a specific flow. Thus, the EGR flow is a constant percentage of engine airflow. Verify EGR valve is present and not modified or purposely damaged. Ensure thermal vacuum switches,

pressure transducers, speed switches, etc., (if applicable) are not by-passed or modified. Ensure vacuum hose(s) to EGR valve is not plugged.

Fig. 10: Typical Negative Backpressure EGR Valve Courtesy of GENERAL MOTORS CORP. Digital EGR Valve

NOTE:

This article is provided for general information only. Not all information applies

to all makes and models. For more complete information, see appropriate article (s) in the ENGINE PERFORMANCE Section. The digital EGR valve operates independently of engine manifold vacuum. This valve controls EGR flow through 3 orifices. These 3 orifices are opened and closed by electric solenoids. The solenoids are, in turn, controlled by the Electronic Control Module (ECM). When a solenoid is energized, the armature with attached shaft and swivel pintle is lifted, opening the orifice. See Fig. 11. The ECM uses inputs from the Coolant Temperature Sensor (CTS), Throttle Position Sensor (TPS) and Mass Airflow (MAF) sensors to control the EGR orifices to make 7 different combinations for precise EGR flow control. At idle, the EGR valve allows a very small amount of exhaust gas to enter the intake manifold. This EGR valve normally operates above idle speed during warm engine operation. Verify EGR valve is present and not modified or purposely damaged. Ensure thermal vacuum switches, pressure transducers, speed switches, etc., (if applicable) are not by-passed or modified. Ensure vacuum hose(s) to EGR valve is not plugged. Ensure electrical connector to EGR valve is not disconnected.

Fig. 11: Typical Digital EGR Valve Courtesy of GENERAL MOTORS CORP. Integrated Electronic EGR Valve

NOTE:

This type functions similar to a ported EGR valve with a remote vacuum regulator. The internal solenoid is normally open, which causes the vacuum signal to be vented off to the atmosphere when EGR is not controlled by the Electronic Control Module (ECM). The solenoid valve opens and closes the vacuum signal, controlling the amount of vacuum applied to the diaphragm. See Fig. 12. The electronic EGR valve contains a voltage regulator, which converts ECM signal and regulates current to the solenoid. The ECM controls EGR flow with a pulse width modulated signal based on airflow, TPS and RPM. This system also contains a pintle position sensor, which works similarly to a TPS sensor. As EGR flow is increased, the sensor output increases. Verify EGR valve is present and not modified or purposely damaged. Ensure thermal vacuum switches, pressure transducers, speed switches, etc., (if applicable) are not by-passed or modified. Ensure electrical connector to EGR valve is not disconnected.

Fig. 12: Cutaway View Of Typical Integrated Electronic EGR Valve Courtesy of GENERAL MOTORS CORP. SPARK CONTROLS (SPK) NOTE:

Spark control systems are designed to ensure the air/fuel mixture is ignited at the best possible moment to provide optimum efficiency and power and cleaner emissions.

Ensure vacuum hoses to the distributor, carburetor, spark delay valves, thermal vacuum switches, etc., are in place and routed properly. On Computerized Engine Controls (CEC), check for presence of required sensors (O2, MAP, CTS, TPS, etc.). Ensure they have not been tampered with or modified. Check for visible modification or replacement of the feedback carburetor, fuel injection unit or injector(s) with a non-feedback carburetor or fuel injection system. Check for modified emission-related components unacceptable for use on pollution-controlled vehicles. AIR INJECTION SYSTEM (AIS) Air Pump Injection System (AP)

NOTE:

The air pump is a belt-driven vane type pump, mounted to engine in combination with other accessories. The air pump itself consists of the pump housing, an inner air cavity, a rotor and a vane assembly. As the vanes turn in the housing, filtered air is drawn in through the intake port and pushed out through the exhaust port. See Fig. 13. Check for missing or disconnected belt, check valve(s), diverter valve(s), air distribution manifolds, etc. Check air injection system for proper hose routing.

Fig. 13: Typical Air Pump Injection System Courtesy of GENERAL MOTORS CORP.

Pulsed Secondary Air Injection (PAIR) System

NOTE:

PAIR eliminates the need for an air pump and most of the associated hardware. Most systems consists of air delivery pipe(s), pulse valve(s) and check valve(s). The check valve prevents exhaust gases from entering the air injection system. See Fig. 14. Ensure required check valve(s), diverter valve(s), air distribution manifolds, etc., are present. Check air injection system for proper hose routing.

Fig. 14: Typical Pulsed Secondary Air Injection System Courtesy of GENERAL MOTORS CORP. OXYGEN SENSOR (O2) NOTE:

The O2 sensor is mounted in the exhaust system where it monitors oxygen content of exhaust gases. Some

vehicles may use 2 O2 sensors. The O2 sensor produces a voltage signal which is proportional to exhaust gas oxygen concentration (0-3%) compared to outside oxygen (20-21%). This voltage signal is low (about .1 volt) when a lean mixture is present and high (1.0 volt) when a rich mixture is present. As ECM compensates for a lean or rich condition, this voltage signal constantly fluctuates between high and low, crossing a reference voltage supplied by the ECM on the O2 signal line. This is referred to as cross counts. A problem in the O2 sensor circuit should set a related trouble code. COMPUTERIZED ENGINE CONTROLS (CEC) NOTE:

The CEC system monitors and controls a variety of engine/vehicle functions. The CEC system is primarily an emission control system designed to maintain a 14.7:1 air/fuel ratio under most operating conditions. When the ideal air/fuel ratio is maintained, the catalytic converter can control oxides of nitrogen (NOx), hydrocarbon (HC) and carbon monoxide (CO) emissions. The CEC system consists of the following sub-systems: Electronic Control Module (ECM), input devices (sensors and switches) and output signals. EARLY FUEL EVAPORATION (EFE) NOTE:

The EFE valve is actuated by either a vacuum actuator or a bimetal spring (heat-riser type). The EFE valve is closed when engine is cold. The closed valve restricts exhaust gas flow from the exhaust manifold. This forces part of the exhaust gas to flow up through a passage below the carburetor. As the exhaust gas quickly warms the intake mixture, distribution is improved. This results in better cold engine driveability, shorter choke periods and lower emissions. Ensure EFE valve in exhaust manifold is not frozen or rusted in a fixed position. On vacuum-actuated EFE system, check EFE thermal vacuum valve and check valve(s). Also check for proper vacuum hose routing. See Fig. 15.

Fig. 15: Typical Vacuum-Actuated EFE System Courtesy of GENERAL MOTORS CORP. EMISSION MAINTENANCE REMINDER LIGHT (EMR) (IF EQUIPPED) NOTE:

If equipped, the EMR light (some models may use a reminder flag) reminds vehicle operator that an emission system maintenance is required. This indicator is activated after a predetermined time/mileage. When performing a smog check inspection, ensure EMR indicator is not activated. On models using an EMR light, light should glow when ignition switch is turned to ON position and should turn off when engine is running. If an EMR flag is present or an EMR light stays on with engine running, fail vehicle and service or replace

applicable emission-related components. To reset an EMR indicator, refer to appropriate MAINTENANCE REMINDER LIGHTS in the MAINTENANCE section. MALFUNCTION INDICATOR LIGHT (MIL) NOTE:

The Malfunction Indicator Light (MIL) is used to alert vehicle operator that the computerized engine control system has detected a malfunction (when it stays on all the time with engine running). On some models, the MIL may also be used to display trouble codes. As a bulb and system check, malfunction indicator light will glow when ignition switch is turned to ON position and engine is not running. When engine is started, light should go out.

D - ADJUSTMENTS - V8 ENGINE PERFORMANCE General Motors On-Vehicle Adjustments

INTRODUCTION NOTE:

Introduction information not available.

ENGINE COMPRESSION Check engine compression pressure with engine at normal operating temperature and all spark plugs removed. Ensure throttle plates are wide open and battery is fully charged. On fuel injected engines, remove fuel pump or ECM fuse. On engines equipped with Direct Ignition System (DIS), disconnect battery connector from coil. On engines equipped with Integrated Direct Ignition (IDI) system, remove cover and 11-pin IDI harness connector. On all other engines, disconnect battery terminal from HEI distributor. The lowest cylinder reading should not be less than 70 percent of the highest cylinder reading. No cylinder reading should be less than 100 psi (7 kg/cm2 . COMPRESSION SPECIFICATIONS Application 4.5L (VIN 3) 5.0L (VIN E & F) 5.0L (VIN Y) 5.7L (VIN 7 & 8) Min. Compression Pressure Max. Variation Between Cylinders

Compression Ratio 9.5:1 9.3:1 8.0:1 9.3:1 100 psi (7 kg/cm2 Less than 30%

VALVE CLEARANCE NOTE:

All models use hydraulic lifters. No adjustments are required.

IGNITION TIMING NOTE:

Procedures for timing adjustment are for engines equipped with HEI-EST distributors only. All other models are equipped with either C(3)I, DIS or IDI ignition system. Timing on these systems is not adjustable

NOTE:

Some engines are equipped with a socket for a magnetic probe timing meter, located 9.5 degrees ATDC. DO NOT use this location for timing with a conventional timing light.

4.5L (VIN 3) 1. Place transmission in Park. Start engine and warm to normal operating temperature. Turn diagnostic display, A/C and all accessories off. Connect timing light to No. 1 spark plug wire. Connect tachometer. 2. Ground ALDL test connector, located under driver's side dash. "Set Timing" message should appear on the Driver Information Center (DIC). This indicates ECM is in set timing mode. 3. Adjust ignition timing to specification. See IGNITION TIMING SPECIFICATIONS table. Tighten distributor housing and recheck timing. Remove jumper from ALDL test connector. 5.0L (VIN Y) 1. Place transmission in Park. Start and warm engine to normal operating temperature. Turn A/C and all accessories off. Connect tachometer to engine. Connect timing light to No. 1 spark plug wire. 2. With engine running, ground ALDL test connector, located under driver's side dash. Loosen distributor hold-down bolt. Set timing to specification. See IGNITION TIMING SPECIFICATIONS table. Tighten distributor housing and recheck timing. With engine still running, disconnect jumper from ALDL test connector. If jumper is removed before engine is shut off, no trouble code will be stored). 5.0L (VIN E & F) & 5.7L (VIN 7 & 8) 1. Place transmission in Park. Start and warm engine to normal operating temperature. Turn A/C and all accessories off. Ensure "SERVICE ENGINE SOON" light is off. 2. Put EST into by-pass mode by unplugging "Set Timing" connector. Connector is a single wire in the wiring harness near distributor. DO NOT unplug 4-wire connector at distributor. 3. Connect timing light to No. 1 spark wire. Loosen distributor hold-down bolt. Set timing to specification. See IGNITION TIMING SPECIFICATIONS table. Tighten distributor and recheck timing. Reconnect "Set Timing" connector. Clear ECM trouble code by momentarily disconnecting ECM power source. IGNITION TIMING SPECIFICATIONS Application 4.5L (VIN 3) 5.0L (VIN E) 5.0L (VIN F) 5.0L (VIN Y)

Degrees BTDC @ RPM (1) 10 (2) 6 @ 400

6 @ 700

5.7L (VIN 7)

(3) 20 @ 1100 (2) 6 @ 600

5.7L (VIN 8) A/T

(2) 6 @ 400

M/T (1) Set timing below 800 RPM in Park. (2) A/T in Drive. (3) A/T in Park.

(4) 6 @ 450

(4) M/T in Neutral.

IDLE SPEED & MIXTURE NOTE:

Idle mixture is controlled by the Electronic Control Module (ECM). Idle mixture adjustment is not possible on fuel injected models. On carbureted models, mixture should be adjusted only if vehicle fails emission testing or carburetor has been disassembled.

COLD (FAST) IDLE RPM (CARBURETED) 5.0L (VIN Y)

1. Engine must be at normal operating temperature with choke fully open. Air cleaner must be installed and A/C off. 2. Disconnect and plug vacuum hoses at EGR valve. Place cam follower on low step of fast idle cam. Using a hand-held vacuum pump, apply vacuum to Idle Load Compensator (ILC) to retract ILC plunger. Turn fast idle screw to set correct fast idle RPM. Adjust fast idle speed within 15 seconds after idle speed reaches 700 RPM. FAST IDLE SPEED SPECIFICATIONS Application 5.0L (VIN Y)

RPM (In Drive) 550

V8 IDLE SPEED (CARBURETED) NOTE:

Engine must be running at normal operating temperature and in "Closed Loop" during idle speed adjustments.

IDLE SPEED WITH IDLE LOAD COMPENSATOR (ILC) 1. Place transmission in Park, set parking brake and block wheels. Remove air cleaner and plug hose to Thermal Vacuum Valve (TVV). Disconnect and plug hoses to EGR, canister purge port, and ILC. 2. Back out throttle stop screw on carburetor 3 turns. With engine running, A/C off and transmission selector in Drive and ILC plunger in the fully extended position (no vacuum applied). Adjust plunger to obtain specified RPM. Hold jam nut on plunger to avoid damaging ILC guide tabs. See IDLE LOAD COMPENSATOR ADJUSTMENT table. 3. Measure distance from jam nut to tip of plunger. Measurement must not exceed 1" (25.4 mm). If measurement exceeds 1" (25.4 mm), check for cause of a low idle condition. 4. Reconnect engine vacuum to ILC and observe idle speed. Idle speed should match retracted RPM. See IDLE LOAD COMPENSATOR ADJUSTMENT table. If idle speed is correct, no further adjustment of ILC is necessary. If idle speed is not as specified, proceed to next step. 5. Turn engine off and remove ILC. Remove rubber cap from center outlet tube and then remove metal plug (if equipped) from tube.

NOTE:

It is not necessary to remove idle load compensator if Allen wrench is modified to clear obstructions.

6. Insert .090" (3/32") hex key wrench through center outlet to engage adjusting screw inside tube. One complete turn clockwise of screw will increase idle speed about 75-100 RPM. One complete turn counterclockwise will decrease idle speed about 75-100 RPM. 7. Recheck idle speed with transmission in Drive and closed loop mode. Turn engine off and disconnect power feed to ECM for 10 seconds. This allows ECM to reset TPS value. IDLE LOAD COMPENSATOR ADJUSTMENT (RPM) Application Plunger Retracted 5.0L (VIN Y) 425-475

Plunger Extended 650-750

V8 IDLE SPEED (FUEL INJECTED) MINIMUM IDLE (DEVILLE & FLEETWOOD) 1. Warm engine to normal operating temperature. Turn A/C and all accessories off. Enter diagnostics by placing the cruise control ON/OFF switch in the ON position and pushing the "OFF" and "WARMER" buttons on the climate control panel. Check for any trouble codes. See appropriate SELF-DIAGNOSTICS article in this section for trouble code definitions and diagnostics. 2. Check and adjust engine timing. Cooling fan must not be running during adjustments. Place steering wheel in straight ahead position and transmission selector in Park. Disable the alternator by grounding the Green "test" connector, near the alternator. The "NO CHARGE" light should come on. 3. Select ECM "ISC MOTOR" override E.5.3 by pressing the "HI" button. When display shows E.9.5, press "ECON" and "WARMER" buttons simultaneously. Retract ISC by pressing the "COOLER" button on climate control panel. Wait a minimum of 20 seconds for ISC plunger to retract. 4. ISC plunger should now be retracted. If plunger still contacts throttle lever, turn plunger in, so it is not touching. With ISC plunger fully retracted and not touching throttle lever, check minimum idle speed RPM. See MINIMUM IDLE SPEED table. If idle speed is incorrect, adjust idle speed stop screw. Proceed to THROTTLE POSITION SENSOR (TPS) in this article to check and adjust TPS if necessary. Once TPS is adjusted, perform MAXIMUM ISC EXTENSION (DEVILLE & FLEETWOOD) in this article. MINIMUM IDLE (ELDORADO & SEVILLE) 1. Warm engine to normal operating temperature. Turn A/C and all accessories off. Enter diagnostics by pushing the "OFF" and "WARMER" buttons on the climate control panel. Check for any trouble codes. See appropriate SELF-DIAGNOSTICS article in this section for trouble code definitions and diagnostics. 2. Check and adjust engine timing. Cooling fan must not be running during adjustments. Place steering wheel in straight ahead position and transmission selector in Park. Select ECM "ISC MOTOR" override E.S.3. Retract ISC by pressing the "COOLER" button on climate control panel. Wait a minimum of 20 seconds for ISC plunger to retract. 3. ISC plunger should now be retracted. If plunger still contacts throttle lever, turn plunger in, so it is not touching. With ISC plunger fully retracted and not touching throttle lever, check minimum idle speed

RPM. See MINIMUM IDLE SPEED table. If idle speed is incorrect, adjust idle speed stop screw. Proceed to THROTTLE POSITION SENSOR (TPS) in this article to check and adjust TPS if necessary. Once TPS is adjusted, perform MAXIMUM ISC EXTENSION (ELDORADO & SEVILLE) in this article. MINIMUM IDLE SPEED Application Deville, Eldorado, Fleetwood & Seville

Idle Speed (RPM) 500-550

MAXIMUM ISC EXTENSION (DEVILLE & FLEETWOOD) 1. Prior to adjusting maximum ISC extension, check minimum idle and TPS adjustment. See MINIMUM IDLE (DEVILLE & FLEETWOOD) and THROTTLE POSITION SENSOR (TPS) in this article. With igniton on and engine off, select ECM "ISC MOTOR" override E.5.3. Fully extend the ISC motor by pressing "WARMER" button on the Electronic Control Center (ECC) on dash. Fuel data center should display E.5.3 and 99 alternately, indicating override function has started. 2. ISC should extend to maximum extend position. With the ISC at maximum extended position, the TPS voltage should be between 1.15-1.20 volts. If TPS is not within this range, adjust ISC plunger. Adjust ISC plunger, clockwise or counterclockwise, until TPS parameter reads 1.18 volts. 3. Recheck maximum extend setting. Press "COOLER" button to retract ISC plunger. Wait 5 seconds. Press "WARMER" button and check TPS voltage. Readjust ISC plunger is necessary. MAXIMUM ISC EXTENSION (ELDORADO & SEVILLE) 1. Prior to adjusting maximum ISC extension, check minimum idle and TPS adjustment. See MINIMUM IDLE (ELDORADO & SEVILLE) and THROTTLE POSITION SENSOR (TPS) in this article. With igniton on and engine off, select ECM "ISC MOTOR" override E.S.3. Fully extend the ISC motor by pressing "WARMER" button on the Electronic Control Center (ECC) on dash. Fuel data center should display E.S.3. and 99 alternately, indicating override function has started. 2. ISC should extend to maximum extend position. With the ISC at maximum extended position, ensure 13.0-13.8 degrees is displayed on the Driver Information Center. If TPS is not within this range, adjust ISC plunger. Adjust ISC plunger, clockwise or counterclockwise, until TPS parameter reads 13.4 degrees on Driver Information Center. 3. Recheck maximum extend setting. Press "COOLER" button to retract ISC plunger. Wait 5 seconds. Press "WARMER" button and check TPS voltage. Readjust ISC plunger is necessary. NOTE:

On 5.0L (VIN E & F) and 5.7L (VIN 7 & 8) engines, idle speed is controlled by ECM and will normally vary. Idle speed adjustment is not normally required. The following adjustment is for minimum idle speed only.

5.0L (VIN E & F) & 5.7L (VIN 7 & 8) 1. Pierce idle stop screw plug with an awl and remove it. With Idle Air Control (IAC) motor connected, ground ALDL test connector, under driver's side dash. Disconnect distributor "Set Timing" connector, located by distributor. 2. Turn ignition on, but DO NOT start engine. Wait 45 seconds. With ignition on, disconnect IAC

connector. Remove jumper from ALDL test connector and start engine. Allow engine to go into "closed loop" mode. 3. Adjust idle screw to specifications. See IDLE SPEED table. Turn ignition off and reconnect IAC motor. Check TPS adjustment. See THROTTLE POSITION SENSOR (TPS) in this article. Start engine and check for proper idle operation. IDLE SPEED Application 5.0L (VIN E) "B" Body 5.0L (VIN E & F) "F" Body 5.7L (VIN 7 & 8) "D", "F" & "Y" Bodies

RPM 450-500 400-450 400-450

IDLE MIXTURE NOTE:

Idle mixture adjustment is not required on fuel injected models. On carbureted models, mixture should be adjusted only if vehicle fails emission testing or carburetor has been disassembled.

5.0L (VIN Y) 1. Mixture control solenoid must be checked before attempting mixture adjustment. Stop engine. Remove air cleaner and gasket. Insert Float Gauge (J-34935-1 or BT-8420-A) in "D" shaped hole in air horn (next to idle air bleed valve cover). Gauge checks float level externally. It may be necessary to grind material off gauge to allow it to enter hole. 2. With gauge installed, observe that mark on gauge lines up with top of air horn casting. Setting should be within +/- 2/32" of specified float level setting. See FLOAT LEVEL SPECIFICATIONS table. If float level is not as specified, remove air horn and adjust float level. If float level is correct, go to next step. 3. Set parking brake and block drive wheels. Disconnect and plug canister purge hose. Connect tachometer to engine. Check ignition timing and adjust, if necessary. 4. Connect dwell meter positive lead to Green wire from mixture control solenoid in carburetor and negative lead to ground. Set dwell meter to 6-cylinder scale. Warm engine to normal operating temperature. A varying dwell should be noted on dwell meter. NOTE:

Engine must be at operating temperature to ensure coolant temperature sensor and oxygen sensor are functional.

5. With engine idling in Drive or Neutral on manual transmission. Observe dwell reading. If dwell is moving within a range of 10-50 degrees, no adjustment is necessary. If dwell is fixed at one point or outside of this range, see appropriate G - TESTS W/ CODES or TESTS W/O CODES article in this section. If adjustments are necessary, proceed to next step. 6. Stop engine. Cover carburetor air intake and vents with tape. Drill rivet heads on idle air bleed plug (above primary bores). Remove plug and blow out metal chips and rivet pieces. 7. Install Gauge (J-33815-2 or BT-8253-B) in "D" shaped hole on throttle side of air horn. Position gauge so upper end is over open cavity next to idle air bleed valve.

8. Lightly hold gauge down to seat solenoid plunger against its stop. Adjust idle air bleed valve so gauge will pivot over and just touch top of valve. Remove gauge. 9. Start engine and allow it to reach normal operating temperature. Ensure canister purge hose is disconnected and plugged. While idling in Drive or Neutral on manual transmission, adjust idle air bleed valve with screwdriver until dwell varies within 25-35 degree range. Try to get as close to 30 degrees as possible. NOTE:

Perform Step 9) carefully. Idle air bleed valve is very sensitive in controlling air/fuel ratios. Idle air bleed valve should be turned in 1/8 turn increments only.

10. If dwell reading does not vary and is not within 25-35 degree range after this adjustment, it will be necessary to remove plugs covering idle mixture screws. Remove carburetor for access to air mixture screws. Using Remover/Installer (J-29030-B or BT-7610-B), remove both idle mixture screws and springs. 11. Inspect needles for damage. Inspect needle openings for damage or foreign material. Reinstall mixture screws and springs in throttle body. Using remover/installer, turn both mixture screws clockwise until lightly seated and then back out evenly. 12. Reinstall carburetor on engine. Start and warm engine to normal operating temperature. Check dwell reading. If unable to set dwell to 25-35 degrees, and dwell is below 25 degrees, turn both mixture screws out one turn. If dwell is above 35 degrees, turn both mixture screws in one turn. 13. Readjust idle air bleed valve to obtain dwell limits. Seal idle mixture screws with silicone sealer or RTV. Mixture control adjustment is complete if dwell at 3000 RPM varies between 10-50 degrees and there is at least a 300-RPM drop from full rich to full lean. 14. Idle mixture adjustment is complete if closed loop dwell at idle varies between 10-50 degrees and engine idle is not rough. FLOAT LEVEL SPECIFICATIONS Carburetor No. 17086008 17086009 17088115

Setting 11/32" 14/32" 11/32"

THROTTLE POSITION SENSOR (TPS) NOTE:

All testing procedures are made with engine at normal operating temperature. TPS adjustment screw is factory-sealed. No adjustment should be performed unless indicated by System Performance Check.

THROTTLE POSITION SENSOR (TPS) - 5.0L (CARBURETED) 1. Using a 5/64" drill bit, drill a hole 1/16 - 1/8" (1.6-3.2 mm) deep in plug covering TPS adjustment screw. DO NOT damage screw head. Start a 1/2" long, No. 8 screw in drilled hole, seating only enough for good thread engagement. Using a screwdriver, pry against screw to remove plug. Discard plug.

2. Apply vacuum to Idle Load Compensator (ILC) to retract ILC plunger. Using TPS Wrench (J-28696 or BT-7967-A), adjust TPS screw to obtain .31-.51 volts on "Scan" tester. If adjustment value cannot be obtained, replace TPS. 3. Install new plug to seal setting after adjustment. Clear ECM memory if diagnostic trouble code was set during adjustment. THROTTLE POSITION SENSOR (TPS) - 4.5L (DEVILLE & FLEETWOOD) 1. Install TPS Jumper Harness (J-38490) and digital volt-ohmmeter (DVOM) between TPS and TPS wiring harness connector. Warm engine to normal operating temperature. Turn ignition on, engine off. Enter diagnostics on climate control panel and select ECM override E.5.3. "ISC MOTOR". Press "COOLER" button to retract ISC motor to minimum idle setting. Adjust if necessary. See MINIMUM IDLE (DEVILLE & FLEETWOOD) in this article. 2. Loosen TPS screws enough to permit sensor rotation. Open throttle and allow throttle lever to snap shut against the minimum idle screw. Adjust TPS so voltage reading is between .48-.53 volt. Tighten TPS mounting screws and recheck voltage. 3. With ignition on, engine off, select ISC motor override E.5.3. Press the "WARMER" button on climate control panel. The fuel data center should display E.5.3. and 99 alternately, indicating that the override function has started. The ISC motor will extend to the maximum extended position. Check and adjust maximum extension as necessary. See MAXIMUM ISC EXTENSION (DEVILLE & FLEETWOOD) under IDLE SPEED & MIXTURE in this article. 4. Recheck ISC plunger maximum extended setting. Press the "COOLER" button to retract ISC plunger. Wait 5 seconds. Press "WARMER" button and read TPS voltage. Readjust ISC motor plunger if readings are not within range. 5. While still in diagnostic mode, turn ignition off. Allow approximately 20 seconds ECM to retract ISC motor relearn the TPS setting. Re-enter diagnostics and repeat this step. It takes 2 cycles for a successful TPS learn to occur. THROTTLE POSITION SENSOR (TPS) - 4.5L (ELDORADO & SEVILLE) 1)Ensure vehicle is at normal operating temperature. Turn ignition on, engine off. Enter diagnostics on climate control panel and select ECM override E.S.3. "ISC MOTOR". Press "COOLER" button to retract ISC motor to minimum idle setting. Adjust if necessary. See MINIMUM IDLE (ELDORADO & SEVILLE) in this article. Enter ECM data parameter ED01 "TPS". 2) Loosen TPS screws enough to permit sensor rotation. Open throttle and allow throttle lever to snap shut against the minimum idle screw. Adjust TPS so voltage reading of -.5 to +.5 degrees is displayed on the Driver Information Center). Tighten TPS mounting screws and recheck voltage. 3) With ignition on, engine off, select ISC motor override E.S.3. Press the "WARMER" button on climate control panel. The fuel data center should display E.S.3. and 99 alternately, indicating that the override function has started. The ISC motor will extend to the maximum extended position. Check and adjust maximum extension as necessary. See MAXIMUM ISC EXTENSION (ELDORADO & SEVILLE) under IDLE SPEED in this article. 4) Recheck ISC plunger maximum extended setting. Press the "COOLER" button to retract ISC plunger. Wait 5

seconds. Press "WARMER" button and read TPS voltage. Readjust ISC motor plunger if readings are not within range. 5) While still in diagnostic mode, turn ignition off. Allow approximately 20 seconds ECM to retract ISC motor relearn the TPS setting. Re-enter diagnostics and repeat this step. It takes 2 cycles for a successful TPS learn to occur. THROTTLE POSITION SENSOR (TPS) - 5.0L & 5.7L (VIN E, F, 7 & 8) 1. Install 3 jumper wires between TPS and harness connector or use "Scan" tester. With ignition on and engine off, connect digital volt-ohmmeter (DVOM) to terminals "A" and "B". Loosen TPS adjusting screws. 2. Adjust TPS to obtain .5 volt with throttle valves closed and 5.0 volts at wide open throttle. Turn ignition off. Remove jumper wires and connect wiring harness to TPS. TPS ADJUSTMENT Application 4.5L (VIN 3) 5.0L (VIN E & F) 5.0L (VIN Y) 5.7L (VIN 7) 5.7L (VIN 8) (1) At idle RPM. (2) Not adjustable.

Voltage (1) .48-.53 (2)

.40-4.9 .50-5.0 (2)

C - SPECIFICATIONS - V8 ENGINE PERFORMANCE Service & Adjustment Specifications

INTRODUCTION Use this article to quickly find specifications related to servicing and on-vehicle adjustments. This article may be used for quick reference when you are familiar with proper adjustment procedures and only need a specification.

BATTERY SPECIFICATIONS BATTERY SPECIFICATIONS Application 4.5L (VIN 3) 5.0L (VIN E & F) Standard Heavy Duty 5.0L (VIN Y) 5.7L (VIN 7) Standard Heavy Duty 5.7L (VIN 8)

Cold Crank Amps @ 0°F (-18°C) 770

Reserve Capacity Minutes 115

525 570 730

75 90 115

630 730 525

90 115 75

FLUID CAPACITIES - V8 FLUID CAPACITIES Application Crankcase (2) 4.5L (VIN 3) 5.0L (VIN E & F) 5.0L (VIN Y) 5.7L (VIN 7 & 8) Cooling System (Includes Heater) 4.5L (VIN 3) 5.0L (VIN E & F) 5.0L (VIN Y) 5.7L (VIN 7 & 8) Automatic Transaxle (Dexron-II) (3) 4.5L (VIN 3) 5.0L (VIN E & F)

(1) Quantity Qts. (L)

5.0 (4.7) 4.0 (3.8) 4.5 (4.3) 4.5 (4.3) 13.2 (12.5) 18.0 (17.0) 15.2 (14.4) 16.5 (15.6) 6.0 (5.7) 4.9 (4.6)

5.0L (VIN Y) & 5.7L (VIN 7) 200-4R 4L60 Automatic Transmission (Dexron-II) (3) 5.7L (VIN 7) 200-4R 4L60 Manual Transmission 5.0L (VIN E & F) 5.7L (VIN 8)

3.5 (3.3) 4.9 (4.6)

3.5 (3.3) 4.9 (4.6) (4) 3.0 (2.8) (5) 2.2 (2.1)

(1) Fluid capacities listed are approximate. Always fill to FULL mark. (2) Does not include oil filter capacity. (3) Drain and refill capacity only. Does not include torque converter. (4) Dexron II (5) SAE 5W-30

SERVICE INTERVALS & SPECIFICATIONS REPLACEMENT INTERVALS Component Oil & Filter

Interval (Miles) (1) 7500

Air Filter Cam Timing Belt

30,000

Coolant Fuel Filter

30,000

Spark Plugs (1) On turbo engines, replace every 5000 miles.

30,000

(2) (2)

(2) No scheduled replacement interval given by manufacturer. Check and replace as necessary.

SERPENTINE BELT ADJUSTMENT SPECIFICATIONS BELT ADJUSTMENT Application Serpentine Belt 5.0L (VIN E & F) 5.7L (VIN 7 & 8) (1) Tension in Lbs. (kg) Using Belt Tension Gauge.

(1) Tension

99-121 (45.0-55.0) 99-121 (45.0-55.0)

V-BELT ADJUSTMENT SPECIFICATIONS V-BELT ADJUSTMENT SPECIFICATIONS (1) (2)(3) Tension Application 4.5L (VIN 3) 100 (45.0) 5.0L (VIN Y) A/C Compressor 168 (76.3) Air Injection Pump 146 (66.3) Alternator Clogged Belt 146 (66.3) Plain Belt 157 (71.3) Power Steering 169 (77.0) (1) Engines equipped with serpentine belts have automatic tensioner. If tension reading is not as specified, check belt if within operating length or check tensioner's operating range. Replace as necessary. (2) Tensions are for new belts only. (3) Tension in Lbs. (kg) Using Belt Tension Gauge.

ENGINE COMPRESSION SPECIFICATIONS COMPRESSION RATIO SPECIFICATIONS Application 4.5L (VIN 3) 5.0L (VIN E & F) 5.0L (VIN Y) 5.7L (VIN 7 & 8)

Specification 9.5:1 9.3:1 8.0:1 9.3:1

VALVE CLEARANCE NOTE:

All models are equipped with hydraulic lifters. No adjustments are required.

V8 VALVE ARRANGEMENT 4.5L (VIN 3) V8 Valve Arrangement

Both Banks - E-I-I-E-E-I-I-E (Front-to-rear). 5.0L (VIN Y) V8 Valve Arrangement

Both Banks - I-E-I-E-E-I-E-I (Front-to-rear). 5.0L & 5.7L (VIN E, F, 7 & 8) V8 Valve Arrangement

Both Banks - E-I-I-E-E-I-I-E (Front-to-rear).

IGNITION SYSTEM SPECIFICATIONS IGNITION COIL IGNITION COIL RESISTANCE Application All Models W/ HEI-EST

Value (1)

(1) See BASIC IGNITION SYSTEM CHECKS in the BASIC TESTING article.

PICK-UP COIL PICK-UP COIL RESISTANCE Application All Models W/ HEI-EST

Ohms 500-1500

HIGH TENSION WIRE RESISTANCE HIGH TENSION WIRE RESISTANCE Application (1) All Models (1) Not applicable to direct ignition systems.

Ohms 30,000 Maximum

SPARK PLUG SPECIFICATIONS SPARK PLUG TYPE Application 4.5L (VIN 3) 5.0L (VIN E & F) 5.0L (VIN Y) 5.7L (VIN 7 & 8) SPARK PLUG GAP & TORQUE SPECIFICATIONS Application Gap - In. (mm) 4.5L (VIN 3) .060 (1.52) 5.0L (VIN E & F) .035 (0.89) 5.0L (VIN Y) .060 (1.52) 5.7L (VIN 7 & 8) .035 (0.89) 4.5L (VIN 3) FIRING ORDER & TIMING MARKS

AC R44LTS6 R45TS FR3LS6 R45TS

Torque - Ft. Lbs. (N.m) 11 (15) 22 (30) 25 (34) 22 (30)

Fig. 1: 4.5L (VIN 3) Firing Order & Timing Marks 5.0L (VIN Y) FIRING ORDER & TIMING MARKS

Fig. 2: 5.0L (VIN Y) Firing Order & Timing Marks 5.0L (VIN E & F) & 5.7L (VIN 7 & 8) FIRING ORDER & TIMING MARKS

Fig. 3: 5.0L (VIN E & F) & 5.7L (VIN 7 & 8) Firing Order & Timing Marks

IGNITION TIMING NOTE:

For timing procedures, see the appropriate D - "Engine Type" ADJUSTMENTS article in this section.

IGNITION TIMING (Degrees BTDC @ RPM) Application Man. Trans. 4.5L (VIN 3) N/A

Auto. Trans. (1) 10

5.0L (VIN E)

N/A

(2) 6 @ 400

5.0L (VIN F)

6 @ 700

(2) 6 @ 600

5.0L (VIN Y) 5.7L (VIN 7)

N/A N/A

(2) 6 @ 600

5.7L (VIN 8)

6 @ 450

(2) 6 @ 400

(1) Set timing below 800 RPM in Park. (2) With Auto. Trans. in Drive.

FUEL SYSTEM

20 @ 1100

FUEL PUMP FUEL PUMP PERFORMANCE psi (kg/cm2 40-50 (2.81-3.52) 9-13 (0.63-0.91) 41-47 (2.88-3.30) 6-7 (0.42-0.49) 9-13 (0.63-0.91) 41-47 (2.88-3.30)

Application 4.5L (VIN 3) 5.0L (VIN E) 5.0L (VIN F) 5.0L (VIN Y) 5.7L (VIN 7) 5.7L (VIN 8) INJECTOR RESISTANCE INJECTOR RESISTANCE SPECIFICATIONS Application 4.5L (VIN 3) 5.0L (VIN E) 5.0L (VIN F) 5.7L (VIN 7) 5.7L (VIN 8) (1) Resistance specification is at 140°F (60°C).

(1) Resistance (Ohms)

16.2 1.2 10.0 1.2 16.0

IDLE SPEED & MIXTURE NOTE:

Idle mixture is controlled by the Electronic Control Module (ECM). Idle mixture adjustment is not required or possible on fuel injected models. On carbureted models, mixture should be adjusted only if vehicle fails emission testing or carburetor has been disassembled.

FAST IDLE SPEED (CARBURETED) FAST IDLE SPECIFICATIONS Application 5.0L (VIN Y)

RPM (1) 525-575

(1) A/T in Drive and on low step of fast idle cam.

THROTTLE POSITION SENSOR (TPS) NOTE:

On 4-cylinder models, TPS is not adjustable. For further testing, refer to SELFDIAGNOSTICS article in this section.

TPS ADJUSTMENT VOLTAGE

Application 4.5L (VIN 3) 5.0L (VIN E & F) 5.0L (VIN Y) 5.7L (VIN 7) 5.7L (VIN 8) (1) At idle RPM. (2) Not adjustable.

(1) Voltage

.48-.53 (2)

.40 .50 (2)

F - BASIC TESTING ENGINE PERFORMANCE General Motors Basic Diagnostic Procedures

INTRODUCTION NOTE:

This article contains general information on Basic Diagnostic Procedures on GM vehicles. The information in this article should not be used for a specific vehicle application.

The following diagnostic steps can help prevent overlooking simple problems. This is also the place to start diagnosis for a "NO-START" condition. The first step in diagnosing any driveability problem is to verify the problem exists. This may be accomplished by test driving the vehicle under the conditions during which the problem reportedly occurs. Prior to entering self-diagnostics, a careful and complete inspection of several systems is required. Most driveability or "no-start" problems are not related to computerized engine control systems, but are usually simple mechanical, electrical, fuel or vacuum problems. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged or misrouted vacuum hoses. Before considering the computer system as a possible cause of problems, check ignition high tension wires, fuel supply, electrical connections and vacuum hoses. Failure to check these can result in improper diagnosis or lost diagnostic time. NOTE:

All voltage tests should be performed with a Digital Volt- Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in testing procedures.

PRELIMINARY INSPECTION & ADJUSTMENTS VISUAL INSPECTION Perform a visual inspection of all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Inspect electrical connectors and connections for tight fit and corrosion. Repair as necessary. Inspect all vacuum hoses for proper routing, cuts or pinches. If necessary, see VACUUM DIAGRAMS article to verify routing and connections. Repair as necessary. Inspect air induction system for possible vacuum leaks. MECHANICAL INSPECTION Compression

Check engine mechanical condition using a compression gauge, vacuum gauge, or an engine analyzer capable of performing a relative compression test. See engine analyzer instruction manual for availability and description of relative compression feature.

CAUTION: Use a remote starter to crank engine during compression test. DO NOT use the ignition switch. The fuel injectors on many fuel-injected models are triggered by the ignition switch during the cranking mode. The excess fuel can cause flooding, crankcase contamination or hydrostatic lock. Exhaust System Backpressure

Before replacing any components, check exhaust system for restrictions. The exhaust system can be checked with a vacuum gauge or a 1-10 psi pressure gauge. If a vacuum gauge is used, connect it to intake manifold vacuum and start engine. Observe gauge and hold throttle steady at 2000-2500 RPM. If vacuum gauge reading slowly drops after stabilizing, exhaust system may be restricted. 



Check at AIR Pipe Remove rubber hose at exhaust manifold AIR pipe check valve and remove check valve. Install pressure gauge to hose and nipple via Propane Enrichment Device (J26911). Nipple should be inserted into exhaust manifold AIR pipe. Check at O2 Sensor Remove O2 sensor. Install backpressure tester in place of O2 sensor. After test is completed, coat O2 sensor threads with anti-seize compound. Diagnosis 1. Start engine and bring to operating temperature. Increase engine speed to 2000-2500 RPM and note gauge. Reading should not exceed 1.25 psi (.09 kg/cm2 ). Exhaust system is restricted if specification is exceeded. 2. Check exhaust system for collapsed pipe, heat distress and possible internal muffler failure. If none of these conditions exist, check for restricted catalytic converter. Replace as required.

NO START DIAGNOSIS DEFINITION No start is defined as engine cranks properly, but does not start. Engine may fire a few times. NO START - ENGINE CRANKS OKAY (CARBURETED) NOTE:

Check battery, engine cranking speed and fuel supply before performing the following tests.

General Inspection

1. Ensure proper starting procedure is being used. 2. Check vacuum hoses for splits, kinks and proper connections, as shown on underhood Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. 3. Remove spark plugs. Check and replace as necessary. Remove distributor cap and check for moisture, dust, cracks, burns and arcing to ground through coil mounting screws or rotor.

4. Try to turn distributor shaft by hand. Drive gear pin may be broken. 5. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline. Ignition System

1. Disconnect tachometer wire at distributor (if equipped). A shorted tachometer will not allow vehicle to start. 2. Check for battery voltage at BAT terminal at distributor with ignition on. Repair as necessary. 3. Connect ST-125 spark tester to end of one plug wire and crank engine. See Fig. 1 . If spark exists, check fuel delivery. 4. If spark does not exist, disconnect 4-wire EST connector at distributor. If spark now occurs, replace pickup coil in distributor. 5. If spark does not occur, reconnect EST connector and check voltage at TACH terminal at distributor with ignition on. 6. If voltage is less than one volt, repair faulty coil connection or replace faulty coil. If voltage is 1-10 volts, replace ignition module and recheck for spark. If spark still does not occur, replace ignition coil. 7. If voltage reading at TACH terminal of distributor is greater than 10 volts, remove and invert distributor cap with wires connected. Fabricate an HEI coil spark tester by trimming a spark plug boot and connecting it to ST-125 spark tester. See Fig. 1 . Crank engine. 8. If spark occurs, check cap for cracks, water or other defects. Check pick-up coil connector and ignition coil lead wire colors. Ignition coil with Yellow and Red wires should be used with Yellow pick-up coil connector. Ignition coil with White and Red wires should be used with Clear or Black pick-up coil connector. 9. If spark does not occur, turn ignition off and disconnect pick-up coil leads from module. Turn ignition on. With voltmeter connected to TACH terminal of distributor and fabricated coil spark tester connected, momentarily touch test light, connected to battery voltage, to terminal "P" of ignition module. DO NOT touch test light to terminal "P" for more than 5 seconds. 10. If voltage at TACH terminal does not drop, check ignition module ground and for open in ignition coil-tomodule wires. If wiring is okay, replace ignition module. 11. If voltage at TACH terminal does drop, check for spark at spark tester as test light is removed from terminal "P". If spark occurs, check pick-up coil connections and check for 500-1500 ohms resistance at pick-up coil leads. Repair as necessary. 12. If spark does not occur, test ignition module with module tester. If module tests okay, check ignition coil wire. If module tester is not available, replace ignition coil and again touch terminal "P". If spark occurs, system is okay. If spark does not occur, reinstall original ignition coil and replace ignition module. Fuel System

1. Remove air cleaner and check carburetor choke valve, vacuum break(s), linkage and unloader operation. Choke valve should move smoothly, be closed when cold and open when hot. 2. Check for presence of fuel by noting carburetor accelerator pump operation. Look for gasoline squirt in carburetor bore while quickly opening throttle lever. If no squirt occurs, check for fuel in tank, carburetor fuel inlet filter dirty or clogged and float needle for proper operation. 3. Check for proper fuel pump pressure and capacity. Check fuel pump vacuum. See BASIC FUEL

SYSTEM CHECKS in this article. If no problems are found, crank engine and check for flooding. If engine is not flooded, check ignition system. See BASIC IGNITION SYSTEM CHECKS in this article.

Fig. 1: Checking HEI Distributor Coil Spark Courtesy of GENERAL MOTORS CORP.

Fig. 2: Carbureted Ignition System Courtesy of GENERAL MOTORS CORP. NO START - ENGINE CRANKS OKAY (TBI WITH HEI) NOTE:

Check battery, engine cranking speed and fuel supply before performing the following tests.

General Inspection

1. Make sure proper starting procedure is being used. 2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on underhood Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. 3. Remove spark plugs. Check and replace as necessary. 4. Remove distributor cap and check for moisture, dust, cracks, burns and arcing to ground through coil mounting screws or rotor. 5. Try to turn distributor shaft by hand. Drive gear pin may be broken. 6. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline. Ignition System

1. Disconnect tachometer wire at distributor TACH terminal (if equipped). A shorted tachometer will not allow vehicle to start. 2. Check for battery voltage at BAT terminal at distributor with ignition on. Repair as necessary. 3. Connect ST-125 spark tester to end of one plug wire and crank engine. If spark occurs, check fuel delivery. 4. If spark does not occur, disconnect 4-wire EST connector at distributor. If spark now occurs, replace

5. 6. 7.

10. 11.

12.

pick-up coil in distributor. If spark does not occur, reconnect EST connector and check voltage at TACH terminal at distributor with ignition on. If voltage is less than one volt, repair faulty coil connection or replace faulty coil. If voltage is 1-10 volts, replace ignition module and recheck for spark. If spark still does not occur, replace ignition coil. If voltage reading at TACH terminal of distributor is greater than 10 volts, remove and invert distributor cap with wires connected. Fabricate an HEI coil spark tester by trimming a spark plug boot and connecting it to ST-125 spark tester. See Fig. 1 . Crank engine. If spark occurs, check cap for cracks, water or other defects. Check pick-up coil connector and ignition coil lead wire colors. Ignition coil with Yellow and Red wires should be used with a Yellow pick-up coil connector. Ignition coil with White and Red wires should be used with a Clear or Black pick-up coil connector. If spark does not occur, turn ignition off and disconnect pick-up coil leads from module. Turn ignition on. With voltmeter connected to distributor TACH terminal and fabricated coil spark tester connected, momentarily touch test light, connected to a remote voltage source (1.5-8.0 volts), to ignition module terminal "P." If voltage at TACH terminal does not drop, check ignition module ground and for open in wires from ignition coil to module. If all is okay, replace ignition module. If voltage at TACH terminal does drop, check for spark at spark tester as test light is removed from terminal "P". If spark occurs, check pick-up coil connections and check for 500-1500 ohms resistance at pick-up coil leads. Repair as necessary. If spark does not occur, test ignition module with module tester. If module tests okay, check ignition coil wire. If module tester is not available, replace ignition coil and again touch terminal "P." If spark occurs, system is okay. If spark does not occur, reinstall original ignition coil and replace ignition module.

Fuel System

1. Prior to checking fuel system for a no-start condition, check ignition for adequate spark. Check for proper fuel pump pressure (9-13 psi for all models except 2.8L W Body and 26-32 psi for 2.8L W Body) and capacity (one pint in 30 seconds). See BASIC FUEL SYSTEM CHECKS in this article. 2. Crank engine and watch for injector spray. If injector spray occurs, go to step 5). If no spray occurs, disconnect injector harness and check for battery voltage at harness. Battery voltage should be present on one of the injector terminals. If battery voltage is not present, check for blown injector power fuse. If battery voltage is present on both terminals, check for wires shorted to one another. 3. If battery voltage is present on only one terminal, connect injector test light to injector harness. Crank engine and note light. If light flashes, check for stored ECM codes. If no codes are present, refer to HARD START symptom in TESTS W/O CODES article. If light does not flash, momentarily touch test light from battery voltage to ECM RPM reference terminal (circuit No. 430). 4. Each time test light is removed from ECM RPM reference terminal, injector test light should flash. If test light does not flash, check for open in RPM reference wire, injector drive (ground) circuit, or replace faulty ECM. 5. If injector spray occurred while cranking engine, disconnect injector harness and crank engine. If injector spray or leakage occurs, this could cause a no-start condition due to excessive fuel being delivered during cranking. Repair faulty injector or injector seal. If no spray or leakage occurs, refer to HARD START symptom in appropriate TESTS W/O CODES article.

Fig. 3: 2.0L Sunbird TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 4: 5.0L Camaro & Firebird TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 5: 5.7L Brougham TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 6: 5.0L & 5.7L Caprice & Custom Cruiser TBI Ignition System Courtesy of GENERAL MOTORS CORP.

NO START - ENGINE CRANKS OKAY (TBI WITH DIS) NOTE:

Check battery, engine cranking speed and fuel supply before performing the following tests.

General Inspection

1. Ensure proper starting procedure is being used. 2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs. 3. Remove spark plugs. Check and replace as necessary. 4. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline. Ignition System

1. Disconnect tachometer wire (if equipped). A shorted tachometer will not allow vehicle to start. 2. With ignition on, check for battery voltage at Pink or Pink/Black wire of 2-wire connector at ignition module. Check for continuity to ground on Black/White wire of 2-wire connector. Repair as necessary. 3. Connect ST-125 spark tester to end of one plug wire and crank engine. Leave matching plug wire connected to spark plug. If spark occurs, check spark on matching wire. If spark occurs on both wires, check fuel system. If spark occurs on only one wire, go to step 5). 4. If spark does not occur on both wires, remove crankshaft sensor and check resistance. On 2.5L engine, it is necessary to remove ignition module in order to remove sensor. Resistance should be 800-900 ohms at room temperature. Lay a flat piece of metal on tip of sensor to determine if sensor is still magnetized. Replace if necessary. If sensor is okay, check wiring harness to and from ignition module for opens or shorts. If harness is okay, replace ignition module. 5. If spark occurred on only one wire in step 3), note which wire had no spark. Turn ignition off and remove ignition coils. Check for carbon tracking or faulty connections between coil and ignition module. Repair or replace as necessary. If no problems are noticeable, switch coil positions on module and recheck for spark. 6. If same plug wire has no spark, replace ignition module. If spark now occurs on plug wire which previously had no spark and no spark occurs on a different plug wire, replace defective ignition coil. Fuel System

engine and note light. If light flashes, check for stored ECM codes. If no codes are present, refer to HARD START symptom in TESTS W/O CODES article. If light does not flash, momentarily touch test light connected to battery voltage to ECM RPM reference terminal (circuit No. 430). See Fig. 7 -11. 4. Each time test light is removed from ECM RPM reference terminal, injector test light should flash. If test light does not flash, check for open in RPM reference wire, injector drive (ground) circuit, or replace faulty ECM. 5. If injector spray occurred while cranking engine, disconnect injector harness and crank engine. If injector spray or leakage occurs this could cause a no-start condition due to excessive fuel being delivered during cranking. Repair faulty injector or injector seal. If no spray or leakage occurs, refer to HARD START symptom in appropriate TESTS W/O CODES article.

Fig. 7: 2.2L Beretta & Corsica TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 8: 2.2L Cavalier TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 9: 2.5L (VIN R) Celebrity & Century Wagon TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 10: 2.5L (VIN R) Cutlass Cruiser Wagon TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 11: 2.5L (VIN U) Grand Am & Skylark TBI Ignition System

Courtesy of GENERAL MOTORS CORP.

Fig. 12: 2.5L (VIN U) Cutlass Calais TBI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 13: 2.5L (VIN R) Lumina TBI Ignition System Courtesy of GENERAL MOTORS CORP. NO START - ENGINE CRANKS OKAY (PFI WITH HEI) NOTE:

Check battery, engine cranking speed and fuel supply before performing the following tests.

General Inspection

1. Ensure proper starting procedure is being used. 2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on underhood Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. 3. Remove spark plugs. Check and replace as necessary. 4. Remove distributor cap and check for moisture, dust, cracks, burns and arcing to ground through coil mounting screws or rotor. 5. Try to turn distributor shaft by hand. Drive gear pin may be broken. 6. In very cold temperatures, ensure oil is proper viscosity and not contaminated with gasoline. Ignition System (Remote Coil)

1. Disconnect tachometer wire at coil (if equipped). If tachometer lead is not used, it may be taped against harness near coil. A shorted tachometer will not allow vehicle to start. 2. Disconnect 2-wire connector at distributor. Turn ignition on. Check voltage on "C" and "+" terminals of harness. If voltage to "C" terminal only is less than 10 volts, check for open or ground in wire between terminal "C" at distributor and ignition coil. If wire is okay, fault is in ignition coil or ignition coil connector. 3. If voltage at both terminals is less than 10 volts, repair wire from module "+" terminal to ignition coil or repair primary circuit to ignition coil. 4. If voltage at both terminals is over 10 volts, reconnect 2-wire connector at distributor. Check voltage at tachometer terminal at coil with ignition on. Tachometer connector may be taped back against harness. If voltage is greater than 10 volts, go to step 5). If voltage is less than one volt, repair open in tachometer lead and repeat voltage check. If voltage is 1-10 volts, replace ignition module and check for spark from coil wire. If spark occurs, system is okay. If spark does not occur, replace ignition coil also. 5. Connect a test light from tach terminal to ground. Crank engine. If test light illuminates and does not flash, go to step 6). If test light flashes, replace ignition coil and recheck for spark with tester. If spark is still not present, replace ignition module and retest. 6. If test light was on steady in last step, turn ignition off and remove 4-wire connector at distributor. Remove distributor cap and disconnect pick-up coil leads from ignition module. Turn ignition on. With voltmeter connected to tachometer terminal of distributor, momentarily touch test light connected to a remote voltage source (1.5-8.0 volts) to terminal "P" of ignition module. 7. If voltage at tachometer terminal does not drop, check ignition module ground. If all is okay, replace ignition module.

8. If voltage at tachometer terminal does drop, check for spark at spark tester connected to coil wire. If spark occurs as test light is removed from terminal "P", check pick-up coil connections and check for 500-1500 ohms resistance at pick-up coil leads. Check if pole piece is still magnetized. Repair connections or replace pick-up coil as necessary. 9. If spark does not occur, test ignition module with module tester. If module tests okay, check ignition coil wire. If module tester is not available, replace ignition coil and again touch terminal "P". If spark occurs, system is okay. If spark does not occur, reinstall original ignition coil and replace ignition module. Ignition System (Integral Coil)

1. Disconnect tachometer wire at distributor (if equipped). A shorted tachometer will not allow vehicle to start. 2. Check for battery voltage at "BAT" terminal at distributor with ignition on. Repair as necessary. 3. Connect ST-125 spark tester to end of one plug wire and crank engine. Check for spark at several plug wires. If spark occurs, check fuel delivery system. 4. If spark does not occur, check voltage at distributor "BAT" terminal while cranking engine. If voltage is less than 7 volts, repair primary circuit to ignition switch. If voltage is greater than 7 volts, check voltage to distributor TACH terminal. If voltage is greater than 10 volts, go to step 6). If voltage is less than one volt, repair faulty ignition coil connection or replace defective ignition coil. 5. If voltage is 1-10 volts, replace ignition module and recheck for spark. If spark occurs, system is okay. If spark does not occur, replace ignition coil also. 6. If voltage reading at TACH terminal of distributor is greater than 10 volts, remove and invert distributor cap with wires connected. Fabricate an HEI coil spark tester by trimming a spark plug boot and connecting it to ST-125 spark tester. See Fig. 1 . Crank engine. 7. If spark occurs, check cap for cracks, water or other defects. Check for rotor burn-through. Check pick-up coil connector and ignition coil lead wire colors. Ignition coil with Yellow and Red wires should be used with Yellow pick-up coil connector. Ignition coil with White and Red wires should be used with Clear or Black pick-up coil connector. 8. If spark does not occur, turn ignition off and disconnect pick-up coil leads from module. Turn ignition on. With voltmeter connected to TACH terminal of distributor and fabricated coil spark tester connected, momentarily touch test light, connected to battery voltage, to terminal "P" of ignition module. DO NOT touch test light to terminal "P" for more than 5 seconds. 9. If voltage at TACH terminal does not drop, check ignition module ground and for open in wires from ignition coil to module. If wiring is okay, replace ignition module. 10. If voltage at TACH terminal does drop, check for spark at spark tester as test light is removed from terminal "P". If spark occurs, check pick-up coil connections and check for 500-1500 ohms resistance at pick-up coil leads. Repair connections or replace pick-up coil as necessary. 11. If spark does not occur, test ignition module with module tester. If module tests okay, check ignition coil wire. If module tester is not available, replace ignition coil and again touch terminal "P". If spark occurs, system is okay. If spark does not occur, reinstall original ignition coil and replace ignition module. Fuel System

1. Prior to checking fuel system for a no-start condition, check ignition for proper spark. Check for proper fuel pump pressure (approximately 40-47 psi) and capacity (one pint in 30 seconds). See BASIC FUEL

SYSTEM CHECKS in this article. 2. Disconnect injector harness. Turn ignition on and check for battery voltage at each injector harness. See Fig. 12 -17. Battery voltage should be present on one side of each injector. If battery voltage is not present, check for blown injector power fuse. If battery voltage is present on both injector terminals, check for wires shorted together. 3. If battery voltage is present on only one terminal, connect injector test light to injector harness. Crank engine and note light. Repeat on other injector connectors. If light flashes, check for stored ECM codes. If no codes are present, refer to HARD START symptom in TESTS W/O CODES article. 4. If light does not flash, disconnect distributor 4-wire (5-wire on Cadillac) connector. Momentarily touch test light from battery voltage to ECM RPM reference wire (circuit No. 430) of 4-wire connector. Each time test light is removed from ECM RPM reference terminal, injector test light should flash. If test light does not flash, check for open in RPM reference wire, injector drive (ground) circuit or replace faulty ECM.

Fig. 14: 2.0L Turbo Sunbird PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 15: 3.1L Camaro & Firebird PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 16: 4.5L Cadillac PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 17: 4.5L Cadillac PFI Injector System Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 18: 5.0L & 5.7L Camaro & Firebird PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 19: 5.7L Corvette PFI Ignition System Courtesy of GENERAL MOTORS CORP. NO START - ENGINE CRANKS OKAY (PFI WITH DIS) NOTE:

Check battery, engine cranking speed and fuel supply before performing the following tests.

General Inspection

1. Ensure proper starting procedure is being used. 2. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both coil pack and spark plugs. 3. Remove spark plugs. Check and replace as necessary. 4. In very cold temperatures, check oil is proper viscosity and not contaminated with gasoline. Ignition System

1. Disconnect tachometer wire (if equipped). A shorted tachometer will not allow vehicle to start. 2. With ignition on, check for battery voltage at Pink/Black wire of 2-wire connector at ignition module. Check for continuity to ground on Black/White wire of 2-wire connector. Repair as necessary. 3. Connect ST-125 spark tester to end of one plug wire and crank engine. Leave matching plug wire connected to spark plug. If spark occurs, check spark on matching wire. If spark occurs on both wires,

check fuel delivery. If spark occurs on only one wire, go to step 5). 4. If spark does not occur on either wire, remove crankshaft sensor and check resistance. Resistance should be 900-1200 ohms at room temperature. Lay a flat piece of metal on tip of sensor to determine if sensor is still magnetized. Replace if necessary. If sensor is okay, check wiring harness to and from ignition module for opens or shorts. If harness is okay, replace ignition module. 5. If spark occurred on only one wire in step 3), note which wire had no spark. Turn ignition off and remove ignition coils. Check for evidence of carbon tracking or faulty connections between coil and ignition module. Repair or replace as necessary. If no problems are noticeable, switch coil positions on module and recheck for spark. 6. If same plug wire has no spark, replace ignition module. If spark now occurs on plug wire which previously had no spark and no spark occurs on a different plug wire, replace defective ignition coil. Fuel System

1. Prior to checking fuel system for a no-start condition, check ignition for adequate spark. Check for proper fuel pump pressure (approximately 40-47 psi) and capacity (one pint in 30 seconds). See BASIC FUEL SYSTEM CHECKS in this article. 2. Disconnect injector harness. Turn ignition on and check for battery voltage at each injector harness terminal. Battery voltage should be present on one injector harness terminal at each injector. If battery voltage is not present, check for blown injector power fuse. If battery voltage is present on both terminals, check for wires shorted to one another. 3. If battery voltage is present on only one terminal, connect injector test light to injector harness. Crank engine and note light. Repeat on other injector connectors. If light flashes, check for stored ECM codes. If no codes are present, refer to HARD START symptom in TESTS W/O CODES article. 4. If light does not flash, turn ignition off. Disconnect ignition module 6-wire connector. Turn ignition on. Momentarily touch test light from battery voltage to ECM RPM reference wire (circuit No. 430) of 6wire connector. Each time test light is removed from ECM RPM reference terminal, injector test light should flash. If test light does not flash, check for open in RPM reference wire, injector drive (ground) circuit or replace faulty ECM.

Fig. 20: 3.1L Beretta & Corsica PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 21: 3.1L Cavalier PFI Ignition System

Courtesy of GENERAL MOTORS CORP.

Fig. 22: 3.1L Celebrity & 6000 PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 23: 3.1L Grand Prix, Cutlass Supreme & Lumina PFI Ignition System Courtesy of GENERAL MOTORS CORP. NO START - ENGINE CRANKS OKAY (PFI WITH IDI) NOTE:

Check battery, engine cranking speed and fuel supply before performing the following tests.

General Inspection

1. Disconnect tachometer wire from IDI module (if equipped). A shorted tachometer will not allow vehicle to start. Temporarily remove IDI assembly and install spark plug Jumper Wires (J 36012). Check for adequate spark with Spark Tester (ST-125). Check for spark on 2 adjacent plug wires (1-2 or 3-4, not 23). Leave matching plug wire connected while checking for spark. If spark jumps tester on both plug wires, check fuel system. If spark did not jump tester on either plug wire, go to step 4). 2. If spark jumped tester on only one plug wire, disconnect plug jumper wires and remove coil housing.

Disconnect coil harness connector at module. Install test light between module terminal "A" and control terminal for coil which did not spark. See Fig. 22 -24. Crank engine and note test light. If test light blinks at both test terminals, repair faulty harness, poor connection or replace faulty coil. If test light did not blink on both terminals, repair module connections or replace faulty module. If spark did not occur on either plug wire in step 1), Turn ignition off. Disconnect 11-pin connector at module. Turn ignition on and connect test light between terminals "K" and "L" at harness. If test light is not on, repair open or short in module ground or power supply. If test light is on in step 4), install injector test light in any injector. Connect a test light to battery voltage and repeatedly touch to IDI module terminal "H". Injector test light should flash. If test light flashes, go to step 6). If not, check injector drive circuits for open or short to voltage. If ground circuits are okay, check injector power supply. If power supply is okay, repair poor connections at ECM or replace faulty ECM. Connect DVOM between terminals "B" and "C" of IDI module harness connector. Place DVOM on 2volt AC scale. Crank engine and note voltage. Voltmeter should read greater than 20mV. If voltage is correct, replace IDI module. If voltage is not correct, remove crankshaft sensor from block. Measure sensor resistance. Resistance should be 500-900 ohms. Place a flat piece of metal on tip of sensor to verify sensor is still magnetized. Inspect sensor harness. Repair or replace as necessary.

Fuel System

1. Prior to checking fuel system for a no-start condition, check ignition for proper spark. Check for proper fuel pump pressure (40-47 psi) and capacity (one pint in 30 seconds). See BASIC FUEL SYSTEM CHECKS in this article. 2. Disconnect injector harness. Turn ignition on and check for battery voltage at each injector harness. Battery voltage should be present on one of the injector terminals. If battery voltage is not present, check for blown injector power fuse. If battery voltage is present on both terminals, check for wires shorted to one another. 3. If battery voltage is present to each injector, connect injector test light to injector harness. Crank engine and note light. Repeat on other injector connectors. If light flashes, check for stored ECM codes. If no codes are present, refer to HARD START symptom in TESTS W/O CODES article. 4. If light does not flash, access IDI ignition module harness connector. Disconnect connector and momentarily touch test light from battery voltage to ECM RPM reference wire (circuit No. 430) of module harness. Each time test light is removed from ECM RPM reference terminal, injector test light should flash. If test light does not flash, check for open in RPM reference wire, injector drive (ground) circuit or replace faulty ECM.

Fig. 24: 2.3L Beretta PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 25: 2.3L Cutlass Supreme & Grand Prix PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 26: 2.3L Grand Am & Skylark PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 27: 2.3L Cutlass Calais PFI Ignition System Courtesy of GENERAL MOTORS CORP.

NO START - ENGINE CRANKS OKAY (PFI WITH C(3)I) NOTE:

Before performing following tests, check battery condition, engine cranking speed, and for adequate fuel in the tank.

General Inspection

1. Disconnect tachometer wire (if equipped). A shorted tachometer will not allow vehicle to start. Check for adequate spark with Spark Tester (ST-125). Check for spark on plug wires No. 1, 3 and 5 (one at a time). Leave matching plug wire connected while checking for spark. If spark jumped tester on all plug wires, check fuel system. If spark did not occur on any plug wire, go to step 4). If spark did not jump tester on all plug wires, verify plug wire resistance is less than 30,000 ohms. Replace as necessary. If wires are okay, go to next step. 2. If spark jumped tester on one, but not all plug wires, remove 2 fasteners holding effected coil assembly. Remove coil from module. Connect a test light to 2 exposed terminals on the module. Crank engine. If test light flashes, check for poor coil to module connections. If connections are okay, replace faulty coil. 3. If test light does not flash, replace ignition module. Also, check primary coil resistance (.5-.9 ohm). Replace coil if necessary. 4. Turn ignition off. Disconnect ignition module connector. Turn ignition on. Check for battery voltage on terminal "M" of ignition module harness. See Fig. 25 and Fig. 26 . Repair open or short, or replace ignition fuse as necessary. If battery voltage is present, turn ignition off and disconnect fuel pump relay. Install injector test light in injector harness connector. Connect test light to battery voltage and repeatedly touch to terminal "C" of the ignition module harness connector. 5. Injector test light should flash each time test light is touched to terminal "C". If injector test light flashes, go to step 7). If not, backprobe ECM injector drive terminals (BC11 and BC12) with a test light to ground. If light is off, check for loss of power to fuel injector harness or open between injectors and drive terminals. If test light is on, disconnect ALL injectors. With test light connected to ground, check for voltage on both terminals of each injector harness. 6. If voltage is present on both wires of any or all injectors, check for short to voltage on injector drive circuit. If battery voltage is present on only one wire of each injector harness, check for open or shorted circuit No. 430 (RPM reference high), poor connections at ECM terminals BC11 and BC12 or a faulty ECM. 7. Turn ignition off and reconnect ignition module connector. Disconnect dual crank (combination) sensor. Turn ignition on. Using a DVOM, measure voltage between sensor harness terminals "C" and "D." If 1012 volts are not present, check for poor connections at ignition module, open or short in combination sensor harness or replace faulty ignition module.

8. If 10-12 volts are present at combination sensor connector, turn ignition off. Disconnect No. 6 spark plug wire from coil tower. NEVER crank engine with a spark plug wire off coil. Damage to coil or ignition module may occur. Attach Spark Tester (ST-125) to coil tower. Install injector test light in any injector harness. 9. Turn ignition on. Jumper dual crank sensor connector terminal "A" to terminal "B". Using a test light connected to ground, momentarily touch terminal "A". If injector test light flashes and spark tester sparks, check for poor connections at dual crank sensor. If connections are okay, replace faulty dual crank sensor. Inspect dual crank sensor and pulley for signs of rubbing. 10. If spark did not occur and injector test light did not flash, check for poor connections at ignition module or replace faulty ignition module. Ignition System (3.8L)

1. Ensure that fuel quantity and quality is okay. Turn ignition on with throttle closed. Service engine soon light should be ON. (If not see SERVICE ENGINE SOON LIGHT INOPERATIVE). Connect scan tool according to manufacturer's instructions. TPS should scan less than 2.5 volts (2500 ma). (If not see CODE 21 chart in appropriate TESTS W/CODES article.) Disconnect cam sensor and crank engine. If it starts, see CODE 41 chart in appropriate TESTS W/CODES article. If not, continue. On a cold engine (not run for 8 hours) MAT should be close to CTS value. If not, compare scan value of coolant temperature sensor to actual coolant temperature. Values should be close. If not, replace coolant temperature sensor. 2. Reconnect cam sensor. Depress throttle to approximately 1/4 position. attempt to start engine. If engine starts, check Idle Air Control system. If engine does not start, disconnect all injector connectors and install injector test light J 34730-2 or equivalent in each injector harness connector. Test lights should be off. If test lights are on, go to step 3. If test lights are off, Crank engine and observe if test lights blink. If test lights do not blink, go to step 3. If test lights blink, go to step 4). 3. If light is glowing steadily, disconnect ECM gray connector. If light does not turn off, repair short to ground in injector wiring. If light turns off, ECM is faulty. If test light is off, check INJ fuse. If fuse is not okay, repair short to ground in CKT 839 and replace fuse. If fuse is okay, remove injector test light. Probe injector harness CKT 839 at each injector terminal "A" with a test light to ground. If test light is off, check circuit from ignition feed for an open circuit. If test light is on, go to step 6). NOTE:

If an injector driver circuit has been continuously grounded check oil for fuel contamination and exhaust system restriction.

4. Turn ignition off, install fuel pressure gauge and note pressure after ignition is turned ON for 2 seconds, pressure should be 40-47 psi (280-325 kpa) and holding. If no pressure is read, go to FUEL SYSTEM below. If pressure is incorrect, go to FUEL PRESSURE CHECK (PFI). If pressure is correct, go to step 4). 5. Check for spark with spark tester (ST-125) J 26792, or equivalent on plug wires 1, 3 & 5 one at a time while cranking, with remaining plug wires still connected. If there is spark on all wires, check for fouled spark plugs. Clean or replace as necessary, then check Idle Air Control system. No spark on all wires, check for faulty ignition module connection or module. If there is no spark on one or more wires, check the following:  Verify that plug wire resistance is less than 30k ohms. If resistance is not as specified, replace wire.  Verify coil secondary resistance is 5000-6500 ohms at approximately. 70°F. If resistance is not as

specified, replace coil. ď Ź Remove coil for cylinder(s) that did not fire. Verify coil primary resistance is .3 -.5 ohms. If resistance is not as specified, replace coil. ď Ź Connect a test light between ignition module terminals for problem coil. The test light should blink while cranking engine. If test light does not blink, the ignition module is faulty. If test light does blink, the ignition coil connection or coil is faulty. Turn ignition off. Disconnect 14 pin harness connector from ignition module. Install an injector test light in any injector harness connector. Turn ignition ON, connect a test light to 12 volts and repeatedly touch to ignition module harness terminal "D". Injector test light should blink. If test light blinks, go to step 7). If test light does not blink, Check injector driver circuit from ECM for an open or short to voltage. If circuit is okay, check CKT 430 for open or short to ground or to voltage. If circuit is ok, check for poor connection at ECM terminal "G9" or faulty ECM. If circuit is not okay, repair injector driver circuit. Turn ignition off. Using appropriate jumper adaptor from connector test adaptor kit J 35616, connect a fused jumper between ignition module harness connector terminal "N" (CKT 644) and B+. Connect a second jumper between ignition module harness connector terminal "M" (CKT 645) and ground. Connect test light between ignition module harness connector terminal "H" (CKT 646) and B+. Test light should flash ON and OFF as starter is bumped. If test light does flash, go to step 8). If test light is on all the time, check CKT 646 for a short to ground. If circuit is okay, check for a faulty crank sensor. If test light is never on, check CKT 646 for an open or short to voltage, CKT 645 for an open, and CKT 644 for an open or short to ground. If circuit is okay, check for a faulty crank sensor. Connect test light between ignition module harness connector terminal "G" (CKT 643) and B+. Observe test light while repeatedly bumping starter. Test light should flicker as starter is bumped. If test light flickers, go to step 9). If test light is on all the time, check CKT 643 for a short to ground. If okay, check for a faulty crank sensor. If test light is never on, Check CKT 643 for an open or short to voltage. If okay, it's a faulty crank sensor. Turn ignition on. Probe ignition module harness connector terminal "P" (CKT 839) with a test light to ground. If test light is on, check for poor connections at ignition module or faulty ignition module. If test light is not on, repair open CKT 839 to ignition module.

Fuel System

1. Before checking fuel system for a no-start condition, check ignition for proper spark. Check for proper fuel pump pressure (40-44 psi 3.3L or 40-47 psi 3.8L) and capacity (one pint in 30 seconds). See BASIC FUEL SYSTEM CHECKS in this article. 2. Disconnect injector harness. Turn ignition on and check for battery voltage at each injector harness. Battery voltage should be present on one of the injector terminals. If battery voltage is not present, check for blown injector power fuse. If battery voltage is present on both terminals, check for injector drive circuit shorted to voltage. 3. If battery voltage is present to each injector, connect injector test light to injector harness. Turn ignition on. DO NOT crank engine. If light is off, go to step 4). If injector test light illuminates without cranking engine, turn ignition off. Disconnect ECM C-D connector. If light is off, replace faulty ECM. If light is still on, check for short to ground in injector drive circuit. 4. Crank engine and note light. Repeat on other injector connectors. If light flashes, check for stored ECM codes. If no codes are present, refer to HARD START symptom in TESTS W/O CODES article. 5. If light does not flash, disconnect ignition module connector and momentarily touch test light from

battery voltage to ECM RPM reference wire (circuit No. 430) of module harness. Each time test light is removed from ECM RPM reference terminal, injector test light should flash. If test light does not flash, check for open in RPM reference wire, injector drive (ground) circuit, or replace faulty ECM.

Fig. 28: 3.3L Century & Cutlass Ciera PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 29: 3.3L Skylark PFI Ignition System Courtesy of GENERAL MOTORS CORP. ALTERNATE WIRING COLORS "A" & "N" BODY CARS (1) Circuit No. Original Color 646 LT BLU/WHT 645 GRY/RED 644 WHT/BLK 643 DK BLU/WHT 239 PNK/WHT 839 PNK/WHT (1) For schematic in Fig. Fig. 29 .

Alternate Color WHT/BLK DK BLU/WHT LT BLU/WHT GRY/RED PNK/BLK PNK/BLK

Fig. 30: 3.8L Electra, Park Avenue & LeSabre PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 31: 3.8L Bonneville & Touring Sedan PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 32: 3.8L Delta 88 & Ninety-Eight PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 33: 3.8L Reatta & Riviera PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 34: 3.8L Toronado & Trofeo PFI Ignition System Courtesy of GENERAL MOTORS CORP.

Fig. 35: 3.8L Regal PFI Ignition System Courtesy of GENERAL MOTORS CORP.

BASIC FUEL SYSTEM CHECKS FUEL PUMP TESTS (CARBURETED) NOTE:

Cover fuel line fittings with a shop rag to prevent fuel spillage when releasing fuel lines.

Fuel Pump Test 1

Connect a section of hose to fuel pump outlet line. Place end of hose into a unbreakable graduated container. Start engine and idle for 15 seconds. Fuel pump should deliver 1/2 pint of fuel in 15 seconds. Fuel Pump Test 2

Connect a short section of hose and a vacuum gauge to fuel pump inlet side. Start or crank engine until maximum vacuum reading is obtained. Vacuum reading should be 15 in. Hg. NOTE:

If fuel pump fails both Tests 1 and 2, replace fuel pump. If fuel pump failed Test 1 and passes Test 2, check fuel hoses and replace as necessary. If pump and hoses are okay and fuel delivery is still insufficient, remove fuel tank and inspect fuel tank strainer.

Fuel Pump Test 3

Connect a 8-10" hose and a pressure gauge to fuel pump outlet line. Hold gauge so it is about 16" above fuel pump. If equipped, pinch off fuel return line. Start engine and idle on fuel in carburetor. Fuel pressure should be 5.5-6.5 psi (.39-.46 kg/cm2 ). If pressure is too low, too high or varies greatly with RPM change, replace fuel pump. FUEL SYSTEM PRESSURE TEST (EFI) CAUTION: Fuel system trouble shooting and diagnosis begins with checking fuel injection system pressure. High fuel pressure may be present in fuel lines and component parts. Relieve fuel pressure before disconnecting any fuel system components. Fuel Pressure Relief (Throttle Body Injection)

Disconnect negative battery cable. Remove fuel filler cap. Since these TBI units contain an internal bleed-down feature, after a short time, system fuel pressure should dissipate. Fuel Pressure Relief (PFI)

Fuel system is under pressure. Pressure must be relieved prior to servicing fuel system. Fuel pressure may be relieved by using one of the following methods. ď Ź

ď Ź

Disconnect fuel pump at rear body connector. Start engine and run engine until it stalls. Crank starter for 3 seconds to remove remaining fuel from fuel lines. Reconnect rear body connector. Install Fuel Pressure Gauge (J-34730-1) on fuel pressure connection of fuel rail. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Install gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

Fuel Pressure Check (Throttle Body Injection)

1. Relieve fuel pressure (if necessary). Remove air cleaner and plug thermal vacuum port on throttle body. When removing fuel line, always use 2 wrenches. Install Fuel Pressure Gauge (J-29658B or BT-8205) and Adapter (J-29658-85) in fuel line between steel line and flexible hose. NOTE:

DO NOT pinch off fuel return line completely. DO NOT exceed pressure build-up of more than 32 psi (2.0 kg/cm2 ) on 2.5L "W" Body or 13 psi (.9 kg/cm2 ) on all other models as regulator may be damaged.

2. Turn ignition on and observe fuel pressure reading. Fuel pressure should read 26-32 psi (1.8-2.2 kg/cm2 ) on 2.5L "W" Body (VIN R) or 9-13 psi (.6-.9 kg/cm2 ) on all other models . If no fuel pressure is indicated, go to step 5). If fuel pressure is okay but engine will not start, proceed to NO START DIAGNOSIS. If fuel pressure is present but is too high, go to step 4). If fuel pressure is present but is too low, gradually pinch off fuel return line to fuel tank. 3. If fuel pressure remains low, check for plugged fuel filter or restriction in fuel delivery line. If filter is okay and no restrictions are present, replace fuel pump. If fuel pressure increases when return line is pinched, replace fuel pressure regulator. 4. If fuel pressure is present but is higher than specification, check for restriction in fuel return line. If return line is not restricted, replace fuel pressure regulator. 5. If no fuel pressure is observed, turn ignition off. Apply battery voltage to fuel pump test connector using a 10-amp fused jumper wire. For location of fuel pump test connector, refer to COMPONENT LOCATIONS in appropriate SYSTEM/COMPONENT TESTS article. Observe fuel pressure reading. If fuel pressure is still not evident, check wiring between test connector and fuel pump. If wiring is okay, replace fuel pump. 6. If fuel pressure is present with voltage applied to test connector, test fuel pump relay and voltage supply to relay. Refer to the appropriate SYSTEM/COMPONENT TESTS article. 7. After all repairs, allow fuel pressure to dissipate. Remove fuel pressure gauge and reconnect fuel line. Start engine and watch for fuel system leaks. For further details on fuel pressure testing, proceed to the appropriate SYSTEM/COMPONENT TESTS article. Fuel Pressure Check (PFI)

1. Relieve fuel pressure as previously described in FUEL PRESSURE RELIEF (PFI). Connect Fuel Pressure Gauge (J-34730-1) to fuel pressure fitting on fuel rail. 2. With gauge installed at fuel rail connector, turn ignition on. With ignition on and engine off, pressure

should read within specification. See SPECIFICATIONS - 4-CYL article (for 4-cylinder models), See SPECIFICATIONS - V6 article (for V6 models),See SPECIFICATIONS - V8 article (for V8 models). Start engine. Pressure should drop 3-10 psi (.2-7 kg/cm2 ). For more details on fuel system pressure testing, see SYSTEM/COMPONENT TESTS article. Fuel Pump Relay

See RELAYS, SOLENOIDS, MOTORS & MODULES in SYSTEM/COMPONENT TESTS article. Fuel Pump Relay By-Pass Procedure

See FUEL DELIVERY in SYSTEM/COMPONENT TESTS article. SYSTEM PERFORMANCE CHECK (CARBURETED) This verifies the computerized engine control system is functioning correctly and should always be made after any repair of computerized engine control system. Ensure parking brake is engaged and DRIVE wheels are blocked. Parking brake on FWD models does NOT hold drive wheels. NOTE:

On some engines, oxygen sensor will cool off after a short time while engine is idling. This will cause system to go into "open loop". To restore "closed loop" mode, run engine at part throttle for several minutes and accelerate from idle to part throttle several times.

1. Start engine and warm to operating temperature. Run engine at 2000 RPM for one minute to ensure O2 sensor is warm. Connect tachometer to engine. Ground diagnostic test terminal "B". See Fig. 32 . Disconnect mixture control solenoid and ground Green mixture control dwell lead. Increase engine speed to 3000 RPM and hold throttle held steady, while reconnecting mixture control solenoid. Note RPM change. This checks carburetor's ability to change air/fuel mixture. Disconnecting M/C solenoid makes carburetor run full rich. Reconnecting it with dwell lead grounded makes carburetor run full lean. RPM normally drops 300-1000 RPM as solenoid is reconnected. If RPM drops as described, go to step 3). Remove ground from dwell lead before returning to idle. 2. If RPM dropped less than 300 RPM or RPM increased in step 1), check evaporative canister and related valves for fuel saturation. If plugging PCV, purge or bowl vent hose causes RPM to drop more than 300 RPM, the hose that caused the RPM to change will lead to source of problem. If RPM increases as M/C solenoid is connected, system is running extremely rich. If no faults are found during system checks, service carburetor. 3. Connect dwell meter (on 6-cylinder scale) to Green mixture control solenoid dwell lead. Set carburetor on highest step of fast idle cam. Run for one minute or until dwell begins to vary, whichever happens first. Allow engine to idle and note dwell. This checks for proper control of idle circuit. Normal dwell will vary between 10 and 50 degrees, indicating "closed loop" operation. If dwell does NOT vary between 10 and 50 degrees, see appropriate heading:  Dwell Fixed Less Than 10 Degrees  Dwell Fixed Between 10 & 50 Degrees  Dwell Fixed Greater Than 50 Degrees 4. If dwell is varying between 10 and 50 degrees, observe dwell at 3000 RPM to check for proper control of

main metering system. RPM must be at least 3000 RPM to enter main metering system operation. Normal response is varying between 10 and 50 degrees. If dwell is less than 10 degrees, check air injection system for valve supplying air to exhaust manifold at 3000 RPM. A missing "O" ring between the switching valve solenoid and valve, or a defective valve, may cause air to leak into the exhaust ports at higher RPM only. If air is not being supplied to exhaust or dwell at 3000 RPM is greater than 50 degrees, service internal carburetor problems. Dwell Fixed Less Than 10 Degrees

This indicates a full rich command from the ECM to the carburetor, caused by one of the following:    

Severe engine misfire. False lean O2 sensor signal caused by grounded or open O2 sensor circuit. High TPS signal voltage caused by open in ECM ground circuit No. 452 or sticking TPS. False cold engine signal caused by open in coolant temperature sensor circuit. 1. Ensure vehicle is at operating temperature. With dwell meter still connected to Green dwell lead, increase engine speed to 2000 RPM. Choke engine and note dwell (allow one minute for maximum change). This determines if problem is computer or engine related. Dwell should start increasing as soon as engine is choked and increase until it is greater than 50 degrees. 2. If dwell responds, problem is a lean signal from the oxygen sensor. Check for air or vacuum leaks, including air injection system and deceleration valve (if equipped). Check for exhaust leaks near oxygen sensor. Check for proper vacuum hose routing. Check for proper EGR valve operation. 3. If dwell does not respond when choking engine at 2000 RPM, disconnect oxygen sensor. Connect a DVOM (minimum 10-megohm input impedance) set on the 20-volt scale between the Purple oxygen sensor lead to the ECM and the positive post of the battery. This checks ECM response to input to O2 sensor circuit. The voltmeter is used to put a voltage signal on the O2 sensor circuit to simulate a rich condition. Dwell should increase (lean command) if ECM and harness are good. If dwell increases, check for on open oxygen sensor ground circuit (terminal No. 14 of ECM) or replace faulty oxygen sensor. 4. If dwell does not increase, check coolant temperature using a "Scan" tester. This checks for a normal coolant sensor circuit condition. Temperature on a hot engine should be greater than 167°F (75°C). If reading is less than specified, check for an open in the coolant temperature sensor circuit or an out-of-calibration sensor. See SYSTEM/COMPONENT TESTS article for testing of the coolant temperature sensor. 5. If coolant temperature scans 167°F (75°C) or greater, check for grounded or open oxygen sensor circuits. If circuits are okay, scan throttle position sensor voltage. If TPS is greater than 1.1 volts, adjust or replace TPS as necessary. If TPS scans less than 1.1 volts, check for faulty connection at ECM terminal No. 14. If connection is okay, replace ECM.

Dwell Fixed Between 10 & 50 Degrees

This indicates an "open loop" condition caused by one of the following:  

Open O2 sensor circuit or bad sensor. Open coolant temperature sensor circuit.



Open circuit No. 413 from ECM terminal No. 14 to ground. 1. Run engine at 2000 RPM for one minute to ensure normal operating temperature. Idle engine and check mixture control solenoid dwell. Disconnect oxygen sensor and jumper ECM harness terminal (not sensor) to ground. Grounding O2 sensor input checks ECM response to a "lean" signal. Normal response is dwell decreasing to full rich command. If dwell does not change as indicated, go to step 4). 2. If dwell decreases with oxygen sensor ECM harness terminal grounded, check for open in oxygen sensor ground circuit (ECM terminal No. 14). On some ECMs, an open circuit to terminal No. 14 can cause "open loop". Repair as necessary. If circuit is not open, leave oxygen sensor lead to ECM grounded. Connect a DVOM (minimum 10-megohm input impedance) set on the 2-volt scale to the oxygen sensor Purple lead. This checks O2 sensor output with full rich command from ECM caused by grounding O2 sensor input circuit. 3. Normal response is O2 sensor voltage reading greater than .8 volt. If DVOM does not read greater than .8 volt, replace oxygen sensor. If DVOM does read greater than .8 volt, repair faulty connections at oxygen sensor. 4. If dwell did not change when oxygen sensor lead to ECM was grounded, jumper ECM terminal No. 9 to terminal No. 14. This grounds O2 sensor circuit at ECM to check for open in wiring to ECM terminal No. 9. Normal response to "lean" signal is a decrease in dwell. If dwell decreases, check for open in circuit No. 412 (Purple wire of oxygen sensor). 5. If there is no change in dwell when terminal No. 9 is jumpered to terminal No. 14, turn ignition off. Turn ignition on with engine off. Using a "Scan" tester, check coolant temperature sensor parameter. This checks coolant sensor input. Normal reading on a warm engine is greater than 167° F (75°C). An open coolant sensor signal or ground circuit would cause a reading of approximately 77°F (25°C). If this is the indicated reading, check coolant sensor harness for opens. Also, check coolant sensor for an being out of calibration. See SYSTEM/COMPONENT TESTS article. 6. If coolant temperature scans greater than 167°F (75°C), check for faulty connections to ECM terminals No. 9 or No. 14. If connections are okay, replace ECM.

Dwell Fixed Greater Than 50 Degrees

This indicates a full lean command from the ECM to the carburetor caused by one of the following:    

M/C solenoid wires reversed. Leaking bowl vent valve, excessive fuel in vapor canister or fuel in crankcase. Faulty carburetor calibration or carburetor. Silicone-contaminated O2 sensor. 1. Run engine at fast idle for at least 2 minutes to ensure vehicle has reached normal operating temperature. Allow engine to idle. Monitor mixture control solenoid dwell while creating a large vacuum leak. This determines if problem is related to engine or electronics. Normal response is dwell decrease. If dwell decreases, this indicates O2 sensor, harness and ECM are okay. Problem is a rich engine condition. If engine is very rich, a large air leak may be required to lean mixture. When mixture is lean enough, engine will begin to run rough and dwell will drop at least 20 degrees. 2. If dwell drops at least 20 degrees, check evaporative canister for being loaded with fuel. Check related purge and vent valves. If plugging PCV or bowl vent vacuum hose causes dwell to decrease,

that hose leads to source of problem. Also check for fuel in crankcase. If no problems are found, service carburetor, including checking float level. 3. If dwell did not drop at least 20 degrees when vacuum leak was created, disconnect oxygen sensor harness connector and ground ECM side of harness (not sensor). This checks ECM response to a "lean" O2 signal. Normal response is drop in dwell. No dwell change indicates a defective ECM. This test also eliminates the possibility of an open sensor wire. An open wire would cause "open loop" operation and may set Code 13. 4. If dwell drops to less than 10 degrees when ECM side of oxygen sensor harness is grounded, turn ignition off. Turn ignition on with engine off. Remove ground from ECM side of oxygen sensor harness. Using a DVOM, check voltage on ECM side of harness. If reading is less than .55 volt, replace oxygen sensor. If reading is .55 volt or greater, check for short to voltage on harness. If short to voltage is not present, replace ECM. FIELD SERVICE MODE CHECK (FUEL INJECTED) NOTE:

On some engines, oxygen sensor will cool off while engine is idling. This causes system to go into "open loop". To restore "closed loop" mode, run engine at part throttle several minutes and accelerate from idle to part throttle several times.

This confirms proper fuel system operation and verifies "closed loop" operation. Clear codes and perform this test after any repair is completed. When performing this check, always engage parking brake and block DRIVE wheels. Parking brake on FWD models does NOT hold drive wheels. 1. Start engine. With engine running, ground "test" terminal "B" of the ALDL diagnostic connector. See Fig. 38 . In "closed loop" mode, SERVICE ENGINE SOON light will flash once a second. 2. In "open loop", light will flash 2.5 times a second. If light is off most of the time, a lean exhaust is indicated. If light is on most of the time, a rich exhaust is indicated.

BASIC IGNITION SYSTEM CHECKS HEI-EST DISTRIBUTOR NOTE:

The only adjustments that can be made to HEI/EST ignition system are basic ignition timing and spark plug gap.

Spark

1. If factory tachometer is connected to ignition coil tachometer terminal, disconnect it before performing tests. When removing spark plug wire from spark plug, twist and pull on boot, NOT on wire. 2. Using Spark Tester (ST-125), check for spark at coil wire (if applicable) and at each spark plug wire using spark tester. Check spark plug wire resistance on suspect wires. Resistance should be no greater than 30,000 ohms. Ignition Coil Power Source

1. Turn ignition on. Using voltmeter, check voltage between terminal "B" of ignition coil and ground on models with remote-mounted coil. 2. On models equipped with integral ignition coil, check voltage between "BAT" terminal and ground at distributor. Battery voltage should exist. If not, check for open circuit, blown ignition fuse or defective ignition switch. Ignition Coil Resistance (Externally Mounted)

1. Remove coil connectors and secondary coil wire. In test "A", use high ohmmeter scale. See Fig. 36 . Resistance value should be very high (infinite). If not, replace coil. 2. In test "B", use low ohmmeter scale. Reading should be approximately zero ohms or replace coil. In test "C", use high ohmmeter scale. If there is no continuity, replace coil.

Fig. 36: Testing Ignition Coil Resistance (External Coil) Courtesy of GENERAL MOTORS CORP. Ignition Coil Resistance (Internally Mounted)

1. Turn ignition off. Remove the distributor cap and coil assembly. Turn cap upside down. See Fig. 37 . Set ohmmeter to low scale. Connect leads to coil BAT and TACH terminals. If resistance is more than zero, replace ignition coil.

2. Set ohmmeter on high scale. Connect one lead to coil secondary terminal and other lead first to TACH terminal and then to ground terminal. If resistance reading in BOTH instances is infinite, replace ignition coil.

Fig. 37: Testing Ignition Coil Resistance (Internal Coil) Courtesy of GENERAL MOTORS CORP. Distributor Pick-up Coil Short & Resistance Checks

1. Disconnect pick-up coil leads from HEI/EST module terminals "N" and "P". Set ohmmeter to middle scale. Connect one ohmmeter lead to either pick-up coil lead and the other lead to distributor housing. Flex pick-up coil leads by hand to check for intermittent shorts to ground. Reading should be infinity at all times. If resistance is not infinite, replace pick-up coil.

2. Connect ohmmeter between both pick-up coil leads. Check for intermittent opens by flexing wires and connectors. Resistance should be 500-1500 ohms. If resistance is not as specified, replace pick-up coil. Tach Pulse (RPM) Signal

Connect a "Scan" tester to the ALDL diagnostic connector. RPM should be indicated on tester when engine is cranked or running. Tach pulse (RPM reference will be indicated as a voltage signal when a DVOM (minimum 10-megohm input impedance) is touched to circuit No. 430 ECM terminal. For circuit and terminal reference, see appropriate schematic in NO START - ENGINE CRANKS OKAY in this article. DIS Spark

1. If factory tachometer is connected to ignition coil tachometer terminal, disconnect it before performing tests. When removing spark plug wire from spark plug, twist and pull on boot, NOT on wire. 2. Using Spark Tester (ST-125), check for spark at each spark plug wire using spark tester. Leave opposed firing plug connected while checking for spark. Check spark plug wire resistance on suspect wires. Resistance should be no greater than 30,000 ohms. Ignition Coil Power Source

Turn ignition on and check Pink or Pink/Black wire of ignition module for battery voltage. If battery voltage is not present, check ignition/ECM fuse. If fuse is not blown, check for open between fuse and ignition module. Ignition Coil Resistance

1. Disconnect leads from ignition coil. Using an ohmmeter, check secondary ignition coil resistance. See DIS SECONDARY COIL RESISTANCE table. 2. Primary resistance and secondary resistance values on models not listed in DIS SECONDARY COIL RESISTANCE table are not supplied by manufacturer. DIS SECONDARY COIL RESISTANCE Application Beretta & Corsica (2.2L & 3.1L) Cavalier (2.2L) Century (2.5L) Cutlass Calais, Grand Am & Skylark (2.5L)

Resistance 5000-10,000 5000-10,000 5000-10,000 5000-10,000

Crankshaft Sensor Pick-Up Coil Short & Resistance Checks

1. Set DVOM on the 2000-ohm scale. Connect leads to crank angle sensor, located on side of engine block. On 2.5L models, it will be necessary to remove ignition module. Crankshaft sensor resistance should be within specification in CRANKSHAFT SENSOR RESISTANCE table. If resistance is not as specified, replace sensor. 2. Connect one ohmmeter lead to either sensor terminal. Touch other lead of ohmmeter to engine block. No

continuity should exist. If continuity exists, sensor is shorted to ground and must be replaced. CRANKSHAFT SENSOR RESISTANCE (OHMS) Application Beretta, Cavalier, Corsica, Grand Prix & Lumina Celebrity, Century, Cutlass Calais, Grand Am, Skylark & 6000 (2.5) Celebrity & 6000 (3.1)

Specification 900-1200 800-900 900-1200

Crank Angle Sensor Signal

Set DVOM on the 2-volt AC scale. Connect voltmeter leads to crank angle sensor installed in side of engine block. On 2.5L models it will be necessary to remove ignition module. Crank engine and observe voltmeter reading. Crank angle sensor should generate a voltage signal of about .05 volt at slow cranking speed to greater than .1 volt (100 mV) at high cranking speed. Tach Pulse (RPM) Signal

Connect "Scan" tester to ALDL diagnostic connector. RPM should be indicated on tester when engine is cranked or running. Tach pulse (RPM reference will be indicated as a voltage signal when a DVOM (minimum 10-megohm input impedance) is touched to circuit No. 430 ECM terminal. For circuit and terminal reference, see appropriate schematic in NO START - ENGINE CRANKS OKAY in this article. IDI Spark

Disconnect tachometer wire from IDI module (if equipped). A shorted tachometer will not allow vehicle to start. Temporarily remove IDI assembly and install spark plug Jumper Wires (J 36012). Check for adequate spark with Spark Tester (ST-125). Check for spark on 2 adjacent plug wires (1-2 or 3-4, not 2-3). Leave matching plug wire connected while checking for spark. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire. Ignition Coil Power Source

Turn ignition on. Check for battery voltage on Pink/Black wire to ignition module. If battery voltage is not present, check for blown ignition fuse. If fuse is not blown, check for open between fuse and ignition module. Ignition Coil Resistance

Disconnect leads from ignition coil. Using an ohmmeter, check ignition coil secondary resistance. Secondary resistance should be less than 10,000 ohms on all models. Crankshaft Sensor Pick-Up Coil Short & Resistance Checks

1. Set DVOM on the 2000-ohm scale. Connect leads to crank angle sensor installed in side of engine block. Crankshaft sensor resistance should be 500-900 ohms on all models. If resistance is not as specified, replace sensor.

2. Connect one ohmmeter lead to either sensor terminal. Touch other ohmmeter lead to engine block. No continuity should exist. If continuity exists, sensor is shorted to ground and must be replaced. Crank Angle Sensor Signal

Set DVOM on the 2-volt AC scale. Connect voltmeter leads to crank angle sensor, located on side of engine block. Crank engine and observe voltmeter reading. Crank angle sensor should generate a voltage signal of about .01 volt at slow cranking speed to greater than .02 volt (20 mV) at high cranking speed. Tach Pulse (RPM) Signal

Connect "Scan" tester to ALDL diagnostic connector. RPM should be indicated on tester when engine is cranked or running. Tach pulse (RPM reference will be indicated as a voltage signal when a DVOM with a minimum 10-megohm input impedance) is touched to circuit No. 430 ECM terminal. For circuit and terminal reference, see appropriate schematic in NO START - ENGINE CRANKS OKAY in this article. C(3)I Spark

Disconnect tachometer wire (if equipped). A shorted tachometer will not allow vehicle to start. Disconnect cam sensor and attempt to start engine. If engine starts, see cam sensor trouble code in appropriate SELFDIAGNOSTICS article. Check for adequate spark with Spark Tester (ST-125). Check for spark on plug wires No. 1, 3 and 5 (one at a time). Leave matching plug wire connected while checking for spark. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire. Ignition Coil Power Source

Disconnect ignition coil leads. Use an ohmmeter to check ignition coil resistance. Primary resistance should be .5-.9 ohm. Secondary resistance should be 5000-10,000 ohms. Replace ignition coil if not within specification. Tach Pulse (RPM Reference) Signal

Connect "Scan" tester to ALDL diagnostic connector. RPM should be indicated on tester when engine is cranked or running. Tach pulse (RPM reference will be indicated as a voltage signal when a DVOM with a minimum 10-megohm input impedance) is touched to circuit No. 430 ECM terminal. For circuit and terminal reference, see appropriate schematic in NO START - ENGINE CRANKS OKAY in this article.

IDLE SPEED & IGNITION TIMING Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ON-VEHICLE ADJUSTMENTS article.

DIAGNOSTIC CIRCUIT CHECK (EXCEPT ECM/BCM EQUIPPED VEHICLES) The Diagnostic Circuit Check determines:   

If SERVICE ENGINE SOON light works. If ECM is operating and can recognize a fault. If any codes are stored.

After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in the diagnostic circuit check, if no codes are indicated and driveability problems still exist, see TESTS W/O CODES article and SCAN TESTER USAGE in appropriate TESTS W/CODES - 3.8L PFI article. CARBURETED 1. Check SERVICE ENGINE SOON light operation. With ignition on and engine off, light should be on steady. If light illuminates and stays on steady, go to next step. If light does not illuminate, go to SERVICE ENGINE SOON LIGHT INOPERATIVE. If light flashes, go to step 3). 2. Grounding the ALDL "test" terminal should cause SERVICE ENGINE SOON light to flash a Code 12, followed by any codes stored in ECM memory. If light goes from bright to dim, this is not considered a code. If lights dims or remains on, see SERVICE ENGINE SOON LIGHT ON OR WON'T FLASH CODE 12. 3. If light begins to flash as soon as ignition is turned on, check for a short to ground on the diagnostic test terminal wire between ALDL terminal "B" and ECM terminal No. 5. If circuit is okay, replace ECM. SERVICE ENGINE SOON Light Inoperative

1. If the "SERVICE ENGINE SOON" light does not illuminate with ignition on and engine off, attempt to start engine. If engine starts, go to step 3). If engine does not start, check fusible links at battery and ECM fuse. If fusible links or ECM fuse are blown, repair short to ground. 2. If fusible links and ECM fuse are okay, turn ignition on and check power circuits to ECM, including keep alive memory and ignition feed. See the WIRING DIAGRAMS article in this section for power terminal identification. If power is not available to power terminals of ECM, check for opens in power circuits. If power is available to ECM power terminals, check for poor ECM ground circuits, or replace faulty ECM. 3. If engine starts and "SERVICE ENGINE SOON" light does not illuminate, turn ignition off. Disconnect ECM connectors. Turn ignition on and jumper ECM "SERVICE ENGINE SOON" light driver terminal to ground using a test light. See the appropriate WIRING DIAGRAMS article in this section for power terminal identification. 4. If light is now on, repair light driver terminal connections at ECM or replace faulty ECM. If light stays off when test light is used to ground light driver terminal, check for blown instrument panel fuse, faulty bulb, open in light driver circuit between ECM and bulb, driver circuit shorted to voltage, or an open in the ignition feed to the "SERVICE ENGINE SOON" light. SERVICE ENGINE SOON Light On Or Won't Flash Code 12

1. Check for battery voltage at ECM terminals "C" and "R". Voltage must be greater than 11 volts. With ALDL "test" terminal not grounded, check voltage at lamp driver module terminal "C". 2. If voltage is 11 volts or greater, check for short to voltage on wire between terminal "C" of lamp driver module and ECM terminal "G". If voltage on terminal "C" of lamp driver module is less than 11 volts, ground lamp driver terminal "C" and note SERVICE ENGINE SOON light. If light is off, go to step 4). 3. If light is on, disconnect driver and note SERVICE ENGINE SOON LIGHT. If light is now on, repair short to ground in wire between lamp driver module terminal "E" and SERVICE ENGINE SOON light. If light is off, repair connection at lamp driver module or replace faulty lamp driver module. 4. If light is off with terminal "C" of driver grounded, ground ECM terminal "G" and note light. This should turn light off. If it does, go to next step. If light stays on, repair open in wire between terminal "C" of lamp driver module and terminal "G" of ECM. 5. If light goes off with terminal "G" of ECM grounded, ground ECM terminal No. 5. If light flashes Code 12, repair open in circuit between terminal No. 5 of ECM and ALDL "test" terminal "B". If Code 12 does not flash, check voltage from between ground and ECM terminal "U". This checks for bad ground in ECM. Terminals "A" and "U" are connected together inside ECM. If reading is one volt or greater, repair poor connections from ECM terminals "A" and "U" to ground. 6. If voltage from terminal "U" to ground is less than one volt, turn ignition off. Remove PROM from ECM. Turn ignition on. Wait 30 seconds and check for Code 51. This step distinguishes between a faulty ECM and PROM. Normal response is for Code 51 to flash even though PROM is not installed in ECM. If there is no Code 51, ECM is faulty. If Code 51 is present, check for proper PROM installation. If PROM was installed properly, install new PROM and repeat diagnostic circuit check. If Code 12 is not flashed, replace ECM.

Fig. 38: ALDL Connector Terminal Identification Courtesy of GENERAL MOTORS CORP.

Fig. 39: Carbureted Diagnostic Circuit Schematic Courtesy of GENERAL MOTORS CORP. FUEL INJECTED 1. Check operation of SERVICE ENGINE SOON light. Turn ignition on with engine off. See Fig. 38 . SERVICE ENGINE SOON light should be on steady. If light illuminates and stays on steady, go to next step. If light does not illuminate, go to SERVICE ENGINE SOON LIGHT INOPERATIVE. If light flashes, go to step 3). 2. Grounding the ALDL "test" terminal at this time should cause SERVICE ENGINE SOON light to flash a Code 12, followed by any codes stored in ECM memory. If light goes from bright to dim, this is not considered a code. If light dims or remains on, and does not flash Code 12, see SERVICE ENGINE SOON LIGHT ON STEADY OR WON'T FLASH CODE 12. 3. If light begins to flash as soon as ignition is turned on, check for a short to ground on the diagnostic test terminal wire between ALDL terminal "B" and ECM terminal No. 5. If circuit is okay, replace ECM. SERVICE ENGINE SOON Light Inoperative

1. If SERVICE ENGINE SOON light does not illuminate with ignition on and engine off, attempt to start engine. If engine starts, go to step 3). If engine does not start, check fusible links at battery and ECM fuse. If fusible links or ECM fuse are blown, repair short to ground. 2. If fusible links and ECM fuse are okay, turn ignition on and check power circuits to ECM, including keep alive memory and ignition feed. See appropriate diagram in WIRING DIAGRAMS article for power terminal identification. If power is not available to power terminals of ECM, check for opens in power circuits. If power is available to ECM power terminals, check for poor ECM ground circuits, or replace faulty ECM. 3. If engine starts and SERVICE ENGINE SOON light does not illuminate, turn ignition off. Disconnect ECM connectors. Turn ignition on and jumper ECM SERVICE ENGINE SOON light driver terminal to

ground using a test light. See appropriate diagram in WIRING DIAGRAMS article for power terminal identification. 4. If light is now on, repair light driver terminal connections at ECM or replace faulty ECM. If light stays off when test light is used to ground light driver terminal, check for blown instrument panel fuse, faulty bulb, open in light driver circuit between ECM and bulb, driver circuit shorted to voltage, or an open in the ignition feed to the SERVICE ENGINE SOON light. SERVICE ENGINE SOON Light On All The Time Or Won't Flash Code 12

1. Turn ignition off. Disconnect ECM connectors. Turn ignition on. If SERVICE ENGINE SOON light is on, check for short to ground in light driver circuit between light and ECM driver terminal. See appropriate diagram in WIRING DIAGRAMS article for terminal identification. 2. If light is off with ECM connectors disconnected, turn ignition off. Reconnect ECM connectors. Turn ignition on with engine off. Using a DVOM, check voltage at ALDL "test" terminal "B". See Fig. 38 . If voltage is greater than 9 volts, check for a short to voltage on ALDL terminal "B" wire between ECM and ALDL connector. If voltage is 5-6 volts, proceed to next step. If voltage is less than 5 volts, backprobe appropriate ECM terminal with DVOM. See appropriate diagram in WIRING DIAGRAMS article for terminal identification. If 5-6 volts is now present, repair open or short in wire between ECM and ALDL terminal "B". 3. If voltage at terminal "B" of ALDL connector is 5-6 volts, jumper that wire terminal at ECM to ground. If SERVICE ENGINE SOON light flashes a Code 12, and ALDL terminal "A" was used when grounding terminal "B", check terminal "A" for continuity to ground. If SERVICE ENGINE SOON light does not flash when ECM end of terminal "B" wire is jumpered to ground, check PROM/MEM-CAL for proper installation. If installed correctly, replace ECM, using original PROM/MEM-CAL. Repeat diagnostic circuit check. If Code 12 still does not flash, replace PROM/MEM-CAL. Replace PROM/MEM-CAL only after replacing ECM, as PROM/MEM-CAL is not likely to be at fault.

Fig. 40: Typical Fuel Injection Diagnostic Circuit Schematic Courtesy of GENERAL MOTORS CORP.

SUMMARY If no problems were found while performing BASIC TESTING , no trouble codes (or only intermittent ones) were found while performing DIAGNOSTIC CIRCUIT CHECK and driveability problems exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnosis procedures.

ENGINE PERFORMANCE General Motors - Removal, Overhaul & Installation

INTRODUCTION Removal, overhaul and installation procedures (when given by manufacturer) are covered in this article. If component removal and installation is primarily an unbolt and bolt on procedure, only a simple torque specification may be supplied. FUEL SYSTEM (CARBURETOR) The Rochester E4MC carburetor is used only on the 5.0L (VIN Y) engines. Carburetor number is stamped vertically on float bowl, near secondary throttle. See Fig. 1 . This number must be used for ordering replacement components and performing adjustments. Carburetor identification number must be transferred onto new float bowl if float bowl is replaced. These carburetors are equipped with a computer control feedback system. This is indicated by the first letter "E" of identification number. The last letter of identification number indicates type of choke used. Letter "C" indicates a hot air type choke.

Fig. 1: Carburetor Identification Label Courtesy of GENERAL MOTORS CORP.

ON-VEHICLE ADJUSTMENTS

NOTE:

For all on-vehicle adjustments, see ON-VEHICLE ADJUSTMENTS article.

REMOVAL & INSTALLATION ELECTRONIC CONTROL MODULE (ECM) CAUTION: Electronic components used in control systems are designed to carry very low voltages, as little as a 30-volt charge created by static electricity can cause a total or degrading failure in ECM or other electronic components containing integrated circuits. Before servicing ECM, ground yourself and ground the work area to discharge stored electricity. STATIC CHARGE Movement Handling Clear Plastic Bag Handling Vinyl Envelope Sliding On Velour Seat Walking On Carpet Walking On Tile/Vinyl

Relative Humidity 1020% 20,000 7000 15,000 35,000 12,000

Relative Humidity 6590% 1200 600 400 1500 50

CAUTION: DO NOT remove part from packaging until ready to install. Ground any static-proof package PRIOR to opening. DO NOT touch electrical terminals of components unless properly grounded. DO NOT lay electrical components on car seat, carpeting or dashboard. Use electrostatic protection mat and ground strap whenever possible.

Fig. 2: Servicing ECM Using 3M Anti-Static Mat Courtesy of GENERAL MOTORS CORP. NOTE:

Prior to replacement of ECM, a careful inspection of all wiring and control components should be made. Failure to test for shorts, grounds and reasons for Quad-Driver failure may cause repeat failure of ECM. To prevent internal damage to ECM, ignition switch must be in OFF position when disconnecting or reconnecting ECM connectors or 12-volt components.

Removal

Turn ignition switch to OFF position. Disconnect negative battery cable. Remove electrical connectors from ECM. Remove ECM from vehicle. Remove MEM-CAL or PROM and CALPAC (if equipped) from ECM. Installation

Install PROM and CALPAC (if equipped) or MEM-CAL in new ECM. Reinstall ECM into vehicle. Reconnect electrical connectors to ECM. Install access panels. Reconnect negative battery cable to battery. CALPAC Removal & Installation

Some ECM models use a CALPAC as well as a PROM. See Fig. 3 . The CALPAC must also be removed from replaced ECM and installed in new one. Removal and replacement procedures for CALPAC are same as for PROM. See Programmable Read-Only Memory (PROM) in this article. If units are installed improperly,

grounding diagnostic test lead will set Code 52.

Fig. 3: ECM With PROM & CALPAC Courtesy of GENERAL MOTORS CORP. MEM-CAL Removal

Disconnect negative battery cable. Remove ECM from vehicle. Using 2 fingers, push retaining clips back from MEM-CAL. At same time, grasp it at both ends and lift up out of socket. DO NOT remove MEM-CAL cover. Installation

1. Carefully align MEM-CAL pins with ECM pin holes. DO NOT press in middle of MEM-CAL. Push downward evenly on ends of MEM-CAL until retaining clips on ends of MEM-CAL snap into place. 2. Install ECM. Reconnect negative battery cable. Turn ignition on and ground ALDL connector. Code 12 should flash at least 4 times (if not other codes are present). If code(s) 42, 43, 51 or 52 is present, or if CHECK ENGINE light stays on constantly with code(s) present, MEM-CAL is not fully seated or defective. If it is necessary to remove MEM-CAL, follow previous removal instructions. PROGRAMMABLE READ-ONLY MEMORY (PROM) Removal

1. Remove ECM from vehicle as previously described. Position ECM so that bottom cover is facing upward. Remove slide-off PROM access cover by depressing locking tab. 2. Using PROM removal tool, grasp PROM at narrow ends. Gently rock PROM from end to end while pulling up. If new PROM is to be installed, remove old PROM from PROM carrier.

NOTE:

Note reference notch locations in PROM, carrier and ECM for reassembly reference.

Installation

1. Ensure new PROM has same service number as old one. Place new PROM in PROM carrier. Position squarely over ECM PROM socket. Press on PROM carrier until PROM is firmly seated in ECM. NOTE:

Ensure reference notches in both ECM and PROM are properly aligned. If PROM is installed backwards and key is turned on, PROM will be destroyed.

2. Reinstall PROM access cover on ECM. Reinstall ECM in vehicle as previously described. Start engine and ground ALDL diagnostic test connector. Watch for trouble Code 51 or 52. 3. If this occurs, PROM is not fully seated in ECM, installed backwards, has bent pins or is defective. If pins are bent and crack when straightened, PROM must be replaced. If PROM is installed backwards or is defective, it must be replaced. ELECTRONIC SPARK CONTROL (ESC) MODULE NOTE:

The ESC is located on a bracket behind the distributor, mounted to firewall.

Removal & Installation

Turn ignition off. Remove screws holding bracket to firewall. Rotate bracket to access ESC module. Disconnect ESC module harness connector. Remove ESC mounting screws and remove ESC. To install, reverse removal procedure. THROTTLE BODY Removal

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI) in this article. Remove air inlet ducts. Disconnect and mark electrical connections and vacuum hoses from throttle body. Disconnect control cables from throttle body. 2. Drain cooling system. Remove coolant hoses. Remove throttle body retaining bolts. Remove throttle body and gasket. NOTE:

Identification number is stamped on throttle body near coolant cover. Identification number must be used for ordering replacement components.

Installation

1. To install, reverse removal procedure using new gasket. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS at end of article. Fill cooling system. 2. If a new Idle Air Control (IAC) is being installed, ensure proper IAC pintle length setting prior to

installation. See appropriate IDLE AIR CONTROL VALVE under REMOVAL & INSTALLATION in this article. Adjust idle speed and TPS (if removed). See ON-VEHICLE ADJUSTMENTS . FUEL PRESSURE REGULATOR Removal (2.0L, 2.3L, 3.3L, 3.8L & 4.5L)

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI) in this article. Disconnect pressure regulator-to-fuel rail hose. On 2.3L, remove fuel rail. See FUEL RAIL & INJECTORS in this article. 2. On all models, remove pressure regulator retaining bolts. Remove pressure regulator from fuel rail. On 2.3L, remove pressure regulator retainer and seal from fuel rail. Installation (2.0L, 2.3L, 3.3L, 3.8L & 4.5L)

To install, reverse removal procedures. Lubricate fuel rail seal with oil and install in regulator. Tighten bolts to specification. See TORQUE SPECIFICATIONS at end of article. Removal (3.1L)

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI) in this article. Remove fuel rails. See FUEL RAIL & INJECTORS in this article. 2. Remove inlet and return fuel fittings and gaskets. Remove pressure regulator-to-bracket retaining bolts. Separate fuel rails from pressure regulator. 3. Remove pressure regulator base-to-fuel rail connector tubes from pressure regulator. Installation (3.1L)

1. To install, reverse removal procedures. Lubricate new "O" rings with oil. Install fuel return "O" rings on fuel rails. Return "O" rings are larger in diameter than connector tube "O" rings. 2. Tighten bolts to specification. See TORQUE SPECIFICATIONS at end of article. Removal (5.0L & 5.7L)

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI) in this article. Remove fuel rails. See FUEL RAIL & INJECTORS in this article. 2. Remove front crossover tube retainer on right fuel rail. Remove rear crossover tube retainer at pressure regulator on right fuel rail. Separate fuel rail assemblies. 3. Remove pressure regulator bracket-to-fuel rail bolt. Remove bracket to regulator base bolt. Remove bracket. Remove fuel outlet tube-to-right fuel rail bolt. Remove base-to-right fuel rail bolt. 4. Remove pressure regulator assembly from fuel rail. Rotate pressure regulator and remove from outlet tube. Remove base-to-fuel rail connector tube. Remove "O" rings from connector tube, outlet tube, and crossover tubes. Installation (5.0L & 5.7L)

To install, reverse removal procedures. Install new "O" rings and lubricate with oil. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS at end of article. FUEL RAIL & INJECTORS CAUTION: DO NOT remove fuel inlet fitting on 2.3L or 3.3L models. Inlet fitting is staked to the fuel rail. Removal (2.0L, 3.3L, 3.8L & 4.5L)

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI) in this article. Turn ignition off. Disconnect negative battery cable. Disconnect wiring connectors from injectors. Disconnect and plug hoses to fuel rail. 2. On 4.5L, remove power steering pump and move to side. On all models, remove fuel rail retaining bolts. Remove injector-to-fuel rail retaining clip (if used). Separate fuel rail from injectors. Remove injectors. See Fig. 4 .

Fig. 4: View Of 2.0L, 3.3L & 3.8L Fuel Rail Assembly Courtesy of GENERAL MOTORS CORP.

Fig. 5: View Of 4.5L Fuel Rail Assembly Courtesy of GENERAL MOTORS CORP. NOTE:

If injector is replaced, ensure replacement injector has the same part number as that removed.

Installation (2.0L, 3.3L, 3.8L & 4.5L)

To install, reverse removal procedure. Coat new "O" rings with oil. Install "O" rings on injectors. Tighten fuel rail retaining bolts to specification. See TORQUE SPECIFICATIONS at end of article. Removal (2.3L)

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI) in this article. Remove crankcase ventilation oil/separator. 2. Remove fuel lines from fuel rail. Remove vacuum line at pressure regulator. Disconnect wiring connector while pushing inward on connector. Remove fuel rail retaining bolts. Remove fuel rail. See Fig. 6 .

3. Remove injector-to-fuel rail retaining clip. Remove injector from fuel rail. Remove injector "O" rings.

Fig. 6: View Of 2.3L Fuel Rail Assembly Courtesy of GENERAL MOTORS CORP. Installation (2.3L)

To install reverse removal procedure. Lubricate injector "O" rings with oil. Install injector-to-fuel rail retaining clip with open end facing injector electrical connection. Tighten fuel rail retaining bolts. Removal (3.1, 5.0L & 5.7L)

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI) in this article. Disconnect negative battery cable. Remove intake manifold upper plenum. Disconnect and mark vacuum lines. Remove EGR-to-intake manifold retaining bolts. Some models use an EGR pipe which requires removal at EGR base. 2. Remove throttle cable bracket bolts. Disconnect cables and electrical wiring connections from throttle body. Remove throttle body from intake manifold. Remove plenum and gasket. See Fig. 7 .

Fig. 7: View Of 3.1L, 5.0L & 5.7L Fuel Rail Assembly Courtesy of GENERAL MOTORS CORP. 3. Disconnect vacuum hose to pressure regulator. Relieve fuel pressure. Remove runners. Disconnect fuel lines from fuel rail. With ignition off, disconnect electrical connections from injectors. 4. Remove fuel rail retaining bolts. Remove fuel rail and injectors. On 5.0L and 5.7L, rotate injector retaining clip to unlock position. 5. On all models, remove injectors from fuel rail. Remove "O" rings from injectors. Installation (3.1, 5.0L & 5.7L)

To install, reverse removal procedure. Coat new "O" rings with oil. Install "O" rings on injectors. Tighten bolts to specification. See TORQUE SPECIFICATIONS at end of article. IDLE SPEED CONTROL MOTOR (4.5L VIN 3) Removal & Installation

Remove air cleaner. Disconnect electrical connector. Remove retaining screws and Idle Speed Control (ISC). To install, reverse removal procedure. To adjust ISC minimum and maximum authority, see ON-VEHICLE ADJUSTMENTS article in this section. NOTE:

The ISC motor is factory calibrated and should not be disassembled. Replace as complete assembly only. DO NOT soak ISC motor in carburetor cleaner.

IDLE AIR CONTROL (IAC) VALVE (PFI) CAUTION: For calibration purposes, several different IAC style valves are used. Ensure replacement valve is same part number as original valve.

Removal

Remove electrical connector from IAC valve. Remove IAC valve and gasket or "O" ring. IAC valve screws into housing on 2.0L, 5.0L and 5.7L vehicles. Retaining screws are used on 2.3L, 3.1L, 3.3L and 3.8L vehicles. Installation

1. The extended distance of a new IAC must be checked prior to installation. Damage will occur if measurement is incorrect. Distance must not exceed 1 1/8" (28 mm). Measurement should be taken from valve housing flange to end of cone. DO NOT extend or retract pintle on IAC valve which has been in service or damage to internal worm drive may occur. 2. To retract pintle on new IAC (except 2.0L models), slowly exert finger pressure on valve. On 2.0L models, identify IAC valve as being either a type I or type II valve. Type I IAC valve has a collar around the connector end of IAC valve. See Fig. 8 . 3. To retract type I IAC valve, exert firm pressure on plunger (a slight side-to-side movement may be helpful). To retract plunger on type II IAC valve, compress retaining spring from valve while turning valve inward with a clockwise motion. Return spring to original position with straight portion of spring end aligned with flat surface of valve. 4. Install new "O" ring or gasket on valve. Coat "O" ring with oil. Install IAC valve. Tighten IAC valve to specifications. See TORQUE SPECIFICATIONS at end of article. 5. Install electrical connector. The IAC resets when ignition switch is turned from the "ON" to the "OFF" position (at speeds greater than 35 MPH on 2.0L). On some models it may be necessary to shift transmission into Drive (auto. trans.) or Neutral (man. trans.) before learning process is complete.

Fig. 8: 2.0L IAC Valve Identification Courtesy of GENERAL MOTORS CORP. THROTTLE BODY An 8-digit unit identification number is stamped on throttle body assembly. On model 220, number is stamped vertically on front of throttle body at Throttle Position Sensor (TPS) side. On model 700, number can be found on TPS side of mounting flange. Letter codes are stamped on throttle body at external tube locations to identify vacuum hose connections. Removal

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (TBI) in this article. Disconnect negative battery cable. Remove air cleaner and related ducting. 2. Remove electrical connectors from IAC, TPS and fuel injector(s). Lay wiring harness aside. Remove throttle cable, return springs, transmission/transaxle cable, and cruise control cable (if equipped). Label and remove vacuum hoses. 3. Remove fuel feed and return lines. Use 2 wrenches to prevent fuel nuts in throttle body from loosening. Remove fuel line "O" rings and discard. Remove throttle body retaining bolts. Remove TBI unit and base gasket. Discard base gasket. Installation

1. Using new base gasket, install throttle body unit to intake manifold. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS at end of article. Install new "O" rings onto fuel lines. 2. Connect fuel feed and return lines to throttle body. Use a back-up wrench to prevent fuel line fittings in throttle body from turning. Tighten fuel line nuts to specification. See TORQUE SPECIFICATIONS at end of article. Install vacuum hoses and brackets. To complete installation, reverse removal procedure. THROTTLE BODY INJECTOR Removal (Model 220)

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (TBI) in this article. Remove throttle body cover and leave cover gasket in place. Using screwdriver and fulcrum, carefully pry injector out. See Fig. 9 . Remove small "O" ring from nozzle end of injector. 2. Carefully rotate injector fuel filter back and forth to remove fuel filter from base of injector. Remove and discard throttle body cover gasket. Remove large "O" ring and steel back-up washer from top counterbore of throttle body injector cavity. Installation (Model 220)

1. Install fuel filter on nozzle end of fuel injector. Large end of filter must face injector so that filter covers raised rib at base of injector. Lubricate small "O" ring with ATF and push "O" ring on nozzle end of injector until it presses against injector filter. 2. Install steel back-up washer in top counterbore of throttle body injector cavity. Lubricate large "O" ring with ATF and install "O" ring directly over back-up washer. See Fig. 31 . Ensure that "O" ring is seated

properly in cavity and is flush with top of throttle body casting. CAUTION: Back-up washer and large "O" ring must be installed before injector. Improper seating of "O" ring will cause fuel leak. 3. Install "O" ring on injector. Install injector into cavity by aligning raised lug on injector base with cast-in notch of throttle body cavity. Push down on injector until fully seated. Electrical terminals of injector will be approximately parallel with throttle shaft. Install throttle body cover. Removal (Model 700)

Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (TBI) in this article. Remove fuel injector retainer screw and retainer. Using screwdriver and fulcrum on side of injector opposite connector terminals, carefully pry injector out. See Fig. 9 . Remove upper and lower "O" rings and discard.

Fig. 9: Typical Throttle Body Injector Removal Courtesy of GENERAL MOTORS CORP. Installation (Model 700)

1. Lubricate new upper and lower "O" rings with engine oil and place them on injector. Ensure upper ring is in groove and lower ring is flush against filter. 2. Position injector in fuel meter assembly with electrical connector facing cutout for wire grommet. 3. Push injector down to seat in cavity. Install injector retainer. Coat injector retainer screw with thread locking compound and install. Tighten screw to 27 INCH lbs. (3.0 N.m). IDLE AIR CONTROL (IAC) VALVE (TBI) Removal

Remove air cleaner and related ducting. Remove Idle Air Control (IAC) electrical connector. On model 220, unscrew IAC valve. On model 700, remove IAC retaining screws and remove IAC valve. Replace as necessary. Installation

1. Inspect gasket or "O" ring for damage. Replace as necessary. Measure distance from IAC contact flange to tip of pintle. Distance should not exceed 1 1/8" (28 mm). If valve is extended too far, damage to valve will result during installation. 2. To set IAC pintle length on a new IAC, use finger pressure to slowly retract pintle. Lubricate new "O" ring with ATF and install new gasket. Install IAC valve on throttle body. Tighten IAC valve to specification. See TORQUE SPECIFICATIONS at end of article. CAUTION: DO NOT extend or retract pintle if IAC valve has been in service or damage to worm gear will result. 3. Connect electrical lead to IAC valve and install air cleaner. Start engine and allow it to reach normal operating temperature. Drive vehicle at least 43 MPH to allow ECM to reset idle speed. It may be necessary to cycle ignition off and restart vehicle before proper idle will be initialized. FUEL PUMP (FUEL INJECTION) Removal (Camaro & Firebird)

1. Relieve fuel system pressure. Disconnect battery negative terminal. Raise car on hoist. Drain fuel from fuel tank. Disconnect exhaust pipe at converter and rear hanger. Allow exhaust to hang over axle assembly. 2. Remove tailpipe and muffler heat shields. Remove fuel filler neck shield behind left rear tire. Remove rear suspension track bar and brace. Disconnect harness connector to fuel pump assembly. 3. Disconnect all fuel lines. Remove fuel line retaining bracket on left side and remove brake line clip from bracket. 4. Position support jack under axle assembly. Disconnect lower ends of shock absorbers. Disconnect rear stabilizer bar from frame (if equipped). 5. On models equipped with 2-piece driveshaft, remove center support bearing-to-rear axle torque arm bolts. On all models, remove rear axle torque arm-to-differential housing bolts/nuts. Wire end of rear axle torque arm aside. Remove driveshaft-to-differential yoke bolts/screws. Wire end of driveshaft aside.

6. Lower rear suspension as far as possible without damaging brake lines and cables and remove both coil springs. Remove tank straps bolts. Remove fuel tank by rotating front of tank down and sliding to the right. Remove fuel pump assembly from fuel tank. Removal (Corvette)

1. Relieve fuel system pressure. Remove fuse marked "Fuel Pump" from fuse block in passenger compartment. Crank engine. Engine will start and run until fuel in line is exhausted. When engine stops, engage starter again for 3 seconds to ensure engine will not start. 2. Remove battery ground cable. Remove fuel cap, fuel tank filler door. Remove filler neck housing and disconnect drain hose. Remove screws attaching fuel meter and pump assembly to tank. Disconnect fuel hoses, vapor hose and electrical connector from fuel meter and pump assembly. Pull pump up into pulsator while pulling outward away from bottom support. Remove pump. Removal (Except Camaro, Corvette & Firebird)

1. Disconnect negative battery cable. Relieve fuel pressure. Relieve fuel pressure. See FUEL PRESSURE RELIEF under FUEL SYSTEM (TBI) or FUEL PRESSURE RELIEF under FUEL SYSTEM (PFI). Remove filler neck. Lower fuel tank. Disconnect fuel lines and electrical connection. 2. Remove fuel level sending unit and pump retaining bolts or cam lock ring. Lift assembly from fuel tank and remove fuel pump from sending unit. 3. Pull fuel pump upward while pulling outward away from bottom support. Use care not to damage rubber insulator and strainer. Installation

To install, reverse removal procedure using new "O" ring/gasket. IGNITION MODULE (DIS) Removal & Installation (2.2L, 2.5L & 3.1L)

1. Disconnect negative battery cable. Unplug connectors at ignition module. Disconnect spark plug wires from coil pack. Remove ignition module from engine block. Remove coils and assembly plate. 2. On 2.5L engines, inspect crankshaft sensor "O" ring for wear, cracks or other damage. Replace if necessary. Lubricate new "O" ring with engine oil before installing. 3. To install, reverse removal procedure. Tighten ignition coil nuts and module to specification. See TORQUE SPECIFICATIONS at the end of article. NOTE:

If spark plug boots adheres to spark plugs, use Boot Remover (J-36011). Twist first and then pull upward. Boots must be in place on housing prior to ignition system assembly installation or damage may result.

IGNITION MODULE (IDI) Removal & Installation (2.3L)

1. Disconnect negative battery cable. Disconnect 11-pin harness connector. Remove 4 ignition module cover-to-cam carrier bolts. 2. Remove ignition system assembly from engine. Remove 4 housing cover screws. Remove housing cover. Remove coil harness connector from module. Remove module-to-cover screws. Remove module from cover. To install, reverse removal procedure. NOTE:

DO NOT wipe grease from module or coil if module is not being replaced. If a new module is being installed, silicone grease will be included. Spread grease on metal face of module and on the cover where the module seats. This grease is necessary for module cooling purposes.

Fig. 10: Distributorless Ignition Module Components (3.1L) Courtesy of GENERAL MOTORS CORP. IGNITION MODULE (C3I) Removal & Installation (3.3L & 3.8L)

Disconnect negative battery cable. Unplug 14-way connector at ignition module. Disconnect spark plug wires from coil pack. Remove nuts and washers securing ignition module to bracket. Remove coil-to-ignition module Torx screws. Note wire colors for reassembly. Unplug connectors between ignition coil and module. Remove module. To install, reverse removal procedure.

CRANKSHAFT/COMBINATION SENSOR (C3I) Removal (3.3L & 3.8L)

1. Remove serpentine belt from crankshaft pulley. Raise vehicle on hoist. Remove right front tire and wheel assembly. Remove right side lower engine compartment filler panel and right lower wheelwell-to-engine compartment bolt, if necessary. 2. Using 28-mm socket, remove crankshaft harmonic balancer retaining bolt. Remove harmonic balancer. Disconnect sensor harness connector. Remove sensor and pedestal (as an assembly) from block. Installation (3.3L & 3.8L)

1. Loosen pinch bolt until sensor is free to slide in pedestal. Position sensor, with pedestal attached, onto Installer (J-37089). Position installer onto crankshaft. See Fig. 11 . 2. Install pedestal-to-block bolts and pedestal pinch bolt. Tighten bolts. Remove installer. Place harmonic balancer onto installer. Rotate balancer on installer. If any vanes of interrupter rings contact installer, replace harmonic balancer. 3. Install balancer on crankshaft. To complete installation, reverse removal procedure. Tighten balancer retaining bolt to specification. See TORQUE SPECIFICATIONS at end of article.

Fig. 11: Installing C3I Crankshaft/Combination Sensor Courtesy of GENERAL MOTORS CORP.

CRANKSHAFT POSITION SENSOR (DIS & IDI) Removal & Installation (2.5L)

Remove DIS ignition module. Remove crankshaft sensor mounting screws and remove sensor from DIS module. Inspect "O" ring for wear, before installing DIS module. Replace if necessary. To install, reverse removal procedure. See TORQUE SPECIFICATIONS in this article. Removal & Installation (2.0L, 2.3L & 3.1L)

1. Disconnect the negative battery cable. Remove serpentine belt from crankshaft. Raise and support vehicle. Remove right front tire and wheel assembly. Remove right inner fender access cover. 2. Using a 28mm socket, remove harmonic balancer retaining bolt. Remove harmonic balancer. Disconnect the crankshaft sensor electrical connector. 3. Remove the crankshaft sensor retaining and pinch bolts. See Fig. 12 or Fig. 13 . Remove the crankshaft sensor and mounting bracket as an assembly from engine block. Remove the crankshaft sensor from its mounting bracket. Installation

1. Loosely install the crankshaft sensor onto its mounting bracket. Position the sensor/bracket assembly onto the Alignment Tool (J-37089). Position the Alignment Tool onto the crankshaft. 2. Install and tighten the crankshaft sensor retaining bolts to 22 Ft. Lbs. (30 N.m). Install and tighten the mounting bracket pinch bolt to 89 INCH Lbs. (10 N.m). Remove the Alignment Tool from the crankshaft sensor/bracket assembly. Place the Alignment Tool onto the harmonic balancer and turn the harmonic balancer. 3. If any vane of the harmonic balancer touches the Alignment tool, replace the balancer assembly. Install the balancer onto the crankshaft. Tighten the harmonic balancer retaining bolt to 219 Ft. Lbs. (298 N.m). Install inner fender shield. 4. Install the right front tire and wheel assembly. Tighten the lug nuts to 100 Ft. Lbs (140 N.m). Lower vehicle and install the serpentine belt.

Fig. 12: Removing/Installing Crankshaft & Camshaft Sensors (2.0L, 2.3L, 3.3L & 3.8L)

Fig. 13: Removing/Installing Crankshaft & Camshaft Sensors (3.1L) CAMSHAFT SENSOR (C3I) Removal & Installation (3.3L & 3.8L)

Disconnect the negative battery cable. Remove water pump pulley retaining bolts. Remove serpentine belt. Remove water pump pulley. Remove the weather pack connector. Remove the camshaft sensor retaining bolt. See Fig. 12 . Pull and twist the sensor to remove it from the engine front cover. Installation

Lubricate the camshaft sensor "O" ring. Push and twist the camshaft sensor to install. Install the sensor retaining bolt, weather pack connector, water pump pulley, and serpentine belt. Tighten the camshaft sensor retaining bolt to 75 INCH Lbs. (8.5 N.m). Install and tighten the water pump pulley retaining bolts to 115 INCH Lbs. (13 N.m). Reconnect the negative battery cable. IGNITION COIL (C3I) Type II (3.3L)

Disconnect negative battery cable. Remove spark plug wires from coil. Remove bolts securing coil to module. Remove coil assembly. To install, reverse removal procedure. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS at end of article.

Type III (3.8L)

Disconnect negative battery cable. Remove spark plug wires from coil pack. Remove Torx screws securing coil to ignition module. Tilt coil assembly back. Disconnect module connectors and remove coil pack. To install, reverse removal procedure. Tighten retaining bolts to specifications. See TORQUE SPECIFICATIONS at end of article. IGNITION COILS (DIS & IDI) Removal & Installation (2.0L, 2.2L, 2.5L & 3.1L)

Disconnect negative battery cable. Remove spark plug wires from coils. Remove nuts or screws from ignition coils. Remove coils. To install, reverse removal procedure. Removal & Installation (2.3L)

Disconnect negative battery cable. Disconnect 11-pin harness connector. Remove ignition cover-to-cam carrier bolts. Remove ignition system assembly from engine. Remove housing cover screws. Remove housing cover. Remove coil harness connector from module. Remove module-to-cover screws. Remove module from cover. To install, reverse removal procedures. See TORQUE SPECIFICATIONS in this article. THROTTLE POSITION SENSOR (TPS) Removal

Disconnect electrical connection from TPS. Remove TPS retaining screws. Remove TPS. Installation

1. With throttle valve in closed position, install TPS on throttle body. Ensure TPS lever engages with drive lever on throttle shaft. Install retaining screws and electrical connection. 2. The TPS on most models are self-zeroing and are not adjustable. On these models, as long as voltage is within a certain range, or less than 1.25 volts, TPS need not be serviced. On adjustable models, adjust TPS to specification and tighten retaining screws. See ON-VEHICLE ADJUSTMENTS article in this section. OXYGEN (O2) SENSOR O2 sensor is mounted in the exhaust pipe just below the exhaust manifold. It is equipped with a permanent pigtail which must be protected from damage when the sensor is removed. Removal

1. Ensure sensor is free of contaminants, avoid using cleaning solvents of any type. Sensor may be difficult to remove when engine temperature is less than 120Â°F (48Â°C). Excessive removal force may damage threads in exhaust manifold or pipe. 2. Disconnect negative battery cable at battery. Disconnect electrical connector from oxygen sensor. Carefully remove oxygen sensor from exhaust pipe.

CAUTION: Correct torque of O2 sensor is critical to prevent crushing glass beads in graphite anti-seize compound. Crushing glass beads will cause sensor to seize in exhaust manifold. This may necessitate replacement of exhaust manifold upon next removal attempt. Installation

1. Whenever an oxygen sensor is removed, threads must be coated with anti-seize compound before it is reinstalled. New oxygen sensors will already have this compound applied to threads. 2. Install oxygen sensor in exhaust pipe and tighten sensor to 30 ft. lbs. (41 N.m). Reconnect electrical connector to oxygen sensor. Reconnect negative battery cable. TURBOCHARGER ASSEMBLY NOTE:

Turbocharger is not serviceable and must be replaced as a unit.

Removal (2.0L VIN M)

1. Disconnect negative battery terminal. Raise vehicle. Drain cooling system. Remove lower fan retaining screw. Remove exhaust pipe. Remove rear A/C support bracket bolt. Loosen remaining bolts. 2. Remove oil drain tube at turbo. Lower vehicle. Remove coolant recovery pipe and move to one side. Remove induction tube, coolant fan, oxygen sensor, and oil feed pipe at union. 3. Remove air intake pipe and actuator vacuum hose. Remove exhaust manifold retaining nuts and lift out assembly. Remove turbocharger from exhaust manifold. Remove support bracket from turbine housing. Removal (3.1L VIN V)

1. Disconnect negative battery terminal. Drain coolant from radiator. Remove intercooler-to-intake manifold duct. Remove air cleaner-to-turbocharger duct at turbo unit. 2. Remove air cleaner inlet duct assembly, air cleaner and intercooler duct at turbocharger. Remove turbocharger heat covers. Remove oxygen sensor. 3. Disconnect coolant return line and oil supply line at turbocharger. Disconnect vacuum lines at turbocharger compressor outlet and actuator assembly. 4. Remove wastegate actuator arm retaining clip and remove actuator arm from wastegate. Remove wastegate actuator from turbocharger. Remove cruise control servo and set aside. 5. Remove turbocharger downpipe, coolant hose and oil drain hose. Remove exhaust crossover from turbocharger. Remove turbocharger assembly. NOTE:

Each turbocharger has a unique sound or noise level when operating. If the sound cycles up and down, check for air restrictions in the intake tube and dirt build-up in the compressor housing/wheel. If a high pitched noise or whistle occurs, look for an inlet air or exhaust gas leak.

Inspection (All Models)

1. Check for loose duct connections from air cleaner to turbo assembly, cross-over duct to intake system. Check turbo wheels for impact damage from foreign objects and wheel contact against housing walls. 2. Check shaft for free rotation. Push inward on one of the shaft wheels while turning it by hand and feel for any rubbing or binding. Do the same on the other side. Wheels should turn freely without contacting hosing, backplate or shroud. 3. Check oil drain line for restriction. Any restriction can cause severe oil loss through the turbo seals. Check for traces of burned oil on turbine housing exterior. Check oil supply line for restrictions. Restricted oil flow will cause severe damage to turbocharger. Installation (All Models)

Clean cylinder head and exhaust manifold mating surfaces prior to installing new gaskets. To install, reverse removal procedure. Tighten to specification; oil feed lines, coolant feed and return lines, oxygen sensor, air intake duct, and vacuum hose to actuator. See TORQUE SPECIFICATIONS at end of article. WASTEGATE/ACTUATOR ASSEMBLY Removal & Installation (2.0L VIN M & 3.1L VIN V)

1. Disconnect induction tube. On 3.1L (VIN V), drain cooling system. Remove coolant return line at turbocharger. 2. On all models, remove clip securing actuator rod to wastegate control arm. Remove vacuum hose. Remove actuator retaining screws and bolts. Remove actuator assembly. 3. To install, reverse removal procedure. Tighten retaining bolts to specification. See TORQUE SPECIFICATIONS table.

OVERHAUL (CARBURETOR) DISASSEMBLY IDLE MIXTURE SCREW PLUG 1. Idle mixture screw plugs should be removed (if equipped) prior to disassembly of carburetor. Invert carburetor. Using hacksaw, saw 2 parallel cut areas in throttle body between locator points near idle mixture plug. See Fig. 14 .

Fig. 14: Removing Idle Mixture Screw Plugs Courtesy of GENERAL MOTORS CORP. 2. Distance between cut areas should be near size of punch to be used for plug removal. Cut downward to the plug. Cut area should not exceed more than 1/8" beyond locator points. 3. Place flat punch near end of cut areas. Holding punch at a 45 degree angle, drive punch inward toward throttle body to break casting away. Use a center punch to break plug and expose idle mixture screw. Repeat procedure for remaining plug. DISASSEMBLY AIR HORN 1. Place carburetor in Holding Fixture (J-9789-118). Remove fuel filter, spring and fuel inlet nut. Remove Idle Load Compensator (ILC) assembly. Remove primary and secondary vacuum break assemblies and linkage (if equipped). 2. Air bleed valve cover must be removed. Seal bowl vents and air inlets with tape. Using a 7/64" drill bit, drill out head of air bleed valve cover retaining rivet. 3. Remove rivets and air bleed valve cover. Clean metal shavings from top of carburetor. Remove air bleed valve assembly. Remove "O" rings from air bleed valve. 4. Remove secondary metering rod holder retaining screw. Remove metering rod holder and metering rods. Remove choke lever retaining screw. Remove choke lever. 5. Pull upward on choke link. Hold intermediate choke lever outward while twisting choke link from lever. Remove pump link retainer at pump lever. Remove pump link from pump lever. DO NOT remove pump

lever from air horn. 6. Remove air horn-to-float bowl retaining screws. Lift air horn straight up from main body. Invert air horn. Remove TPS plunger. NOTE:

Use care not to damage mixture control solenoid connector, TPS adjustment lever and small tubes protruding from air horn. DO NOT attempt to remove small tubes.

7. Using small screwdriver, remove pump stem seal and TPS plunger seal retainer. Remove seals from air horn. Remove solenoid adjusting screw plug and adjusting screw (if equipped). See Fig. 16 . DISASSEMBLY FLOAT BOWL 1. Remove air horn-to-float bowl gasket. Remove mixture control solenoid plunger. Remove accelerator pump assembly. Remove spring and cup from accelerator pump. 2. Remove TPS and spring. Remove mixture control solenoid-to-air horn gasket. Remove solenoid connector retaining screws. Using Mixture Control Adjuster (J-28696-10 or BT-7928), remove solenoid mixture adjusting screw and rich limit stop. 3. Remove solenoid plunger. Remove primary metering rods and springs. Remove float bowl insert. Remove mixture control solenoid assembly. DO NOT remove plunger return spring or connector wires from solenoid. 4. Remove aneroid cavity insert. Remove solenoid return spring and adjusting screw spring. Remove float, needle and hinge pin. 5. Using Needle Seat Remover/Installer (J-22769), remove needle seat and gasket. Using Metering Jet Remover (J-28696-4 or BT-7928), remove primary jets. CAUTION: DO NOT remove secondary jets. Secondary jets are pressed into float bowl. If jets are damaged, float bowl must be replaced. 6. Remove discharge plug retainer, discharge ball and pump well baffle. Drill out choke cover retaining rivet heads. Remove choke cover retainers. Remove choke cover, thermostat assembly and gasket. Remove choke housing-to-float bowl retaining screw and washer. 7. Remove choke housing. Remove choke housing-to-float bowl seal. Remove secondary throttle lock-out lever. Remove intermediate choke lever. Invert float bowl. Remove intermediate choke shaft seal. 8. Remove internal choke thermostat lever retaining screw. Remove choke thermostat lever, intermediate choke shaft, lever and link assembly and fast idle cam. Separate fast idle cam from shaft. Remove intermediate choke shaft seal. DISASSEMBLY THROTTLE BODY 1. Using Idle Mixture Socket (J-29030-B or BT-7610B), remove idle mixture screws and springs. Note and record number of turns required for idle mixture screw removal for reassembly reference. 2. Remove throttle body-to-float bowl retaining screws. Separate throttle body and gasket from float bowl.

CLEANING & INSPECTION 1. Clean parts thoroughly in carburetor cleaner. DO NOT soak solenoids, TPS, choke cover and thermostat assembly, plastic, or rubber parts in cleaner. After cleaning, rinse all metal parts with HOT water. 2. Blow dry with compressed air. Choke shaft must operate freely in air horn. Inspect idle mixture screws for grooves or nicks. Replace if damaged. 3. Inspect float for damage or fuel absorption. Inspect all solenoids for damaged wiring. Using ohmmeter, check mixture control solenoid resistance. Replace solenoid if resistance is not between 20-26 ohms. 4. Check mixture control solenoid for ground. Place one ohmmeter lead on solenoid case and remaining lead on one solenoid terminal. Resistance should be infinite. Replace solenoid if grounded. 5. Pump system operation should be checked. Install new pump cup and spring on pump plunger. Install pump discharge ball, plug and pump well baffle in float bowl. Fill float chamber and pump well with clean solvent. 6. Seal 2 pump discharge passages located on top of float bowl surface. Push pump assembly downward in well area. Pump should not reach bottom of travel area. Only movement should be compression of the duration spring. 7. Excessive pump travel indicates improper seating of pump cup, worn pump well or pump discharge plug is leaking. Repair defective components. 8. Refill float chamber and pump well with clean solvent. Slowly move pump downward in pump well until solvent appears at top of pump discharge passages. Remove pump assembly and note solvent level in passages. 9. Solvent level should not decrease. If level decreases, check for missing discharge ball, improper discharge ball seating or defective ball or seat. Repair as necessary. CAUTION: Float bowl containing a machined pump well may be identified by the letters "MW" stamped on front of float bowl near fuel filter. Ensure replacement float bowl contains proper lettering. REASSEMBLY FLOAT BOWL ASSEMBLY 1. Install new float bowl-to-throttle body gasket. Ensure all passages align. Install throttle body and retaining screw. 2. Install carburetor on holding fixture. Install idle mixture screws and springs. Adjust to location recorded during disassembly. Install intermediate choke shaft seal in choke housing with seal lips toward float bowl. 3. Install fast idle cam on intermediate choke shaft with stepped areas facing downward. Install cam and choke shaft in housing. Install choke thermostat lever on intermediate choke shaft. Install retaining screw. 4. Install choke shaft seal in float bowl with seal lips facing outward. Install choke housing seal in float bowl. Install secondary lock-out lever. Using Choke Lever Installer (J-23417), install intermediate choke lever in float bowl cavity. 5. Install choke housing assembly so intermediate choke shaft engages with intermediate choke lever. Ensure fast idle cam is located above vacuum break lever. 6. Install choke housing retaining screws. Check choke linkage for freedom of movement. Adjust choke coil lever adjustment. See CHOKE COIL LEVER under ADJUSTMENTS in this article.

7. Install pump well baffle with slot area toward bottom of float bowl. Install pump discharge ball and spring (if equipped). Install discharge ball plug. Install primary metering jets. 8. Using Needle Seat Installer (J-22769), install needle seat and gasket. Install float needle on float. Ensure float needle does not engage with slot area on float. 9. Install float hinge pin with open end facing pump well. Install float assembly. Adjust float level. See FLOAT LEVEL under ADJUSTMENTS in this article. 10. Install mixture control solenoid return spring, adjusting screw spring and aneroid cavity insert (if equipped). Install mixture control solenoid with solenoid pin aligned with float bowl hole. 11. Install solenoid retaining screw and connector-to-air horn gasket. Adjust solenoid mixture screw. See MIXTURE CONTROL SOLENOID MIXTURE SCREW under ADJUSTMENTS in this article. 12. Install float bowl insert, primary metering rods and springs. Install TPS adjusting spring and TPS. Push downward on connector to position below casting surface. 13. Install new cup and spring on accelerator pump. Install accelerator pump and spring. Install float bowl-toair horn gasket. Install mixture control solenoid plunger. REASSEMBLY AIR HORN 1. Using Mixture Control Adjuster (J-28696-10), install TPS adjusting screw. TPS final adjustment is made after carburetor installation. Install pump stem seal and TPS seal with seal lips facing outward. 2. Install seal retainers. Stake seal retainers in 3 places. Install TPS actuator plunger. Install mixture control solenoid stop screw and spring. Using Stop Screw Adjuster (J-28696-4), lightly seat stop screw then back out 1/4 turn. 3. Hold air horn gasket downward while installing air horn. Ensure accelerator pump aligns with hole of air horn. Using small screwdriver, hold TPS adjusting lever and plunger upward while installing air horn on float bowl. 4. Ensure air horn tubes align with float bowl and gasket. Install air horn screws. Tighten screws in proper sequence. See Fig. 15 . 5. Install pump link in throttle lever and pump lever. Install pump link retainer. Install choke link in intermediate choke lever while holding fast idle cam upward. 6. Install choke lever on choke link. Engage choke lever with choke shaft. Install retaining screw. Install secondary metering rods and holder. Ends of metering rods must face each other. Install holder retaining screw. 7. Operate air valves to ensure freedom of movement. Coat new "O" rings for air bleed valve with ATF. Install "O" rings on air bleed valve with thick ring in upper groove and thin ring in lower groove. 8. Install air bleed valve. Adjust air bleed valve. Refer to AIR BLEED VALVE under ADJUSTMENTS in this article. Install and adjust vacuum break assemblies. 9. Install ILC. Install spring, fuel filter and fuel inlet nut. Tighten fuel inlet nut. Place fast idle cam on highest step. 10. Install choke cover, thermostat assembly and gasket in choke housing. Ensure coil tang engages with choke thermostat lever and cover notch aligns with housing projection. Install choke cover retainers and rivets. Perform necessary adjustments. See ADJUSTMENTS in this article. 11. Install carburetor to intake manifold using new base gasket. Tighten bolts A-D in sequence to 12 ft. lbs. (16 N.m). See Fig. 15 .

Fig. 15: Air Horn & Throttle Plate Tightening Sequence Courtesy of GENERAL MOTORS CORP.

Fig. 16: Exploded View of Rochester Model E4MC Carburetor Courtesy of GENERAL MOTORS CORP.

ADJUSTMENTS (CARBURETOR) FLOAT LEVEL

1. Remove air horn, solenoid plunger, air horn gasket and metering rods. Remove plastic float bowl insert. If solenoid lean mixture screw requires removal, use Mixture Control Adjuster (J-28696 or BT-7928). Count and record number of turns required to lightly seat lean mixture screw prior to removal. 2. Install Bracket (J-34817-1 or BT-8227A-1) on float bowl. See Fig. 17 . Install Float Positioner (J-34817-3 or BT-8227-A) on float bowl with pin contacting outer edge of float lever. 3. Using "T" Scale (J-9789-90 or BT-8037), measure distance from top of casting to top of float, approximately 3/16" from large end of float. Float level must be within 2/32" of float level specification. See FLOAT LEVEL SPECIFICATIONS table. 4. If float level requires adjustment, use Float Adjuster (J-34817-15 or BT-8233) to bend float lever for correct setting. Recheck float level after each adjustment. Ensure float alignment is straight and does not contact float bowl. 5. Lightly seat lean mixture screw and readjust to original location (if removed). Reverse removal procedure for remaining components. Tighten air horn in correct sequence. See Fig. 15 . FLOAT LEVEL SPECIFICATIONS Carburetor No. 17086008 17086009 17088115

Setting 11/32" 14/32" 11/32"

Fig. 17: Adjusting Float Level Courtesy of GENERAL MOTORS CORP. MIXTURE CONTROL SOLENOID MIXTURE SCREW 1. Install Mixture Control Solenoid Gauge (J-33815-1 or BT-8253-A) over throttle lever side metering jet guide. Temporarily install solenoid plunger. 2. Install lean mixture screw 6 threads. Install rich limit stop. Hold solenoid plunger downward against solenoid stop. Using Mixture Adjuster (J-28696-10 or BT-7928), slowly turn lean mixture screw in or out until solenoid plunger just contacts solenoid stop and mixture control solenoid gauge. See Fig. 18 . 3. Adjustment is correct when solenoid plunger is contacting BOTH the solenoid stop and gauge. Remove solenoid plunger and gauge. Install plug at proper location. See Fig. 20 .

Fig. 18: Adjusting Solenoid Mixture Screw Courtesy of GENERAL MOTORS CORP. MIXTURE CONTROL SOLENOID STOP SCREW 1. With solenoid lean mixture screw properly adjusted and air horn installed, install Float Gauge (J-34935-1 or BT-8420-A) in air horn vent hole. Allow float gauge to contact mixture control solenoid plunger. See Fig. 19 . Note line indicated with top of air horn casting. 2. Press downward on float gauge and note indicator mark. Release float gauge. This difference between the indicator lines is the solenoid plunger travel. 3. Using Stop Screw Adjuster (J-28696-10 or BT-7928), turn rich mixture stop screw until total solenoid travel equals 4/32" (3.17 mm). 4. After adjustment, install lean mixture screw plug and rich mixture stop screw plug. Plugs must be installed at specified location to seal settings and to prevent fuel vapor loss. See Fig. 20 .

Fig. 19: Adjusting Mixture Control Solenoid Stop Screw Courtesy of GENERAL MOTORS CORP.

Fig. 20: Installing Lean Mixture Screw Plug & Solenoid Stop Screw Plug Courtesy of GENERAL MOTORS CORP. AIR BLEED VALVE 1. Install Air Bleed Valve Gauge (J-33815-2 or BT-8253-B) in throttle side of vent hole of air horn so gauge contacts solenoid plunger. See Fig. 21 . 2. Position upper end of air bleed valve gauge over open cavity next to valve. Hold gauge downward so solenoid plunger is against solenoid stop and rotate gauge. Adjust air bleed valve so gauge pivots over and just contacts top of valve. See Fig. 21 .

Fig. 21: Adjusting Air Bleed Valve Courtesy of GENERAL MOTORS CORP.

AIR VALVE SPRING 1. Loosen shaft lock screw using Allen wrench. Rotate spring fulcrum pin counterclockwise until throttle valves open. See Fig. 22 . 2. Rotate spring fulcrum pin clockwise until throttle valves close. Then rotate spring fulcrum pin proper amount of revolutions. See E4MC CARBURETOR SPECIFICATIONS table. 3. Hold spring fulcrum pin and tighten lock screw. Apply a light coat of grease to spring contact area.

Fig. 22: Adjusting Air Valve Spring Courtesy of GENERAL MOTORS CORP. CHOKE COIL LEVER 1. Remove choke cover retaining rivets. Remove choke cover and coil assembly from choke housing. See Fig. 23 . Position fast idle cam on highest step of fast idle lever. 2. Push upward on choke coil lever to close choke valve. Install a .120" (3.04 mm) drill or pin gauge in choke housing hole. See Fig. 23 . Lower edge of choke lever should just contact pin gauge. Bend choke rod to adjust.

Fig. 23: Adjusting Choke Coil Lever Courtesy of GENERAL MOTORS CORP. CHOKE ROD (FAST IDLE CAM) 1. Install rubber band to vacuum break lever of intermediate choke shaft. See Fig. 24 . Open throttle, allowing choke valve to close. Install Angle Gauge (J-26701-A) on choke valve. 2. Adjust angle gauge to choke rod specification. Refer to the E4MC CARBURETOR SPECIFICATIONS table. Place fast idle cam on second step of cam lever. 3. If cam lever does not contact cam, adjust fast idle screw. Bend tang on fast idle assembly until angle gauge bubble is centered. See Fig. 24 .

Fig. 24: Adjusting Choke Rod (Fast Idle Cam) Courtesy of GENERAL MOTORS CORP. NOTE:

Choke coil lever and choke rod (fast idle cam) adjustments must be correct before performing primary (front) vacuum break adjustment.

PRIMARY (FRONT) VACUUM BREAK 1. Install rubber band to vacuum break lever of intermediate choke shaft. Open throttle, allowing choke valve to close. Install Angle Gauge (J-26701-A) on choke valve. See Fig. 25 .

2. Adjust angle gauge to specification. See E4MC CARBURETOR SPECIFICATIONS table. Plug vacuum break bleed holes (if equipped). 3. Using vacuum pump, apply 15 in. Hg vacuum to vacuum break. Ensure bucking spring is seated. See Fig. 24 . If air valve rod restricts vacuum break plunger from retracting, release vacuum and bend rod to allow full plunger travel. 4. Reapply vacuum and note bubble reading on angle gauge. Adjustment is correct when angle gauge bubble is centered. Adjust screw located on bucking screw to center bubble. See Fig. 24 .

Fig. 25: Adjusting Front Vacuum Break Courtesy of GENERAL MOTORS CORP. NOTE:

Choke coil lever and choke rod (fast idle cam) adjustments must be correct before performing secondary (rear) vacuum break adjustment.

SECONDARY (REAR) VACUUM BREAK

1. Install rubber band to vacuum break lever of intermediate choke shaft. Open throttle, allowing choke valve to close. Install Angle Gauge (J-26701-A) on choke valve. See Fig. 26 . 2. Adjust angle gauge to specification. See E4MC CARBURETOR SPECIFICATIONS table. Plug vacuum break bleed holes (if equipped). 3. Using vacuum pump, apply 15 in. Hg vacuum to vacuum break. Ensure bucking spring is compressed (if equipped). See Fig. 24 . If air valve rod restricts vacuum break plunger from retracting, release vacuum and bend rod to allow full plunger travel. 4. Reapply vacuum and note bubble reading on angle gauge. Adjustment is correct when angle gauge bubble is centered. Rotate adjusting screw located on rear of vacuum break (if equipped). On models without adjusting screw, use Linkage Adjuster (J-9789-111) while supporting rod at "S" area and bend vacuum break rod. See Fig. 26 .

Fig. 26: Adjusting Secondary (Rear) Vacuum Break Courtesy of GENERAL MOTORS CORP.

AIR VALVE ROD (FRONT) 1. Plug vacuum break bleed hole (if equipped). Using vacuum pump, apply 15 in. Hg vacuum to vacuum break. Ensure air valves are fully closed. See Fig. 27 . 2. Measure clearance between rod and end of lever slot. Install a .015" (.38 mm) drill or pin gauge between rod and end of slot. See Fig. 29 . 3. Bend rod at point shown to obtain a clearance of .015" (.38 mm) with vacuum applied. Reconnect vacuum hose to diaphragm.

Fig. 27: Adjusting Front Air Valve Rod Courtesy of GENERAL MOTORS CORP. NOTE:

Choke coil lever and choke rod (fast idle cam) adjustments must be correct before performing choke unloader adjustment.

CHOKE UNLOADER 1. Install rubber band to vacuum break lever of intermediate choke shaft. Open throttle, allowing choke valve to close. Install Angle Gauge (J-26701-A) on choke valve. See Fig. 28 . 2. Adjust angle gauge to specification. See E4MC CARBURETOR SPECIFICATIONS table. Hold secondary lock-out lever away from pin. See Fig. 28 . 3. Hold throttle lever in wide open position. Note bubble on angle gauge. Adjustment is correct when angle gauge bubble is centered. Using Linkage Adjuster (J-9789-111), adjust fast idle lever to center bubble.

Fig. 28: Adjusting Choke Unloader Courtesy of GENERAL MOTORS CORP. SECONDARY THROTTLE VALVE LOCK-OUT LEVER (SIDE CLEARANCE) 1. Place fast idle cam on highest step of cam lever. Hold throttle lever closed. Measure secondary throttle valve lock-out side clearance between pin and lock-out lever. See Fig. 29 . 2. Lock-out lever side clearance should be .010-.020" (.25-50 mm). Adjust clearance by bending pin. SECONDARY THROTTLE VALVE LOCK-OUT LEVER (OPENING CLEARANCE) 1. Push down on tail of fast idle cam, allowing lock-out lever to move away from pin. Rotate throttle lever to position minimum clearance between lock-out lever and pin. See Fig. 29 . 2. Measure specified opening clearance between end of pin and lock-out lever toe. See Fig. 29 . Clearance should be .015" (.38 mm). Adjust clearance by filing end of pin.

Fig. 29: Adjusting Secondary Throttle Valve Lock-Out Courtesy of GENERAL MOTORS CORP. E4MC CARBURETOR SPECIFICATIONS Application 17086008 & 17088115 Accelerator Pump Air Valve Rod Air Valve Spring Automatic Choke Choke Unloader Choke Coil Lever Choke Rod Float Level Idle Air Bleed Secondary Lock-Out

Specification Tamper Resistant .025" (1) 1/2

Tamper Resistant 35° .120" 14° (2) 11/32"

1.756" .015"

Vacuum Break Primary Secondary (1) Specification is number of turns.

25Â° 43Â°

(2) Carb. No. 17086009 float level is 14/32".

FUEL SYSTEM (PFI) FUEL PRESSURE RELIEF 1. Fuel system is under pressure. Pressure must be relieved prior to servicing fuel system. Fuel pressure may be relieved by using one of 2 different methods. 2. One method is to disconnect fuel pump at rear body connector. Start engine and allow to run until it stops. Operate starter for 3 seconds to remove remaining fuel from fuel lines. Reconnect fuel pump once repair is completed. 3. The other method is to install Fuel Pressure Gauge (J-34730-1) on fuel pressure connection. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. 4. Place gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

FUEL SYSTEM (TBI) FUEL PRESSURE RELIEF Disconnect negative battery cable. Remove fuel filler cap. Since these TBI units contain an internal bleed-down feature, after a short time, system fuel pressure should dissipate. THROTTLE BODY OVERHAUL Disassembly

Disassembly of throttle body unit for immersion in cleaning solvent requires removal of throttle body cover or fuel meter assembly, TPS and IAC assembly. Throttle valve screws are staked in position and should not be removed. Before working on throttle body assembly, it is essential that residual pressure be relieved before throttle body is removed. See FUEL PRESSURE RELIEF under FUEL SYSTEM (TBI) in this article. WARNING: Pressure regulator includes spring under heavy tension which may cause personal injury if released. DO NOT immerse cover in any type of cleaning solvent. THROTTLE BODY COVER (MODEL 220) Place throttle body on Holding Fixture (J-9789-118 or BT 30-15) to prevent damage to throttle valve. Remove screws holding cover to throttle body, noting location of 2 short screws. Remove throttle body cover. See Fig. 31 . Throttle body cover and pressure regulator are serviced as an assembly. DO NOT remove screws attaching

pressure regulator to cover. FUEL METER ASSEMBLY (MODEL 700) Remove fuel meter-to-throttle body retaining screws. Remove fuel meter assembly. See Fig. 30 . Discard gasket. If fuel pressure regulator cover is removed, regulator diaphragm must be replaced to prevent fuel leaks.

Fig. 30: Exploded View of Model 700 Throttle Body Assembly Courtesy of GENERAL MOTORS CORP.

Fig. 31: Exploded View of Model 220 Throttle Body Assembly Courtesy of GENERAL MOTORS CORP. CLEANING & INSPECTION 1. Clean all metal parts in a cold immersion-type cleaner such as Carbon X (X-55). Blow dry with compressed air. 2. DO NOT immerse TPS, IAC, throttle body cover, fuel meter assembly and pressure regulator assembly, fuel injector, fuel filter, rubber parts and diaphragms in cleaner solvent. 3. Inspect mating surfaces for damage that may prevent gasket sealing. Repair or replace components which may be cause of problems.

REASSEMBLY THROTTLE BODY COVER (MODEL 220) 1. Install new dust seal into recess of throttle body. Install fuel outlet passage gasket on cover. Install throttle body cover gasket on throttle body. Install cover, making sure that pressure regulator dust seal and cover gaskets are in place. 2. Apply thread locking compound to cover attaching screws. Install cover screws and lock washers. Tighten screws. Connect electrical lead to fuel injector and install air cleaner. REASSEMBLY FUEL METER ASSEMBLY (MODEL 700) 1. Install new fuel meter-to-throttle body assembly gasket. Match cutout portions of gasket with openings in throttle body assembly. 2. Place fuel meter assembly on throttle body. Install fuel meter-to-throttle body retaining screws and washers (screws should be coated with locking compound). Tighten screws to specification. See TORQUE SPECIFICATIONS at end of article. 3. Install new "O" rings on fuel lines. Using a back-up wrench on fuel fittings, tighten fuel line nuts to 20 ft. lbs. (27 N.m). To complete reassembly, reverse disassembly procedure.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Catalytic Converter Hanger Bolts/Screws (Camaro & Firebird) Center Support Bearing-To-Rear Axle Torque Arm Bolts (Camaro & Firebird With 2-Piece Driveshaft) Driveshaft-To-Differential Yoke Bolt/Screw (Camaro & Firebird) Fuel Tank Strap Bolts (Camaro & Firebird) Harmonic Balancer (C3I) 3.3L & 3.8L Ignition System DIS Module-to-Block Bolt 2.2L, 2.5L & 3.1L IDI Cover Assembly Bolt (4) PFI System Fuel Inlet & Return Line Nuts (1) 2.0L, 5.0L & 5.7L 2.3L, 3.3L & 4.5L 3.1L Fuel Rail Bolt 2.0L & 3.3L 2.3L 4.5L 5.0L & 5.7L

Ft. Lbs. (N.m) 37 (50) 37 (50) 16 (22) 25 (34) 200-239 (270-325)

15-22 (20-30) 19 (26)

20 (27) 22 (30) 17 (23) 15-20 (20-27) 19 (26) 18 (24) 15 (20)

IAC Valve 2.0L, 5.0L & 5.7L Intake Runner Bolts 5.0L & 5.7L Oxygen Sensor Plenum Bolts 3.1L 5.0L & 5.7L Throttle Body Bolt 2.0L 2.3L, 3.1L, 5.0L & 5.7L 3.8L 4.5L Throttle Body Nut 3.3L Rear Axle Torque Arm Outer Transmission Bracket (Camaro & Firebird) Bolt Front Lower Rear Upper Nut Rear Axle Torque Arm-To-Differential Housing Bolts/Nuts (Camaro & Firebird) Rear Axle Track Bar Brace-To-Body Bracket Bolts (Camaro & Firebird) Left Right Rear Axle Track Bar-To-Left Coil Spring Seat Bolt/Nut (Camaro & Firebird) Rear Axle Track Bar-To-Right Body Bracket Bolt/Nut (Camaro & Firebird) Rear Exhaust Pipe Hanger Nut (Camaro & Firebird) Rear Exhaust Pipe-To-Catalytic Converter Outlet Flange Bolts/Screws (Camaro & Firebird) Rear Stabilizer Shaft Insulator Clamp Nuts (Camaro & Firebird) Rear Stabilizer Shaft Link Bolts/Nuts (Camaro & Firebird) Shock Absorber Lower Mounting Nut (Camaro & Firebird) TBI System Fuel Inlet Fitting Fuel Outlet Fitting (Model 220) Fuel Outlet Fitting (Model 700) Fuel Line Nut Idle Air Control Valve (Model 220) Oxygen Sensor Throttle Body-to-Manifold Bolt

13 (18) 19 (26) 30 (41) 16 (22) 19 (26) 10-15 (14-20) 19 (26) 11 (15) 14 (19) 21 (28)

37 (50) 20 (27) 30 (41) 97 (132)

35 (47) 80 (108) 61 (83) 80 (108) 16 (22) 15 (20) 18 (24) 17 (23) 70 (95) 30 (41) 22 (30) 30 (41) 20 (27) 13 (18) 30 (41) 18 (24)

Turbocharger Coolant Feed & Return Line Fitting Exhaust Downpipe-to-Turbo Bolt Exhaust Manifold Bolt Exhaust Pipe-To-Elbow Bolt Intake Manifold Bolt Oil Feed Line Fitting Oil Return Line Fitting Throttle Body Nut Turbo-To-Exhaust Manifold Nut Turbo-To-Exhaust Outlet Elbow Stud Turbo Support Bracket Lower Bolt Retaining Nut Wheel Lug Nuts (Camaro & Firebird) Ignition System Coil-to-Cover Screws 2.3L Crankshaft/Combination Sensor-to-Block Bolt 2.2L 2.3L 3.1L Crankshaft Sensor-to-Module Screws 2.5L Ignition Coil-to-Module Screws 2.2L, 2.5L & 3.1L Module-to-Cover Screws (3) 2.3L Muffler Hanger Retaining Bolts/Nuts (Camaro & Firebird) PFI System Coolant Cover Screws 2.3L 3.1L Crossover Tube Retainer Bolt 5.0L & 5.7L Fuel Rail Bolt 3.1L Fuel Return Line Clamp Bolt 2.3L IAC Valve Housing

21 (29) 17 (23) 16 (22) 18 (24) 18 (24) 15 (20) 30 (41) 18 (24) 18 (24) 18 (24) 37 (50) 18 (24) 81 (110) INCH Lbs. (N.m)

35 (4.0) 53-106 (6-12) 89 (10) 71 (8.0) 20 (2.3) 41 (4.6) 35 (4.0) 89 (10)

9 (1.0) 27 (3.0) 44 (4.9) 89 (10) 53 (6.0)

27 (3.0) IAC Valve Retaining Screw 2.3L, 3.1L, 3.3L & 3.8L 18 (2.0) Pressure Regulator Base-To-Rail Bolt 5.0L & 5.7L 44 (4.9) Pressure Regulator-To-Bracket Bolts 5.0L & 5.7L 44 (4.9) TBI System Fuel Injector Screw (Model 700) 27 (3.0) Fuel Meter Assembly Screw (Model 700) 31 (3.5) Idle Air Control Valve Retaining Screw (Model 700) 27 (3.0) Lower Throttle Body-To-Upper Throttle Body Screw (220) 35 (4.0) Throttle Body Cover Screw (Model 220) 27 (3.0) Throttle Position Sensor Screw 18 (2.0) Vacuum Tube Assembly Screw (Model 700) 27 (3.0) (1) On 2.3L and 3.3L, fuel rail inlet fitting must not be removed from fuel rail. Fitting is staked in place.

ENGINE PERFORMANCE Systems & Component Testing

INTRODUCTION Before testing separate components or systems, it is highly recommended that all procedures listed in BASIC TESTING article be performed. Since many computer controlled and monitored components will set a trouble code if they malfunction, it is also recommended that self-diagnosis be performed. See appropriate TESTS W/CODES article. NOTE:

Testing individual components does not isolate possible shorts or opens in the control harness of electronically controlled systems. Use an ohmmeter and appropriate wiring diagram in WIRING DIAGRAMS to isolate shorts or opens in harness. All voltage tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in testing procedures.

AIR INDUCTION SYSTEMS (TURBOCHARGERS) WASTEGATE/BOOST PRESSURE TEST 1. Inspect wastegate and actuator assembly for linkage damage. Check condition of hose from throttle body to wastegate solenoid and from wastegate solenoid to actuator. Remove hose. 2. Connect a hand-held Vacuum/Pressure Pump (J-23738) in series with component Gauge (J-28474) to actuator assembly hose. 3. With 4 psi (.28 kg/cm2 ) pressure applied, actuator should move rod .015" (.38 mm). Replace actuator if not operating properly. Check new unit and crimp threads on rod to maintain proper calibration. Remove test equipment. Reconnect actuator-to-wastegate solenoid hose. WASTEGATE ACTUATOR 1. Disconnect vacuum hose to wastegate actuator. Apply vacuum to actuator. If wastegate actuator moves, replace wastegate control valve solenoid. 2. If wastegate actuator does not move, check vacuum hose. Replace vacuum hose if defective. If vacuum hose is okay, disconnect actuator linkage at wastegate. Apply vacuum to actuator. If actuator moves, wastegate is sticking. If actuator does not move, replace actuator. WASTEGATE SOLENOID Disconnect wastegate solenoid connector and vacuum hose. Apply 12-volt power source to solenoid. Using a hand-held vacuum pump, apply vacuum to solenoid. A clicking noise should be heard from wastegate solenoid and vacuum should flow through valve. If these conditions are not met, solenoid is defective.

Fig. 1: 2.0L Sunbird Turbocharger System Courtesy of GENERAL MOTORS CORP.

Fig. 2: 3.1L Grand Prix Turbocharger System Courtesy of GENERAL MOTORS CORP.

ENGINE SENSORS & SWITCHES

A/C ON SWITCH SYSTEM TEST 1. Turn ignition switch to RUN position. Move mode selector switch to OFF position. With A/C control assembly connector connected, measure voltage between mode selector switch Brown wire and ground. For wiring schematics, see mini-schematics in A/C CLUTCH under MISCELLANEOUS ECM CONTROLS in this article. 2. Battery voltage should be present. If battery voltage is present, mode selector switch is operating normally. If battery voltage is not present, check Brown wire from selector switch to fuse for an open circuit. 3. Check voltage between mode selector Brown/White wire and ground. Voltage should not be present. If voltage was present, replace mode selector switch. A/C PRESSURE SENSOR (2.3L & 3.1L J BODY) A malfunction in A/C pressure sensor circuit will set a related trouble code. For testing procedures, see appropriate TESTS W/CODES article in this section. For wiring schematics, see mini-schematics in A/C CLUTCH under MISCELLANEOUS ECM CONTROLS in this article. A/C PRESSURE SWITCH 1. Connect A/C pressure gauges to system and start engine. Note pressure readings. If pressures are normal, go to step 2). If pressures are less than normal, check system for leaks. Evacuate and recharge as necessary. If pressures are high, check for system overcharge, overheating or mechanical failure in freon delivery system. 2. Using an ohmmeter, check continuity between pressure switch terminals. Continuity should be present on both high and low switches (if equipped with both). If continuity is not present, check switch terminal connectors. If terminal connectors are okay, replace A/C pressure switch. For wiring schematics, see mini-schematics in A/C CLUTCH under MISCELLANEOUS ECM CONTROLS in this article. BRAKE SWITCH Disconnect brake switch harness connector. Using an ohmmeter, check continuity between brake switch terminals. Continuity should be present. Depress brake pedal or activate brake switch, continuity should not be present. CAMSHAFT SENSOR (3.8L VIN C) A malfunction in the camshaft sensor circuit will set a related trouble code. For testing procedures, see appropriate TESTS W/CODES article. COOLANT LEVEL SENSOR/COOLANT LEVEL LIGHT 1. Ensure radiator coolant level is full and Codes 14, 26 and 32 are not set. Correct as necessary. Turn ignition on and note coolant level light. It should be on as a bulb check. If not, go to step 2). Start engine and note coolant level light. It should be off. If light stays on and coolant level is not low, check for a short in the bulb ground circuit. If short is not present, connect a test light to battery voltage and touch ECM coolant level light driver terminal. If test light illuminates, go to step 4).

2. Disconnect ECM connector containing coolant level light driver terminal. Turn ignition on. Using a jumper wire, ground ECM coolant level light driver terminal. If light does not illuminate, check for an open in the coolant level light circuit, including a bad bulb. If light does illuminate, ECM driver is faulty. 3. Disconnect coolant level sensor harness connector (located on right side of radiator), coolant light should come on again. If it does, no problem is present. If light does NOT come on again, check for terminal "B" circuit of sensor shorted to ground. 4. Disconnect sensor wiring harness connector. Connect jumper wire between harness side terminal "B" to ground. If coolant light does not go out, go to step 5). If coolant light does go out, check circuit between wiring harness side terminals "A" and "C" to ECM. If circuit is okay, replace defective coolant level sensor. 5. Using a voltmeter, check for 5 volts at harness side terminals "B" and "C". See Fig. 3. If 5 volts is not available, check for open circuit, faulty ECM connection or faulty ECM. If both terminals read 5 volts, disconnect ECM connector. Check sensor terminal "B" and "C" circuits for short to voltage or each other. If circuits are okay, ECM is faulty.

Fig. 3: Coolant Level Sensor Circuit Courtesy of GENERAL MOTORS CORP. COOLANT TEMPERATURE SENSOR (CTS) If a coolant sensor related code is present, see appropriate TESTS W/CODES article. An out-of-calibration sensor may not set a trouble code. Use following procedure to test sensor calibration. Disconnect coolant temperature sensor connector. Measure resistance between sensor terminals. Resistance should be high when engine is cold and drop as engine warms up. See CTS RESISTANCE VALUES table.

CTS RESISTANCE VALUES Temperature Â°F (Â°C) 210 (100) 160 (70) 100 (38) 70 (20) 20 (-7) 0 (-18) -40 (-40)

Resistance (Ohms) 185 450 1800 3400 13,500 25,000 100,700

CRANKSHAFT POSITION SENSOR (2.3L IDI) Disconnect crankshaft sensor connector, located above oil filter. Set ohmmeter to 2K position, measure resistance across sensor terminals. Resistance should be between 500-900 ohms. Set voltmeter on the 2-volt AC scale. Crank engine and measure voltage across sensor terminals. Voltmeter reading should be .1 volt or greater. If resistance reading is not as specified or sensor does not produce a voltage reading, replace faulty crank sensor. Also, check if sensor is still magnetized. Replace as necessary. CRANKSHAFT POSITION SENSOR (DIS) Disconnect crankshaft sensor harness connector. Set ohmmeter to 2K position, measure resistance across sensor terminals. Resistance should be 900-1200 ohms. Set voltmeter on the 2-volt AC scale. Crank engine and measure voltage across sensor terminals. See the Voltmeter reading should be .1 volt or greater. If resistance reading is not as specified or sensor does not produce a voltage reading, repair faulty wiring or crank sensor. NOTE:

The following table contains information updated as per Technical Service Bulletin Numbers 89-6E-28 (Buick) and 90-168-6E (Chevrolet).

NORMAL CRANK SENSOR VOLTAGE OUTPUT RANGE (3.1L VIN "T") Application Specification Room Temperature/Charged Battery .8-1.4 Volts (800-1400 mV) Slow Cranking/Low Battery .3 Volt (300 mV) DUAL CRANK (COMBINATION) SENSOR (3.3L C(3)I SYSTEM) This test should only be performed if vehicle will not start, injectors will not pulse and spark plugs will not fire. This simulates a dual crank sensor signal. If spark and injector pulse occur, dual crank sensor or sensor connections are bad. 1. Turn ignition off. Disconnect No. 6 spark plug wire from coil tower. Install Spark Tester (ST-125) to coil tower. Install spark plug wire to spark tester. 2. Connect injector test light to any injector connector. Connect jumper wire across dual crank sensor connector terminals "A" and "B". See Fig. 4 and Fig. 5. Turn ignition on, engine off (DO NOT crank engine). 3. Using a test light connected to ground, momentarily touch dual crank sensor terminal "A". Note injector

test light and spark tester. Test light should blink and spark should be present at spark tester. NOTE:

Repeatedly grounding terminal "A" at dual crank sensor or terminals "C" and "B" at C(3)I module may cause engine to flooded.

4. If spark was present and test light came on, check for poor connection at dual crank sensor terminal. If connections are okay, replace faulty dual crank sensor. If spark and test light did not come on, check for poor connection at C(3)I module or replace faulty C(3)I module.

Fig. 4: Century & Cutlass Ciera C(3)I W/Dual Crank Sensor Courtesy of GENERAL MOTORS CORP.

Fig. 5: Skylark C(3)I W/Dual Crank Sensor Courtesy of GENERAL MOTORS CORP. EGR POSITION SENSOR See EMISSION SYSTEMS & SUB-SYSTEMS in this article. ENGINE OIL TEMPERATURE SENSOR (5.7L VIN 8) Disconnect engine oil temperature sensor connector. Using an ohmmeter, measure resistance between sensor terminals. Resistance should be as specified. See ENGINE OIL TEMPERATURE SENSOR RESISTANCE table. Also see CODE 52 and CODE 62 in 3.1L, 5.0L & 5.7L TROUBLE CODE CHARTS. ENGINE OIL TEMPERATURE SENSOR RESISTANCE °F (°C) 210 (100) 160 (70) 100 (38) 70 (20) 40 (4) 20 (-7) 0 (-18) -40 (-40)

Resistance (Ohms) 185 450 1800 3400 7500 13,500 25,000 100,700

KNOCK SENSOR Disconnect knock sensor harness connector. Using an ohmmeter, measure knock sensor resistance between sensor terminal and engine block. Resistance should be 3300-4500 ohms. Connect voltmeter between sensor terminal and ground. Set voltmeter to 2-volt AC scale. Start and idle engine. Tap on engine block near sensor. A signal should be indicated on voltmeter. If no signal is indicated, replace knock sensor. Also see TIMING CONTROL SYSTEMS in this article and appropriate TESTS W/CODES article. CAMSHAFT SENSOR/HALL EFFECT SWITCH (CADILLAC EXCEPT BROUGHAM) 1. Turn ignition off. Disconnect 6-terminal, 5-wire connector at HEI distributor. Connect a DVOM to terminal "E" (pos.) and terminal "D" (neg.) on distributor side of connector. See Fig. 6. 2. Turn ignition on and note DVOM reading. Using ignition key, bump starter to rotate distributor. Note DVOM reading. Repeat procedure several times. DVOM should read either zero or 12 volts. Voltmeter should NOT read a steady voltage. 3. Crank engine and note voltage reading. Depending on voltmeter, reading may fluctuate between zero and 12 volts or average about 6 volts. If voltmeter readings are correct, Hall Effect switch is okay. 4. If voltmeter readings are not correct, turn ignition off and remove distributor. Reconnect 3-terminal connector and connect voltmeter to 6-terminal, 5-wire connector as previously described. Turn ignition on and rotate distributor by hand. Replace Hall Effect switch if voltage remains either high or low.

Fig. 6: Cadillac HEI Ignition With Hall Effect Switch Courtesy of GENERAL MOTORS CORP. MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

A malfunction in the MAP sensor circuit should set a related code in ECM memory. If a code is present, see appropriate TESTS W/CODES article. An out-of-calibration sensor may not set a trouble code. Use following procedure to test sensor calibration. If driveability problems exist, MAP sensor failure is suspected and no MAP code is present, disconnect MAP sensor connector. If driveability condition improves, replace MAP sensor. 1. With ignition on and engine off, check MAP sensor parameter using a "Scan" tester connected to the ALDL connector. Voltage should be as specified in MAP SENSOR VOLTAGE RANGE table. If MAP sensor voltage is as specified, go to step 2). If voltage is not as specified, check for 5-volt reference supplied to sensor. Check harness integrity. If no problems are evident, replace MAP sensor. 2. Using a hand-held vacuum pump, apply 10 in. Hg to MAP sensor and note voltage change. Voltage should drop to about 1.2-2.3 volts or less than as specified in table. If voltage is not as specified or voltage reading does not immediately follow vacuum change, MAP sensor is faulty.

Fig. 7: Typical MAP Sensor Circuit Courtesy of GENERAL MOTORS CORP. MAP SENSOR VOLTAGE RANGE Altitude (Ft.) Below 1000 1000-2000 2000-3000 3000-4000 4000-5000 5000-6000 6000-7000 7000-8000 8000-9000 9000-10,000 MANIFOLD AIR TEMPERATURE (MAT) SENSOR

Range (Volts) 3.8-5.5 3.6-5.3 3.5-5.1 3.3-5.0 3.2-4.8 3.0-4.6 2.9-4.5 2.8-4.3 2.6-4.2 2.5-4.0

If a MAT sensor related code is present, see appropriate TESTS W/CODES article. An out-of-calibration sensor may not set a trouble code. Use following procedure to test calibration. Disconnect MAT sensor harness connector. Connect ohmmeter between sensor terminals. Sensor resistance should be as specified. See MAT SENSOR RESISTANCE table. With vehicle sitting overnight, MAT sensor and coolant sensor should have close to the same resistance reading. MAT SENSOR RESISTANCE Temperature Â°F (Â°C) 210 (100) 160 (70) 100 (38) 70 (20) 40 (4) 20 (-7) 0 (-18) -40 (-40)

Resistance (Ohms) 185 450 1800 3400 7500 13,500 25,000 100,700

MASS AIRFLOW SENSOR A malfunction in the MAF sensor circuit will result in the setting of a related trouble code. For testing procedures, see appropriate code(s) in appropriate TESTS W/CODES article. OXYGEN SENSOR (O2) 1. Start engine and warm to operating temperature. Disconnect oxygen sensor. Connect a DVOM between Purple lead of oxygen sensor and ground. Place meter on the 2-volt scale. Voltmeter reading should increase to greater than .8 volt. 2. Using another DVOM on the 20-volt scale. Connect voltmeter in series between the Purple wire from the ECM and the positive post of battery. Reading on voltmeter connected to oxygen sensor should decrease to a low voltage (less than .3 volt). 3. If a second DVOM is not available, install short jumper in Purple wire from the ECM. Hold jumper in one hand and touch positive post of battery with other hand to cause oxygen sensor to produce less than .3 volts. For additional testing procedures, see appropriate TESTS W/CODES article. P/N SWITCH Disconnect P/N switch (located on transmission) harness connector. Connect ohmmeter between the P/N switch terminals. See Fig. 8. Continuity should be present only when gear shift selector is in Park or Neutral. If continuity is not present, check P/N switch adjustment or replace defective P/N switch.

Fig. 8: Typical P/N Switch Circuit Courtesy of GENERAL MOTORS CORP. POWER STEERING PRESSURE SWITCH (PSPS) Disconnect P/S pressure switch harness connector. Connect ohmmeter between P/S pressure switch terminals. Start engine. With no-load on power steering, continuity should not be present. Turn steering wheel to full stop, continuity should now be present. If readings are not as specified, replace defective P/S pressure switch. PRESSURE/BARO SENSOR CARBURETED 5.0L (VIN Y) 1. Connect jumper harness between sensor and sensor harness to enable checking voltage with DVOM with circuit intact. With ignition on, engine off, check voltage between pressure sensor terminals "A" and "B". See Fig. 9. Voltage should be as specified. See PRESSURE SENSOR VOLTAGE RANGE table. If okay, go to next step. If voltage is not as specified, check vacuum hose. If vacuum hose is okay, replace pressure sensor. 2. Using a hand-held vacuum pump, apply 10 in. Hg to pressure sensor and note voltage change. Voltage should drop to about 1.2-2.3 volts or less from specified sensor voltage range on table. If voltage is not as specified or if voltage reading does not immediately follow vacuum change, pressure sensor is faulty. NOTE:

"Scan" tester will not read same voltage as voltmeter since ECM inverts voltage signal internally.

Fig. 9: Pressure (Baro) Sensor Circuit Courtesy of GENERAL MOTORS CORP. PRESSURE SENSOR VOLTAGE RANGE Altitude (Ft.) Below 1000 1000-2000 2000-3000 3000-4000 4000-5000 5000-6000 6000-7000 7000-8000 8000-9000 9000-10,000

Range (Volts) 3.8-5.5 3.6-5.3 3.5-5.1 3.3-5.0 3.2-4.8 3.0-4.6 2.9-4.5 2.8-4.3 2.6-4.2 2.5-4.0

THROTTLE POSITION SENSOR (TPS) Install jumper wires to enable connection of a DVOM in parallel between TPS harness connectors. Connect DVOM positive lead to Blue wire terminal. Connect negative lead to Black wire terminal. See Fig. 10. Turn ignition on, engine off. Signal voltage should gradually change from less than one volt at closed throttle to about 5.0 volts at wide open throttle position. If reading is not as specified, adjust or replace TPS. See the appropriate ADJUSTMENTS article. A malfunction in the TPS circuit should set a related trouble code. For further information, see appropriate TESTS W/CODES article. Also see TPS adjustment procedure in the appropriate ADJUSTMENTS article in this section.

Fig. 10: Typical Throttle Position Sensor Circuit Courtesy of GENERAL MOTORS CORP. VEHICLE SPEED SENSOR (PM GENERATOR TYPE) Disconnect vehicle speed sensor harness connector (located in transaxle). Place gear selector in Neutral. Raise vehicle drive wheels off the ground. Turn drive wheels by hand (greater than 3 MPH). Measure AC signal voltage between sensor terminals. Voltage reading should be vary from 0.1-0.5 volt AC as the wheel is turned. If reading is not as specified, replace vehicle speed sensor. VEHICLE SPEED SENSOR (LED TYPE) A speed sensor or buffer malfunction should set a related code in ECM memory. If a code is set, refer to appropriate TESTS W/CODES article in this section for diagnosis.

RELAYS A/C RELAYS See MISCELLANEOUS ECM CONTROLS in this article. FUEL PUMP RELAY 1. Disconnect fuel pump relay. See SYSTEM & COMPONENT TESTING article. Apply battery voltage and ground to fuel pump relay winding terminals. To identify fuel pump relay terminals, see appropriate wiring diagram in WIRING DIAGRAMS. 2. Using an ohmmeter, check continuity between fuel pump relay power and fuel pump relay drive terminals. Continuity should exist. If continuity does not exist, fuel pump relay is defective. 3. To by-pass fuel pump relay on-vehicle (fuel pump not operating), turn ignition off. Disconnect fuel pump relay connector. Using a fused jumper wire, connect fuel pump test connector to positive side of battery. Fuel pump should run. 4. If fuel pump runs, check for faulty connections to relay or replace defective relay. To locate fuel pump

test connector, see the SYSTEM & COMPONENT TESTING article in this section.

Fig. 11: Typical Fuel Pump Relay Schematic Courtesy of GENERAL MOTORS CORP.

SOLENOIDS NOTE:

All ECM controlled solenoids should have at least 20 ohms of resistance.

CANISTER PURGE SOLENOID See Canister Purge Solenoid tests in the Fuel Evaporation Control Section.. MIXTURE CONTROL SOLENOID See FUEL SYSTEM in this article and CODE 23 in 5.0L CARBURETED TROUBLE CODES in appropriate TESTS W/CODES article. ILC/RVB/EGR SOLENOID 1. Disconnect solenoid harness connector. Install vacuum pump to manifold vacuum side of solenoid. Apply vacuum to solenoid. Vacuum should pass through when solenoid connector is disconnected. 2. Apply battery voltage and ground to solenoid terminals. Solenoid should energize. With solenoid energized, apply vacuum to solenoid. Vacuum should not pass through solenoid. If results are not as

specified, replace defective solenoid. WASTEGATE SOLENOID See AIR INDUCTION SYSTEMS in this article.

MOTORS IDLE AIR CONTROL (IAC) MOTOR See IDLE CONTROL SYSTEM in this article. IDLE SPEED CONTROL (ISC) MOTOR See IDLE CONTROL SYSTEM in this article.

FUEL SYSTEM NOTE:

For fuel system pressure testing, see BASIC DIAGNOSTIC PROCEDURES article.

FUEL PRESSURE REGULATOR (PFI) 1. Install fuel pressure gauge to fuel rail fuel pressure test fitting. Remove vacuum hose from fuel pressure regulator. Turn ignition on and note fuel pressure on gauge. 2. Start engine. Check for manifold vacuum at pressure regulator vacuum hose. Repair as necessary. Reconnect vacuum hose to pressure regulator and note fuel pressure on gauge. Compare first and second reading. Fuel pressure reading should be 4-7 psi (.28-.49 kg/cm2 ) less with vacuum hose installed. Fuel pressure should decrease as vacuum increases. If results are unsatisfactory, replace fuel pressure regulator. FUEL PRESSURE REGULATOR (TBI) Fuel pressure regulator is mechanically controlled by internal spring pressure. Regulator is adjusted at factory and is not serviceable. If fuel pressure is too low, check for fuel filter, fuel pump pressure and volume. If fuel pressure is too high, check for restricted fuel tank return line. If no faults are found and pressure is too high or too low, replace fuel pressure regulator. FUEL PUMP RELAY See RELAYS, SOLENOIDS, MOTORS & MODULES in this article. FUEL PUMP RELAY BY-PASS PROCEDURE If fuel pump will not energize, relay may be by-passed to test fuel pump. Turn ignition off. Using a fused jumper wire, apply battery voltage to fuel pump test connector (located in engine compartment). Fuel pump

should turn on. For fuel pump test connector location, refer to SYSTEM & COMPONENT TESTING article.

FUEL CONTROL (CARBURETED) NOTE:

For testing of feedback system, including oxygen sensor, mixture control solenoid, ECM and related wiring, refer to SYSTEM PERFORMANCE CHECK in BASIC TESTING article.

FLOAT LEVEL (ON-VEHICLE) 1. Warm engine to normal operating temperature. With engine at idle and choke wide open, insert Float Level Gauge (J-34935-1 or BT-8420-A) into carburetor air horn vent slot. Allow gauge to float freely. 2. Observe that mark on gauge lines up with top of air horn casting. Setting should be within 2/32" of specified float level setting. See FLOAT LEVEL SPECIFICATIONS table. If float level is not as specified, remove air horn and adjust float level. FLOAT LEVEL SPECIFICATIONS Carburetor No. 17086008 17086009 17088115

Setting 11/32" 14/32" 11/32"

HOT AIR CHOKE 1. Warm engine to normal operating temperature. Check choke valve. Choke valve should be fully open. If choke is not fully opened, touch choke housing and hot air inlet pipe or hose to determine if sufficient heat is reaching choke thermostatic spring. 2. If choke housing or hot air inlet pipe is not getting hot, check choke housing, choke heat pipe or manifold choke heat stove for restricted passages. Repair or replace components. MIXTURE CONTROL SOLENOID Disconnect mixture control solenoid harness connector. Check resistance between solenoid terminals. Normal resistance is 20-32 ohms. Check for unwanted shorts to ground between solenoid connector terminals and solenoid body. Resistance to ground should be infinite. If resistance is less than 10 ohms or if solenoid has continuity to ground, replace solenoid. OXYGEN SENSOR See ENGINE SENSORS & SWITCHES in this article. VACUUM BREAK Plug air bleed hole (if equipped) on vacuum break. Using a hand-held vacuum pump, apply 15 in. Hg to vacuum break. Check and see if plunger has moved through its full travel. Observe vacuum gauge. Vacuum should hold for at least 20 seconds. If plunger did not move to its full travel or vacuum did not hold as specified,

replace vacuum break.

FUEL CONTROL (FUEL INJECTED) FUEL INJECTOR(S) Disconnect fuel injector harness connector. Measure resistance across injector terminals. Resistance should be as specified. See FUEL INJECTOR RESISTANCE table. FUEL INJECTOR RESISTANCE Application 2.0L (VIN K) 2.0L Turbo (VIN M) 2.2L (VIN G) 2.3L (VIN A & D) 2.5L (VIN R & U) 3.1L (VIN T) 3.1L Turbo (VIN V) 3.3L (VIN N)

(1) Resistance (Ohms)

1.6 2.0 1.6 1.9-2.1 1.6 12.0-12.4 12.0-12.4 (2) (2)

3.8L (VIN C) 5.0L (VIN E) 5.0L (VIN F) 5.7L (VIN 7) 5.7L (VIN 8) (1) Injector resistance specification is at 140°F (60°C).

1.2 10.0 1.2 10.0

(2) Information not available from manufacturer. Solenoid should have resistance; however, infinite

resistance indicates an open injector winding. NOTE:

If injectors are dirty, they should be cleaned using approved injector cleaning procedure before performing INJECTOR BALANCE TEST.

INJECTOR BALANCE TEST The injector balance test is used to pulse the injector for a precise amount of time, spraying a measured amount of fuel in the intake manifold. As each injector is pulsed, a drop in fuel rail pressure occurs. This pressure drop can be recorded and compared to other injectors. An injector with a pressure drop of 1.5 psi (.11 kg/cm2 ) or more, greater than or less than other injectors, should be considered faulty. NOTE:

Allow engine to cool down to avoid irregular readings due to "Hot Soak" fuel boiling. To prevent flooding, the INJECTOR BALANCE TEST should not be repeated more than once without starting and running engine.

CAUTION: To avoid possible vehicle fire, wrap a shop towel around fitting to avoid fuel spillage. 1. With ignition off, connect Fuel Pressure Gauge (J-34730-1) to pressure tap. Unplug harness connector at all injectors. Connect Injector Tester (J-34730-3) to one of the injectors. 2. Follow manufacturer's instructions when installing adapter harness. Ignition should be turned off at least 10 seconds to complete ECM shutdown cycle. 3. Turn ignition on. Fuel pump should run at least 2 seconds after ignition is turned on. Bleed air from gauge and hose to ensure accurate gauge reading. Repeat this procedure until all air is bled from system. Turn ignition off for at least 10 seconds. 4. Turn ignition on again to bring fuel pressure to maximum. Record initial pressure reading. Energize tester one time and note pressure drop at lowest point. 5. Disregard any slight pressure drop after low point is reached. Subtracting second pressure reading from initial reading indicates amount of injector pressure drop. 6. Repeat step 4) on each injector and compare pressure drop. Recheck injectors not within pressure drop range. Replace injector(s) failing second check. 7. If injectors are all okay, plug in harness connectors and review SYMPTOMS in H - TESTING W/O CODES article. OXYGEN SENSOR See ENGINE SENSORS & SWITCHES in this article.

IDLE CONTROL SYSTEM IDLE AIR CONTROL (IAC) MOTOR 1. Disconnect harness connector to motor. Check resistance across IAC coil terminals "A" to "B" and "C" to "D". Resistance should be 40-80 ohms. See Fig. 12. If okay, go to next step. If resistance is not as specified, replace IAC motor. 2. Check resistance between IAC terminals "B" to "C" and "A" to "D". Resistance should be infinite. If resistance is not as specified, replace IAC motor. NOTE:

Testing Idle Air Control (IAC) motor requires a "Scan" tester capable of cycling ECM output devices. Flow charts in the TESTS W/CODES articles may refer to the Tech 1 tester, General Motors' version of this tester.

Fig. 12: Typical IAC Motor Circuit Courtesy of GENERAL MOTORS CORP. IDLE SPEED CONTROL (ISC) MOTOR (CADILLAC EXCEPT BROUGHAM) A malfunction in the ISC circuit will set a trouble code. For testing procedures, see appropriate TESTS W/CODES article. Also, see ISC minimum and maximum adjustment procedures in ADJUSTMENTS article. IDLE SWITCH (CADILLAC EXCEPT BROUGHAM) The ISC motor is equipped with an internal idle switch (also called a throttle or nose switch) which informs the ECM when it should be controlling idle. Disconnect ISC connector. Connect an ohmmeter across Pink and Black/White wire terminals ("A" and "B") of ISC motor connector. See Fig. 13. With throttle closed, continuity should exist. With throttle open enough to relieve tension from the ISC plunger, continuity should not exist.

Fig. 13: Idle Speed Control Solenoid/Idle Switch Schematic Courtesy of GENERAL MOTORS CORP. IDLE LOAD COMPENSATOR (ILC)

1. With engine running and transmission in Park, hold throttle lever part way open and allow ILC plunger to fully extend. Apply finger pressure to ILC plunger. Using a hand-held vacuum pump/gauge, apply 20 in. Hg to ILC plunger. 2. Plunger should begin to retract. If not, replace ILC plunger. If plunger retracts, observe vacuum gauge. Vacuum should hold for at least 20 seconds. If vacuum does not hold, replace ILC plunger.

IGNITION SYSTEM (C3I) CHART C-4-1 (C3I MISFIRE AT IDLE 3.3L VIN N) 1. If engine misfires under load only, see C-4-2 below. With engine idling at normal operating temperature, disconnect IAC. While observing engine RPM, temporarily disconnect each injector connector. All injector(s) should result in a drop in RPM. If it does, see ROUGH, UNSTABLE OR INCORRECT IDLE in TESTS W/O CODES article If it doesn't, turn ignition OFF, and install injector tester J 34730-2 or equivalent on injector connector which did not result in an RPM drop. Crank engine while observing injector test light. Light should blink. If it doesn't, see NO START (PFI W/C3I). If it does, then proceed to next step. 2. With ignition OFF, install spark tester (ST-125) J 26792 or equivalent on plug lead(s) which did not result in drop in RPM (1,3,5 at plug and 2,4,6 at coil). Spark should jump tester gap while cranking engine. If it does, check for faulty, worn or cracked spark plug(s), plug fouling due to engine mechanical fault. If spark plugs are OK, then see CUTS OUT MISSES in TESTS W/O CODES article. If it doesn't, then check resistance of plug wire which did not fire spark tester. Wire resistance should be less than 30,000 ohms each and wires shouldn't be grounded. Are wires are OK. If Not, then replace faulty wire(s) and retest. If OK go to next step. 3. Remove coil from module. Inspect coils, plug wire and plug wire nipples. They should be free of carbon tracking. If NOT, replace faulty component. If OK got to next step. 4. Check secondary coil resistance. It should be 5-8K Ohms resistance for 3.3 VIN N models and 10-13 Ohms resistance for 3.8L VIN C models. If NOT, replace coil. If YES, then go to next step. 5. Install a known good coil. Spark should jump tester gap at problem cylinder with engine idling. If it did not, then there is a faulty C(3)1 module. If it did, then original ignition coil is faulty.

Fig. 14: Chart C-4-1 Schematic, Misfire At Idle (3.3L VIN N)

Fig. 15: Chart C-4-1 Schematic, Misfire At Idle (3.8L VIN C)

CHART C-4-2 (C3I MISFIRE UNDER LOAD IDLE 3.3L VIN N) 1. If engine misfires at idle, see C-4-1 above. With engine idling at normal operating temperature, disconnect IAC. While observing engine RPM, temporarily disconnect each injector connector. All injector(s) should result in a drop in RPM. If it does, check for faulty, worn or cracked spark plug(s), plug fouling due to engine mechanical fault. If spark plugs are OK, then see CUTS OUT MISSES in TESTS W/O CODES article. If it doesn't, turn ignition OFF, and install injector tester J 3470-2 or equivalent on injector connector which did not result in an RPM drop. Crank engine while observing injector test light. Light should blink. If it doesn't, see NO START (PFI W/C3I). If it does, then proceed to next step. 2. With ignition OFF, install spark tester (ST-125) J 26792 or equivalent on plug lead(s) which did not result in drop in RPM (1,3,5 at plug and 2,4,6 at coil). Spark should jump tester gap while cranking engine. If it does, check for faulty, worn or cracked spark plug(s), plug fouling due to engine mechanical fault. If spark plugs are OK, then see CUTS OUT MISSES in TESTS W/O CODES article. If it doesn't, then check resistance of plug wire which did not fire spark tester. Wire resistance should be less than 30,000 ohms and shouldn't be grounded. Are wires are OK? If Not, then replace faulty wire(s). If OK go to next step. 3. Remove coil from module. Inspect coils, plug wires and plug wire nipples. They should be free of carbon tracking. If NOT, replace faulty component. If YES , then check secondary coil resistance. It should be 58K Ohms resistance for 3.3 VIN N models and 10-13 Ohms resistance for 3.8L VIN C models. If NOT, replace coil. If YES, then go to next step. 4. Install a known good coil. Spark should jump tester gap at problem cylinder with engine idling. If it did not, then there is a faulty C3I module. If it did, then original ignition coil is faulty.

Fig. 16: Chart C-4-2 Schematic, Misfire Under Load (3.3L VIN N)

Fig. 17: Chart C-4-2 Schematic, Misfire At Idle (3.8L VIN C)

IGNITION SYSTEM (EXC. C3I) NOTE:

For basic ignition system checks, see BASIC TESTING article.

TIMING CONTROL SYSTEMS ELECTRONIC SPARK TIMING (EST) ADVANCE SYSTEM 1. A malfunction in the EST circuit should set a related trouble code. Start engine and warm to operating temperature. On vehicles equipped with a manual transmission, increase engine speed to about 2000 RPM. On vehicle equipped with an automatic transmission, slightly increase idle speed. 2. On all vehicles, ground "test" terminal "B" of ALDL. A noticeable change in engine speed should occur. If no change occurs, see DIAGNOSTIC CIRCUIT CHECK in BASIC TESTING article. ELECTRONIC SPARK CONTROL (ESC) RETARD SYSTEM (WITHOUT ESC CONTROLLER) 1. An open or short circuit on the ESC wire to the ECM will set a related trouble code. A false detonation signal will not cause ECM to set a code. 2. If a "Scan" tester is available, connect it to the ALDL connector. Tap on engine next to knock sensor and note "knock" parameter. Knock should be indicated on "Scan" tester. 3. If a "Scan" tester is not available, connect tachometer to engine. Start engine and hold above idle. Using a

metal object, tap on engine close to knock sensor. A noticeable decrease in engine RPM should occur. If no RPM decrease occurred, check knock sensor to ECM circuit. 4. On vehicles equipped with automatic transmission, it may be necessary to place transmission in Drive for timing change to occur. Also, see KNOCK SENSOR in ENGINE SENSORS & SWITCHES in this article. ELECTRONIC SPARK CONTROL (ESC) RETARD SYSTEM (WITH ESC CONTROLLER) 1. An open or short circuit on the ESC wire to the ECM will cause a loss of the 12-volt ESC controller signal. This will cause the ECM to fully retard ignition timing. 2. If a "Scan" tester is available, connect it to the ALDL connector. Tap on engine next to knock sensor and note "knock" parameter. Knock should be indicated on "Scan" tester. 3. If a "Scan" tester is not available, connect a DVOM to the ECM ESC signal terminal. With engine idling, 12 volts should be present at this terminal. Using a metal object, tap on engine close to knock sensor. Voltage signal at ECM terminal should drop to zero volts, and return when knock signal ceases. 4. If signal does not respond as described, check knock sensor signal to controller signal. On vehicles equipped with automatic transmission, it may be necessary to place transmission in Drive for timing change to occur. Also, see KNOCK SENSOR in ENGINE SENSORS & SWITCHES in this article.

AIR INJECTION AIR PUMP Accelerate engine to approximately 1500 RPM and observe airflow from hoses. If airflow increases as engine is accelerated, pump is working properly. If airflow does not increase, check hoses, pump belt tension, leaky valves or defective air injection pump. CHECK VALVE Detach check valve and blow through valve in direction of check valve flow (to cylinder head). Attempt to suck back. Replace valve if airflow is allowed against the direction of flow. DECELERATION VALVE 1. Remove air cleaner. Remove and plug vacuum hose to air cleaner. Connect tachometer to engine. With engine at idle, remove deceleration valve signal hose from vacuum port. 2. Reconnect signal hose to deceleration valve while listening for air flow through ventilation pipe into deceleration valve. Engine speed should drop when hose is reconnected. 3. If airflow lasts less than one second or engine speed does not drop, check for defective hose(s) or deceleration valve. ELECTRIC DIVERT & ELECTRIC SWITCHING VALVE (EDES) With engine at idle, check for at least 10 in. Hg to EDES. Run engine at part throttle (less than 2000 RPM). Air should go into exhaust ports until system goes into closed loop, then divert the air to atmosphere. If not, check terminal harness connector to EDES or replace defective EDES.

PRESSURE OPERATED ELEC. DIVERT/ELEC. SWITCHING (PEDES) 1. When engine is cold, port solenoid should be energized, allowing airflow to exhaust ports. 2. When engine is warming up, port switch should be de-energized (off) and converter solenoid should be energized, forcing airflow past the converter valve to the catalytic converter. 3. On the divert mode, both solenoids are de-energized, which opens the converter valve, allowing air out to divert/relief tube to atmosphere. If valves are not operating as specified, check circuit to solenoids. Repair or replace components as necessary.

EARLY FUEL EVAPORATION (EFE) CARBURETED 5.0L (VIN Y) NOTE:

Before performing EFE testing, allow engine to cool until coolant temperature is less than 105°F (41°C).

EARLY FUEL EVAPORATION SYSTEM CHECK 1. Locate and note position of EFE actuator arm. On some models, actuator arm may be protected by metal cover, which must be removed and then replaced after service has been performed. 2. When engine is cold, valve should close as actuator link pulls into diaphragm housing. If valve closes, go to step 6). If not, stop engine and remove vacuum hose to EFE valve. Restart engine and check for vacuum at hose. If vacuum is present, go to step 4). 3. If vacuum is not present, check vacuum supply to Thermal Vacuum Switch (TVS), located in coolant passage of intake manifold. Repair as necessary. If vacuum is present at TVS and coolant temperature is less than 105°F (40°C), replace TVS. CAUTION: Exhaust manifold will become very hot once engine is started. Wear heavy gloves when handling exhaust system components. 4. Attempt to move actuator arm by hand. If valve opens freely, vacuum motor diaphragm is defective. Replace EFE valve and actuator motor. 5. If lever will not move freely, try to free valve using Manifold Valve Lubricant (1050422). Allow time for lubricant to penetrate. If valve cannot be freed, replace valve and actuator motor. 6. If valve closes in step 2), allow engine to warm. When coolant temperature exceeds 105°F (40°C), valve should open. If valve does not open, stop engine, remove vacuum hose from EFE valve. Restart engine. If vacuum is present at vacuum hose and coolant temperature is greater than 105°F (40°C), replace TVS.

EXHAUST GAS RECIRCULATION (EGR) NOTE:

Some vehicles may use integral EGR/ILC/RVB, TCC/EGR, or EGR/CP solenoid valves.

There are 5 types of EGR systems used: backpressure (positive and negative), digital, electronic and pulse width modulated systems.

SYSTEM TEST Start and run engine to normal operating temperature. With engine at idle, RPM should drop as EGR valve is opened by pushing up on underside of EGR diaphragm. CAUTION: Wear gloves when handling EGR valve when it is hot .

EGR CONTROL SOLENOID 1. Disconnect EGR solenoid electrical harness connector and vacuum hoses. Connect a hand-held vacuum pump to solenoid vacuum source port. Connect vacuum gauge to solenoid EGR port. Pump up vacuum pump. Vacuum should not be present at port to EGR valve. 2. Activate EGR solenoid with a 12-volt power supply. Vacuum should now be present or registered at vacuum gauge. Solenoid should have at least 20 ohms of resistance. DIGITAL EGR VALVE 1. Start and allow engine to idle. With engine at normal operating temperature, disconnect digital EGR valve solenoid harness connector. Using a 12-volt power source, very quickly energize EGR solenoid No. 1. RPM should drop slightly. See Fig. 18. 2. Next, energize EGR solenoid No. 2. RPM should drop slightly more than step 1). If RPM drops, EGR is okay. If not, check for plugged EGR passages or defective digital EGR valve. Check EGR solenoid resistance. See DIGITAL EGR SOLENOID RESISTANCE table. For additional testing procedures, see appropriate TESTS W/CODES article. DIGITAL EGR SOLENOID RESISTANCE (1) Terminals No. A-D B-D C-D (1) See Fig. 18 for terminal location.

Resistance (Ohms) 20-30 20-30 10-17

Fig. 18: Digital EGR Solenoid Circuit Courtesy of GENERAL MOTORS CORP. POSITIVE BACKPRESSURE EGR VALVE 1. Place transmission in Park or Neutral. Set parking brake and block drive wheels. Connect tachometer. With engine running at normal operating temperature, run engine at 2000 RPM. 2. On carbureted engines, place fast idle cam on high step. Disconnect vacuum hose from EGR valve and plug hose. EGR valve diaphragm should move down and engine RPM should increase. NOTE:

On some engines with ECM controlled solenoid, EGR vacuum is locked out in Park/Neutral and solenoid must not be by-passed.

3. Reconnect vacuum hose. EGR diaphragm should move up and engine RPM should decrease. A slight vibration of diaphragm plate may be noticed in backpressure EGR valves. 4. If engine RPM did not change and EGR diaphragm moved, the EGR valve is functioning properly. If engine RPM did not change and diaphragm did not move, remove EGR valve and apply 10 in. Hg to EGR vacuum signal port. EGR valve should not open. 5. If EGR valve opens, replace EGR valve. With vacuum still applied, direct a stream of air (15 psi maximum) into valve seat. EGR valve should open completely. 6. If air is not available, connect a short piece of hose over EGR valve seat. Connect vacuum pump to signal port. With thumb plugging intake port of EGR valve, operate vacuum pump while alternately blowing and pausing through hose. 7. With vacuum present at signal port, EGR valve should open while pressure is applied and should close when no vacuum is present. NEGATIVE BACKPRESSURE EGR VALVE With engine off, disconnect vacuum hose to EGR valve. Connect vacuum pump to EGR and apply 10 in. Hg. EGR diaphragm should move up and stay up for 20 seconds. If not, replace EGR valve.

PULSE WIDTH MODULATED EGR VALVE 1. Place transmission in Park or Neutral. With engine at idle and at normal operating temperature, push up on EGR valve diaphragm. Engine RPM should drop. If engine RPM did not drop, clean EGR valve and passages. 2. Check EGR valve movement with engine RPM change from 2000 RPM to idle. If EGR valve moves with RPM change, check Park/Neutral switch adjustment or open circuit. If EGR valve did not move, ground ALDL test connector. If EGR valve moves now, EGR valve is functioning properly. If not, go to next step. 3. Turn engine off and disconnect EGR solenoid connector. Connect 12-volt test light between EGR solenoid connector terminals. Turn ignition on and ground ALDL test connector. Test light should flash repeatedly. 4. If test light flashes, check vacuum to EGR solenoid at 2000-3000 RPM. If engine does not use a vacuum regulator, at least 7 in. Hg should be present at solenoid. If engine is equipped with a vacuum regulator, 2-10 in. Hg should be present. 5. If vacuum is greater than 10 in. Hg, replace regulator. If vacuum is less than 2 in. Hg, vacuum at solenoid is okay. Check EGR solenoid connections and/or faulty EGR solenoid. INTEGRATED ELECTRONIC EGR VALVE 1. Turn ignition off. Connect vacuum pump to EGR valve. Apply vacuum and observe EGR valve. EGR valve should not move. If it does, check vent filter for restriction. Replace EGR valve if necessary. 2. Turn ignition on and repeat step 1). When applying vacuum, EGR valve should not move. If EGR moves, a fault code should be present. See appropriate TESTS W/CODES article.

FUEL EVAPORATION CONTROL NOTE:

Two types of canister control valves are used on General Motors vehicles. One is fixed to canister (Type 1) and the other is removable (Type 2).

CANISTER CONTROL VALVE (TYPE 1) 1. Note vacuum hose location and disconnect hoses from control valve and canister. Install a short vacuum hose to lower tube of carbon canister valve. Blow into hose. Air should not pass through canister. If it does, replace valve/canister. 2. Using a hand-held vacuum pump, apply 15 in. Hg to trigger port. With vacuum applied, again blow into hose installed on bowl vent tube. Air should now flow through canister. If not, replace valve/canister. CANISTER CONTROL VALVE (TYPE 2) 1. Note vacuum hose location and remove valve from vehicle. Install a short length of hose to vacuum trigger port. Blow into hose. Air should not pass through. If it does, diaphragm is ruptured and valve must be replaced. 2. Using a hand-held vacuum pump, apply 15 in. Hg to vacuum trigger port. Vacuum should hold for 20 seconds. If not, replace valve.

3. With vacuum still applied to trigger port, blow through canister tube. Air should exit from vacuum purge tube. If not, replace valve. CANISTER PURGE SOLENOID 1. Disconnect canister purge solenoid harness connector and vacuum hose. Apply 10 in. Hg to ported intake manifold vacuum side of solenoid valve. If vacuum holds, go to next step. If vacuum does not hold, replace canister purge solenoid. 2. Using a 12-volt power source, energize canister purge solenoid. Vacuum should release. If vacuum does not release, replace canister purge solenoid. EVAP PURGE VALVE SOLENOID 1. Disconnect purge valve solenoid harness connector and vacuum hose. Apply 10 in. Hg to ported vacuum side of solenoid valve. If vacuum holds, go to next step. If vacuum does not hold, replace canister purge solenoid. 2. Using a 12-volt power source, energize purge valve solenoid. Vacuum should release. If not, replace purge valve solenoid. Solenoid resistance should be at least 20 ohms. FUEL TANK PRESSURE CONTROL VALVE Apply approximately 15 in. Hg to tank pressure control valve. The diaphragm should hold vacuum for at least 20 seconds. If not, replace tank pressure control valve. THERMAL BOWL VENT VALVE (TBVV) CARBURETED 5.0L (VIN Y) 1. Remove thermal bowl vent valve. Allow valve to cool to less than 90°F (32°C). Install a short hose to either valve port. Lightly blow into hose. No air should pass through valve. If it does, replace TBVV. 2. Warm valve to greater than 120°F (49°C). Once again, blow into hose. Air should now pass through valve. If not, replace TBVV.

PCV CHECKING PCV VALVE FUNCTION The PCV system may require service for obstructions if any of the following conditions exist:     

Rough Idle Stalling or Slow Idle Speed Oil Leaks Oil in Air Cleaner Sludge in Engine

A PCV leaking valve or hose could cause:   

Rough Idle Stalling High Idle speed

If engine idles roughly, check for clogged PCV valve, plugged or broken hoses BEFORE adjusting idle. Check correct PCV valve application to ensure the correct valve is fitted. Replace PCV valve if required. PCV VALVE FUNCTION 1. Remove PCV valve from rocker cover. Run engine at idle. Place thumb over open end of valve to check for vacuum. If there is no vacuum at valve, check for obstruction in manifold port, hoses or PCV valve. Repair or replace as necessary. 2. Turn engine off. Remove PCV valve. Shake valve and listen for rattle of check valve inside. If a clear rattle is not heard, replace PCV valve. 3. Visually inspect valve for varnish or deposits which may make PCV valve operation sticky, restricted or cause incomplete seating of valve. Replace if necessary. 4. An engine must be sealed for the PCV system to function as designed. If leakage, sludging or dilution of oil is noted and the PCV system is functioning properly, check engine for cause and repair as required to insure PCV system will continue to function properly. 5. An engine operating without any crankcase ventilation can be damaged so it is important to replace PCV valve and air cleaner breather at regular intervals (at least every 30,000 miles). Check all hoses and clamps for failure or deterioration.

THERMOSTATIC AIR CLEANER TEMPERATURE SENSOR 1. Air cleaner temperature should be less than 86°F (30°C). Place thermometer as close to sensor inside air cleaner. Start and idle engine. Damper door should close off outside air immediately. 2. When damper door starts to open snorkel passage, remove air cleaner cover and read thermometer temperature. Thermometer should read 131°F (55°C). 3. If damper door does not open to outside air at the specified temperature, replace defective thermostatic air cleaner temperature sensor. VACUUM DIAPHRAGM MOTOR 1. Turn engine off. Disconnect vacuum hose to vacuum motor. Apply 7 in. Hg to vacuum motor. Damper door should close. If not, check if linkage is properly hooked up. 2. With vacuum still applied, trap vacuum in vacuum diaphragm motor by bending hose. Damper door should remain closed. If damper door does not remain closed, replace vacuum diaphragm motor assembly.

MISCELLANEOUS ECM CONTROLS

NOTE:

Although not considered true engine performance-related systems, some controlled devices may affect driveability if they malfunction.

A/C CLUTCH A/C Clutch Relay

1. Disconnect A/C clutch relay harness connector. Using proper mini-schematic and an ohmmeter, check continuity between A/C clutch relay winding terminals. Continuity should exist. Check continuity between clutch drive circuit terminals of relay. Continuity should not exist. See Fig. 19-38. 2. Using jumper wires, apply ground and battery voltage to relay winding of relay. Continuity should now exist between clutch drive circuit terminals of relay. Replace A/C clutch relay if readings are not as specified.

Fig. 19: Sunbird 2.0L TBI A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 20: Sunbird 2.0L PFI A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 21: Beretta & Corsica 2.2L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 22: Cavalier 2.2L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 23: Beretta 2.3L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 24: Calais, Grand Am & Skylark 2.3L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 25: Cutlass Supreme & Grand Prix 2.3L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 26: Cutlass Calais, Grand Am & Skylark 2.5L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 27: Celebrity, Century & Cutlass Cruiser 2.5L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 28: Lumina 2.5L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 29: Beretta & Corsica 3.1L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 30: Camaro & Firebird 3.1L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 31: Cavalier 3.1L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 32: Celebrity & 6000 3.1L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 33: Cutlass Supreme, Grand Prix & Regal 3.1L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 34: Lumina 3.1L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 35: Century 3.3L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 36: Skylark 3.3L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 37: Bonneville, Delta 88, Electra, LeSabre, Ninety-Eight & Park Avenue 3.8L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 38: Corvette 5.7L A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP. A/C WOT CUT-OUT RELAY 1. Disconnect WOT cut-out relay harness connector. Using an ohmmeter, check continuity between relay terminals "A" and "C" and "B" and "E". Continuity should be present on these circuits. 2. Using jumper wires, apply battery voltage to relay terminal "C" and ground to relay terminal "A". Continuity should not exist between relay terminals "B" and "E" while relay is energized. If continuity is not as specified, replace defective WOT cut-out relay.

Fig. 39: Brougham Carbureted A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 40: Carbureted (Except Brougham) A/C Clutch Schematic Courtesy of GENERAL MOTORS CORP.

COOLING FAN NOTE:

For additional information on electric cooling fans, see ELECTRIC COOLING FANS article in ENGINE COOLING.

COOLING FAN SYSTEM & QUAD-DRIVER CHECK 1. Connect a test light to battery voltage. Touch test light probe to the cooling fan control driver terminal of the ECM. See Fig. 41-62. Disconnect coolant temperature sensor. This should set a code, causing ECM to engage cooling fan through relay. On some models it may be necessary to jumper the coolant temperature sensor harness connectors. On some models, grounding the ALDL with the ignition on and engine off will cause the ECM to activate the cooling fan control driver (ground circuit). 2. If test light illuminates and cooling fan does not come on, check cooling fan relay, power circuits, cooling fan motor, and relay and fan motor ground circuits. If test light does not illuminate, problem is a faulty ECM connector or ECM. Clear trouble code(s) from ECM memory after testing. 3. If cooling fan functions normally during testing but fails to operate under normal conditions, check ECM monitored inputs which affect cooling fan operation. These include the following: coolant temperature sensor, A/C request signal from A/C control switch and A/C pressure sensor or pressure/temperature switch signals (if equipped).

COOLING FAN RELAY 1. Disconnect cooling fan relay harness connector. Using an ohmmeter, check continuity of relay winding. See Fig. 41-62. Continuity should exist. Check continuity across power delivery terminals of relay. With relay not energized, no continuity should exist. 2. With ohmmeter still attached to power delivery terminals of relay, apply battery voltage and ground to energize relay winding. Continuity should now be present between cooling fan relay power delivery terminals. Replace cooling fan relay if readings are not as specified. COOLING FAN MOTOR Disconnect cooling fan motor harness connector. Apply battery voltage to one of the fan motor terminals and jumper the other terminal to ground. Fan motor should activate. If fan motor does not activate, replace faulty fan motor.

Fig. 41: Sunbird 2.0L TBI Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 42: Sunbird 2.0L PFI Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 43: Beretta & Corsica 2.2L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 44: Cavalier 2.2L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 45: Beretta 2.3L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 46: Calais, Grand Am & Skylark 2.3L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 47: Cutlass Supreme & Grand Prix 2.3L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 48: Cutlass Calais, Grand Am & Skylark 2.5L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 49: Celebrity, Century & Cutlass Cruiser 2.5L Cooling Fan Schematic

Courtesy of GENERAL MOTORS CORP.

Fig. 50: Lumina 2.5L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 51: Beretta & Corsica 3.1L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 52: Camaro & Firebird 3.1L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 53: Cavalier 3.1L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 54: Celebrity & 6000 3.1L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 55: Cutlass Supreme, Grand Prix (Except Turbo), Lumina & Regal 3.1L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 56: Grand Prix 3.1L Turbo Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 57: Century 3.3L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 58: Skylark 3.3L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 59: Bonneville, Delta 88, Electra, LeSabre, Ninety-Eight & Park Avenue 3.8L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 60: Reatta, Riviera, Toronado & Trofeo 3.8L Cooling Fan Schematic

Courtesy of GENERAL MOTORS CORP.

Fig. 61: Camaro & Firebird 5.0L & 5.7L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 62: Corvette 5.7L Cooling Fan Schematic Courtesy of GENERAL MOTORS CORP.

COOLANT LEVEL LIGHT See COOLANT LEVEL SENSOR & COOLANT LEVEL LIGHT in ENGINE SENSORS & SWITCHES in this article.

HOT LIGHT OR COOLANT TEMPERATURE LIGHT 1. Turn ignition on and note indicator light. Light should be on as a bulb check. If light is not on, go to step 2). Start engine. Light should go off. If light stays on and engine temperature is low, scan coolant temperature sensor reading. If reading indicates a false high reading, see COOLANT TEMPERATURE SENSOR in this article. If reading is low, check for a short in the bulb ground circuit. If short is not present, connect a test light to battery voltage and touch ECM temperature light driver terminal. If test light illuminates, ECM is faulty. 2. Disconnect ECM connector containing temperature light driver terminal. Turn ignition on. Using a jumper wire, ground ECM temperature light driver terminal. If light does not illuminate, check for an open in the temperature light circuit, including a bad bulb. If light does illuminate, ECM driver is faulty.

TRANSMISSION CONVERTER CLUTCH SOLENOID

Disconnect harness connector to TCC solenoid. Measure resistance between TCC solenoid terminals "A" and "D". Solenoid resistance should be greater than 20 ohms. NOTE:

Some solenoids have an internal pressure switch in series with the solenoid winding and will not show continuity until that pressure switch is applied by transmission hydraulic pressure. See Fig. 63-86.

CONVERTER LOCK-UP SIGNAL AT TRANSMISSION 1. Warm engine to operating temperature. Raise vehicle and support drive wheels. Support suspension where necessary to prevent damage to drive axles. 2. Disconnect converter clutch connector at transmission. Connect a test light across terminals "A" and "D" of converter clutch harness. Start engine and place transmission in Drive. Accelerate vehicle to 45 MPH and note test light. 3. If test light is not on, check solenoid power supply wire of harness for open or short to ground. Check ground circuit for open between harness connector and ECM. If harness is okay, see CONVERTER LOCK-UP SIGNAL FROM ECM. CONVERTER LOCK-UP SIGNAL FROM ECM 1. Warm engine to operating temperature. Raise vehicle and support drive wheels. Support suspension where necessary to prevent damage to drive axles. 2. Connect a test light to battery voltage. Touch TCC control driver terminal with test light. See Fig. 63-86. Accelerate vehicle to 45 MPH and note test light. If test light does not illuminate, problem is a faulty ECM connector or ECM. On some models, lock-up signal may be checked at ALDL terminal "F" instead of at ECM terminal.

Fig. 63: Carbureted Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 64: 2.0L PFI Sunbird Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 65: 2.0L TBI, 2.2L & 2.5L Celebrity, Century, Cutlass Calais, Cutlass Cruiser, Grand Am & Skylark Converter Clutch Courtesy of GENERAL MOTORS CORP.

Fig. 66: 2.2L Beretta & Corsica Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 67: 2.3L Cutlass Calais, Cutlass Supreme, Grand Am, Grand Prix & Skylark Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 68: 2.5L Lumina Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 69: 3.1L Beretta & Corsica Converter Clutch Schematic

Courtesy of GENERAL MOTORS CORP.

Fig. 70: 3.1L Camaro & Firebird Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 71: 3.1L Cavalier Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 72: 3.1L Celebrity & 6000 With 3T40 Transmission Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 73: 3.1L Celebrity & 6000 With 4T60 Transmission Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 74: 3.1L Lumina With 125C Transmission Converter Clutch Schematic

Courtesy of GENERAL MOTORS CORP.

Fig. 75: 3.1L Cutlass Supreme, Grand Prix, Regal & Lumina With 4T60 Transmission Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 76: 3.3L Century & Skylark With 3T40 Transmission Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 77: 3.3L Century With 4T60 Transmission Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 78: 3.8L Bonneville, Delta 88 & Ninety-Eight Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 79: 3.8L Reatta & Riviera Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 80: 3.8L Toronado & Trofeo Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 81: 4.5L DeVille, Eldorado, Fleetwood & Seville Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 82: 5.0L TBI Camaro & Firebird Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 83: 5.0L & 5.7L TBI Caprice & Custom Cruiser Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 84: 5.0L & 5.7L PFI Camaro & Firebird Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 85: 5.7L Brougham Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP.

Fig. 86: 5.7L Corvette Converter Clutch Schematic Courtesy of GENERAL MOTORS CORP. SHIFT LIGHT (MANUAL TRANSMISSION) 1. These tests assume a shift light problem exists. Use this procedure only if the light will not illuminate, or illuminates all of the time. 2. Turn ignition on, with engine off. Note shift light. Shift light should not be on. If light is on, check for a short to ground between the bulb and the ECM, or a bad ECM. 3. With ignition on and engine off, ground "test" terminal of ALDL connector. SERVICE ENGINE SOON light should start to flash and shift light should come on. If light comes on, go to next step. If SERVICE ENGINE SOON light does not flash, perform DIAGNOSTIC CIRCUIT CHECK as described in BASIC TESTING article. 4. If shift light does not come on, ground Tan/Black wire at ECM terminal B7 (A12 on Corvette or GF4 on 2.3L Beretta, Cutlass Calais & Grand Am) using a jumper wire. If light still does not come on, check for blown GAUGES fuse (AIRBAG fuse on Corvette), blown bulb or open circuit between fuse and ECM. If light came on when grounding terminal B7 (or A12 or GF4) with a jumper wire, problem is a bad ECM connection or bad ECM.

Fig. 87: Shift Light Schematic (Except Corvette) Courtesy of GENERAL MOTORS CORP.

Fig. 88: Shift Light Schematic (Corvette) Courtesy of GENERAL MOTORS CORP. 1-4 SHIFT SYSTEM CHECK (MANUAL TRANSMISSION CORVETTE) 1. With engine off, depress clutch and place transmission in 1st gear. Shift transmission into 2nd or 3rd gear. If transmission cannot be shifted into 2nd or 3rd gear, check for short to voltage on circuit No. 138 between 1-4 shift relay and 1-4 shift solenoid, defective 1-4 shift solenoid, or internal mechanical transmission problem. See Fig. 90. 2. Turn ignition on with engine not running. Ground ALDL "test" terminal "B". Shift transmission into 2nd or 3rd gear. If transmission cannot be shifted into 2nd or 3rd gear, system is functioning correctly. 3. If transmission can be shifted into 2nd and 3rd gear, turn ignition off. Disconnect 1-4 shift relay connector. Turn ignition on and check for voltage from ground to harness terminals "D" and "E". If voltage is not present on both harness terminal, check for blown fuses or open circuit to terminal which did not illuminate test light. 4. If test light illuminated when touched to both terminals, ground ALDL "test" terminal "B" and connect test light from battery voltage to terminal "F" of 1-4 shift relay harness connector. 5. If test light does not illuminate, check for open in circuit No. 108 between relay and ECM, poor ECM terminal contact or defective ECM. If test light did illuminate, perform 1-4 SHIFT RELAY test procedures.

1-4 SHIFT LIGHT (MANUAL TRANSMISSION CORVETTE) 1. This testing procedures assumes that a problem exists with the 1-4 shift light. Use this procedure only if the light will not illuminate, or illuminates all of the time. 2. Turn ignition on, with engine off. Note shift light. Shift light should not be on. If light is on, check for a short to ground between the bulb and the ECM, or a bad ECM. 3. With ignition on and engine off, ground "test" terminal "B" of ALDL connector. SERVICE ENGINE SOON light should start to flash and 1-4 shift light should come on. If light comes on, go to next step. If SERVICE ENGINE SOON light does not flash, perform DIAGNOSTIC CIRCUIT CHECK as described in BASIC TESTING article. 4. If 1-4 shift light does not come on, ground ECM terminal C13 using a jumper wire. If light still does not come on, check for blown GAUGES fuse, blown bulb or open circuit between fuse and ECM. If light came on when grounding terminal C13 with a jumper wire, problem is a bad ECM connection or bad ECM.

Fig. 89: Corvette 1-4 Shift Light Schematic Courtesy of GENERAL MOTORS CORP. 1-4 SHIFT RELAY (MANUAL TRANSMISSION CORVETTE) 1. Turn ignition off. Disconnect 1-4 shift relay connector. Check for continuity between terminals "D" and "F" of relay. If continuity does not exist, replace relay. If continuity does exist, check for continuity between relay terminals "C" and "A". Continuity should also exist when relay is not energized. If not, replace relay. 2. Energize relay by applying battery voltage to terminal "D" of relay and ground to terminal "F". Check continuity between terminals "A" and "E". Continuity should exist while relay is energized. Replace relay if it does not test as described.

Fig. 90: Corvette 1-4 Shift Relay Schematic Courtesy of GENERAL MOTORS CORP.

COMPONENT LOCATIONS

Fig. 91: Component Location for 5.0L (VIN Y) "B" Body Courtesy of GENERAL MOTORS CORP.

Fig. 92: Component Location for 5.0L (VIN Y) "D" Body Courtesy of GENERAL MOTORS CORP.

Fig. 93: Component Location for 2.0L (VIN K) "J" Body Courtesy of GENERAL MOTORS CORP.

Fig. 94: Component Location for 2.2L (VIN G) "J" Body Courtesy of GENERAL MOTORS CORP.

Fig. 95: Component Location for 2.2L (VIN G) "L" Body Courtesy of GENERAL MOTORS CORP.

Fig. 96: Component Location for 2.5L (VIN R) "A" Body Courtesy of GENERAL MOTORS CORP.

Fig. 97: Component Location for 2.5L (VIN R) "W" Body Courtesy of GENERAL MOTORS CORP.

Fig. 98: Component Location for 2.5L (VIN U) "N" Body Courtesy of GENERAL MOTORS CORP.

Fig. 99: Component Location for 5.0L (VIN E) "B" Body Courtesy of GENERAL MOTORS CORP.

Fig. 100: Component Location for 5.7L (VIN 7) "B" Body Courtesy of GENERAL MOTORS CORP.

Fig. 101: Component Location for 5.0L (VIN E) "F" Body Courtesy of GENERAL MOTORS CORP.

Fig. 102: Component Location for 5.7L (VIN 7) "D" Body Courtesy of GENERAL MOTORS CORP.

Fig. 103: Component Location for 2.0L (VIN M) "J" Body Courtesy of GENERAL MOTORS CORP.

Fig. 104: Component Location for 2.3L (VIN A & D) "N" Body Courtesy of GENERAL MOTORS CORP.

Fig. 105: Component Location for 2.3L (VIN A & D) "W" Body Courtesy of GENERAL MOTORS CORP.

Fig. 106: Component Location for 2.3L (VIN A) "L" Body Courtesy of GENERAL MOTORS CORP.

Fig. 107: Component Location for 3.1L (VIN T) "A" Body Courtesy of GENERAL MOTORS CORP.

Fig. 108: Component Location for 3.1L (VIN T) "F" Body Courtesy of GENERAL MOTORS CORP.

Fig. 109: Component Location for 3.1L (VIN T) "J" Body Courtesy of GENERAL MOTORS CORP.

Fig. 110: Component Location for 3.1L (VIN T) "L" Body Courtesy of GENERAL MOTORS CORP.

Fig. 111: Component Location for 3.1L (VIN T) "W" Body Courtesy of GENERAL MOTORS CORP.

Fig. 112: Component Location for 3.1L (VIN V) "W" Body Courtesy of GENERAL MOTORS CORP.

Fig. 113: Component Location for 3.3L (VIN N) "A" Body Courtesy of GENERAL MOTORS CORP.

Fig. 114: Component Location for 3.3L (VIN N) "N" Body Courtesy of GENERAL MOTORS CORP.

Fig. 115: Component Location for 3.8L (VIN C) "C" & "H" Body Courtesy of GENERAL MOTORS CORP.

Fig. 116: Component Location for 3.8L (VIN C) "E" Body Courtesy of GENERAL MOTORS CORP.

Fig. 117: Component Location for 3.8L (VIN C) "E" Body Courtesy of GENERAL MOTORS CORP.

Fig. 118: Component Location for 3.8L (VIN L) "W" Body (Regal) Courtesy of GENERAL MOTORS CORP.

Fig. 119: Component Location for 5.0L (VIN F) "F" Body Courtesy of GENERAL MOTORS CORP.

Fig. 120: Component Location for 5.7L (VIN ) "F" Body Courtesy of GENERAL MOTORS CORP.

Fig. 121: Component Location for 5.7L (VIN ) "Y" Body Courtesy of GENERAL MOTORS CORP.

Fig. 122: Component Location for 4.5L (VIN 3) "C" Body Courtesy of GENERAL MOTORS CORP.

Fig. 123: Component Location for 4.5L (VIN 3) "E" Body Courtesy of GENERAL MOTORS CORP.

Fig. 124: Component Location for 4.5L (VIN 3) "K" Body Courtesy of GENERAL MOTORS CORP.

H - TESTS W/O CODES ENGINE PERFORMANCE General Motors Trouble Shooting - No Codes

INTRODUCTION Before attempting to diagnose symptoms or intermittent faults, ensure steps in the BASIC TESTING and also in the appropriate TESTS W/CODES articles have been performed. Use this article to diagnose driveability problems that exist when a hard fault code is not present. Symptom checks are intended to direct the technician to malfunctioning component(s) so that further diagnosis may be performed. A "symptom" should lead to further testing of specific components or systems, or verification of adjustment specifications. Use intermittent test procedures to locate intermittent driveability problems that do not occur when the vehicle is being tested. These problems may cause a noticeable driveability problem or cause the "malfunction" warning light to illuminate on some vehicles. It is also possible that certain driveability concerns have been rectified by the manufacturer through substitution of a revised calibration chip or computer control unit. Check with manufacturer for latest information on updated chips and control units. NOTE:

For specific testing procedures, refer to the article SYSTEM/COMPONENT TESTS in this section. For verifying specifications, refer to appropriate ADJUSTMENTS article in this section.

SYMPTOMS PRELIMINARY CHECKS This portion of article is used only AFTER you have checked the following: 

  

 

Verify the on-car diagnostics are working by performing DIAGNOSTIC CIRCUIT CHECK located in BASIC TESTING article in this section. Verify that the ECM and "SERVICE ENGINE SOON" light are functioning properly. Verify that there are no trouble codes stored, or only intermittent ones. Verify that the fuel control system is operating properly by performing appropriate SYSTEM PERFORMANCE CHECK chart (carbureted models), FIELD SERVICE MODE CHECK (fuel injected models except Cadillac) or PFI SYSTEM CHECK (Cadillac except Brougham) located in BASIC TESTING article in this section. Perform fuel system pressure test on EFI vehicles. Perform a careful visual inspection of all systems.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. Not all items listed under each symptom apply to all models and systems. These

procedures will normally recommend testing of a system or component on vehicle, such as EGR, EST, TCC, etc. These are covered in the SYSTEM/COMPONENT TESTS article in this section. NOTE:

On TBI and PFI vehicles, if ECM displays data but engine fails to start, proceed to NO START - ENGINE CRANKS OKAY, in the BASIC TESTING article in this section.

HARD START - COLD (CARBURETED MODELS) SYMPTOM DEFINITION Engine cranks, but does not start for a long time. Eventually, engine does run. If engine starts but immediately dies (as soon as key is released), refer to the NO START - ENGINE CRANKS OKAY in procedures in the BASIC TESTING article in this section. Possible Cause & Correction

- Check the following items.  

  

     



 

Ensure driver is using proper starting procedure. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. Check for air leaks at carburetor mounting and intake manifold. Check wires for pinches, cuts, and proper connections. Check choke valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by foreign material and gum, clean with non-oil base solvent. Check choke and vacuum break operation adjustment. Check EGR valve system for faulty operation that could cause valve to stick open. Check float level using external float gauge. Adjust float to specification, if required. Check carburetor fuel inlet filter. Replace if required. Check ignition system. Check distributor for worn shaft, bare and shorted wires, pick-up coil resistance and connections, loose ignition coil ground, and moisture in distributor cap. Remove spark plugs and check for wet plugs, wear, improper gap, burned electrodes or heavy deposits. Clean or replace as necessary. Check ignition timing and adjust if necessary. Check fuel pump pressure, volume and vacuum

HARD START - HOT (CARBURETED MODELS) SYMPTOM DEFINITION

Engine cranks, but does not start for a long time. Eventually, engine does run. If engine starts but immediately dies (as soon as key is released), see NO START - ENGINE CRANKS OKAY in the appropriate BASIC TESTING article in this section. Possible Cause & Correction

- Check the following items.  

 

      

 



Ensure driver is using proper starting procedure. Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. Check wires for pinches, cuts, and proper connections. Check choke valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by foreign material and gum, clean with non-oil base solvent. Check choke and vacuum break operation adjustment. Check EGR valve system for faulty operation that could cause valve to stick open. Check for carburetor flooding. Check float level using external float gauge. Adjust float to specification, if required. Check carburetor fuel inlet filter. Replace if required. Check for obvious overheating problems. Check EFE system operation as described in the article SYSTEM/COMPONENT TESTS in this section. EFE valve should be open. Check ignition system. Check distributor for worn shaft, bare and shorted wires, pick-up coil resistance and connections, loose ignition coil ground, and moisture in distributor cap. Remove spark plugs and check for wet plugs, wear, improper gap, burned electrodes or heavy deposits. Clean or replace as necessary. Check ignition timing and adjust if necessary.

HARD START (EFI MODELS) SYMPTOM DEFINITION Engine cranks okay, but does not start for a long time. Engine eventually starts, may immediately die or run okay. Possible Cause & Correction

- Check the following items. 

Check fuel pump relay. To do this, connect test light between fuel pump test terminal (terminal "G" of ALDL on most vehicles) and ground. Turn ignition on. Light should illuminate for 2 seconds. If not, see FUEL PUMP RELAY in SYSTEM/COMPONENT TESTS article. For location of fuel pump test

   



 



connector, see COMPONENT LOCATIONS in the article SYSTEM/COMPONENT TESTS in this section. Check for poor quality or water contaminated fuel. Check that TPS is not sticking or binding. Check EGR operation. Check for a leaking injector. To do this on TBI systems, disconnect injector electrical connector at injector. Crank engine and watch for fuel leakage. Check that resistance of coolant sensor circuit or coolant sensor is not too high. See CODE 15 chart in appropriate TESTS W/CODES article in this section, or the SENSOR RANGE CHARTS article in this section. Check ignition system for a worn distributor shaft, bare or shorted wires, incorrect pick-up coil resistance, loose ignition coil ground or moisture in distributor cap. Check for adequate spark using Spark Tester (ST-125). Check for shorts by spraying plug wires with fine mist of water. Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits. Check for correct fuel pressure in all speed ranges. A faulty in-tank fuel pump check valve will allow fuel in lines to drain back to tank after engine is stopped. To check this condition, turn ignition off, disconnect fuel pressure line at fuel rail, remove filler cap, and connect a radiator test pump and apply 15 psi (1.0 kg/cm2 ) pressure. If pressure will hold for 60 seconds, check valve is okay. Check that PROM/MEM-CAL in vehicle is correct for that vehicle. Check with dealer for latest application information. Check for restricted exhaust system.

STALL AFTER START - COLD (CARBURETED MODELS) SYMPTOM DEFINITION This condition is with engine in warm-up mode at room or outside temperature, within 3 minutes after start. Vehicle stalls after brief idle, dies as soon as any load is placed on engine (such as A/C turned on or transmission engaged) or dies on initial driveaway. If symptom is present when vehicle is both cold and hot, go to symptom STALL AFTER START - HOT. Possible Cause & Correction

- Check the following items. 

  

Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label (in engine compartment). Make sure hot air tube is connected to air cleaner. Check for proper operation of thermostatic air cleaner. Check choke valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by

       

foreign material and gum, clean with non-oil base solvent. With engine off, check all choke adjustments, including vacuum breaks and TVS if used. Check carburetor accelerator pump operation. Check fast idle speed and curb idle speed if applicable. Check EFE system for proper operation. EFE vacuum valve should be closed when cold. Check choke and vacuum break operation adjustment. Check EGR valve system for sticky operation that could cause valve to stick open. Check ignition timing and adjust if necessary. Check for poor or contaminated gasoline.

STALL AFTER START - HOT (CARBURETED MODELS) SYMPTOM DEFINITION This condition is with engine in warm-up mode at room or outside temperature, within 3 minutes after start. Vehicle stalls after brief idle, dies as soon as any load is placed on engine (such as A/C turned on or transmission engaged) or dies on initial driveaway. Possible Cause & Correction

- Check the following items. 

  

          

Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Make sure hot air tube is connected to air cleaner. Check for proper operation of thermostatic air cleaner. Check choke valve, throttle and fast idle cam for sticking. Replace any malfunctioning parts. If caused by foreign material and gum, clean with non-oil base solvent. With engine off, check all choke adjustments, including vacuum breaks and TVS if used. Check carburetor accelerator pump operation. Check fast idle speed and curb idle speed if applicable. Check EFE system for proper operation. EFE valve should be open. Check choke and vacuum break operation adjustment. Check EGR valve system for faulty operation that could cause valve to stick open. Check ignition timing and adjust if necessary. Check for poor or contaminated gasoline. Check for obvious overheat condition. Check for overcharged A/C system. Check operation of power steering cut-out switch.

STALLS AFTER STARTING (EFI MODELS)

SYMPTOM DEFINITION Engine starts okay but dies after brief idle, dies as soon as any load is placed on engine (such as turning on air conditioner or engaging transmission), or on initial driveaway. Possible Cause & Correction

- Check the following items.     

 

  

Make sure that hot air tube is connected to air cleaner. Check for proper operation of thermostatic air cleaner. Check for proper operation of Idle Air Control (IAC) system. Check PCV valve for proper operation. Unplug MAF or MAP sensor. ECM will substitute a default value for sensor signal. If stall condition is eliminated, replace sensor. Check EGR system for proper operation. If stall occurs when air conditioner is turned on, check for air conditioner clutch signal to ECM terminal. Voltage at A/C terminal of ECM should be battery voltage when air conditioner compressor clutch is engaged. A high voltage surge due to a shorted compressor clutch diode could cause ECM shutdown. Check for an overcharged air conditioner system. Check for plugged or restricted fuel lines. Using Spark Tester (ST-125), check for a weak spark from ignition coil.

HESITATION, SAG OR STUMBLE (CARBURETED MODELS) SYMPTOM DEFINITION This is defined as a momentary lack of response as accelerator is pushed down. It can occur at all vehicle speeds. Usually, it is most severe when first trying to make vehicle move. Occasionally, this condition may cause vehicle to stall. Possible Cause & Correction

- Check the following items. 

    

   

     

Check carburetor accelerator pump operation. Check fast idle speed and curb idle speed, if applicable. Check EFE system for proper operation. EFE valve should be closed. Check vacuum hose to pressure sensor for leaks, restrictions and proper connections (should be manifold vacuum). Check EGR valve operation. Check TPS adjustment. See the appropriate ADJUSTMENTS article in this section. Check canister purge system. Check for open ignition coil ground and for intermittent ECM ground. Check engine ignition timing. Check for poor quality or contaminated gasoline.

HESITATION, SAG OR STUMBLE (EFI MODELS) SYMPTOM DEFINITION Momentary lack of response when accelerator is pushed down. Can occur at all vehicle speeds. Usually occurs when taking off from a stop. Possible Cause & Correction

- Check the following items. 

 

       

Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check ignition wires for cracking, hardness and proper connections at both distributor cap and spark plugs. Check wires for pinches, cuts, and proper connections. Check that fuel pressure is correct in all speed ranges. Also check for poor quality or water contaminated fuel. Check for fouled spark plugs. Check that PROM/MEM-CAL in vehicle is correct for that vehicle. Check with dealer for latest application information. Check for a binding or sticking TPS. Make sure that initial ignition timing is properly set. Make sure that ECM controlled idle speed is correct. Check EGR system for proper operation. Disconnect fuel injector electrical connectors. Crank engine and check for injector leaks. Check for an open in HEI ground circuit. Check canister purge system for proper operation. Check charging system output. Repair charging system if voltage is less than 9 volts or more than 16 volts.



On PFI vehicles, perform INJECTOR BALANCE TEST in the appropriate SYSTEM/COMPONENT TESTS article in this section.

VEHICLE SURGES SYMPTOM DEFINITION Engine power varies under steady throttle or cruise. Feels like vehicle speeds up and slows down without changing position of accelerator pedal. Possible Cause & Correction

- Check the following items.         

 



 

Check operation of thermostatic air cleaner damper door. Check that Park/Neutral switch is properly adjusted. Check for intermittent open or short to ground in Torque Converter Clutch (TCC) or HEI by-pass circuits. Check for proper operation of canister purge system. Check for proper operation of ESC system. Check for proper operation of EGR system. Make sure that initial ignition timing is properly set. Check for adequate spark output using Spark Tester (ST-125). Check O2 sensor for lead or RTV sealant contamination. This will cause a false high voltage signal to ECM. ECM will respond by leaning air/fuel ratio. Check in-line fuel filter and replace if dirty or clogged. Check fuel for water contamination. On carbureted models, check fuel pressure, volume and fuel pump vacuum. On EFI models, check that fuel system pressure is correct at all engine speeds. Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits. Also check condition of distributor cap, rotor and spark plug wires. Check A/C for excessive charge. Check for restricted exhaust system.

LACK OF POWER OR SLUGGISH SYMPTOM DEFINITION Engine delivers less power than expected. Little or no increase in speed when accelerator is pushed down. Possible Cause & Correction

- Check the following items. 

Check that air filter and fuel filter are not plugged. Replace if necessary. Check for incorrect fuel

        



   

pressure. Check for proper operation of thermostatic air cleaner damper door. Check for proper float level using external gauge (carbureted). Make sure that initial ignition timing is properly set. Check for proper operation of TCC or VCC system. Check ESC system for excessive retard. Check EST system for proper operation. Make sure that EGR valve is not open all the time. Check for proper operation of EFE valve (carbureted). Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See RESTRICTED EXHAUST SYSTEM CHECK in the BASIC TESTING article in this section. Check charging system output. Repair charging system if voltage is less than 9 volts or more than 16 volts. Check MAP or pressure sensor output. Using Spark Tester (ST-125), check for available secondary voltage. Check engine valve timing and compression. Check engine for a worn camshaft.

ENGINE BACKFIRES SYMPTOM DEFINITION Fuel ignites in intake manifold or in exhaust system making a loud popping noise. Possible Cause & Correction

- Check the following items.    

     

Check for proper valve timing. Check for engine vacuum leaks and/or engine not tuned to specifications. Check for faulty air injection divert valve or check valve. Check for electric air switching valve or air divert valve not switching air pump discharge to air cleaner during engine starting or deceleration. Check engine for sticking or leaking valves. Check for fuel or water in vacuum hose to MAP sensor. Also check for restricted hose. Using Spark Tester (ST-125), check available output voltage of ignition coil. Check for crossfire between spark plugs, distributor cap and spark plug wires. Check for an intermittent ignition system problem. Make sure that initial ignition timing is properly set.

CUTS OUT, MISSES SYMPTOM DEFINITION Cuts out, misses is defined as a steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. The exhaust may have a steady spitting sound at idle or low speed. Perform a careful visual inspection as described in the appropriate BASIC TESTING article in this section. Possible Cause & Correction

- Check the following items.  

    

   

     

Check ignition wires for short or faulty insulation. Check Distributor cap (if equipped) for moisture, dust or cracks. Spray spark plug wires with a fine mist of water to check for shorts. Connect Spark Tester ST-125 to spark plug and check for adequate spark. Check ignition system for faulty grounds. Check that EST wiring harness is not routed too close to wiring which may cause induced voltage signals. Check ignition coil connections. Remove spark plugs and check for correct heat range, wear, cracks, wetness, improper gap or heavy deposits. Check for poor or contaminated (water) fuel. Check for improper fuel pressure. Check float level on carbureted vehicles. Using INJECTOR BALANCE TEST located in the article SYSTEM/COMPONENT TESTS , check fuel injected vehicles for plugged injectors. Check for EGR valve sticking open. Check ECM for proper ground circuits. TPS for sticking or binding. TPS voltage should be less than 1.25 volts at idle. Check for proper crank angle sensor (DIS and IDI) or pick-up coil (HEI distributor) resistance. Check for restricted exhaust as described in BASIC TESTING article in this section. Check for bent push rods, broken valve springs or worn camshaft lobes.

MISFIRE ISOLATION (FUEL INJECTION) 1. Start engine. Disconnect IAC motor. Using insulated pliers, remove one spark plug wire from a spark plug and ground it against the engine. 2. Note engine RPM as wire is grounded. Reconnect spark plug wire. Repeat procedure for all cylinders. Stop engine and reconnect IAC motor. If engine speed dropped equally (within 50 RPM) on all cylinders, refer to ROUGH, UNSTABLE OR INCORRECT IDLE symptom. If there was no engine RPM drop or excessive variation on one or more cylinder, check spark on the respective cylinder(s).

ROUGH, UNSTABLE OR INCORRECT IDLE SYMPTOM DEFINITION Engine runs unevenly at idle. If bad enough, vehicle will shake. Idle may vary in RPM. Engine idles at incorrect RPM. Possible Cause & Correction

- Check the following items.    

    



Make sure that throttle linkage and/or TPS are not sticking or binding. Make sure that initial ignition timing is properly set. Check engine idle speed, both base idle and ECM idle. Check Idle Air Control (IAC) system. Check for foreign material in IAC bore. See DIAGNOSTIC AIDS in CODE 35 chart in the appropriate TESTS W/CODES article in this section. Check for proper operation of EGR system. Check ISC/ILC operation. Check P/N switch circuit. Also make sure that P/N switch is properly adjusted. Check power steering pressure switch circuit. Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See RESTRICTED EXHAUST SYSTEM CHECK in the BASIC TESTING article in this section below. If rough idle only occurs when engine is hot, check PCV valve for proper operation, check evaporative emission control system, check for proper spark plug gap and check engine compression.

ENGINE WILL NOT IDLE (CARBURETED MODELS) SYMPTOM DEFINITION Defined as engine starts okay, but dies at idle. Engine will run if accelerator is held at part throttle. Possible Cause & Correction

- Check the following items. 

    

Visually check vacuum hoses for splits, kinks and proper connections, as shown on Vehicle Emission Control Information label. Check for air leaks at carburetor mounting and intake manifold. Check carburetor for flooding. Check float level using external float gauge. Check engine idle speed, both base and ECM controlled. Check EGR system. Check for loose valve or sticking plunger. The EGR system should not function at

 



idle. Pulse width modulated systems do not work in Park or Neutral. Check carburetor idle adjustment. If unable to adjust, check carburetor idle system. Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. Check spark plug condition and gap.

ENGINE WILL NOT IDLE (EFI MODELS; EXC. PARK AVENUE) SYMPTOM DEFINITION Engine starts but will not run at idle. Engine will run if accelerator is held at part throttle. Possible Cause & Correction

- Check the following items. 

  



Problem is most likely in Idle Air Control (IAC) system. See DIAGNOSTIC AIDS in CODE 35 chart in the appropriate TESTS W/CODES article in this section. Check EGR system. Check P/N switch. On PFI vehicles, perform INJECTOR BALANCE TEST located in SYSTEM/COMPONENT TESTS article in this section. Disconnect MAF or MAP sensor. If condition is corrected, replace sensor.

ENGINE WILL NOT IDLE (EFI MODELS; PARK AVENUE) SYMPTOM DEFINITION The engine runs unevenly at idle. If bad enough, the car may shake. Also, the idle may vary in rpm (called "hunting"). Either condition may be bad enough to cause stalling. Engine idles at incorrect speed. 

Perform careful visual (physical) check. Clean injectors using tool J 35800 or equivalent.

Possible Cause & Correction

- Check the following items. * Throttle linkage for sticking or binding. * TPS for sticking or binding, be sure output is stable at idle and adjustment specification is correct. * IAC system, CHART C-2. * Generator output voltage. Repair if less than 9 or more than 16 volts.

* P/N switch circuit. Code 31, or use "SCAN" tool, and be sure tool indicates vehicle is in drive with gear selector in drive. * Injector balance. See CHART C-2A. * PCV valve for proper operation by placing finger over inlet hole in valve end several times. Valve should snap back. If not, replace valve. * Evaporative emission control system, CHART C-3. * ECM ground circuits. * EGR valve: There should be no EGR at idle. 

    

 

Monitoring block learn values may help identify the cause of the problem. If the system is running lean (block learn greater than 138) refer to DIAGNOSTIC AIDS in Code 44. If the system in running rich (block learn values less than 118) refer to Diagnostic Aids in Code 45. Run a cylinder compression check. Check for fuel in pressure regulator hose. If present, replace regulator assembly. Check ignition system; wires and plugs. Check for loose or damaged gaskets between MAF sensor and throttle body. Disconnect MAF sensor and if condition is corrected, replace sensor. "SCAN" tool should read 4-8 grams per second at idle. If problem exists with A/C "ON," check A/C system operation CHART C-10. Inspect motor mounts for damage, grounding out or mispositioned.

POOR FUEL ECONOMY SYMPTOM DEFINITION Fuel economy, as measured by an actual road test, is noticeably lower than expected. Fuel economy is noticeably lower than was on this vehicle at one time. Possible Cause & Correction

- Check the following items.   

  

Check for proper operation of thermostatic air cleaner damper door. Also check for a clogged air filter. Check cooling system thermostat for proper heat range and operation. Check coolant sensor for shift in calibration. Use temperature-to-resistance table in the SENSOR RANGE CHARTS article in this section. Make sure that speedometer is properly calibrated. Check engine compression. Check for dragging brakes.

   



 

  

Check A/C for "full time" operation. Make sure that initial ignition timing is properly set and check for proper EST and ESC operation. Check for proper operation of TCC or VCC. Check air pump output not shifting to catalytic converter upon signal from TVS and/or faulty electrical and/or vacuum circuits. Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See RESTRICTED EXHAUST SYSTEM CHECK in BASIC TESTING article in this section. Check oxygen sensor for silicone or lead contamination. Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits. Make sure that speedometer is properly calibrated. Check engine compression. Check for dragging brakes.

ENGINE DIESELING/RUN-ON SYMPTOM DEFINITION Engine continues to run after ignition is turned off but runs very rough. If engine runs smoothly, check ignition switch. Possible Cause & Correction

- Check the following items.  



Check for binding throttle linkage. Check for leaking injectors on EFI vehicles. On PFI vehicles, perform INJECTOR BALANCE TEST located in the article SYSTEM/COMPONENT TESTS in this section. Check IAC (EFI) system. See DIAGNOSTIC AIDS in CODE 35 chart in the appropriate TESTS W/CODES article in this section. Check ILC (carb.) for proper operation. Testing is located in SYSTEM/COMPONENT TESTS article in this section. Check engine for overheating.

DETONATION/SPARK KNOCK SYMPTOM DEFINITION A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with amount of acceleration. Possible Cause & Correction

- Check the following items.    

     

 

Check for obvious overheating problems. Make sure that initial timing is correct. Check TPS adjustment and operation. On fuel injected models, check fuel system for low pressure or volume. Also check for induction air leaks. Make sure that ESC system is operating properly. Make sure that EGR valve is not open all the time. Make sure that TCC or VCC system is operating properly. Make sure that correct PROM is installed in ECM. Remove carbon from engine with top engine cleaner. If excessive carbon exists in combustion chamber, check for excessive oil burning due to leaking valve guide seals. Check for incorrect basic engine parts such as camshaft, cylinder heads and pistons. Check that PROM/MEM-CAL in vehicle is correct for that vehicle. Check with dealer for latest application information.

EXCESSIVE EXHAUST EMISSION (ODORS) SYMPTOM DEFINITION Vehicle fails emission test. Vehicle may also have excessive "rotten egg" smell (hydrogen sulfide) being emitted from exhaust pipe. Possible Cause & Correction

- Check the following items. 



Check for lead contamination of catalytic converter. Look for removal/tampering at restrictor in fuel filler neck. Check that air is not being diverted to exhaust manifold during normal engine operation and that air is being diverted to catalytic converter during normal engine operation. If emission test shows excessive carbon monoxide (CO) and hydrocarbons (HC) emissions and vehicle also has excessive odor being emitted, check all systems and components that could cause engine to run rich. See DIAGNOSTIC AIDS in the CODE 45 chart in the appropriate TESTS W/CODES article in this section. If emission test shows excessive oxides of nitrogen (NOx) emissions, check all systems and components that could cause engine to run lean or to run too hot. See DIAGNOSTIC AIDS in the CODE 44 chart in the appropriate TESTS W/CODES article in this section.

TURBOCHARGER TROUBLE SHOOTING

SYMPTOMS To trouble shoot the following symptoms, refer to appropriate number under PROBABLE CAUSES below. Engine Lacks Power

Check probable causes No. 1, 4-11, 18, 20, 21, 22 and 25-30. Black Smoke

Check probable causes No. 1, 4-11, 18, 20, 21, 22 and 25-30. Blue Smoke

Check probable causes No. 1, 4, 8, 9, 19, 21, 22, 32, 33, 34 and 36. Excessive Oil Consumption

Check probable causes No. 2, 8, 17, 19, 20, 33, 34, 36 and 37. Excessive Oil At Turbine End

Check probable causes No. 2, 7, 8, 16, 17, 19, 20, 22, 32, 33, 34 and 36. Excessive Oil At Compressor End

Check probable causes No. 1, 2, 4, 5, 6, 8, 9, 16, 19, 20 and 21. Insufficient Lubrication

Check probable causes No. 15, 16, 12, 23, 24, 31 and 36. Oil In Exhaust Manifold

Check probable causes No. 2, 7, 19, 20, 22, 28, 29, 30, 33 and 34. Damaged Compressor Wheel

Check probable causes No. 3, 6, 8, 20, 21, 23, 24 and 36. Damaged Turbine Wheel

Check probable causes No. 7, 8, 18, 20, 21, 22, 34 and 36. Drag Or Bind In Rotating Assembly

Check probable causes No. 3, 6, 7, 8, 13-16, 20, 21, 22, 31, 34 and 36.

Worn Bearings, Journals Or Bearing Bores

Check probable causes No. 6, 7, 8, 12-16, 20, 23, 24, 31, 35 and 36. Noisy Operation

Check probable causes No. 1, 3-11, 18, 20, 21 and 22. Sludged Or Coked Center Housing

Check probable causes No. 21, 15 and 17. PROBABLE CAUSES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27.

Dirty air cleaner element. Plugged crankcase breathers. Air cleaner element missing, leaking, not sealing correctly or loose connections to turbocharger. Collapsed or restricted air tube to turbocharger. Restricted or damaged crossover pipe from turbocharger to the inlet manifold. Foreign object between turbocharger and air cleaner. Foreign object in exhaust system (restricted exhaust). Loose turbocharger clamps or bolts. Inlet manifold cracked or gaskets loose, damaged or missing. Cracked exhaust manifold or gaskets loose, damaged or missing. Restricted exhaust system. Oil delay to turbocharger on start-up. Insufficient lubrication. Lubrication oil contaminated with dirt or other material. Improper lubrication oil being used. Restricted oil feed line. Restricted oil drain line. Turbine housing damaged or restricted. Turbocharger seal leaking. Worn journal bearings. Excessive dirt buildup in compressor housing. Excessive carbon buildup behind turbine wheel. Excessive acceleration on initial start (lubrication lag time). Too little warm-up time allowed. Fuel pump malfunction. Worn or damaged injectors. Improper valve timing.

28. 29. 30. 31. 32. 33. 34. 35. 36.

Burned valves. Worn piston rings. Burned pistons. Leaking oil feed line. Excessive engine pre-oil. Excessive engine idling. Coked or sludged center housing. Oil pump malfunction. Oil filter plugged.

INTERMITTENT PROBLEM DIAGNOSIS Intermittent fault testing requires the duplication of circuit or component failure, in order to identify the fault. These procedures may lead to the computer recording a fault code (on some systems) which may help in diagnosis. If problem vehicle does not produce fault codes, it will be necessary to monitor voltage or resistance values using a DVOM while attempting to reproduce conditions which will create an intermittent fault. A change in status on the DVOM will indicate a fault has been located. When using a voltmeter to pinpoint faults, monitor voltage reading with ignition on, or vehicle running. A change in status on the voltmeter while performing intermittent TEST PROCEDURES will indicate area of fault. When using an ohmmeter to detect problems in the circuit, monitor circuit resistance (ohms) with ignition switch in the OFF position, or with battery disconnected. A change in ohmmeter reading while performing TEST PROCEDURES will indicate area of fault.

TEST PROCEDURES INTERMITTENT SIMULATION To reproduce the conditions which create an intermittent fault so that it may be identified during testing, some of the following methods may be used:     

Applying light vibration to components. Heating a component. Wiggling or bending a wiring harness. Applying humidity to a component. Remove or apply a vacuum supply source.

Monitor circuit/component voltage or resistance while attempting to simulate intermittent. If vehicle is running, monitor for self-diagnostic codes. Use the results of these tests to identify a faulty component or an area which should be checked closely for the problem.

INTERMITTENT TROUBLE SHOOTING SYMPTOM DEFINITION "SERVICE ENGINE SOON" light comes on but does not stay on. A stored code may or may not exist. Possible Cause & Correction

- To track down possible causes of an intermittent "SERVICE ENGINE SOON" light check the following items. 

    



 



Check for poor mating of one connector to another. Terminals may not be fully seated. Check for improperly formed or damaged terminals. Check wire to terminal connections. Check for poor connection from ignition coil to ground or arcing at spark plug wires or plugs. Check wire from "SERVICE ENGINE SOON" light to ECM for short to ground. Check wire from ALDL "test" terminal for intermittent short to ground. Check for poor connections in ECM ground terminals. Check for loss of trouble code memory. To check code memory on fuel injected models, disconnect TPS and run engine at idle until "SERVICE ENGINE SOON" light comes on. Code 22 should be stored and retained in memory when ignition is turned off. On carbureted engines, ground dwell lead for 10 seconds with ALDL "test" lead left ungrounded. Code 23 should be stored and retained in memory after ignition is turned off. If not, ECM is faulty. Check for electrical system interference caused by a defective relay or an ECM driven solenoid or switch which may cause a sharp electrical surge. This type of problem will normally occur when faulty component is operated. Check for aftermarket parts which may not have been produced to manufacturers' specifications. Solenoids without original equipment diodes for circuit protection and HEI-EST module or voltage regulator using transistors instead of silicon-chip circuitry may possibly cause voltage surges (up to 300 volts) in ECM wiring, causing temporary ECM shutdown. ECM shutdown is a normal response to system overvoltage (over 16 volts on most models). ECM will repower when condition ceases to exist. This could cause a flickering "SERVICE ENGINE SOON" light with no codes set in memory. Check for improper installation of electrical accessories such as auxiliary lights or 2-way radios. Make sure that EST wires are kept away from spark plug wires, distributor wires, distributor housing, ignition coil and generator. Make sure that ground wire from ECM to distributor or ignition module is connected to a good ground. Check for intermittent short to ground on terminal "B" (diagnostic enable) of ALDL or in "SERVICE ENGINE SOON" light circuit. On vehicles not equipped with a driver information center, check for intermittent wiring problem using "Scan" tester. See SCAN TESTER USAGE in the appropriate TESTS W/CODES article in this section.

ENGINE PERFORMANCE Self-Diagnostics - 5.0L 4-Bbl.

SELF-DIAGNOSTIC SYSTEM DESCRIPTION The ECM is equipped with a self-diagnostic system, which detects system failures or abnormalities. When a malfunction occurs, ECM will illuminate the SERVICE ENGINE SOON light located on instrument panel. When malfunction is detected and light is turned on, a corresponding trouble code will be stored in ECM memory. To retrieve stored codes, see RETRIEVING CODES (NON-SCAN) in this article. Malfunctions are recorded as HARD FAILURES or as INTERMITTENT FAILURES. Hard Failures

Hard failures cause SERVICE ENGINE SOON light to illuminate and remain on until the malfunction is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but loss of good driveability will most likely be encountered. Intermittent Failures

Intermittent failures cause SERVICE ENGINE SOON light to flicker or illuminate and go out about 10 seconds after the intermittent fault goes away. The corresponding trouble code, however, will be retained in ECM memory. If related fault does not reoccur within 50 engine restarts, related trouble code will be erased from ECM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in H - TESTING W/O CODES article in this section. DIAGNOSTIC PROCEDURE Diagnosis of the computerized engine control system should be performed in the following order: 1. Make sure all engine systems not related to the computer system are operating properly. Do not proceed with testing unless all other problems have been repaired. Appropriate DIAGNOSTIC CIRCUIT CHECK

for that system MUST be performed prior to utilizing trouble code charts. See BASIC TESTING article. 2. If trouble codes were displayed (other than Code 12), decide whether codes are hard or intermittent trouble codes. Hard codes will cause the SERVICE ENGINE SOON light to illuminate continuously while engine is running. See HARD OR INTERMITTENT TROUBLE CODE DETERMINATION in this article. For diagnosing hard codes, proceed to appropriate trouble code chart in this article. For diagnosing intermittent codes, proceed to INTERMITTENTS in H - TESTING W/O CODES article. Exceptions are Code 13, 15, 24, 44 and 45 charts, which may be used to help diagnose intermittent codes. 3. If no trouble codes were displayed and a driveability problem exists, refer to SYMPTOMS in H TESTING W/O CODES article. The comments there will send you to the proper system or component to check in SYSTEM/COMP TESTS article. 4. After any repairs are made, clear any trouble codes and perform SYSTEM PERFORMANCE CHECK or FIELD SERVICE MODE check in BASIC TESTING article. RETRIEVING CODES (NON-SCAN) 1. Turn ignition on. Do not start engine. SERVICE ENGINE SOON light should glow. Locate Assembly Line Data Link (ALDL) connector attached to ECM wiring harness. Most ALDL connectors are located under dash on driver's side of vehicle. For exact location of ALDL, see appropriate COMPONENT LOCATIONS illustration in SYSTEM/COMP TESTS article. Turn ignition on. Insert jumper wire from terminal "B" (diagnostic test terminal) to terminal "A" (ground) of ALDL connector. See Fig. 1 . NOTE:

Inserting jumper wire into test and ground terminals of ALDL connector with engine running will cause fuel injected vehicles to enter field service mode. Codes will not flash if this is done. See FIELD SERVICE MODE in BASIC TESTING article.

2. SERVICE ENGINE SOON light should begin to flash codes. Each code will be repeated 3 times. If codes are not flashed, perform DIAGNOSTIC CIRCUIT CHECK. To exit diagnostic mode, turn ignition off and remove jumper wire from ALDL connector.

Fig. 1: ALDL Connector Terminal Identification Courtesy of GENERAL MOTORS CORP. READING TROUBLE CODES The ECM stores component failure information under a related trouble code which can be recalled for diagnosis and repair. Trouble codes may be read by counting flashes of the SERVICE ENGINE SOON light, or by reading the output of a diagnostic "Scan" tester connected to the ALDL connector. The tester is faster to use, more accurate, and capable of reading information which otherwise would necessitate testing individual ECM and sensor/solenoid connector terminals with a digital voltmeter. See SCAN DATA TABLES and SCAN TESTER USAGE in this article. NOTE:

When using a "Scan" tester, there is a time delay between serial data updates. For instantaneous response, a digital voltmeter must be used.

If "Scan" tester is not available, it is possible to read flashes of the SERVICE ENGINE SOON light by grounding the diagnostic terminal of the ALDL with ignition on and engine off. For example, FLASH, FLASH, pause, FLASH, longer pause, identifies Code 21. The first series of flashes are the first digit of trouble code. The second series of flashes are the second digit of trouble code. Trouble codes are displayed starting with the lowest numbered code. Each code is displayed 3 times. Codes will continue to repeat as long as ALDL test terminal is grounded. NOTE:

Trouble codes will be recorded at various operating times. Some codes require operation of that sensor or switch for 5 seconds; others may require operation for 5 minutes or longer at normal operating temperature, road speed and load. Therefore, some codes may not set in a service bay operational mode.

ECM TROUBLE CODE DEFINITION Code No. 12 (1) 13 14 15 16 21 22 23 " 24 25 26 27, 28 & 29 31 "

Circuit Affected No RPM reference pulse Open oxygen sensor circuit CTS signal voltage low CTS signal voltage high System voltage high TPS signal voltage high TPS signal voltage low MAT sensor signal voltage high M/C solenoid voltage low VSS circuit MAT sensor signal voltage low Quad-Driver error Gear switch problem Wastegate error (turbo) Purge solenoid voltage high (carburetor.)

" 32 33 " 34 " " 35 38 39 41 " " 42 43 44 45 46 " 48 51 52 52 53 " " 54 " 55 61 62 62 63 64 65 " 66

Park/Neutral switch EGR system error MAP sensor signal voltage high MAF sensor signal voltage high (PFI) MAP sensor signal voltage low MAF sensor signal voltage low (PFI) Pressure sensor circuit (carb.) IAC idle speed error Brake switch TCC No distributor reference (carburetor.) C(3)I ignition - cam sensor loss Cylinder select error (MEM-CAL) EST circuit open or grounded ESC retard signal too low Lean exhaust indicated Rich exhaust indicated Anti-theft fault Power steering pressure switch Misfire diagnosis Faulty PROM, MEM-CAL or ECM Faulty/missing CALPAC or MEM-CAL Engine oil temperature low (Corvette) Faulty alternator, voltage high EGR system malfunction Anti-theft circuit fault Fuel pump voltage low MC solenoid voltage high (carb.) Faulty ECM Degraded O2 sensor Gear switch error Engine oil temperature high (Corvette) EGR flow error EGR flow error EGR flow error Fuel injector current low A/C pressure sensor voltage out of specification (1) Display of a Code 12 is normal when no reference pulses are received by ECM (engine not running).

NOTE:

Trouble code charts should only be used if SERVICE ENGINE SOON light is illuminated (indicating a current problem exists). Exceptions are Code 13, 15,

24, 44 and 45 charts, which may be used to help diagnose intermittent codes. Anytime Codes 51, 52, 54 or 55 are displayed with another code, start with 50series code first, then proceed to low profile numbered codes. HARD OR INTERMITTENT TROUBLE CODE DETERMINATION During any diagnostic procedure, it must be determined if codes are hard failure codes or intermittent failure codes. Diagnostic charts will not usually help analyze intermittent codes. To determine hard codes and intermittent codes, proceed as follows: 1. MANUALLY enter diagnostic mode. Read and record all stored trouble codes. Exit diagnostic mode and clear trouble codes. See CLEARING TROUBLE CODES. 2. Apply parking brake and place transmission in Neutral or Park. Block drive wheels and start engine. SERVICE ENGINE SOON light should go out. Run warm engine at specified curb idle for 2 minutes and note SERVICE ENGINE SOON light. 3. If SERVICE ENGINE SOON light comes on, MANUALLY enter diagnostic mode. Read and record trouble codes. This will reveal hard failure codes. Codes 13, 15, 24, 44, 45 and 55 may require a road test to reset hard failure after trouble codes were cleared. 4. If SERVICE ENGINE SOON light does not come on, all stored trouble codes were intermittent failures. Exceptions are noted under each DIAGNOSTIC PROCEDURE. CLEARING TROUBLE CODES Turn ignition switch to ON position and ground diagnostic terminal lead at ALDL connector. Turn ignition switch to OFF position and remove ECM fuse from fuse block for 10 seconds. Replace fuse. Remove diagnostic terminal ground lead. ECM LOCATION On most vehicles the ECM is located behind the right side of the dash, or behind the right kick panel. On the Grand Prix and Lumina, the ECM is located on the right side of the engine compartment. On Corvette, the ECM is located in the left rear corner of the engine compartment, next to the battery. DIAGNOSTIC MATERIALS Diagnostic Aids

Diagnostic aids (located in many trouble code charts) are additional tips used to help diagnose trouble codes when inspected circuit checks out okay. Diagnostic aids may help lead to a definitive solution to that trouble code problem. System Performance Check (Carbureted)

This check verifies that computerized engine control system is functioning correctly. This check should always be made after any repair of computerized engine control system. Performance check can be found by proceeding to SYSTEM PERFORMANCE CHECK in BASIC TESTING article.

Special Tools (Diagnostic)

NOTE:

Special "Scan" testers plugged into the ALDL may be used to read trouble codes and check voltages in the system on the serial data line (terminal "D" on carbureted, terminal "E" on EFI and terminal "M" on EFI with P-4 systems). These testers can save a great deal of time. For additional information, see SCAN TESTER USAGE and SCAN TESTER DATA tables in this article.

The computerized engine control system is most easily diagnosed using a "Scan" tester; however, other tools may aid in diagnosing problems if a "Scan" tester is unavailable. These tools are a tachometer, dwell meter, test light, ohmmeter, digital voltmeter with 10-megohm input impedance (minimum), vacuum pump, vacuum gauge and 6 jumper wires 6" long (one wire with female connectors at both ends, one wire with male connector at both ends and 4 wires with male and female connectors at opposite ends). A test light, rather than a voltmeter, must be used when indicated by a diagnostic chart. A dwell meter can be used to measure the time M/C solenoid is on or off. Dwell reading indicates if M/C solenoid is working, as well as fuel mixture strength (rich or lean). The dwell meter is set on the 6-cylinder scale regardless of the number of cylinders in engine. Dwell meter is connected to Green connector located near carburetor. This connector should not be connected to any circuit EXCEPT when testing with dwell meter. DO NOT allow terminal wire to come in contact with any ground source, including rubber hoses. NOTE:

If engine operation seems to change when dwell meter is connected to Green connector, remove dwell meter and use another type. Some models may not be compatible with computerized engine control system.

Before engine reaches operating temperature, dwell should be fixed between 10-50 degrees, indicating open loop operation. With engine at operating temperature and idling, dwell meter needle should be varying between 10-50 degrees. This indicates closed loop operation. If (after reaching normal operating temperature) dwell is fixed between 10-50 degrees, less than 10 degrees or more than 50 degrees, refer to SYSTEM PERFORMANCE CHECK in BASIC TESTING article. SCAN TESTER USAGE NOTE:

Prior to connection of "Scan" tester to vehicle, diagnostic system should be checked to determine if system is operating properly and if information received by "Scan" tester will be accurate. This is done by performing appropriate DIAGNOSTIC CIRCUIT CHECK in BASIC TESTING article. If vehicle does not pass diagnostic circuit check, information received by "Scan" tester may be invalid.

However, status parameters are only an indication that output signals have been sent to devices by the ECM. It does not indicate if devices have responded properly to that signal. This will need to be verified at output device using a voltmeter or test light. NOTE:

Code 12 should always exist when ALDL is grounded with key on and engine not running, but may not be indicated by all makes of "Scan" testers.

If trouble codes are not present, this is not an indication that there is not a problem. Driveability related problems with codes displayed occur about 20 percent of the time, while driveability problems without codes occur about 80 percent of the time. Sensors that are out of specification WILL NOT set a trouble code but WILL cause driveability problems. Using a "Scan" tester is easiest method of checking sensor specifications and other data parameters. Tester is also useful in finding intermittent wiring problems by wiggling wiring harnesses and connections (key on, engine off) while observing data parameters. See SCAN DATA tables in this article. NOTE:

Information obtained by "Scan" tester is only as accurate as the tester itself. If erroneous voltage signals are suspected, it will be necessary to verify tester information using a digital voltmeter and wiring schematic. If non-existent codes are displayed, turn ignition off, remove tester, turn ignition on and ground ALDL test terminal. If same codes are not flashed by SERVICE ENGINE SOON light that were indicated by "Scan" tester, tester cannot be used on vehicle and information obtained by it will not be guaranteed accurate.

SCAN DATA NOTE:

Information contained in the following tables is typical of readings taken on vehicle with engine idling, upper radiator hose hot, closed throttle, transmission in Park or Neutral, closed loop status achieved and all accessories off (except as noted in tables). Data parameters are updated every 1 1/4 seconds. On systems using P-4 computers, parameter updates are more often. Not all devices & systems are used on all models.

FULL FUNCTION CARBURETED Tester Position Units Measured A/C Request Yes/No AIR Divert Sol. On/Off " " AIR Switch. Sol. On/Off " " BARO Volts Battery Voltage Volts Can. Purge Sol. On/Off Coolant Temp. Â°C Cross Counts Counts EGR Solenoid On/Off

Nominal Data Value No/Yes (with request) On (air to switching sol.) Off (air to atmosphere) On (to exhaust manifold) Off (to catalytic converter) 3-4.5 13.5-14.5 On engine cold (sometimes at idle) 85-105Â° (normal temp.) 0-255 On when energized

EGR Duty Cycle ILC Solenoid Knock (ESC) M/C Dwell O2 Sensor Open/Closed Loop Status Pressure Sensor P/N Switch PROM I.D. RPM " TCC TPS Trouble Codes VSS or MPH

0-100% On/Off Counts Degrees Millivolts OL/CL Volts P/N/RDL PROM # RPM " On/Off Volts Code # MPH

0/closed-100/fully open On extended/Off retracted 0-255 10-50Â° varying 100 (lean) to 999 (rich) Closed/Open during extended idle 3.0-4.5 (idle), 0-1 (WOT) Park/Neutral Original factory number Spec. +/-25 RPM Drive (A/T) Spec. +/-50 RPM Neut. (M/T) Off (On with command) .5 (closed) to 5.0 (WOT) No codes 0-actual

SUMMARY If no hard fault codes are present, driveability symptoms exist or intermittent codes exist, proceed to H TESTING W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.), or intermittent diagnostic procedures. NOTE:

The following diagnostic flow charts and mini-schematics are supplied courtesy of General Motors Corp.

DIAGNOSTIC TESTS DIAGNOSTIC CIRCUIT CHECK The Diagnostic Circuit Check determines if the "SERVICE ENGINE SOON" light works, the ECM is operating and can recognize a fault and if any codes are stored. This is the starting point for any diagnosis. If no codes are indicated, see SYSTEM PERFORMANCE CHECK. If no additional checks are called out from the System Performance Check, see TROUBLE SHOOTING and SCAN TESTER USAGE. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Check operation of "SERVICE ENGINE SOON" light. With key on, "Scan" tester not connected and engine not running, light should be on steady. 2. Grounding "test" terminal will flash a Code 12 and any stored trouble codes. The light must go completely off to indicate a code. If light goes from bright to dim, see CHART A-6. This is not considered a code. 3. See SCAN TESTER USAGE. If "Scan" tester is not operating properly, try it on another vehicle. If it works on other vehicle, cigar lighter should be checked for battery voltage and a good ground. If "Scan" tester displays "NO DATA" or "NO ALDL" with ignition on, see CHART A-6.

4. No codes at this point indicate the problem is intermittent and SYSTEM PERFORMANCE CHECK should be performed. If one or more codes are displayed, see appropriate trouble code chart.

Fig. 2: Diagnostic Circuit Check Ckt Diag

Fig. 3: Diagnostic Circuit Check Flow Chart SYSTEM PERFORMANCE CHECK NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks carburetor ability to change air/fuel mixture. Disconnecting M/C solenoid makes carburetor run full rich. Reconnecting it with dwell lead grounded makes carburetor run full lean. RPM normally drops 300-1000 RPM as solenoid is reconnected. 1A) If plugging PCV, purge, or bowl vent hose causes RPM to drop more than 300 RPM, plugged hose that caused 300 RPM or more drop leads to source of problem. If RPM increases as M/C solenoid is connected, this indicates system is running extremely rich. If no faults are found during system checks, service carburetor. 2. This test checks for proper control of idle circuit. 2A) Indicates "closed loop" operation. Normal dwell reading is 10-50 degrees but varying. Run engine at 2000 RPM for one minute to ensure O2 sensor is warm. 2B) This indicates an "open loop" condition that can be caused by one of the following:  Open O2 sensor circuit or bad sensor.  Open coolant sensor circuit.  Open circuit No. 413, from ECM terminal No. 14 to ground.

2C) This indicates a full rich command to the carburetor, caused by one of the following:  Lean engine condition.  Grounded O2 sensor circuit No. 412 to ECM terminal No. 9, or bad sensor.  Open circuit No. 413, from ECM terminal No. 14 to ground.  Open circuit No. 452 to ECM terminal No. 22.  Open in coolant sensor circuit No. 410 or No. 452. 2D) This indicates a full lean command which can be caused by one of the following:  M/C solenoid wires reversed.  Leaking bowl vent valve, excessive fuel in vapor canister, fuel in crankcase, faulty carburetor calibration or carburetor, or silicone contaminated O2 sensor. 3. Checks for proper control of main metering system. Engine speed must be at least 3000 RPM to get into the main metering system operation. 3A) A missing "O" ring between the switching valve solenoid and valve, or a defective valve, may cause air to leak into the exhaust ports at higher RPM only.

Fig. 4: System Performance Check Flow Chart

CHART A-1, DWELL FIXED LESS THAN 10 DEGREES NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test determines if problem is CCC or engine related. Dwell should start increasing as soon as engine is choked and increase until it is greater than 50 degrees. If dwell responds, problem is lean engine. 2. This test checks for ECM response to input to O2 sensor circuit. The voltmeter is used to put a voltage signal on the O2 sensor circuit to simulate a rich condition. Dwell should increase (lean command) if ECM and harness are good. 3. This test checks for normal coolant sensor circuit condition. Temperature on a normalized hot engine should be greater than 167°F (75°C). 4. This step checks for a circuit problem or high TPS input signal which could cause a full rich command.

Fig. 5: Chart A-1, Dwell Fixed Less Than 10° Ckt Diag.

Fig. 6: Chart A-1, Dwell Fixed Less Than 10° Flow Chart CHART A-2, DWELL FIXED BETWEEN 10°-50° NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Grounding O2 sensor input checks ECM response to a "lean" signal. Normal response is dwell decreasing to full rich command. 2. This step grounds O2 sensor circuit at ECM to check for open in wiring to ECM terminal No. 9. Normal response to "lean" signal is a decrease in dwell. 3. This step checks coolant sensor input. Normal reading on a warm engine is greater than 167°F (75°C). An open circuit would cause a reading of approximately 77°F (25°C). 4. On some ECMs, an open circuit to terminal No. 14 can cause "open loop".

5. Checks output of O2 sensor with full rich command from ECM caused by grounding O2 sensor input circuit. Normal response is O2 sensor voltage reading greater than .8 volt.

Fig. 7: Chart A-2, Dwell Fixed Between 10Â°-50Â° Ckt Diag.

Fig. 8: Chart A-2, Dwell Fixed Between 10Â°-50Â° Flow Chart CHART A-3, DWELL FIXED GREATER THAN 50 DEGREES NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test determines whether problem is related to engine or electronics. Normal response is dwell decrease. This indicates that O2 sensor, harness and ECM are okay. Problem is a rich engine condition. If engine is very rich, a large air leak may be required to lean mixture. When mixture is lean enough, engine will begin to run rough. 2. This test checks ECM response to a "lean" O2 signal. Normal response to this test is low dwell. No dwell change indicates a defective ECM. This test also eliminates the possibility of an open sensor wire. An open wire would cause "open loop" operation and may set Code 13. 3. This test checks for excessive voltage in O2 line. If less than .55 volt, wire and ECM are okay. Fault is in O2 sensor. If greater than .55 volt, wire is shorted to battery voltage or ECM is faulty.

4. If plugging PCV or bowl vent vacuum hose causes dwell to decrease, that hose leads to source of problem. If no problems are found, service carburetor.

Fig. 9: Chart A-3, Dwell Fixed Greater Than 50Â° Ckt Diag.

Fig. 10: Chart A-3, Dwell Fixed Greater Than 50Â° Flow Chart CHART A-5, NO "SERVICE ENGINE SOON" LIGHT NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This checks for blown gauge fuse or open in "SERVICE ENGINE SOON" light circuit, including I.P. connector, printed circuit and "SERVICE ENGINE SOON" light. Normal response is light on. 2. This test checks for shorted ECM. A grounded ECM terminal "G" will turn "SERVICE ENGINE SOON" light off. If disconnecting ECM turns light on, ECM is shorted. Normal response is light on. 3. This test checks for grounded circuit No. 487 from terminal "C" of light driver to terminal "G" of ECM, an open circuit No. 439 to terminal "B" of light driver, bad ground or faulty light driver. Normal reading is 9-11 volts. If greater than 11 volts, a bad ground or a faulty light driver is indicated. Light driver is located in wiring harness near ECM. 4. This test checks for open in wire to terminal "B". Normal reading is about battery voltage. 4A) This test checks for an open circuit No. 439 to terminal "E" from "SERVICE ENGINE SOON" light. With terminal "E" grounded, normal response is light on. Light off indicates an open. Light on indicates a faulty light driver or light driver connection. 5. This test checks for a grounded circuit No. 487 from driver terminal "C" to ECM terminal "G". Normal response is light on.

Fig. 11: Chart A-5, No "Service Engine Soon" Light Ckt Diag.

Fig. 12: Chart A-5, No "Service Engine Soon" Light Flow Chart CHART A-6, "SES" LIGHT ON, WON'T FLASH CODE 12 NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This step checks for short to battery voltage in wire to terminal "C" or faulty light driver. Normal reading is 9-11 volts.

2. This step checks to see if problem is related to the ECM or light driver. Grounding terminal "C" should turn light off. If it does, problem is related to ECM and its wiring. If it does not, fault is related to light driver and its wiring. Light driver is located in wiring harness near ECM. 3. Grounding terminal "G" at ECM and finding light on indicates an open in circuit No. 487 to terminal "C" of light driver. Grounding terminal "G" should turn light off. 4. This step checks for open in circuit No. 451 from ECM to "test" terminal in ALDL connector. The light should flash Code 12 when terminal No. 5 is grounded. 5. This checks for proper voltage supply to ECM. Both should read greater than 9 volts. Terminal "C" is ignition and terminal "R" is constant battery voltage for long term memory. 6. This test checks for bad ground in ECM. Terminals "A" and "U" are connected together inside ECM. 7. This step distinguishes between a faulty ECM and PROM. Normal response is for Code 51 to flash even though PROM is not installed in ECM. If there is no Code 51, ECM is faulty.

Fig. 13: Chart A-6, "SES" Light On All The Time Or Won't Flash Code 12 Ckt Diag

Fig. 14: Chart A-6, "SES" Light On All The Time Or Won't Flash Code 12 Flow Chart CHART B-1, RESTRICTED EXHAUST SYSTEM CHECK Before any components are replaced, exhaust system must be checked for restrictions. Check at AIR pipe or check at O2 sensor procedure may be used to diagnose condition, depending on engine or tool used.

Check At Air Pipe

Remove rubber hose at exhaust manifold AIR pipe check valve and remove check valve. Install fuel pump pressure gauge to hose and nipple via Propane Enrichment Device (J26911) as shown in illustration. Nipple should be inserted into exhaust manifold AIR pipe.

Fig. 15: Chart B-1, Checking For Restriction at AIR Pipe Check At O2 Sensor

Remove O2 sensor. Install backpressure tester in place of O2 sensor as shown in illustration. After test is

completed, ensure that O2 sensor threads are coated with anti-seize compound before installation.

Fig. 16: Chart B-1, Checking For Restriction at O2 Sensor Diagnosis

1. Start engine and bring to operating temperature. Increase engine speed to 2000 RPM and note gauge. Reading should not exceed 1.25 psi (.09 kg/cm2 ).

2. If specification is exceeded, exhaust system restriction is indicated. 3. Check complete exhaust system for collapsed pipe, heat distress and possible internal muffler failure. 4. If none of these conditions exist, check for restricted catalytic converter. Replace if necessary. CODE 12, NO DISTRIBUTOR REFERENCE PULSES This is a normal code with the ignition on and engine not running. With engine running, Code 12 could mean an open or ground in distributor reference circuit. Code 41 will appear with Code 12 if engine is running with no distributor reference signal. Code 41 will be stored even if problems clear. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests if a poor connection at EST connector is the cause of no reference pulse. Terminal must be removed from connector and carefully inspected. 2. Voltage should be more than .5 volt. This indicates reference signal is being generated by module and fault is either a bad connection at ECM or a faulty ECM. To check ECM connection, terminal must be removed from ECM connector. 3. If circuit No. 430 from terminal No. 10 to module is not open or grounded, source of no signal is the module.

Fig. 17: Code 12, No Distributor Reference Pulse Ckt Diag & Flow Chart CODE 13, OPEN OXYGEN SENSOR CIRCUIT NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests if problem still exists. Code 13 indicates an open in the O2 sensor circuit under the following conditions:  Coolant temperature at least 108°F (42°C).  Neither Code 21 nor Code 22 are stored.  O2 sensor voltage is within a specified range (.34-.55 volt).

Throttle angle is greater than 6 percent (off-idle).  More than 40 seconds have elapsed since start-up.  All conditions have existed for at least 20 seconds. 2. Determines if O2 sensor, wiring or ECM is at fault. 3. This tests O2 sensor circuit wiring. Use only a high impedance (10-megohm minimum) digital voltmeter. 

Fig. 18: Code 13, Open O2 Sensor Ckt Diag

Fig. 19: Code 13, Open O2 Sensor Flow Chart CODE 14, COOLANT TEMP SENSOR SIGNAL VOLTAGE LOW NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 14 indicates the ECM has seen low coolant sensor voltage signal (high temperature) at ECM terminal No. 3 for 90 seconds or more. 2. This tests for grounded circuit No. 410 between ECM and coolant sensor. Diagnostic Aids

After the engine is started, temperature should rise steadily to about 90Â°F (32Â°C), then stabilize when thermostat opens. At normal operating temperature, voltage at terminal No. 3 should be 1.5-2.0 volts.

Fig. 20: Code 14, Coolant Temp Sensor Signal Volt Lo Ckt Diag.

Fig. 21: Code 14, Coolant Temp Sensor Signal Volt Lo Flow Chart CODE 15, COOLANT TEMP SENSOR SIGNAL VOLTAGE HIGH NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 15 indicates ECM has seen high resistance in coolant sensor circuit. This could be due to high

resistance (cold temperature) or high voltage at ECM terminal No. 3 for 5 minutes or more after start. 2. This test simulates conditions for a Code 14. If ECM recognizes the low voltage signal, scan displays greater than 130Â°C and Code 14 sets, the ECM and wiring are not at fault. 3. This test determines if circuit No. 410 is open. Diagnostic Aids

Fig. 22: Code 15, CTS Signal Volt Hi Ckt Diag

Fig. 23: Code 15, CTS Signal Volt Hi Flow Chart CODE 21, TPS SIGNAL VOLTAGE HIGH Code 21 indicates ECM has seen a high Throttle Position Sensor (TPS) voltage under one of the following conditions:   

For more than 10 seconds At less than a specified RPM (normally curb idle) At less than a specified engine load.

Due to the 510K ohm pull-up resistor between terminals No. 21 and No. 2 within the ECM, an open in the TPS circuit will place about 5 volts (high TPS signal) at terminal No. 2 of ECM, resulting in a Code 21. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests circuits No. 417 and No. 452 from TPS connector back to ECM. Installing a jumper lead between harness terminals "B" and "C" should lower voltage at ECM terminal No. 2 to less than 2.5 volts. 2. Test light should be on if ground circuit No. 452 is okay. 3. If test light is on, circuit No. 417 could be open or ECM or connection at ECM could be faulty. Diagnostic Aids

A "Scan" tester displays throttle position in volts. Closed throttle voltage should be less then .31-.41 volt with key on and engine off; however, the ECM "learns" and normalizes TPS reading so a voltage reading of .2-.7 volt is acceptable. Voltage should increase gradually to about 4.5 volts at a steady rate, as throttle angle is increased.

Fig. 24: Code 21, TPS Signal Volt Hi Ckt Diag.

Fig. 25: Code 21, TPS Signal Volt Hi Flow Chart CODE 22, TPS SIGNAL VOLTAGE LOW NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 22 indicates ECM has seen low Throttle Position Sensor (TPS) voltage (less than .2 volt) for longer than 20 seconds (with engine running). 2. Simulates Code 21. If ECM recognizes the high voltage signal, ECM and wiring are okay. Diagnostic Aids

A "Scan" tester displays throttle position sensor voltage. Closed throttle voltage should be less .31-.41 volt with key on and engine off; however, the ECM "learns" and normalizes TPS reading so a voltage reading of .2-.7 volt is acceptable. Voltage should increase gradually to about 4.5 volts, at a steady rate, as throttle angle is increased.

Fig. 26: Code 22, TPS Signal Volt Lo Ckt Diag.

Fig. 27: Code 22, TPS Signal Volt Lo Flow Chart CODE 23, M/C SOLENOID SIGNAL VOLTAGE LOW NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests circuit from battery to M/C solenoid dwell lead. Normal reading should be battery voltage. Battery voltage at M/C solenoid dwell lead means there may be an open circuit or grounded circuit No. 411, between dwell connector and ECM terminal No. 18. No voltage could be caused by either an open between connector and ignition source or a ground on ECM side of M/C solenoid. If no problem is found, see INTERMITTENTS in H - TESTING W/O CODES article in this section. 2. This tests for battery voltage on circuit No. 439 to ignition source. Test light should illuminate between ignition source and ground. 3. This test determines whether fault is in M/C solenoid, a ground in ECM circuit No. 411, or ECM. A light will indicate a ground in circuit No. 411 to terminal No. 18 or a faulty ECM. A test light must be used in this step. A voltmeter may give an inaccurate indication. 4. This tests for ground in circuit No. 411 to ECM terminal No. 18. If circuit is grounded, light will stay on. 5. Checks for open in circuit No. 411 from M/C solenoid to ECM. Normal reading would be about battery voltage at terminal No. 18. 6. M/C solenoid resistance should be 20-32 ohms. If M/C solenoid resistance is less than 10 ohms, the ECM does not have to be replaced because the ECM contains a fault protection Quad-Driver in this circuit.

Fig. 28: Code 23, M/C Solenoid Signal Volt Lo Ckt Diag.

Fig. 29: Code 23, M/C Solenoid Signal Volt Lo Flow Chart CODE 24, VEHICLE SPEED SENSOR The ECM applies and monitors 12 volts on circuit No. 437 to Vehicle Speed Sensor (VSS). VSS alternately opens and grounds circuit No. 437 when drive wheels are turning. This pulsing action takes place about 2000 times per mile and ECM calculates vehicle speed based on time between pulses. "Scan" tester reading should closely match speedometer reading. CAUTION: To avoid damaging drive axle CV joints, control arms must be supported when wheels are turning off of ground.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test monitors ECM voltage on circuit No. 437. With drive wheels turning, pulsing action varies voltage. This variation is greater at low speeds to an average of 4-6 volts at about 20 MPH. Cruise control must be off for accurate test results. 2. A voltage of less than one volt indicates circuit No. 437 is shorted to ground. Disconnect circuit No. 437 at VSS. The VSS is faulty if voltage now reads more than 10 volts. If voltage remains less than one volt, check circuit No. 437 for ground. If circuit is not grounded, check for a faulty ECM connector or ECM. 3. A steady 8-12 volts at ECM connector indicates circuit No. 437 is open, or VSS is faulty. 4. This is a normal voltage condition and indicates a possible intermittent condition. See INTERMITTENTS in H - TESTING W/O CODES article. 5. This step will isolate whether problem is in circuit No. 437 or ECM.

Fig. 30: Code 24, VSS Ckt Diag.

Fig. 31: Code 24, VSS Flow Chart CODE 31, CANISTER PURGE SOLENOID VOLT SIGNAL INCORRECT NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Canister purge solenoid should not be energized with ignition on and engine not running. Test light should be off. If light is on, either circuit No. 428 is shorted to ground or ECM is providing a ground, indicating a faulty ECM. 2. Checks for battery voltage at canister purge solenoid connector. 3. Grounding diagnostic "test" terminal at ALDL should energize solenoid, turning on the test light if ECM and wiring are okay. 4. A low resistance solenoid will allow too much current to pass through ECM terminal No. 17. This will cause voltage at terminal No. 17 to be high even when commanded low by ECM. 5. Previous steps have verified that wiring and solenoid are okay. Faulty connections at the solenoid could cause an open circuit, resulting in Code 31. If connections are okay, condition is intermittent. See INTERMITTENTS in H - TESTING W/O CODES article in this section. Diagnostic Aids

Canister purge solenoid coil resistance must measure more than 20 ohms. Less resistance will cause the canister purge driver to open within the ECM since the canister purge Quad-Driver is fault protected.

Fig. 32: Code 31, Canister Purge Solenoid Volt Signal Incorrect Ckt Diag.

Fig. 33: Code 31, Canister Purge Solenoid Volt Signal Incorrect Flow Chart CODE 34, PRESSURE SENSOR SIGNAL VOLTAGE INCORRECT Code 34 indicates ECM has seen manifold pressure outside a specified voltage range (seen by ECM as voltage at terminal No. 20), engine RPM less than a given value, engine at operating temperature and all conditions exist for a time greater than specified. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. An engine that is able to maintain 18 in. Hg of manifold vacuum will show about 4 volts on "Scan" tester.

2. If ECM and wiring are okay, "Scan" tester will show about .58 volt. 3. Low vacuum to sensor will show as low voltage on "Scan" tester. 4. If circuit No. 452 is open, high voltage will show on "Scan" tester.

Fig. 34: Code 34, Pressure Sensor Signal Volt Incorrect Circuit Diagram

Fig. 35: Code 34, Pressure Sensor Signal Volt Incorrect Flow Chart CODE 41, NO DISTRIBUTOR REFERENCE SIGNAL NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests to see if pressure sensor voltage changes with loss of vacuum supply. When vacuum supply is lost, a properly functioning sensor will change voltage by one volt or more (measured from terminal "A" to "B" at sensor and terminal No. 20 to 22 at ECM). See CODE 34 schematic for reference. 2. This tests for cause of intermittent open or ground in distributor circuit. Fault could also be a pressure sensor intermittently sticking at the same voltage output as an engine running condition, with the ignition switch only in ON position. This condition will produce no reference signal. Terminals must be removed from connector to properly check them. The distributor pick-up coil should also be checked. 3. Since voltage change was less than one volt, problem is in pressure sensor system. The ECM has seen engine running vacuum equivalent with no distributor reference signal, with ignition on and engine not running. If Code 12 is present with engine running, a distributor reference fault is indicated and Code 12

chart should be referred to first. Also see Code 34 chart.

Fig. 36: Code 41, No Distributor Reference Signal Ckt Diag

Fig. 37: Code 41, No Distributor Reference Signal Flow Chart CODE 42, ELECTRONIC SPARK TIMING Code 42 indicates the ECM has seen an open or grounded by-pass circuit (terminal No. 11) or an open or grounded EST circuit (terminal No. 12). A grounded EST circuit may not set a code unless cranked 10 seconds or longer with circuit grounded. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests operation of EST. Grounding ALDL "test" terminal causes timing to go to a fixed value, normally different from that obtained with EST operating, therefore, timing should change. Usually the change can be heard in engine RPM. If timing varies with increase in engine RPM (module advance), a problem is indicated. 2. This step eliminates the ECM and ECM connections from module input. By jumping terminals "A" and "B", the distributor reference signal is fed directly into the EST line of module. By putting voltage through the test light on harness terminal "C", the module is switched to EST mode and vehicle should run. If engine stops, there is no EST signal reaching the module due to open or poor connections, or distributor HEI module is faulty. 3. Removing the jumper opens EST signal and engine should stop. 4. Since the engine ran when the module was jumpered, the problem is not in the distributor (if correct HEI module is installed). The wrong HEI module can set a Code 42. Diagnostic Aids

Possible causes for intermittent Code 42 include loose grounds or electrical connections, extended cranking

time (over 10 seconds with fully charged battery), abrupt recycling of ignition switch from ON to OFF position and back on again (within 5 seconds) or EST harness closely routed to plug wires or other high-load electrical harness.

Fig. 38: Code 42, Elect Spark Timing Ckt Diag & Flow Chart

CODE 43, ELECTRONIC SPARK CONTROL SIGNAL VOLTAGE LOW NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. If knock retard is reading high, the ECM is monitoring a low voltage signal on circuit No. 457 at ECM terminal "L". 2. Probing ESC harness terminal "C" with a test light to battery voltage should result in a low knock retard signal. 3. If more than 6 volts is measured at ECM terminal "L", circuit No. 457 is okay and the fault is due to a poor ECM connection or a faulty ECM. Diagnostic Aids

Check for poor connections or damaged harness. Inspect ECM harness connectors for backed-out terminal "L", improper mating, broken locks, improperly formed or damaged terminals or damaged harness. If connections and harness check out okay, monitor knock signal parameter using "Scan" tester, while moving related connectors and wiring harness. If failure is induced, knock signal will abruptly change. This may help to isolate the malfunction.

Fig. 39: Code 43, ESC Signal Volt Low Ckt Diag & Flow Chart CODE 44, LEAN EXHAUST INDICATION NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. System will return to "open loop" if O2 sensor cools off while engine is idling. Scan "loop" status often during testing. For intermittent condition, see INTERMITTENTS in TESTS W/O CODES article. 2. Check if ECM is able to respond to a rich condition caused by choking the engine. If ECM responds, problem is a lean engine condition, NOT electrical. 3. Placing a high impedance (10-megohm) digital voltmeter in series between the battery and the Purple oxygen sensor lead to the ECM will put a rich O2 signal (about one volt) into terminal No. 9 of ECM. Dwell should increase (lean command). 4. If dwell increases to greater than 50 degrees with heavy choking, fault is an air leak, since ECM was able to respond. If air is going to exhaust ports, disconnect solenoid(s) for the air control valve. If air still goes to ports, valve is faulty. Repair exhaust leaks as necessary. If no exhaust leaks are found, service carburetor.

Fig. 40: Code 44, Lean Exhaust Indicated Ckt Diag & Flow Chart CODE 45, RICH EXHAUST INDICATION NOTE:

Test numbers refer to test numbers on diagnostic chart.

dwell indicates ECM and O2 sensor are not faulty. Look for source of constant rich condition. 3. This step tests ECM response to a lean O2 signal (low voltage). If there is no dwell change with a grounded lead to O2 sensor terminal No. 9, fault is in ECM. Open O2 sensor circuit would have set Code 13. 4. The system's response in step 2) indicates the exhaust is actually rich. This could be due to a reverse connected M/C solenoid or excessive fuel in the engine. If all checks are okay, service carburetor. Diagnostic Aids

Engine should be checked for cause of intermittent rich condition. Check for purge or bowl vent valves leaking, fuel in crankcase, fuel in evaporative canister, or sticking mixture control solenoid or metering rods. If Code 45 is intermittent, see INTERMITTENTS in TESTS W/O CODES article.

Fig. 41: Code 45, Rich Exhaust Indicated Ckt Diag & Flow Chart CODE 51, PROM Code 51 sets in the event of a faulty PROM unit, if PROM unit is improperly installed (may not set a code if installed backward) or if some PROM pins are not making contact (i.e. bent). Ensure PROM pins are not bent and are inserted properly into ECM. Ensure PROM is installed in proper direction as shown in chart. CAUTION: It is possible to install a PROM backward. If PROM is installed backward and ignition is turned on, the PROM circuitry will be destroyed and

replacement will be necessary. Also see caution under ECM in REMOVAL, OVERHAUL & INSTALLATION article in this section. CODE 53, EGR SYSTEM MALFUNCTION (CALIF ONLY) NOTE:

Test numbers refer to test numbers on diagnostic chart. Steps 1-3 represent an EGR system operational check.

1. This tests to see if the EGR passages are restricted or if valve is stuck open. Engine should run roughly or stall as valve is opened manually. 2. EGR valve diaphragm should begin to move as engine speed approaches 2000 RPM. 3. This test should result in EGR solenoid being energized, shutting off vacuum to EGR valve. This indicates system is functioning properly. 4. If vacuum is less than 7 in. Hg at 2000 RPM, a leak or restriction between the EGR diaphragm and vacuum source is indicated. 5. With ignition on and engine stopped, ECM normally grounds terminal "T" to energize the EGR solenoid. This tests EGR solenoid and solenoid electrical control circuit. 6. The EGR is normally de-energized with the engine idling at normal operating temperature. This tests EGR solenoid and solenoid electrical control circuit. 7. This determines whether ECM is providing ground to terminal "T" or circuit No. 435 is shorted to ground. Diagnostic Aids

Vacuum hoses should be checked for internal restrictions. The ECM uses the pressure sensor for checking EGR operation. If there is a question of pressure sensor accuracy, see component test in SYSTEMS & COMPONENT TESTING article. If no problems are found, see INTERMITTENTS in TESTS W/O CODES article.

Fig. 42: Code 53, EGR Malfunction Ckt Diag. (Calif)

Fig. 43: Code 53, EGR Malfunction Flow Chart CODE 54, M/C SOLENOID SIGNAL VOLTAGE HIGH NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests the M/C solenoid resistance to determine if fault is in the solenoid, ECM harness or ECM. Normal resistance reading for a solenoid is 20-32 ohms. Since the ECM is protected by a fault protection

Quad-Driver, if M/C solenoid resistance is less than 10 ohms, only the solenoid needs to be replaced, not the ECM. 2. This tests if reason for high voltage to terminal No. 18 is a faulty ECM or a short to 12 volts in circuit No. 411. If test light to ground lights at M/C solenoid test lead with both ends of harness disconnected, there is a short to 12 volts in circuit No. 411.

Fig. 44: Code 53, M/C Solenoid Signal Volt Hi Ckt Diag & Flow Chart CHART C-1D, PRESSURE SENSOR NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. With ignition on and engine not running, the pressure sensor functions as a BARO sensor.

2. If pressure sensor wiring and ECM are okay, the voltage will drop, simulating a change in altitude. If wiring is open or shorted to ground, "Scan" tester reading will always stay high.

Fig. 45: Chart C-1D, Pressure Sensor Ckt Diag.

Fig. 46: Chart C-1D, Pressure Sensor Flow Chart CHART C-2C, IDLE LOAD COMPENSATOR NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. ILC should be extended as no vacuum is applied.

2. ILC should retract if vacuum is applied. 3. Depressing the TPS simulates a WOT signal. This should make the ECM turn the ILC Quad-Driver on, blocking vacuum to the ILC. Clear long term memory after this procedure. ECM will need to "relearn" correct TPS adjustment. 4. With "test" terminal grounded and TPS depressed, ECM should be turning on ILC solenoid. Test light should be on. 5. Anti-dieseling solenoid is energized anytime ignition is on, so test light should be on. 6. Test light should be off, as ILC Quad-Driver should be turned off. 7. If test light goes out, ECM has to be replaced due to a faulty Quad-Driver.

Fig. 47: Chart C-2C, Idle Load Compensator Ckt Diag.

Fig. 48: Chart C-2C, Idle Load Compensator Flow Chart (1 Of 2)

Fig. 49: Chart C-2C, Idle Load Compensator Flow Chart (2 Of 2) CHART C-2D, REAR VACUUM BREAK NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This checks for normal RVB operation. With engine at normal operating temperature, RVB plunger should retract and pull the choke valve open. 2. This step simulates a cold engine by disconnecting the CTS. After sensor is disconnected, ignition must be cycled for each 30 seconds of RVB action. 3. Checks to see if retracted RVB from step 1) was due to no electrical signal to energize RVB solenoid, or a faulty solenoid. Solenoid should be energized with the ignition on and engine stopped. Test light should be on in step if electrical circuit is okay. 4. This step separates an electrical short from a vacuum problem. By de-energizing the solenoid, the RVB should normally retract. 5. If test light goes off, ECM Quad-Driver within ECM is faulty. Replace ECM.

Fig. 50: Chart C-2D, Rear Vacuum Break Ckt Diag.

Fig. 51: Chart C-2D, Rear Vacuum Break Flow Chart CHART C-2F, TPS ENRICHMENT CHECK NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. TPS idle service specification is .2-.7 volt. 2. "Scan" tester indicates actual TPS signal voltage received by ECM. If voltage drops low at any point while opening throttle, ensure it is not due to movement of the harness causing an intermittent. "Scan" tester only updates information from TPS each 1.25 seconds, so it may be necessary to backprobe ECM terminal No. 23 with a DVOM to locate an intermittent problem. 3. Adjust TPS to specification. If TPS can not be adjusted, replace TPS. 4. The 510,000-ohm resistor inside the ECM should cause the TPS signal to be high when the TPS is disconnected, unless circuit No. 417 is shorted to ground or ECM is faulty. 5. This step distinguishes between a faulty TPS and a circuit problem causing loss of 5-volt reference to TPS. 6. The 510,000-ohm resistor inside the ECM should cause the TPS signal to have 5 volts if the TPS is disconnected, unless circuit No. 417 is shorted to ground or the ECM is faulty. If ECM is putting 5 volts on circuit No. 417 but does not indicate an over 4.50 volt TPS signal on "Scan" tester, the ECM is faulty.

Fig. 52: Chart C-2F, TPS Enrichment Check Ckt Diag.

Fig. 53: Chart C-2F, TPS Enrichment Check Flow Chart CHART C-3, CANISTER PURGE SOLENOID NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Checks to see if solenoid is open or closed. Solenoid is normally de-energized in this step so it should be

2. 3. 4.

closed. Completes functional check. This should normally energize solenoid and allow vacuum to drop (purge "on"). Checks for open or shorted solenoid circuit. Checks to see if ECM control circuit or solenoid is at fault. Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause the canister purge driver inside ECM to open since QuadDrivers are fault protected. If test light goes off with ECM disconnected, Quad-Driver within the ECM is faulty. Replace ECM.

Fig. 54: Chart C-3, Canister Purge Solenoid Ckt Diag. & Flow Chart CHART C-4A, IGNITION SYSTEM CHECK NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This tests for proper output from ignition system. Using Spark Tester (ST-125), check for spark at plugs. Tester requires a minimum of 25,000 volts to fire. This test can be used in case of an ignition misfire because system may provide enough voltage to run the engine, but not enough to fire spark plug under load. 1A) If spark occurs with EST connector disconnected, pick-up coil output is too low for EST operation. 2. Normal reading during cranking is about 8-10 volts. 3. This tests for a shorted module or grounded circuit from ignition coil to module. The distributor module should be turned off so that normal voltage should be about 12 volts. If module is turned on, voltage would be low but greater than one volt. This could cause the ignition coil to fail from excessive heat. With an open ignition coil primary winding, a small amount of voltage will leak through the module from "BAT" terminal to "TACH" terminal. 4. This checks voltage output with pick-up coil triggering module. A spark indicates ignition system has enough output. An intermittent no start or poor performance can result if polarity of ignition coil and pick-up coil is not correct. The color of the pick-up coil connector has to be Yellow if one of the ignition coil leads is Yellow. If ignition coil has a White lead, any pick-up coil connector color EXCEPT Yellow is okay. 5. This tests for an open module or module circuit. Applying 12 volts to terminal "P" of module should turn module on and voltage should drop to about 7-9 volts. 6. This should turn off module and cause a spark. If no spark occurs, fault is most likely in ignition coil, not module. A module tester could determine which is at fault.

Fig. 55: Chart C-4A, Ignition System Check Ckt Diag.

Fig. 56: Chart C-4A, Ignition System Check Flow Chart CHART C-4K, ELECTRONIC SPARK TIMING PERFORMANCE CHECK NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Grounding ALDL "test" terminal causes system to go to a fixed spark advance, which should be different from that obtained with EST operating. Engine is run at fast idle to get more spark advance. Usually, the change in timing is enough so it can be heard as a change in RPM. If so, it is not necessary to check ignition timing. 2. Check timing change with vehicle in Drive. Some engines do not have EST operation in Park/Neutral. 3. This test checks if fault is in pressure sensor system.

Fig. 57: Chart C-4K, EST Performance Check Ckt Diag. & Flow Chart CHART C-5, ELECTRONIC SPARK CONTROL

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This is an ESC functional test. Simulating engine knock by tapping on the engine block should cause a drop in RPM (decrease in timing). If RPM doesn't drop, either timing is not retarding or is retarded all the time. 2. This should cause timing to fully retard by dropping voltage at ECM terminal "L". Retarding timing should cause RPM to drop. 3. Normally voltage should be .08 volt AC, or more for a good knock sensor circuit. 4. "SERVICE ENGINE SOON" light should be on and a Code 43 set because ESC system was retarded too long. If no light comes on, ECM is not retarding the spark because of voltage present on circuit No. 457 to terminal "L" or ECM is faulty. 5. This tests if knock sensor is reason for retard signal. If engine knock is not present and timing increases when knock sensor is disconnected, faulty knock sensor is the cause. 6. This tests if retard signal is due to "noise" on signal wire or a faulty controller. If timing increases when wire is disconnected from controller, fault is due to knock sensor signal wire running too close to an ignition or charging system wire. Reroute wire to correct.

Fig. 58: Chart C-5, Electronic Spark Control Ckt Diag & Flow Chart CHART C-6A, AIR MANAGEMENT CHECK Air management is controlled by electric air divert and air switching valves, each with an ECM controlled vacuum solenoid. When solenoid is grounded by ECM, manifold vacuum will activate valve and allow air pump air to be directed as follows:    

Air control (divert) solenoid not grounded by ECM - Air pump air is diverted. Air control (divert) solenoid grounded by ECM - Air pump air to air switching valve. Air switching solenoid not grounded by ECM - Air pump air to converter. Air switching solenoid grounded by ECM - Air pump air to exhaust ports.

Loss of vacuum would cause air to be diverted to air cleaner. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Air is directed to exhaust ports during "open loop" and engine starting. Engine always starts in "open loop", even on a warm engine. Since the air to exhaust ports time is very short, prepare to observe port delivery prior to start of engine. 2. This should set a Code 23. When any code is set, ECM opens ground circuit No. 429 to air diverter valve. This checks ECM response to a fault. A ground in diverter valve circuit No. 436 to ECM would prevent diverter valve action. 3. This test checks for a grounded circuit No. 429 to ECM. Test light off is normal and indicates circuit is not grounded. 4. This test checks for an open in solenoid control circuits. Grounding ALDL "test" terminal should ground both solenoid circuits. Normally, test light should be on, which indicates problem is not in ECM or wiring. Problem is in solenoid valve or connections. 5. This test checks for a grounded switching valve circuit No. 436. Test light off indicates circuit is okay and fault is in valve. 6. If test light goes off, the Quad-Driver within ECM is faulty and ECM must be replaced.

Fig. 59: Chart C-6A, Air Management Check Ckt Diag.

Fig. 60: Chart C-6A, Air Management Check Flow Chart CHART C-7C, EGR CHECK NOTE:

Test numbers refer to test numbers on diagnostic chart. Steps 1-3 represent an EGR functional check.

4. 5. 6. 7.

indicates system is functioning properly. If vacuum is less than 7 in. Hg at 2000 RPM, a leak or restriction between the EGR diaphragm and vacuum source is indicated. With ignition on and engine stopped, ECM normally grounds terminal "T" to energize the EGR solenoid. This test checks EGR solenoid and solenoid electrical control circuit. The EGR is normally de-energized with the engine idling at normal operating temperature. This test checks EGR solenoid and solenoid electrical control circuit. This determines whether ECM is providing ground to terminal "T" or circuit No. 435 is shorted to ground.

Diagnostic Aids

Vacuum hoses should be checked for internal restrictions.

Fig. 61: Chart C-7C, EGR Check Ckt Diag.

Fig. 62: Chart C-7C, EGR Check Flow Chart CHART C-8, TORQUE CONVERTER CLUTCH ELECT DIAGNOSIS NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test confirms a 12-volt supply as well as continuity of TCC circuit. 2. When ALDL "test" terminal is grounded with engine off, ECM capability is energized to control the solenoid. 3. Test light should go off if circuit is okay because grounding terminal "P" shorts out test light. If test light goes off, ECM is faulty. 4. If test light goes off, the Quad-Driver inside the ECM is faulty. ECM must be replaced. 5. Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause continual opening of ECM Quad-Driver. Using an ohmmeter, check solenoid coil resistance of all ECM-controlled solenoids and relays. Replace any solenoid or relay that measures less than 20 ohms. Diagnostic Aids

An engine coolant thermostat that is stuck open or opens at too low a temperature may result in an inoperative TCC. On 200-4R transmission, if TCC engages before "Scan" tester indicates TCC "ON", wiring may be grounded between TCC solenoid and sump over temperature switch or switch may be faulty.

Fig. 63: Chart C-8, TCC Electrical Diagnosis Ckt Diag.

Fig. 64: Chart C-8, TCC Electrical Diagnosis Flow Chart CHART C-9C, VACUUM ACTUATED EFE SYSTEM CHECK (NON-CEC) NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Engine coolant temperature should be less than 73°F (23°C). 2. There should be at least 10 in. Hg (34 kPa) vacuum available to EFE actuator diaphragm. 3. Valve may be seized. It may be freed using Heat Valve Lubricant (1052627). If valve does not free,

replace valve. 4. EFE valve should be open when temperature is greater than 90°F (32°C). 5. Vacuum at actuator on a warm engine indicates a faulty TVS. If no vacuum is present and actuator does not move, actuator and valve should be replaced.

Fig. 65: Chart C-9C, Vacuum Actuated EFE System Check (Non-CEC) Ckt Diag. & Flow Chart CHART C-10C, A/C CUT-OUT RELAY

The A/C cut-out relay is a normally closed relay. The ECM opens the relay by providing a ground on circuit No. 449. This occurs during wide open throttle, an overheat condition, and momentarily during engine start-up on a warm engine. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. The A/C system must be fully charged so that the pressure cycling switch contacts are closed. 2. If ECM monitors Wide Open Throttle (WOT) simulated by fully depressing the TPS plunger, the A/C cut-out relay Quad-Driver in the ECM is turned on, energizing the relay. This will cause current interruption to A/C clutch. Anytime TPS is fully depressed, long term ECM memory must be cleared to allow resetting of the TPS auto ranging feature. 3. Grounding the ALDL "test" terminal should turn on the A/C cut-out relay and Quad-Driver in the ECM, allowing current to flow through the test light. 4. Test determines if relay is at fault or ECM circuit operation is incorrect. 5. If the test light is on, the circuit is either grounded or ECM Quad-Driver is on. The ECM will have to be replaced if the test light goes off when ECM connector is disconnected because the Quad-Driver in the ECM is faulty.

Fig. 66: Chart C-10C, A/C Cut-Out Relay Ckt Diag. & Flow Chart

G - TESTS W/CODES ENGINE PERFORMANCE 5.0L & 5.7L TBI Model Self-Diagnostics

INTRODUCTION Most engine control problems are the result of mechanical breakdowns, poor electrical connections or damaged vacuum hoses. Before considering the computer system as a possible cause of problems, perform checks and inspections covered in BASIC TESTING article. Failure to do so may result in lost diagnostic time. If no faults were found while performing BASIC TESTING , proceed with DIAGNOSTIC PROCEDURE. If no fault codes or only a non-running Code 12 is present and driveability problems exist, proceed to H - TESTING W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.). If only intermittent codes are present, see INTERMITTENTS in H - TESTING W/O CODES article in this section. The ECM is equipped with a self-diagnostic system, which detects system failures or abnormalities. When a malfunction occurs, ECM will illuminate the SERVICE ENGINE SOON light located on instrument panel. When malfunction is detected and light is turned on, a corresponding trouble code will be stored in ECM memory. To retrieve stored codes, see RETRIEVING CODES (NON-SCAN) in this article. Malfunctions are recorded as HARD FAILURES or as INTERMITTENT FAILURES. HARD FAILURES Hard failures cause SERVICE ENGINE SOON light to illuminate and remain on until the malfunction is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but loss of good driveability will most likely be encountered. INTERMITTENT FAILURES Intermittent failures cause SERVICE ENGINE SOON light to flicker or illuminate and go out about 10 seconds after the intermittent fault goes away. The corresponding trouble code, however, will be retained in ECM memory. If related fault does not reoccur within 50 engine restarts, related trouble code will be erased from ECM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in H - TESTING W/O CODES article in this section.

DIAGNOSTIC PROCEDURE Diagnosis of the computerized engine control system should be performed in the following order: 1. Make sure all engine systems not related to the computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. Appropriate DIAGNOSTIC CIRCUIT CHECK for that system MUST be performed prior to utilizing trouble code charts. See BASIC TESTING article. 2. If trouble codes were displayed (other than Code 12), decide whether codes are hard or intermittent trouble codes. Hard codes will cause the SERVICE ENGINE SOON light to illuminate continuously

while engine is running. See HARD OR INTERMITTENT TROUBLE CODE DETERMINATION in this article. For diagnosing hard codes, proceed to appropriate trouble code chart in this article. For diagnosing intermittent codes, proceed to INTERMITTENTS in H - TESTING W/O CODES article. Exceptions are Code 13, 15, 24, 44 and 45 charts, which may be used to help diagnose intermittent codes. 3. If no trouble codes were displayed and a driveability problem exists, refer to SYMPTOMS in H TESTING W/O CODES article. The comments there will send you to the proper system or component to check in SYSTEM/COMP TESTS article. 4. After any repairs are made, clear any trouble codes and perform SYSTEM PERFORMANCE CHECK or FIELD SERVICE MODE check in BASIC TESTING article.

RETRIEVING CODES (NON-SCAN) 1. Turn ignition on. DO NOT start engine. SERVICE ENGINE SOON light should glow. Locate Assembly Line Data Link (ALDL) connector attached to ECM wiring harness. Most ALDL connectors are located under dash on driver's side of vehicle. For exact location of ALDL, see appropriate COMPONENT LOCATIONS illustration in SYSTEM/COMP TESTS article. Turn ignition on. Insert jumper wire from terminal "B" (diagnostic test terminal) to terminal "A" (ground) of ALDL connector. See Fig. 1 . NOTE:

Fig. 1: ALDL Connector Terminal Identification Courtesy of GENERAL MOTORS CORP. 2. SERVICE ENGINE SOON light should begin to flash codes. Each code will be repeated 3 times. If codes are not flashed, perform DIAGNOSTIC CIRCUIT CHECK in BASIC TESTING article. To exit diagnostic mode, turn ignition off and remove jumper wire from ALDL connector.

READING TROUBLE CODES The ECM stores component failure information under a related trouble code which can be recalled for diagnosis and repair. Trouble codes may be read by counting flashes of the SERVICE ENGINE SOON light, or by reading the output of a diagnostic "Scan" tester connected to the ALDL connector. The tester is faster to use, more accurate, and capable of reading information which otherwise would necessitate testing individual ECM and sensor/solenoid connector terminals with a digital voltmeter. See ECM TROUBLE CODE DEFINITION table and SCAN TESTER USAGE in this article. NOTE:

When using a "Scan" tester, there is a time delay between serial data updates. For instantaneous response, a digital voltmeter must be used.

ECM TROUBLE CODE DEFINITION TABLE ECM TROUBLE CODE DEFINITION Code No. 12 (1) 13 14 15 16 21 22 23 24 25 26 27, 28 & 29 31 32 33

Circuit Affected No RPM reference pulse

Open oxygen sensor circuit CTS signal voltage low CTS signal voltage high System voltage high TPS signal voltage high TPS signal voltage low MAT sensor signal voltage high M/C solenoid voltage low VSS circuit MAT sensor signal voltage low Quad-Driver error Gear switch problem Wastegate error (turbo) Park/Neutral switch EGR system error MAP sensor signal voltage high, MAF sensor signal voltage high (PFI)

34 35 38 39 41 42 43 44 45 46 48 51 52 52 53 54 55 61 62 62 63 64 65 66

MAP sensor signal voltage low, MAF sensor signal voltage low (PFI) IAC idle speed error Brake switch TCC C(3)I ignition - cam sensor loss, Cylinder select error (MEM-CAL) EST circuit open or grounded ESC retard signal too low Lean exhaust indicated Rich exhaust indicated Anti-theft fault, Power steering pressure switch Misfire diagnosis Faulty PROM, MEM-CAL or ECM Faulty/missing CALPAC or MEM-CAL Engine oil temperature low (Corvette) Faulty alternator, voltage high EGR system malfunction, Anti-theft circuit fault Fuel pump voltage low Faulty ECM Degraded O2 sensor Gear switch error Engine oil temperature high (Corvette) EGR flow error EGR flow error EGR flow error, Fuel injector current low A/C pressure sensor voltage out of specification (1) Display of a Code 12 is normal when no reference pulses are received by ECM (engine not running).

NOTE:

Trouble code charts should only be used if SERVICE ENGINE SOON light is illuminated (indicating a current problem exists). Exceptions are Code 13, 15, 24, 44 and 45 charts, which may be used to help diagnose intermittent codes. Anytime Codes 51, 52, 54 or 55 are displayed with another code, start with 50series code first, then proceed to low profile numbered codes.

HARD OR INTERMITTENT TROUBLE CODE DETERMINATION During any diagnostic procedure, it must be determined if codes are hard failure codes or intermittent failure codes. Diagnostic charts will not usually help analyze intermittent codes. To determine hard codes and intermittent codes, proceed as follows: 1. MANUALLY enter diagnostic mode. Read and record all stored trouble codes. Exit diagnostic mode and clear trouble codes. See CLEARING TROUBLE CODES . 2. Apply parking brake and place transmission in Neutral or Park. Block drive wheels and start engine. SERVICE ENGINE SOON light should go out. Run warm engine at specified curb idle for 2 minutes and

note SERVICE ENGINE SOON light. 3. If SERVICE ENGINE SOON light comes on, MANUALLY enter diagnostic mode. Read and record trouble codes. This will reveal hard failure codes. Codes 13, 15, 24, 44, 45 and 55 may require a road test to reset hard failure after trouble codes were cleared. 4. If SERVICE ENGINE SOON light does not come on, all stored trouble codes were intermittent failures. Exceptions are noted under each DIAGNOSTIC PROCEDURE.

CLEARING TROUBLE CODES Turn ignition switch to ON position and ground diagnostic terminal lead at ALDL connector. Turn ignition switch to OFF position and remove ECM fuse from fuse block for 10 seconds. Replace fuse. Remove diagnostic terminal ground lead.

ECM LOCATION The ECM is located behind the right side of the dash, or behind the right kick panel.

DIAGNOSTIC MATERIALS DIAGNOSTIC AIDS Diagnostic aids (located in many trouble code charts) are additional tips used to help diagnose trouble codes when inspected circuit checks out okay. Diagnostic aids may help lead to a definitive solution to that trouble code problem. FIELD SERVICE MODE CHECK (FUEL INJECTED) On fuel injected models, SERVICE ENGINE SOON light will indicate operational mode of engine if ALDL is grounded while engine is running. This test confirms proper operation of fuel system and verifies closed loop operation. Clear codes and perform this test after any repair is completed. Field service mode check can be found by proceeding to FIELD SERVICE MODE CHECK (FUEL INJECTED) in BASIC TESTING article. SPECIAL TOOLS (DIAGNOSTIC) NOTE:

Special "Scan" testers plugged into the ALDL may be used to read trouble codes and check voltages in the system on the serial data line (terminal "E" on EFI and terminal "M" on EFI with P-4 systems). These testers can save a great deal of time. For additional information, see SCAN TESTER USAGE and ECM TROUBLE CODE DEFINITION table in this article.

SCAN TESTER USAGE NOTE:

The "Scan" tester is a specialized tester which, when plugged into ALDL, can be used to diagnose on-board computer control systems by providing instant access to circuit voltage information without need to crawl under dash or hood to back-probe sensors and connectors. "Scan" testers cut down diagnostic time dramatically by furnishing input data (voltage signals) which can be compared to specification parameters. See ECM TROUBLE CODE DEFINITION table in this article. They may also furnish information on output device (solenoids and motors) status. However, status parameters are only an indication that output signals have been sent to devices by the ECM. It does not indicate if devices have responded properly to that signal. This will need to be verified at output device using a voltmeter or test light. NOTE:

Code 12 should always exist when ALDL is grounded with key on and engine not running, but may not be indicated by all makes of "Scan" testers.

SCAN DATA

NOTE:

THROTTLE BODY INJECTION Tester Position A/C Clutch A/C Request AIR Divert Sol. AIR Switching Sol. BARO Battery Voltage Block Learn Brake Switch Canister Purge Sol. Clear Flood Coolant Fan Coolant Temp. Crank RPM Cross Counts Cruise Cont. Sw. EGR Solenoid EGR Duty Cycle Fan Relay Fan Request Fuel Back-Up IAC Ignition/Crank Injector Pulse Width INT (Integrator) Knock Retard (ESC) Knock Signal MAT MAP Open/Closed Loop Status O2 Sensor P/N Switch

Units Measured On/Off Yes/No On/Off On/Off Volts Volts Counts On/Off On/Off On/Off On/Off °C RPM Counts On/Off On/Off 0-100% On/Off On/Off Yes/No Counts On/Off Mil./Sec Counts Counts Yes/No °C Volts OL/CL Millivolts P/N/RDL

Nominal Value Off (On with A/C) No/Yes (with request) On (air to switching sol.), Off (air to atmosphere) On (to exhaust manifold), Off (to catalytic converter) 3-4.5 13.5-14.5 118-138 (128 normal) On when engaged On/engine cold (idle some) ***See Tester Manual*** Off below 216°F (102°C) 85-105° (norm. temperature) 100-900 0-255 On when engaged On when energized 0/closed-100/fully open On when energized On with request Yes when engaged 0-50 On with ignition/crank .8-3.0 110-145 (128 normal) 0-255 Yes when knock exists 10-90° 1 (idle) to 4.5 (WOT) Closed/Open during extended idle 100 (lean) to 999 (rich) Park/Neutral

P/S Switch PROM I.D. RPM

Norm/Hi PROM # RPM

Spark Advance TCC TPS Throttle Angle Trouble Codes Turbo Boost Upshift Light (M/T) VSS or MPH 3rd Gear Switch 4th Gear Switch

No. Deg On/Off Volts 0-100% Code # On/Off On/Off MPH On/Off On/Off

Normal Original factory number Spec. +/-25 RPM Drive (A/T), Spec. +/-50 RPM Neut. (M/T) Varies Off (On with command) 1.25 (idle) to 5.0 (WOT) 0 (idle) to 110 (WOT) No codes On when activated Off 0-actual On/3rd & 4th gear On/4th gear

The following diagnostic flow charts and mini-schematics are supplied courtesy of General Motors Corp.

DIAGNOSTIC CODES CODE 13, OPEN OXYGEN SENSOR CIRCUIT The O2 sensor is like an open circuit and produces no voltage when its temperature is less than about 600Â°F (316Â°C). An open sensor circuit or cold sensor causes "open loop" operation. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 13 will set at normal operating temperature if at least 2 minutes have passed since engine start, O2 signal voltage is steady between .35-.55 volt and throttle position sensor signal is greater than 7 percent (1200 RPM). All conditions must be met for a precalibrated period of time. 2. This test determines if the O2 sensor, ECM or wiring is at fault. 3. Use only a high-impedance DVOM for this test. This checks for continuity in signal and ground circuits. If ground circuit is open, voltage on signal circuit will be greater than .6 volt. Diagnostic Aids

Verify a clean, tight connection for ground circuit No. 413. An open circuit at sensor signal terminal or ground terminal will result in a Code 13.

Fig. 2: Code 13, Open O2 Sensor Ckt Diag

Fig. 3: Code 13, Open O2 Sensor Flow Chart CODE 14, COOLANT SENSOR SIGNAL VOLTAGE LOW Coolant temperature is one of the inputs used by the ECM in determining control of fuel delivery, engine timing (EST), idle (IAC) and converter clutch (TCC). As the engine warms, the sensor resistance reduces. At normal operating temperature, voltage signal will be about 1.5-2.0 volts at ECM coolant sensor signal terminal. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This checks if code was set because of a hard failure or intermittent condition. Code 14 will set if signal voltage indicates a coolant temperature above 275Â°F (135Â°C) for more than 3 seconds. 2. This simulates conditions for a Code 15. If the ECM recognizes the open circuit by displaying a low

temperature, the ECM and wiring are not at fault. Diagnostic Aids

After the engine is started, the temperature should rise steadily to about 194Â°F (90Â°C), then stabilize when thermostat opens. If the engine is allowed to cool overnight, the coolant temperature sensor and MAT sensor should read close to each other, when measured with a "Scan" tester. When Code 14 is set, the ECM will turn on the cooling fan. A Code 14 will also set if sensor signal circuit is shorted to ground.

Fig. 4: Code 14, Coolant Sensor Signal Volt Lo Ckt Diag.

Fig. 5: Code 14, Coolant Sensor Signal Volt Lo Flow Chart CODE 15, COOLANT SENSOR SIGNAL VOLTAGE HIGH As the engine warms, the sensor resistance reduces and voltage drops. At normal engine operating temperature, voltage will be about 1.5-2.0 volts at ECM coolant sensor signal terminal. If sensor signal circuit opens, ECM will see -40Â°F (-40Â°C) and deliver fuel for this temperature.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This checks if code was set as a result of a hard failure or intermittent condition. Code 15 will set if time since engine start is more than 2 minutes and signal voltage indicates a coolant temperature less than -22째 F (-30째C) for more than 60 seconds. 2. This simulates conditions for a Code 14. If the ECM recognizes the grounded circuit, and displays a high temperature, the ECM and wiring are not at fault. 3. This determines if there is a problem with ECM or wiring. If ground circuit is open, there may also be a Code 21 stored. Diagnostic Aids

After the engine is started, the temperature should rise steadily to about 194째F (90째C), then stabilize when thermostat opens. If the engine is allowed to cool overnight, the coolant temperature sensor and MAT sensor should read close to each other, when measured with a "Scan" tester. When Code 15 is set, the ECM will turn on the cooling fan. Code 15 will also set if sensor signal and ground circuits are open.

Fig. 6: Code 15, Coolant Sensor Signal Volt Hi Ckt Diag.

Fig. 7: Code 15, Coolant Sensor Signal Volt Hi Flow Chart CODE 21, TPS SIGNAL VOLTAGE HIGH The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to throttle valve angle. Signal voltage will vary from less than about 1.25 volts at idle to about 4.5 volts at wide open throttle. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test confirms Code 21 and checks if fault is because of a hard failure or an intermittent condition. Code 21 will set if TPS voltage is greater than 2.5 volts for 2-8 seconds, engine speed is less than 1800 RPM or MAP sensor signal is equal to a no-load condition.

2. This test simulates conditions for Code 22. If the ECM recognizes the low voltage signal and sets Code 22, the ECM and power and signal circuits are not at fault. 3. This step isolates a faulty sensor, ECM or an open ground circuit. If ground circuit is open, there may also be a Code 15 stored. Diagnostic Aids

A "Scan" tester displays throttle position in volts. Closed throttle voltage should be less than 1.25 volts. TPS voltage should increase at a steady rate to 4.5 volts as throttle angle increases. Code 21 will also result if ground circuit is open or TPS signal circuit is shorted to voltage.

Fig. 8: Code 21, TPS Signal Volt Hi Ckt Diag

Fig. 9: Code 21, TPS Signal Volt Hi Flow Chart CODE 22, TPS SIGNAL LOW The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to throttle valve angle. Signal voltage will vary from less than about 1.25 volts at idle to about 4.5 volts at wide open throttle. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test confirms Code 22 and tests if the fault is because of a hard failure or an intermittent condition. Code 22 will set if engine is running, TPS voltage is less than .2 volt for 2 seconds. 2. This simulates Code 21. If the ECM recognizes a high voltage signal and sets Code 21, the ECM and wiring are not at fault. 3. This checks for voltage to the ECM. If the ECM recognizes the voltage as over 4 volts, the ECM and TPS signal circuit are not at fault. 4. If 5-volt reference circuit is open or shorted to ground, there may also be a Code 34 stored. Diagnostic Aids

A "Scan" tester displays throttle position in volts. Closed throttle voltage should be less than 1.25 volts. TPS

voltage should increase at a steady rate to 4.5 volts as throttle angle increases. Code 22 will also set if TPS signal or ground circuits are open or grounded.

Fig. 10: Code 22, TPS Signal Volt Lo Ckt Diag

Fig. 11: Code 22, TPS Signal Volt Lo Flow Chart CODE 23: MAT SENSOR TEMP LOW The ECM supplies and monitors a voltage signal (4-6 volts) to the sensor. When temperatures are low, sensor resistance is high and the ECM will see a high-monitored voltage signal. As temperature increases, sensor resistance decreases and voltage sensed by the ECM drops. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This checks if Code 23 is because of a hard failure or an intermittent condition. Code 23 will set if engine has been running for a precalibrated period of time and signal voltage indicates a MAT temperature less

than -22Â°F (-30Â°C). 2. This simulates conditions for a Code 25. If the "Scan" tester displays a high temperature, the ECM and wiring are not at fault. 3. This checks for continuity of sensor signal and ground circuits. If ground circuit is open there may also be a Code 33 or Code 21 stored. Diagnostic Aids

If the engine is allowed to cool overnight, the coolant and MAT sensors should read close to each other, when measured with a "Scan" tester. When Code 15 is set, the ECM will turn on the cooling fan. A Code 23 will also result if signal and ground circuits become open.

Fig. 12: Code 23, MAT Sensor Temp Lo Ckt Diag

Fig. 13: Code 23, MAT Sensor Temp Lo Flow Chart CODE 24: VSS The speed sensor, which is a Permanent Magnet (PM) generator, provides the ECM with vehicle speed information. The PM generator, mounted in the transmission, produces a pulsing voltage signal whenever the vehicle speed is more than 3 MPH. The voltage level and pulses increase with vehicle speed. The ECM converts the pulsing voltage to MPH, which is used by the ECM in calculations to determine vehicle adjustments.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. A Code 24 will set when MPH reads zero, transmission is not in Park or Neutral, engine speed is between 1200-4400 RPM, TPS is less than 2 percent (closed throttle), and a high manifold vacuum is sensed by the MAP sensor. All of these conditions must be met for 3-5 seconds. The PM generator only produces a voltage signal if drive wheels are turning greater than 3 MPH. 2. If 8-12 volts are present at the instrument panel (I/P) connector, there is an open between I/P connector and VSS or a faulty vehicle speed sensor. A voltage signal of less than one volt at the I/P connector indicates signal line is shorted to ground or open. If line is not open or grounded, check for faulty ECM connections or faulty ECM. Diagnostic Aids

A faulty or misadjusted Park/Neutral switch may set a false Code 24. Use "Scan" tester to check for proper signal in Drive, while wiggling shifter.

Fig. 14: Code 24, VSS Ckt Diag (5.0L F Body)

Fig. 15: Code 24, VSS Ckt Diag (5.0L & 5.7L B Body)

Fig. 16: Code 24, VSS Ckt Diag (5.7L D Body)

Fig. 17: Code 24, VSS Flow Chart (All) CODE 25: MAT SENSOR TEMP HIGH The ECM applies and monitors a voltage signal (4-6 volts) to MAT sensor. When manifold air is cold, the sensor resistance is high and the ECM will see a high signal voltage. As air warms, resistance decreases and voltage sensed by the ECM drops. Sensor resistance can be measured at sensor terminals with harness disconnected. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This checks if the code is a hard failure or an intermittent condition. Code 25 will set if a MAT temperature greater than 275Â°F (135Â°C) is sensed for more than 2 seconds. Diagnostic Aids

If the engine is allowed to cool overnight, the coolant temperature sensor and MAT sensor should read close to each other, when measured with a "Scan" tester. A Code 25 will also result if sensor signal circuit is shorted to

ground.

Fig. 18: Code 25, MAT Sensor Temp Hi Ckt Diag

Fig. 19: Code 25, MAT Sensor Temp Hi Flow Chart CODE 32: EGR SYSTEM ERROR

ECM controls a solenoid that regulates vacuum to the EGR valve. Solenoid is normally closed, preventing vacuum from passing until it is energized by ECM. A properly operating EGR will directly affect the MAP sensor signal. If EGR is commanded by the ECM and noticeable MAP sensor signal change is not observed, ECM will set a Code 32. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. When test terminal "B" of the ALDL connector is grounded, EGR solenoid should be energized, allowing vacuum to the EGR valve. Vacuum should hold. 2. When jumper is removed from terminal "B", vacuum to the EGR valve should bleed through a vent in the solenoid. EGR valve should close. Vacuum gauge may or may not bleed off vacuum, however, this does not indicate a problem. 3. Determines if the electrical control part of the system is at fault or if connector or solenoid is at fault. 4. This system uses a negative backpressure EGR valve. Valve should hold vacuum with engine off. 5. When engine is started, backpressure should cause vacuum to bleed off and valve should fully close. Diagnostic Aids

The Code 32 chart is a functional check of the EGR system. If the EGR system works properly and a Code 32 has set, check for other causes for an increased open throttle block learn value.   

Check for a blocked/restricted intake and EGR passages. Check vacuum lines. Check the MAP sensor function. A MAP sensor may shift enough in calibration to affect the air/fuel mixture without setting a MAP related code.

Fig. 20: Code 32, EGR System Ckt Diag.

Fig. 21: Code 32, EGR System Error Flow Chart CODE 33: MAP SENSOR SIGNAL VOLTAGE HIGH The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). If the MAP sensor fails, the ECM will substitute a fixed MAP value and use the TPS input to control fuel delivery. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test confirms Code 33 and determines if it is the result of a hard failure or an intermittent condition. Code 33 will set when voltage signal reading is too high for a time greater than a precalibrated period of time and if the TPS voltage indicates throttle is closed. 2. This step simulates conditions for a Code 34. If the ECM recognizes and sets Code 34, low MAP signal, the ECM and 5-volt reference and MAP signal circuits are not at fault. If ground circuit is open, there may also be a Code 23 stored. Diagnostic Aids

With the ignition switch in the "ON" position and the engine stopped, manifold pressure is equal to atmospheric pressure and the signal voltage will be high. Comparison of the BARO readings from a known good vehicle using the same sensor is a good way to check the accuracy of the suspected sensor. Readings should be the same within +/- .4 volt. Code 33 will also result if ground circuit is open or MAP signal circuit is shorted to voltage or to 5-volt reference circuit.

Fig. 22: Code 33, MAP Sensor Signal Volt Hi Ckt Diag

Fig. 23: Code 33, MAP Sensor Signal Volt Hi Flow Chart CODE 34: MAP SENSOR SIGNAL VOLTAGE LOW The Manifold Absolute Pressure (MAP) sensor responds to changes in manifold pressure (vacuum). If the MAP sensor fails, the ECM will substitute a fixed MAP value and use the TPS input to control fuel delivery. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This confirms Code 34 and determines if code was because of a hard failure or an intermittent condition. Code 34 will set when ignition is on and MAP signal voltage is low. On some systems, engine must be running to set code.

2. Jumpering harness terminals "B" to "C" will determine if sensor is at fault or if there is a problem with the ECM or wiring. 3. "Scan" tester may not display 12 volts. The important thing is the ECM recognizes the voltage as greater than 4 volts (high MAP voltage signal), indicating the ECM and MAP signal circuit are not at fault. Diagnostic Aids

With the ignition switch in the ON position and the engine stopped, manifold pressure is equal to atmospheric pressure and the signal voltage will be high. Compare BARO readings with a known good vehicle using the same sensor is a good way to check the accuracy of the suspected sensor. Readings should be the same within +/- .4 volt. A Code 34 will also result if 5-volt reference and MAP signal circuits are open or shorted to ground. If 5-volt reference circuit is not shorted to ground and a stored Code 22 is stored, check MAP signal circuit for short to ground.

Fig. 24: Code 34, MAP Sensor Signal Volt Lo Ckt Diag

Fig. 25: Code 34, MAP Sensor Signal Volt Lo Flow Chart CODE 42, ELECT SPARK TIMING W/HEI

Code 42 indicates the ECM has seen an open or short to ground in HEI EST or by-pass circuits. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test confirms Code 42 and determines if fault is a hard failure or intermittent condition. 2. This test checks for a normal EST ground path through the ignition module. If circuit No. 423 is shorted to ground, reading will be less than 500 ohms. 3. As test light voltage touches circuit No. 424, the module should switch. This will cause the ohmmeter to "over-range" if meter is in the 1000-2000 ohm position. A higher ohm range will indicate over 5000 ohms. This test assures that the module "switched". 4. If module did not switch, this step will test for a short in circuit No. 423, an open in circuit No. 424, and a faulty ignition module connection or module. 5. This step confirms that Code 42 is a faulty ECM and not an intermittent problem in circuits No. 423 and 424. Diagnostic Aids

The "Scan" tester does not have the ability to help diagnose a Code 42 problem. See INTERMITTENTS in H TESTING W/O CODES article.

Fig. 26: Code 42, EST W/HEI Ignition Ckt Diag

Fig. 27: Code 42, EST W/HEI Ignition Flow Chart CODE 42, ELECT SPARK TIMING W/DIS Code 42 indicates the ECM has seen an open or short to ground in EST or by-pass circuits (DIS ignitions). NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test confirms Code 42 and determines if fault is hard or intermittent. 2. This test checks for a normal EST ground path through the ignition module. If circuit No. 423 is shorted

to ground, reading will be less than 500 ohms. 3. As test light voltage touches circuit No. 424, the module should switch. This will cause the ohmmeter to "over-range" if meter is in the 1000-2000 ohm position. A higher ohm range will indicate over 5000 ohms. This test assures that the module "switched". 4. If module did not switch, this step will test for a short in circuit No. 423, an open in circuit No. 424, and a faulty ignition module connection or module. 5. This step confirms that Code 42 is a faulty ECM and not an intermittent problem in circuits No. 423 and 424. Diagnostic Aids

The "Scan" tester does not have the ability to help diagnose a Code 42 problem. See INTERMITTENTS in H TESTING W/O CODES article.

Fig. 28: Code 42, EST W/DIS Ckt Diag (A, N BODY)

Fig. 29: Code 42, EST W/DIS Ckt Diag (W BODY)

Fig. 30: Code 42, EST W/DIS Flow Chart (All) CODE 43, ELECT SPARK CONTROL SIGNAL VOLT LOW 1. If conditions for a Code 43 exist, "Scan" tester will display "YES". There should not be a knock signal at idle unless an internal or system problem exists. 2. Determines if system is functioning at this time. Usually, a knock signal can be generated by tapping on the exhaust manifold. If no knock signal is generated, try tapping on engine block closer to sensor. 3. Because Code 43 sets when the signal voltage on the spark retard line remains low, this test should cause the signal on that line to go high. The 12-volt signal should be seen by the ECM as a "no knock" signal if the ECM and wiring are okay.

4. This test will determine if the knock signal is being detected on the sensor-to-controller line or if the ESC module is at fault. 5. If sensor line is routed too close to secondary ignition wires, the ESC module may see the interference as a knock signal. 6. This checks ground circuit to module. An open ground will cause the voltage on the monitored line to be about 12 volts. This would cause the Code 43 functional test to fail. 7. Contacting the sensor-to-controller wire with a test light connected to 12 volts will generate a knock signal to the controller. This will determine if the ESC controller is operating correctly. Diagnostic Aids

Code 43 can be caused by a faulty connection at the knock sensor, at the ESC module or at the ECM. Also, check the controller-to-ECM signal line for an open or short to ground.

Fig. 31: Code 43, ESC Signal Volt Low Ckt Diag

Fig. 32: Code 43, ESC Signal Volt Low Flow Chart CODE 44, LEAN EXHAUST INDICATION Sensor acts like an open sensor circuit and produces no voltage when exhaust temperature is less than 600°F (316°C). An open sensor circuit or cold sensor causes "open loop" operation.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 44 is set when O2 sensor signal at ECM is less than .2 volt for 50 seconds or more and system is operating in "closed loop". Diagnostic Aids

Using the "Scan" tester, observe the Block Learn Memory (BLM) value at different RPMs. If conditions for a Code 44 exist, the block learn value will be around 150. O2 Sensor Wire

O2 sensor wire may be mispositioned and laying against the exhaust manifold. Check for ground between sensor and wire connector. Fuel Contamination

Water, even small amounts, near the in-tank fuel pump inlet can be delivered to the injector. The water may cause a lean exhaust and set Code 44. Fuel Pressure

System will be lean if fuel pressure is low. It may be necessary to monitor fuel pressure while driving vehicle. For fuel pressure checking procedure, see BASIC TESTING article. Exhaust Leaks

If the exhaust system has large leaks, exhaust system negative pressure pulses can cause outside air to be drawn into the system and past the O2 sensor. Vacuum or crankcase leaks can also cause a lean condition. If Code 44 is intermittent, see INTERMITTENTS in H - TESTING W/O CODES article.

Fig. 33: Code 44, Lean Exhaust Ckt Diag

Fig. 34: Code 44, Lean Exhaust Flow Chart CODE 45: RICH EXHAUST INDICATION Sensor acts like an open sensor circuit and produces no voltage when exhaust temperature is less than 600Â°F (316Â°C). An open sensor circuit or cold sensor causes "open loop" operation. Code 45 indicates a rich exhaust and diagnosis should begin with these items: fuel pressure, leaking injector, HEI shielding, canister purge saturation, coolant sensor, MAP sensor, O2 sensor contamination and TPS intermittent output. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Test checks to see if O2 sensor is registering a rich condition. Code 45 is set when vehicle is at operating temperature (in "closed loop"), throttle angle is between 3 and 45 percent, O2 sensor signal at ECM is greater than .7 volt for 30 seconds or more and time since engine start is one minute or more. Diagnostic Aids

Code 45, rich exhaust, is most likely caused by one of the following: Fuel Pressure High

If fuel pressure is too high, air/fuel ratios will be rich. For fuel pressure checking procedure, see BASIC TESTING article. The ECM can compensate for slight increases but if air/fuel ratio becomes too rich a Code 45

will be set. Ignition Ground

If an open occurs at circuit No. 453, HEI induced electrical "noise" may result, causing simulated reference pulses to be picked up by ECM on reference line of EST harness. Additional pulses result in a higher than actual engine speed signal. The ECM will increase injector pulse width ("on" time) to match the increased RPM signal. "Scan" tester will show higher than actual RPM, which can help in diagnosing this problem. Fuel Canister

Fuel saturation of the charcoal canister will cause a rich air/fuel ratio. If full of fuel, check canister control and hoses. MAP Sensor

An output that causes the ECM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the ECM to substitute a fixed value for the MAP sensor. If the condition disappears, substitute a different MAP sensor and continue testing. TPS

An intermittent TPS output will cause the system to operate rich due to a false indication of engine acceleration. O2 Sensor Contamination

O2 sensor contamination, caused by silicone in certain fuels or use of improper RTV sealant, may cause a White powdery coating to cover the exterior of the O2 sensor. The false high signal voltage (low oxygen content sensed) produced is interpreted by the ECM as a rich mixture, causing the ECM to set Code 45. EGR Problem

EGR valve sticking open at idle is usually accompanied by a rough idle and/or stalling. If Code 45 is intermittent, see INTERMITTENTS in H - TESTING W/O CODES article.

Fig. 35: Code 45, Rich Exhaust Ckt Diag

Fig. 36: Code 45, Rich Exhaust Flow Chart CODE 51, FAULTY PROM/MEM-CAL Check that all pins are fully inserted in socket. If okay, replace PROM/MEM-CAL, clear memory and recheck. If Code 51 reappears, replace ECM. CODE 52, FAULTY CALPAK Check that all pins are fully inserted in socket. If okay, replace CALPAK, clear memory and recheck. If Code 51 reappears, replace ECM. CODE 53, ANTI-THEFT SYSTEM (5.0L F BODY) Vehicle Anti-Theft System (VATS) is designed to disable vehicle operation if incorrect key or starting procedure is used. Decoder module sends a signal to the ECM if the correct key is being used. If the proper

signal does not reach the ECM, ECM will not pulse injectors. Code will set if the ECM has not received the proper signal and the ignition switch has been turned on. Code 53 does not store in ECM memory but is only present when the condition is current. NOTE:

Test numbers refer to test numbers on diagnostic chart.

Diagnostic Aids

1. If engine cranks but does not start, it indicates that the portion of the module which generates signal to ECM is not operating or circuit to ECM is open or shorted to ground. If decoder module is found to be okay, ECM may be at fault but this is not a likely condition. 2. The engine will not crank indicates that there is a VATS problem or incorrect key or starting procedure is being used. See appropriate service manual for diagnosing entire VATS system.

Fig. 37: Code 53, VATS Ckt Diag (5.0L F Body) CODE 54, FUEL PUMP CIRCUIT (5.0L & 5.7L B & F BODIES) Code 54 will set if the ECM does not see 12 volts on the fuel pump signal voltage monitor during the first 2 seconds after ignition is turned on.

Fig. 38: Code 54, Fuel Pump Ckt Diag (5.0L & 5.7L B Body)

Fig. 39: Code 54, Fuel Pump Ckt Diag (5.0L F Body)

Fig. 40: Code 54, Fuel Pump Flow Chart (All) CODE 54, FUEL PUMP CIRCUIT (5.0L D BODY)

Code 54 will set if the ECM does not see 12 volts on the fuel pump signal voltage monitor during the first 2 seconds after ignition is turned on.

Fig. 41: Code 54, Fuel Pump Ckt Diag (5.0L D Body)

Fig. 42: Code 54, Fuel Pump Flow Chart (5.0L D Body) CODE 55, ECM ERROR Replace ECM. Clear codes, confirm closed loop operation and check operation of "SERVICE ENGINE SOON"

light.

ENGINE PERFORMANCE General Motors - E Theory & Operation

INTRODUCTION This article covers the basic description and operation of engine performance related systems and components. Prior to diagnosing vehicles or systems with which you are not completely familiar, read through this article.

AIR INDUCTION SYSTEM AIRFLOW SENSING Speed Density

On models equipped with MAP and MAT sensors, the speed density method is used to compute the airflow rate. Manifold pressure and temperature are used to calculate the airflow rate to the ECM. The MAP sensor responds to manifold vacuum changes due to engine load and speed changes. The ECM sends a voltage signal to the MAP sensor. Manifold pressure changes result in resistance changes in the MAP sensor. By monitoring MAP sensor output voltage, the ECM determines manifold pressure. If MAP sensor fails, the ECM will supply a fixed MAP value and use the TPS to control fuel. Mass Airflow

Sensor measures flow of air entering the engine in grams per second. This measurement of airflow is a reflection of engine load (throttle opening and air volume), similar to the relationship of engine load to MAP or vacuum sensor signal. MAF signal should remain relatively constant at cruise, gradually changing with throttle angle and rapidly changing on sudden acceleration. The ECM uses this information to control fuel delivery. The frequency generator type MAF sensor produces a frequency signal that cannot be easily measured in testing (32-150 Hertz). This varying signal is proportional to airflow. TURBOCHARGERS Turbocharger is an option on the 2.0L equipped Sunbird and the 3.1L equipped Grand Prix. Turbocharger increases available horsepower from the engine by pressurizing the air/fuel charge prior to its entering the combustion chamber. This increases power output by approximately 15 percent. The turbocharger system includes the turbine assembly, compressor, wastegate, actuator, throttle body and intercooler. Turbine Assembly

The turbine is driven by exhaust gas. The turbine and compressor wheels are connected by a shaft. Exhaust gas enters the turbine housing through a tube. Exhaust gas moving across the turbine blades causes blades to spin. An increase in exhaust gas volume will increase turbine and compressor speed. Compressor

The compressor is connected to the turbine by a shaft. The compressor forces an air charge into the intake manifold which is more dense than what would normally be drawn in at atmospheric pressure. The increased density of the intake mixture results in an increase in engine power. Wastegate & Actuator

When intake manifold pressure reaches a specified level, the wastegate opens and allows a portion of the exhaust gas to by-pass the turbine blades, effectively limiting turbine speed and output. The wastegate actuator is a pressure motor which opens and closes the wastegate. The actuator responds to boost pressure and is controlled by the ECM wastegate solenoid. When the pressure differential across the compressor reaches a specified level, the diaphragm will partially open the wastegate. Intercooler

An intercooler is used on turbocharged engines to lower inlet air temperature and increase inlet air density, allowing a more dense air/fuel charge to enter the combustion chamber. As air is compressed, its temperature increases. This heated, pressurized air is routed through the core of a radiator-type intercooler. Outside air passing through the intercooler lowers the temperature of the air inside of the intercooler. Oil Supply

The turbine and compressor wheels can reach speeds up to 140,000 RPM. A sufficient supply of clean engine oil is absolutely necessary for continued operation. Engine oil is fed directly to center housing rotating assembly. Any contamination or interruption of oil flow will result in severe turbocharger damage. NOTE:

Anytime a basic engine bearing, main bearing, connecting rod bearing, camshaft bearing, or any part of turbocharger assembly has been replaced, the oil and oil filter should be changed as part of the repair procedure. In addition, turbocharger should be flushed with clean engine oil to reduce the possibility of contamination.

Whenever oil and filter are changed on a engine, the system must be primed with oil prior to starting. Disconnect battery power at HEI distributor (2.0L) or DIS module (3.1L). Crank engine until oil light goes out or oil pressure gauge indicates positive pressure. To prevent starter damage, do not crank engine in excess of 30 seconds at a time. Reconnect battery power to ignition and start engine.

COMPUTERIZED ENGINE CONTROLS The computerized engine control system monitors and controls a variety of engine/vehicle functions. The computerized engine control system is primarily an emission control system which is designed to maintain a 14.7:1 air/fuel ratio under most operating conditions. When the ideal air/fuel ratio is maintained, the 3-way catalytic converter can control oxides of nitrogen (NOx), hydrocarbon (HC) and carbon monoxide (CO) emissions.

The computerized engine control system consists of the following sub-systems: Electronic Control Module (ECM), input signals (sensors and switches) and output signals. ELECTRONIC CONTROL MODULE (ECM) ECM is located in passenger compartment. For exact location of ECM, see ECM LOCATION in appropriate TESTS W/CODES article.                 

See TESTS W/CODES - Corvette See TESTS W/CODES - DeVille, Fleetwood See TESTS W/CODES - Eldorado, Seville See TESTS W/CODES - CARBURETED - 5.0L See TESTS W/CODES - BCM - Reatta, Riviera See TESTS W/CODES - ECM - Reatta, Riviera See TESTS W/CODES - 3.8L VIN [L] - Regal See TESTS W/CODES - 2.0L TBI See TESTS W/CODES - 2.2L TBI See TESTS W/CODES - 2.5L TBI See TESTS W/CODES - 5.0L & 5.7L TBI See TESTS W/CODES - 2.0L PFI See TESTS W/CODES - 2.3L PFI See TESTS W/CODES - 3.1L PFI See TESTS W/CODES - 3.3L PFI See TESTS W/CODES - 3.8L PFI See TESTS W/CODES - V8 PFI - Camaro, Firebird

The ECM consists of the Arithmetic Logic Unit (ALU), Central Processing Unit (CPU), power supply and system memories. The ECM has a "learning" ability which allows it to make minor corrections for fuel system variations. If battery power is interrupted, a vehicle performance change may be noticed. This will correct itself and normal performance will return if vehicle is allowed to "relearn" optimum control conditions. This is accomplished by driving vehicle at normal operating temperature, under part throttle, moderate acceleration and idle conditions. Arithmetic Logic Unit (ALU)

This internal component of the ECM converts electrical signals, received by ECM from various engine sensors, into digital signals for use by the CPU. Central Processing Unit (CPU)

Digital signals received by CPU are used to perform all mathematical computations and logic functions necessary to deliver proper air/fuel mixture. CPU also calculates spark timing and idle speed. The CPU commands operation of emission control, "closed loop" fuel control and diagnostic system.

Power Supply

Power for ECM reference output signals (5 volts) and control devices (12 volts) is received from the battery (through ignition circuit when ignition switch is in ON position). Keep alive memory power is received directly from the battery. Memories

The 5 types of memories used in ECMs are: Read Only Memory (ROM), Random Access Memory (RAM), Programmable Read Only Memory (PROM), fuel system CALPAC and Memory Calibration unit (MEM-CAL). 



Read Only Memory (ROM) ROM is programmed information that can only be read by ECM. The ROM program cannot be changed. If battery voltage is removed, ROM information will be retained. Random Access Memory (RAM) RAM is the scratch pad for the CPU. Data input, diagnostic codes and results of calculations are constantly updated and temporarily stored in RAM. If battery voltage is removed from ECM, all information stored in RAM is lost. Programmable Read Only Memory (PROM) PROM is factory programmed engine calibration data which "tailors" ECM for specific transmission, engine, emission, vehicle weight and rear axle ratio application. The PROM can be removed from ECM. If battery voltage is removed, PROM information will be retained. CALPAC Some fuel injected models use a PROM and a device called a CALPAC. The CALPAC provides fuel delivery back-up so engine will run in case of a PROM or ECM failure. Any time ECM is replaced, PROM and CALPAC must both be installed into replacement ECM. If battery voltage is removed, CALPAC information will be retained. MEM-CAL Vehicles with fuel injection may also use another type of ECM containing a Memory Calibration unit (MEM-CAL). This assembly contains functions of PROM and CALPAC and, on some models, the ESC control module. If power to ECM is removed, MEM-CAL information will be retained.

NOTE:

For ease of understanding, components are grouped into 2 categories. The first category, INPUT DEVICES, lists components which modify or produce voltage signals that are monitored by the ECM. The second category, OUTPUT SIGNALS, lists components that are controlled by the ECM (this is usually accomplished by the ECM grounding individual circuits).

INPUT DEVICES Each sensor or switch furnishes electronic (voltage) signals to ECM. The ECM uses these input signals to compute spark timing, air/fuel ratio and idle speed for proper driveability and emission control. Various models are equipped with different combinations of input devices. Not all devices are used on all models. To determine the input usage on a specific model, see appropriate wiring diagram in WIRING DIAGRAMS article. The available input signals include the following: A/C "ON" Switch

The air conditioner "on" switch is mounted in instrument panel. This switch provides a simple "on" or "A/C request" signal which is monitored by the ECM. The ECM uses this signal to determine control of the A/C clutch relay (if equipped) and to adjust idle speed when air conditioner compressor clutch is engaged. On some

models, ECM may also activate radiator cooling fan when this signal is present. If this signal is not present on A/C equipped vehicles, vehicle may idle rough when A/C compressor cycles. To check function of the A/C switch, perform functional check of switch. See SYSTEMS & COMPONENT TESTING article in this section. A/C Pressure Sensor

Some models are equipped with an air conditioner pressure sensor which is used to inform ECM of A/C system pressure levels. Low pressure signal will cause A/C compressor to disengage to prevent system damage. High pressure levels cause ECM to engage high speed fans while A/C compressor clutch is engaged. Extremely high pressure levels will cause ECM to disengage A/C compressor clutch to prevent system damage. A/C Pressure Switches

A/C high and low pressure switches may be used in the A/C compressor clutch or compressor clutch relay circuit. Switches are normally closed, completing the circuit which energizes the compressor clutch. When system freon pressure increases beyond a certain point, high side switch will open, causing compressor clutch to disengage. If system freon level decreases, causing freon pressure to drop below normal, low side pressure switch will open, causing compressor clutch to disengage, preventing compressor damage. A/C Temperature Sensor (4.5L)

Cadillac models (except Brougham) are equipped with air conditioner high side and low side temperature sensors which are used to inform ECM of A/C system temperature levels. Low temperature signal will cause A/C compressor to disengage. High temperature levels help ECM determine control of A/C compressor relative to cooling fans and idle speed. Battery Voltage

Battery voltage is monitored by ECM (and BCM on Eldorado and Seville). If battery voltage swings low, a weak spark or improper fuel control may result. To compensate for low battery voltage, ECM may increase idle speed, advance ignition timing, increase ignition dwell or enrichen the air/fuel mixture. If voltage swings high, ECM may set a charging system fault code and turn on SERVICE ENGINE SOON light. If voltage signal swings excessively low (less than 9 volts) or excessively high (16 volts, most models) ECM will shut down for as long as condition exists. If condition is short-term, vehicle may stumble and SERVICE ENGINE SOON light will flicker. If condition lasts long enough, fuel injected vehicles will die. Carbureted vehicles will lose computer control function, but will continue to run. Brake Switch Feedback

Models equipped with cruise control systems may monitor the brake switch circuit to determine when to engage and disengage cruise control. On vehicles equipped with a Torque Converter Clutch (TCC) or Viscous Converter Clutch (VCC), one circuit of brake switch is in series with the power supply for the TCC or VCC solenoid located in the transmission/transaxle. Coolant Level Sensor

Some models are equipped with a coolant level sensor. Coolant level sensor is located in the right side tank of the radiator. It is a dual-probe, solid state module with switching transistor. A 5-volt reference for sensor is supplied and monitored by the ECM. If coolant level is normal, coolant is contacting both internal coolant probes. This causes the switching transistor to ground the monitored circuit, pulling the 5-volt reference low. If coolant level drops, switching transistor will open the reference circuit and ECM will see a high voltage signal, indicating low coolant and causing the ECM to turn on the low coolant light. Coolant Temperature Sensor (CTS)

The CTS is a thermistor (temperature sensitive resistor) located in an engine coolant passage. The ECM supplies and monitors a 5-volt signal to CTS. This monitored 5-volt signal is then reduced by resistance of the CTS. When coolant temperatures are low, CTS resistance is high and a high monitored voltage signal is seen by the ECM. When coolant temperatures are high, CTS resistance is low and a low monitored voltage is seen by the ECM. When fully warmed, CTS should reflect a temperature of at least 185Â°F (85Â°C). Coolant temperature input is used in the control of fuel delivery, ignition timing, idle speed, emission control devices and converter clutch application. A CTS which is out of calibration will not set a trouble code, but can cause fuel delivery and driveability problems. A coolant sensor circuit problem should set a related trouble code. Camshaft Position Sensor (C(3)I System)

A Hall Effect camshaft position sensor is used on 3.8L C(3)I-equipped models, while 3.3L C(3)I-equipped models use a combination cam and crank Hall Effect sensor. The 4.5L engine uses a Hall Effect camshaft sensor located inside of the HEI distributor. The cam sensor provides ECM with a TDC No. 1 signal used to compute the exact position of valves. This allows ECM to properly time ignition and fuel injection operation on PFI equipped models. A fault in the cam sensor circuit (no cam sensor signal) will result in a no-start condition (except 4.5L) and should set a related trouble code. For additional information, see COMPUTER CONTROLLED COIL IGNITION (C(3)I) and HEIEST DISTRIBUTOR in IGNITION SYSTEM in this article. Crankshaft Position Sensor

Crankshaft position sensor used on 3.3L and 3.8L engines utilizes a Hall Effect switch mounted near vibration damper. The sensor monitors vibration damper position (crankshaft position) and sends signals to ignition module. These signals provide ECM with a TDC position reference for each piston, as well as supplying an engine speed (RPM) signal. The 2.0L, 2.5L and 3.1L Direct Ignition System (DIS) and 2.3L Integrated Direct Ignition (IDI) system crankshaft position sensor protrudes through side of engine block, to within .05" (1.3 mm) of an internallymounted crankshaft reluctor ring. The reluctor ring is a special trigger wheel cast into the crankshaft. As crankshaft rotates, 7 notches in the reluctor ring change the magnetic field at the tip of position sensor. This creates an induced AC voltage signal in the sensor windings, resulting in reference signals which are sent to ECM by ignition module. This allows ECM to compute crankshaft position and RPM, and fire appropriate ignition coil at the proper time. Vehicles equipped with HEI-EST distributor systems utilize the RPM reference signal from the ignition module

in the distributor for a crankshaft position signal. Although there is no differentiation between TDC intake and TDC exhaust, this is not necessary on non-sequential fuel injected or carbureted engines. Signal is used on fuel injection equipped vehicles to trigger fuel injector(s). On carbureted vehicles, signal is used by ECM to determine a running condition and engine speed (RPM). For additional information, see C(3)I and DIS in IGNITION SYSTEM in this article. Fuel Pump Feedback

On some models, the fuel pump circuit between the relay and fuel pump is monitored by the ECM. This enables the ECM to determine when the fuel pump relay is energized and voltage is being delivered to the fuel pump. A failure in this monitored circuit will result in the setting of a related trouble code in ECM memory. Gear Switches

Gear switches are located inside automatic transmission. Switches may be normally open or closed and change status depending upon internal hydraulic pressures. High gear switch information is used by ECM in controlling emission components and engagement of Torque Converter Clutch (TCC), or Viscous Converter Clutch (VCC) on Cadillac (except Brougham). Ignition/Crank Signal

The ECM looks at the initial cranking (RPM) signal on circuit No. 430 to determine when the engine is being started. This information is used for starting enrichment. If this signal is not available on EFI vehicles, hard starting may result. Knock Sensor

The knock sensor is a piezoelectric device which detects abnormal engine vibrations (spark knock) in the engine. This vibration results in the production of a very low AC signal which is sent from the knock sensor back to the ESC controller, or to the MEM-CAL portion of the ECM on models not equipped with a controller. The ECM will then retard ignition timing until the engine knock ceases. A fault in the ESC circuit may set a related trouble code. When a related trouble code is not present and the ESC system is suspected as the cause of a driveability problem, perform functional check of ESC system. See SYSTEMS & COMPONENT TESTING article in this section. Manifold Absolute Pressure (MAP) Sensor

The MAP sensor measures changes in manifold pressure. Changes in manifold pressure result from engine load and speed changes. The MAP sensor converts these changes in manifold pressure into a voltage output signal to ECM (1.5 volts at idle to 4.5 volts at WOT). The ECM can monitor these signals and adjust air/fuel ratio and ignition timing under various operating conditions. If MAP sensor fails, the ECM will substitute a fixed MAP value and will use the TPS to control fuel delivery. A fault in the MAP circuit should set a related trouble code. If a related trouble code is not present and MAP sensor is suspected of causing a driveability problem, perform functional check of MAP sensor. See SYSTEMS & COMPONENT TESTING article in this section. Mass Airflow (MAF) Sensor

The MAF sensor measures flow of air entering the engine in grams per second. This measurement of airflow is a reflection of engine load (throttle opening and air volume), similar to the relationship of engine load to MAP or vacuum sensor signal. MAF signal should remain relatively constant at cruise, gradually changing with throttle angle and rapidly changing on sudden acceleration. The ECM uses this information to control fuel delivery. This frequency generator type MAF sensor produces a frequency signal that cannot be easily measured in testing (32-150 Hertz). This varying signal is proportional to airflow. A fault in the MAF sensor circuit should set a related trouble code. Manifold Air Temperature (MAT) Sensor

The MAT sensor is a thermistor (temperature sensitive resistor) mounted in the intake manifold. Low intake air temperature produces high internal sensor resistance, while high temperature causes low internal sensor resistance. The ECM supplies and monitors a 5-volt signal to sensor through a resistor in ECM. By monitoring this voltage, ECM determines manifold air temperature. After a vehicle has sat overnight, MAT and CTS signals (resistance and temperature) should be close to same reading. Failure in MAT sensor circuit should set a related trouble code. Engine Oil Temperature Sensor

Corvette is equipped with a oil temperature sensor. If sensor indicates oil temperature is high when it should be low, or low when it should be high, a trouble Code 52 (low) or 62 (high) will set in ECM memory; however, sensor will not cause driveability problems. Sensor information is sent from ECM to be used by Central Control Module (CCM) to determine oil life expectancy. If an oil temperature sensor code is set in memory, CCM has been calculating oil life from inaccurate ECM input. Oil and filter must be changed, code must be cleared and oil life monitor must be reset. To reset oil life monitor, turn ignition on. Depress ENG MET button on trip monitor and release. Within 5 seconds, depress and release ENG MET button again. Within 5 seconds, depress and hold the RANGE button on trip monitor. The CHANGE OIL light should flash. Hold the RANGE button depressed until the CHANGE OIL light stops flashing and goes out. When the light goes out, the engine oil life monitor is reset. This should take about 10 seconds. If the light does not reset, turn the ignition off and repeat the procedure. Oxygen (O2) Sensor

The O2 sensor is mounted in the exhaust system where it monitors oxygen content of exhaust gases. Two oxygen sensors are used on some Cadillac models. The oxygen content causes the Zirconia/Platinum-tipped O2 sensor to produce a voltage signal which is proportional to exhaust gas oxygen concentration (0-3%) compared to outside oxygen (20-21%). This voltage signal is low (about .1 volt) when a lean mixture is present and high (about 1.0 volt) when a rich mixture is present. As ECM compensates for a lean or rich condition, this voltage signal constantly fluctuates between high and low crossing a .45-volt reference voltage supplied by ECM on the O2 signal line. This is referred to as "cross counts". The O2 sensor will not function properly (produce voltage) until its temperature reaches 600Â°F (316Â°C). At temperatures less than the normal operating range of the sensor, vehicle will function in "open loop" mode and

ECM will not make air/fuel adjustments based upon O2 sensor signals but will use TPS and MAP or MAF values to determine air/fuel ratio from a table built into memory. When ECM reads a voltage signal greater than .45 volt from the O2 sensor, ECM will begin to alter commands to injector or M/C solenoid to produce either a leaner or richer mixture. Once vehicle has entered "closed loop", a fault in the O2 circuit (cooled-down sensor or open or shorted O2 sensor circuit) is the only thing which can return it to "open loop". A problem in the O2 sensor circuit should set a related trouble code. CAUTION: Do not attempt to measure O2 sensor output voltage with a conventional voltmeter. Current drain of voltmeter could damage sensor. Oxygen sensor voltage signal can be measured using a 10-megohm (minimum input impedance) digital voltmeter. Park/Neutral Switch (P/N)

This switch is connected to transmission gear selector. The switch signals ECM when transmission is in Park or Neutral. Information from P/N switch is used by ECM for determining control of ignition timing, converter clutch and idle speed. To check function of P/N switch, perform functional check of switch. See SYSTEMS & COMPONENT TESTING article in this section. Power Steering (P/S) Switch

This switch informs ECM of engine load conditions which exist when steering wheel is turned from center to full lock position. Information is used by ECM to help control idle speed. To check function of P/S switch, perform functional check of switch. See SYSTEMS & COMPONENT TESTING article in this section. Pressure Sensor Carbureted 5.0L (VIN Y)

This sensor is a combination MAP and BARO sensor. When ignition is first turned on, ECM records sensor input as a barometric pressure reading. After vehicle starts, signal is processed as a MAP sensor input. ECM then internally converts the MAP sensor signal to a vacuum signal by comparing current input to the BARO input stored in memory. Thus, if a Scan tester is used to measure pressure sensor voltage, reading will differ from that obtained with a DVOM at the sensor. This input is used primarily as an indicator of engine load and is utilized by ECM for timing and fuel control calculations. Pressure sensor circuit problems should set a related trouble code. If a related trouble code is not present and pressure sensor is suspected of being the cause of driveability problems, perform functional check of sensor. See SYSTEMS & COMPONENT TESTING article in this section. RPM Reference Signal

The RPM is monitored by ECM through ignition module tach/pulse signals (circuit No. 430) produced by either the HEI module (tach reference line of 4-wire EST connector) or crankshaft position sensor signal (Hall Effect signal on C(3)I, PM generator signal on DIS and IDI). These signals are used by ECM for determining control of timing, fuel delivery, EGR function and idle speed. Throttle Position Sensor (TPS)

The TPS is a variable mechanical resistor connected either directly (EFI) or indirectly (carbureted) to the throttle shaft linkage. The TPS has 3 wires connected to it. One is connected to a 5-volt reference voltage supply from ECM. The second is connected to ECM ground and the third is the signal return which is monitored by ECM. The voltage signal from the TPS varies from closed throttle (.5-1.0 volt) to wide open throttle (4.5-5 volts). This signal is used by ECM for determining control of fuel, idle speed, spark timing and converter clutch. A problem in the TPS circuit may set a related trouble code. Throttle Switch (Cadillac Except Brougham)

On Cadillac models using an Idle Speed Control (ISC) motor, an idle switch is incorporated into ISC motor. This switch will inform ECM when throttle lever is contacting ISC plunger. This allows ECM to determine when to control idle speed. When throttle is open sufficiently to relieve pressure from the ISC plunger, switch will open and ECM will no longer attempt to control idle speed. Vehicle Speed Sensor (VSS)

Depending upon vehicle application, VSS is either a Permanent Magnet (PM) generator mounted in transmission or a Light Emitting Diode (LED) mounted in instrument panel cluster, behind speedometer. The VSS sends a pulsing signal to ECM, which ECM converts into miles per hour (MPH). This sensor input is used by ECM in controlling converter clutch engagement. OUTPUT SIGNALS NOTE:

               

Each vehicle may be equipped with different combinations of computer controlled components. The following listed components may NOT be used on all models. For theory and operation on each output component, refer to the system indicated in brackets, to the right of each component.

Air Injection Control Solenoid (Emission Systems) Canister Purge Valve (Emission Systems) SERVICE ENGINE SOON Light (Self-Diagnostic System) Computer Controlled Coil Ignition - C(3)I (Ignition System) Direct Ignition System - DIS (Ignition System) EGR Control Solenoid Valve (Emission Systems) ESC Timing Retard (Ignition System) Fuel Injectors (Fuel Control) Fuel Pump & Fuel Pump Relay (Fuel Delivery) HEI-EST Ignition (Ignition System) Idle Air Control (IAC) Valve (Fuel Injected - Idle Speed) Idle Speed Control (ISC) Motor (Fuel Injected Cadillac - Idle Speed) Idle Load Compensator (Carbureted - Idle Speed) Integrated Direct Ignition - DIS (Ignition System) Mixture Control (M/C) Solenoid - Carbureted 5.0L (VIN Y) (Fuel Control) Self-Diagnostics (Self-Diagnostic System)

  

Serial Data (Self-Diagnostic System) Converter Clutch (Miscellaneous ECM Controls) Wastegate Solenoid (Air Induction Systems)

FUEL SYSTEM FUEL DELIVERY Fuel Pump (Carbureted)

Carbureted vehicles are equipped with a mechanical fuel pump which is driven off of a camshaft eccentric. Fuel Pump (Fuel Injection)

An in-tank electric fuel pump delivers fuel to injector(s) through an in-line fuel filter. The pump is designed to supply fuel pressure in excess of vehicle requirements. The pressure relief valve in the fuel pump, controls maximum fuel pump pressure (60-90 psi (4.2-6.3 kg/cm2 ) on port fuel injection vehicles). A pressure regulator mounted in fuel rail (port systems) or throttle body unit (throttle body systems) keeps fuel available to injector(s) at a constant pressure of 9-13 psi (.6-.9 kg/cm2 ) at idle for throttle body injection and 30-40 psi (2.1-2.8 kg/cm2 ) at idle for port injection systems. Excess fuel is returned to fuel tank through pressure regulator return line. For exact fuel pressure specifications on PFI systems, see SERVICE & ADJUSTMENT SPECIFICATIONS article in this section. When the ignition switch is turned to the ON position, ECM will turn on the electric fuel pump by energizing the fuel pump relay. The ECM will keep the pump on if the engine is running or cranking (ECM is receiving reference pulses from the ignition module). If there are no reference pulses, ECM turns pump off within 2 seconds after key is turned on. For additional information, see FUEL PUMP RELAY (FUEL INJECTION) in this article. Fuel Pressure Regulator (TBI)

On TBI systems, a constant fuel pressure of 9-13 psi (.6-9 kg/cm2 ) is maintained by a factory preset, nonadjustable, spring loaded diaphragm contained within the throttle body. Spring tension maintains a constant fuel pressure to injector regardless of engine load. Fuel Pressure Regulator (PFI)

Fuel pressure regulator is a diaphragm-operated relief valve with injector pressure on one side and manifold pressure (vacuum) on the other. Pressure regulator compensates for engine load by increasing fuel pressure when low manifold vacuum is experienced. During periods of high manifold vacuum, regulator-to-fuel tank return orifice is fully open, keeping fuel pressure on the low side of its regulated range. As throttle valve opens, vacuum to regulator diaphragm decreases, allowing spring tension to gradually close off return passage. At wide open throttle when vacuum is at its lowest, return orifice is restricted, providing maximum fuel volume and maintaining constant fuel pressure

to injectors. Fuel Pump Relay (Fuel Injection)

When the ignition switch is turned to the ON position, ECM will turn on the electric fuel pump by energizing the fuel pump relay. The ECM will keep the relay energized if the engine is running or cranking (ECM is receiving reference pulses from the ignition module). If there are no reference pulses, ECM turns pump off within 2 seconds after key on. As a back-up system to fuel pump relay, fuel pump is also activated by the oil pressure switch. The oil pressure switch is normally open until oil pressure reaches approximately 4 psi (.28 kg/cm2 ). If fuel pump relay fails, the oil pressure switch closes when oil pressure is obtained, operating the fuel pump. An inoperative fuel pump relay may result in extended cranking times due to the time required to build up oil pressure. Oil pressure switch may be combined into a single unit with an oil pressure gauge sender or sensor. For additional information on fuel pump activation, see the appropriate article in this section: ď Ź ď Ź

See BASIC TESTING See SYSTEM/COMPONENT TESTS

FUEL CONTROL The ECM, using input signals, determines adjustments to the air/fuel mixture in order to provide the optimum ratio for proper combustion under all operating conditions. One of 3 types of fuel control systems are used on General Motors vehicles: carbureted, throttle body injection or port fuel injection. These systems can operate in the "open loop" or "closed loop" mode. Description of these modes is as follows: Open Loop

When engine is cold and engine speed is greater than 400 RPM, ECM operates in "open loop" mode. In "open loop", ECM calculates air/fuel ratio based upon coolant temperature and Manifold Absolute Pressure (MAP) or Mass Airflow (MAF) sensor readings. Engine will remain in "open loop" operation until O2 sensor reaches operating temperature, coolant temperature reaches preset temperature, and a specific period of time has elapsed after engine starts. Closed Loop

When oxygen sensor has reached operating temperature, coolant temperature has reached a preset temperature and a specific period of time has passed since engine start-up, ECM operates in "closed loop". In "closed loop", ECM controls air/fuel ratio based upon O2 sensor signals (in addition to other input parameters) to maintain as close to a 14.7:1 air/fuel mixture as possible. If oxygen sensor cools off (due to excessive idling) or a fault occurs in the oxygen sensor circuit, vehicle will once again enter "open loop" mode. Battery Voltage Correction (Fuel Injection)

ECM compensates for low battery voltage by increasing injector pulse width and increasing idle RPM. ECM is able to perform these commands because of a built-in memory/learning function.

Fuel Cut-Off (Fuel Injection)

Injectors are de-energized when ignition is turned off so that dieseling is prevented. Injectors will not be energized if RPM reference pulses are not received by the ECM, even with ignition on. This prevents flooding before starting. Fuel cut-off will also occur at high RPM to prevent internal damage to engine. Some fuel injected models may also cut off fuel injector signals during periods of high speed, closed throttle deceleration (when fuel is not needed). Carbureted 5.0L (VIN Y)

Carbureted vehicles are equipped with a 4-Bbl. feedback carburetor which uses an ECM controlled Mixture Control (M/C) solenoid. The M/C solenoid operates a metering rod system in the float bowl which supplements fuel supplied by idle and main systems in carburetor to vary air/fuel ratio within a pre-calibrated range. The M/C solenoid also controls air/fuel ratio through use of an idle air bleed that operates in conjunction with metering rod system. Solenoid is spring loaded in the normally open (full rich) delivery mode. When ignition is turned on, current is supplied to solenoid. The ECM controls air/fuel ratio by supplying a ground for the M/C solenoid. This energizing process occurs 10 times per second. The air/fuel ratio is varied by controlling the length of time solenoid is energized during each of the 10 on-off cycles. More "on" time (high dwell) will produce a leaner mixture, while less "on" time (low dwell) will deliver a richer mixture. In "open loop" mode, dwell will be fixed at mid-range (about 30-35 degrees). Solenoid "on" time may be measured in degrees using a dwell meter set on the 6-cylinder scale. A Throttle Position Sensor (TPS) is contained in the carburetor and varies resistance reading to the computer, indicating throttle position changes. An Idle Load Compensator (ILC), mounted on the throttle linkage, is also used to increase idle speed during increased engine load conditions (such as A/C operation or increased power steering loads). ILC will also increase throttle opening during periods of extended deceleration (such as coasting downhill). Throttle Body Injection (TBI)

Injector is located in throttle body unit. Dual injectors are used on 5.0L (VIN E) and 5.7L (VIN 7) engines. Battery voltage is supplied to the injector when the ignition is on. ECM energizes solenoid by providing a ground path through its internal circuitry. By regulating the injector ground circuit, ECM controls injector "on" time (pulse width) to provide proper amount of fuel to engine. Pressure to injector is maintained at 9-13 psi (.6-.9 kg/cm2 ) by the pressure regulator. Excess fuel passes through pressure regulator and is returned to fuel tank. In the "run" mode, ECM uses tach (RPM) signal to determine when to pulse injector. Fuel injectors are pulsed once for each engine revolution, each spray providing 1/2 the fuel required for the combustion process. Thus, 2 injections of fuel (2 rotations of crankshaft) are mixed with incoming air to produce the fuel charge for each combustion cycle. On models equipped with dual injectors in the throttle body, injectors are pulsed alternately. During starting, clear flood mode, deceleration and heavy acceleration, fuel delivery is controlled by internal ECM calibration.



Starting During engine starts, ECM delivers one injector pulse for each distributor reference pulse received (synchronized mode). Injector pulse width is based upon coolant temperature and throttle position. Air/fuel ratio is determined by ECM when throttle position is less than 80 percent open. Engine starting air/fuel ratio ranges from 1.5:1 at -33°F (-36°C) to 14.7:1 at 201°F (94°C). At lower coolant temperatures, injector pulse width is longer (richer air/fuel mixture ratio). When coolant temperature is high, injector pulse width becomes shorter (leaner air/fuel ratio). Clear Flood If engine is flooded, driver must depress accelerator pedal to Wide Open Throttle (WOT) position. At this position, ECM adjusts injector pulse width equal to an air/fuel ratio of 20:1. This air/fuel ratio will be maintained as long as throttle remains in wide open position and engine speed is less than 600 RPM. If throttle position becomes less than 80 percent open and/or engine speed exceeds 600 RPM, ECM changes injector pulse width to that used during engine starting (based upon coolant temperature and manifold vacuum). Heavy Acceleration Fuel enrichment during heavy acceleration is provided by ECM. Sudden opening of throttle valve causes rapid increase in MAP signal. Pulse width is directly related to MAP, throttle position and coolant temperature. Higher MAP and wider throttle angles give wider injector pulse width (richer mixture). During enrichment, injector pulses are non- synchronized (not in proportion to distributor reference signals). Any reduction in throttle angle cancels fuel enrichment. Deceleration During normal deceleration, fuel output is reduced. This reduction in available fuel serves to remove residual fuel from intake manifold. During sudden deceleration, when MAP, throttle position and engine speed are reduced to preset levels, fuel flow is cut-off completely. This deceleration fuel cutoff overrides normal deceleration mode. During either deceleration mode, injector pulses are not in proportion to distributor reference signals.

Port Fuel Injection (PFI)

Individual, electrically pulsed injectors (one per cylinder) are located in intake manifold fuel rails. These injectors are next to intake valves in cylinder head. Standard PFI systems feature simultaneous double-fire injection. Fuel injectors are pulsed once for each engine revolution, each spray providing 1/2 the fuel required for the combustion process. Thus, 2 injections of fuel (2 rotations of crankshaft) are mixed with incoming air to produce the fuel charge for each combustion cycle. The 3.8L and 4.5L models use Sequential Fuel Injection (SFI). Injectors on these models are pulsed sequentially in spark plug firing order. Main differences between sequential and simultaneous systems are injectors, wiring and the ECM. In all systems, constant fuel pressure is maintained to the injectors. Air/fuel mixture is regulated by the time that injector stays open (pulse width). Various sensors provide information to the ECM to control pulse width.

IDLE SPEED Engine idle speed is controlled by the ECM depending upon engine operating conditions. The ECM senses engine operating conditions and determines the best idle speed. Idle Air Control Valve (Fuel Injection - Except Cadillac)

The Idle Air Control (IAC) valve controls engine idle speed during engine load changes to prevent stalling. The

IAC valve is mounted on throttle body and controls the amount of air by-passed around the throttle plate. The IAC valve moves its pintle in and out in steps referred to as "counts" (0 counts-fully seated, 255 counts-fully retracted) to control engine idle speed. Counts can be measured using a Scan tester plugged into the Assembly Line Data Link (ALDL). If engine RPM is too low, pintle is retracted and more air is by-passed around the throttle plate to increase engine RPM. If engine RPM is too high, pintle is extended and less air is by-passed around the throttle plate to decrease engine RPM. Normal counts on an idling engine should be 4-60. When engine is idling, ECM determines proper positioning of IAC valve based on battery voltage, coolant temperature, engine load and engine RPM. If IAC valve is disconnected or connected with engine running, IAC loses its reference point and has to be reset. Resetting of IAC is accomplished on some models by turning ignition on and off. On other models it may be necessary to drive vehicle (at normal operating temperature) over 35 MPH with circuit properly connected. Problems in IAC circuit should set a related code. The IAC valve affects only the idle system. If valve is stuck fully open, excessive airflow into the manifold creates a high idle speed. Valve stuck closed allows insufficient airflow, resulting in low idle speed. For calibration purposes, several different design IAC valves are used. Ensure proper design valve is used during replacement. Idle Speed Control (ISC) Motor (Cadillac Except Brougham)

The ISC, mounted to the throttle body, is an electrically driven actuator which changes throttle angle according to ECM demands. An internal idle switch by-passes this function when throttle is opened enough to allow TPS to move from idle position. The ISC motor is factory calibrated and should not be disassembled. Replace as complete assembly only. Idle Load Compensator (Carbureted)

ILC system controls idle speed during long deceleration modes using a vacuum motor which is regulated by an ECM-controlled vacuum solenoid. To check function of ILC system, perform functional check of ILC system. See SYSTEM/COMPONENT TESTS article in this section.

IGNITION SYSTEM All vehicles are equipped with high energy ignition systems capable of producing in excess of 50,000 volts. Vehicles not using a C(3)I (3.3L and 3.8L), IDI (2.3L) or DIS (2.0L TBI, 2.2L, 2.5L and some 3.1L) systems are equipped with a High Energy Ignition Electronic Spark Timing (HEI-EST) distributor. HEI-EST Distributor

The Delco-Remy High Energy Ignition Electronic Spark Timing (HEI-EST) system consists of distributor housing, rotor, cap, 7 or 8-terminal ignition module, magnetic pick-up, pole piece, pick-up coil, connecting harness and the EST portion of the ECM. The distributor is connected to the EST system by means of a 4-wire connector, leading to Electronic Control Module (ECM). On some models, the ignition coil is contained within the distributor cap, while others have an externally

mounted coil. A capacitor is installed in the distributor for radio noise suppression. No vacuum or centrifugal advance mechanisms are used. All spark timing changes are controlled by the Electronic Control Module (ECM) based upon monitored input signals. Some models use an additional Electronic Spark Control (ESC) ignition retard system in the event of engine detonation (knock). Most models are equipped with sealed ignition coil and ignition module connectors. When the external teeth on the timing core approach, align with, and pass the pick-up coil windings, an alternating current is produced in the pick-up coil windings. In the cranking mode, this alternating current signals switching transistors in the HEI module to make or break the ignition coil primary ground circuit. Once the engine has started, ECM takes control of primary ground circuit (EST mode). When the primary ground circuit is removed, the magnetic field created by the flow of current in the primary windings collapses across the primary and secondary windings of the coil. This induces a high-voltage surge in the secondary windings of the coil. Secondary voltage is then discharged to the rotor which distributes it to the appropriate spark plug terminal. The distributor module may have either a 7-terminal ignition module or an 8terminal ignition module (sealed connector module) depending on application. The 4.5L HEI-EST system is also equipped with a Hall Effect switch inside of the distributor. The Hall Effect switch produces a camshaft signal which is used by the ECM to determine the proper firing sequence for the injectors on the sequential fuel injection system. Loss of the camshaft signal will result in the fuel injection operating in a non-sequential mode and the setting of a related trouble code. Computer Controlled Coil Ignition (C(3)I)

The Computer Controlled Coil Ignition (C(3)I) system, used on 3.3L and 3.8L PFI engines, eliminates the need for a mechanical distributor. The C(3)I ignition system consists of a coil pack (3 coils), ignition module, camshaft and crankshaft (3.8L) or combination (3.3L) sensor, wiring harness, and the Electronic Spark Timing (EST) portion of the Electronic Control Module (ECM). In the C(3)I system, each cylinder is paired with the cylinder that is opposite it in the firing order. Cylinders No. 1/4, 5/2, and 3/6 are paired. Spark occurs simultaneously in the cylinder coming up on the compression stroke and in the cylinder coming up on the exhaust stroke. The cylinder on the exhaust stroke requires less voltage for the spark plug to fire. This leaves the bulk of the available voltage to fire the spark plug for the cylinder on the compression stroke. The process is repeated when the cylinders reverse roles. Each cylinder pair is fired by its own ignition coil. Input from the Hall Effect combination sensor (3.3L) or cam and crank sensors (3.8L) is used by the ignition module to determine when to trigger the appropriate coil pack. On 3.8L models, module passes on camshaft sync-pulse signal to the ECM so that sequential fuel injector timing can be initialized. ď Ź

ď Ź

Type II Ignition Coil Pack (3.3L) On type II ignition coil pack, 3 separate twin tower coils are independently mounted over the C(3)I ignition module. Each coil provides the spark for 2 simultaneously paired spark plugs. Each coil can be replaced separately. Type III Ignition Coil Pack (3.8L) On type III ignition coil pack, 3 twin tower coils are combined into a single coil pack. Coil pack is mounted directly over the C(3)I ignition module. Each coil provides the spark for 2 simultaneously paired spark plugs. All 3 coils must be replaced as a unit. Although old-style type I coil pack will physically fit on ignition module, the No. 1/4 coil pack is in a different location in



relation to module connector. Combination Sensor (3.3L) The combination cam/crank sensor actually consists of 2 Hall Effect sensors mounted, in a single unit, near the harmonic balancer. Since the 3.3L engine uses a double-fire simultaneous injection system rather than a sequential fuel injection system, it does not require a distinctive (TDC No. 1 piston compression) camshaft signal. Instead, each engine revolution, camshaft portion of the combination sensor generates a TDC signal for the No. 1/4 cylinder pair. Each engine revolution, the second sensor crankshaft) generates RPM information and signals for the 1/4, 2/5 and 3/6 cylinder pairs. Camshaft Position Sensor (3.8L) The 3.8L camshaft sensor is located on the timing cover, behind and below water pump. The ECM uses camshaft "sync- pulse" signals (passed to ECM by the ignition module) to determine the exact position of the No. 1 piston. Signal is used by ECM to properly initialize fuel injector firing. If camshaft sensor signal is lost, Code 41 (E041 on some models) will be set. The engine can be restarted and will run in sequential mode; however, without the camshaft signal, there is a 1 in 6 chance of injectors spraying correctly. This provides "walk home" protection against cam sensor failure. Combination 3X & 18X Sensors (3.8L) In addition to the camshaft sensor, the 3.8L engine contains sensors which are similar to the combination sensor used on the 3.3L engine; however, the interrupter rings on the back side of the balancer differ in configuration and purpose. The outside ring contains 18 evenly spaced interrupters, producing 18 pulses per crankshaft revolution. The inner ring has 3 interrupters spaced at irregular intervals (10 degrees, 20 degrees and 30 degrees apart). The ignition module monitors signals generated by the 2 interrupter rings. The 18X ring will change state once during the 10 degree gap of the 3X ring, twice during the 20 degree gap, and 3 times during the 30 degree gap. The changing relationship between the 2 rings allows the ignition module to identify the correct ignition coil to fire within the first 120 degrees of crankshaft rotation. This system provides for a faster start and a more accurate measurement of the crankshaft sensor signals. If the 3X signal to ignition module is lost while the engine is running, the fuel injection system will continue to run in sequential mode; however, loss of the 3X, or the 18X signal, will not allow the vehicle to restart. Fuel Control Signal (3.8L) In addition to the RPM reference (18X) signal and fuel sync (camshaft) signals generated by the ignition module on 3.8L models, a fuel control reference signal must also be passed on to the ECM in order to inform ECM that proper signals are being generated to the ignition module. The fuel control signal is generated by the C(3)I module from calculations involving signals from the 18X and the 3X pulse rings.

Direct Ignition System (DIS)

DIS is a distributorless system used on 2.2L, 2.5L and some 3.1L models. On the 2.3L, a similar system is referred to as the Integrated Direct Ignition (IDI) system. The operation of both systems is quite similar to that of C(3)I system. They consist of 2 or 3 ignition coils (4-cylinder or V6), spark plug wires, ignition module (located under coil pack), a crankshaft position sensor, necessary wiring and the Electronic Spark Timing (EST) portion of the Electronic Control Module (ECM). On 2.3L models, coils, module and spark plug connectors are all combined in one unit which plugs directly onto spark plugs. Rather than a crankshaft position sensor mounted at crankshaft pulley (such as C(3)I), spark is timed by a signal sent from a crankshaft sensor mounted through side of engine block. This signal is received by ECM (through ignition module) and is used to trigger each coil at the proper time. See CRANKSHAFT POSITION SENSOR in INPUT SIGNALS section of this article. As with the C(3)I system, each cylinder is fired consecutively with the cylinder opposite it in the firing order. On the 3.1L, cylinders No. 1/4, 3/6 and 2/5 are paired. On 2.2L, 2.3L

and 2.5L engines, cylinders No. 1/4 and 2/3 are paired. Each pair of cylinders is fired by its own ignition coil. The crankshaft position sensor is mounted on the bottom of the DIS ignition module or near the ignition module. The sensor protrudes through the side of engine block to within .050" (1.3 mm) of an internallymounted crankshaft reluctor ring. Sensor position is not adjustable. The reluctor is a special piece of metal cast with the crankshaft. It has 7 slots machined into it, 6 of which are equally spaced (60 degrees apart). A seventh slot is spaced about 10 degrees from one of the other slots and generates a synchronization pulse signal. As crankshaft rotates, notches in the reluctor ring change the magnetic field at the tip of position sensor. This creates an induced AC voltage signal in the sensor windings, resulting in RPM reference signals which are sent to ECM by ignition module. This allows ECM to compute crankshaft position and RPM, and fire appropriate ignition coil at the proper time.

IGNITION TIMING SYSTEMS Ignition Timing Advance

At engine speeds less than 400 RPM, the ignition module controls spark advance by triggering coil(s) at a predetermined interval based on engine speed only. At engine speeds greater than 400 RPM (EST mode), the ECM takes over control of the ignition timing. On 3.8L engines, when in EST mode, ECM also changes fuel injection timing to a sequential mode. Ignition timing is controlled by the ECM based upon input signals from the engine RPM reference line (ignition module), coolant temperature sensor, manifold air temperature sensor, throttle position sensor, knock sensor, vehicle speed sensor, gear position switch, and the MAF or MAP sensor. The PROM/MEM-CAL portion of the ECM has a programmed spark advance curve based on engine speed. Spark timing is calculated by ECM whenever an ignition pulse is present. Spark advance is controlled only when engine is running (not during cranking). Input signal values are used by ECM to modify PROM/MEMCAL information, increasing or decreasing spark advance to achieve maximum performance with minimum emissions. To check ignition system operation, see the appropriate article in this section:  

See BASIC TESTING See SYSTEM/COMPONENT TESTS

Although several types of ignition systems are used, all ignition systems use the same 4 basic ignition circuits. Models may use a conventional HEI/EST distributor system or one of 3 types of distributorless ignition systems. The C(3)I uses the same ignition module-to-ECM circuits that DIS and distributor type ignition systems use with the addition of fuel control and fuel sync (camshaft) signals on 3.8L engines. For description of fuel control and sync signals, see IGNITION SYSTEM in this article. The ignition module is connected to ECM by 4 EST circuits. Circuits perform the following functions: 

Reference (RPM) Alternating current signals from the pick-up coil (HEI distributor), PM generator (DIS and IDI) or Hall Effect sensors (C(3)I and Cadillac 4.5L) are converted by the ignition module converter to digital signals for use by the ECM. This supplies RPM data and crankshaft position reference to the ECM. Since the signal on this circuit is used as an injector trigger reference on fuel injected vehicles, if



circuit is open or grounded, engine will not run. By-Pass When an engine speed signal of approximately 400 RPM is received by the ECM, ECM considers engine to be running and applies 5 volts to the ignition module on the by-pass wire. This causes ignition module to switch timing control over to the variable timing control circuit in the ECM. On some models, this by-pass wire contains a connector located between the 4-wire connector and the ECM. This is disconnected when adjusting base timing. On all models, an open or grounded by-pass circuit will set a related trouble code in ECM memory. The engine will run at base timing plus a small amount of advance built into the HEI module. EST When 5 volts is present on the by-pass circuit and ignition module has turned control of engine timing over to ECM, the ECM advances or retards spark on this circuit based on calculations involving the reference signal and other sensor input signals. If base timing is incorrectly set, entire advance curve will be incorrect. Ground This is the reference ground circuit. It is grounded at distributor and ECM, ensuring there is no voltage drop in the EST circuit which could affect ignition operation.

ESC Detonation Retard Operation

In conjunction with the HEI-EST system, an Electronic Spark Control (ESC) retard system is used on some models. System consists of the following: a detonation (knock) sensor, a high energy ignition system, an ESC controller (some models), and the ECM. On some fuel injected models, the function of the ESC controller is built into the Memory Calibration (MEM-CAL) unit of the ECM. When detonation (engine knock) occurs, detonation sensor produces a low voltage AC signal. This signal goes to the ESC controller or directly to the MEM-CAL unit inside the ECM, depending upon application. On models using an ESC controller, controller supplies the ECM with a 12-volt signal. When detonation occurs, controller grounds the 12-volt signal to the ECM, pulling the signal down to zero volts. The ECM interprets this as a need to retard timing. The ECM then retards spark timing until the ESC controller returns the 12-volt signal. On vehicles using ECMs containing MEM-CAL units, the ECM supplies and monitors a 5-volt DC reference signal on the knock sensor signal line. Internal circuitry of the knock sensor will pull this voltage down to about 2.5 volts. When knock occurs, the knock sensor produces an AC voltage signal which rides on the 2.5-volt DC signal. The voltage and frequency of this signal depend upon knock signals received by the sensor. The ECM will retard spark timing until signals from detonation sensor cease. If signal wire were to become open or grounded on models utilizing an ESC controller, ECM would continuously provide full ignition timing retard. A malfunction in the ESC circuit should set a related trouble code. If a code is not present and ESC system is suspected as the cause of driveability problems, perform functional check of ESC system. See SYSTEMS & COMPONENT TESTING article in this section.

EMISSION SYSTEMS AIR INJECTION SYSTEM This system helps reduce hydrocarbon (HC) and carbon monoxide (CO) exhaust emissions by injecting air into the exhaust system. The induction of additional air promotes further oxidation (combustion) of unburned and

partially burned exhaust gases. During cold engine operation when air is injected into exhaust manifold, this also helps quickly warm up catalytic converter and oxygen sensor. Air Pump

The air pump is a belt driven, positive displacement vane-type pump. Air drawn into pump is purged of dirt and contaminates by a centrifugal filter mounted behind the pulley. The air pump is permanently lubricated and requires no periodic service. NOTE:

Always cover centrifugal filter fan before cleaning engine to prevent liquid from entering air pump. DO NOT oil air pump.

Check Valve

The check valve prevents the backflow of exhaust gases into the air injection system. The check valve closes when exhaust gas pressure in exhaust manifold exceeds pressure delivered by pump. This occurs when air pump by-passes at high speeds, air delivery is switched to catalytic converter, air is diverted to atmosphere or air cleaner, or when air pump malfunctions. Air Injection Reaction Management System (5.0L VIN Y)

When ECM energizes the air control (divert) and air switching valves on a cold vehicle, air is allowed to flow through the control valve to the air switching valve. The air switching valve then directs this air to the exhaust port. During warm engine operation (closed loop), ECM de-energizes the air switching valve. This causes air switching valve to direct air to the catalytic converter. If air control (divert) valve detects a rapid increase in manifold vacuum (deceleration condition), or if high RPM operation causes pump output pressure to exceed normal operating range, air is mechanically diverted to the air cleaner by the air control (divert) valve. If ECM detects any failure in the computerized engine control system, air control (divert) valve will be de-energized, also causing air to be diverted to the air cleaner or atmosphere. To check function of AIR system, perform functional check of system. See SYSTEM/COMPONENT TESTS article in this section. NOTE:

Air control (divert) valve and air switching valve may be separate or combined into a single assembly.

Electric Air Divert/Electric Air Switching Valves

Electric divert and electric switching valves are used on all Federal vehicles (except 5.0L VIN Y and 3.1L with manual transaxle). System may combine both divert function and air switching function into one integral component. The valves are electrically controlled by the ECM and operated by air pump pressure. The operation of the valves is not dependent on intake manifold vacuum.

For cold engine (open loop) operation, the divert solenoid is energized and air flows to exhaust ports. In warm engine (closed loop) operation, the divert solenoid is de-energized and switching solenoid is energized. This forces airflow to the converter. In the divert mode, both solenoids are de-energized and airflow is allowed to vent to atmosphere. Divert will occur during rich operating condition, when the ECM recognizes a problem and turns on the SERVICE ENGINE SOON light, during deceleration (high vacuum) and during heavy acceleration when air pressure exceeds the setting of the relief valve in the air divert valve. Electric Diverter Valve

The Electric Diverter Valve (EDV) is used on California fuel injected models and 3.1L Cutlass Supreme, Grand Prix and Lumina with manual transaxle. This EDV performs normal diverter valve operation and may provide air divert to the air cleaner for catalytic converter protection during wide open throttle and high temperature conditions. The ECM de-energizes EDV solenoid (located in EDV), preventing manifold vacuum from entering the chamber during the above conditions. Spring tension against the lower diaphragm pushes the diaphragm up, diverting air to air cleaner. Air from the air pump is always shut off from the engine unless ECM grounds EDV circuit (solenoid energized). CATALYTIC CONVERTER A 3-way catalytic converter with dual bed is used to reduce exhaust emissions. This type of converter can reduce hydrocarbons (HC), carbon monoxide (CO) and oxides of nitrogen (NOx). The upstream section of the converter contains a reducing/oxidizing bed to reduce NOx while at the same time oxidizing HC and CO. An air supply pipe from the AIR system injects air between the beds of the converter. This is so the second converter bed can oxidize any remaining HC and CO to efficiently reduce exhaust emissions. EARLY FUEL EVAPORATION The Early Fuel Evaporation (EFE) system is used on carbureted vehicles. EFE system provides heat to engine induction system during cold start, providing rapid engine warm-up. System consists of a butterfly valve and vacuum actuator mounted between the exhaust manifold and the exhaust pipe, a vacuum tube and a coolant activated Thermal Vacuum Switch (TVS). During cold engine operation, less than 105Â°F (40Â°C), manifold vacuum is routed to the EFE vacuum actuator through the TVS, closing the EFE butterfly valve. This routes all exhaust gases from that side of the engine through a special crossover passage in the intake manifold below the carburetor. This results in faster fuel evaporation, more uniform fuel distribution, faster choke opening and reduced emissions. As engine warms, TVS will bleed off vacuum, allowing actuator to open butterfly valve in exhaust manifold. This allows exhaust gases from that side of engine to exit through exhaust manifold on that side of engine. EFE exhaust crossover is not desired on a warm engine as it may cause driveability problems. EXHAUST GAS RECIRCULATION (EGR)

The Exhaust Gas Recirculation (EGR) system is designed to reduce oxides of nitrogen (NOx) emissions by lowering combustion temperatures. A metered amount of exhaust gas is recirculated into the intake manifold and mixed with the air/fuel mixture. There are 5 types of EGR systems used: pulse width modulated, electronic, digital and 2 backpressure (positive and negative) systems. On computer-controlled EGR systems, ECM controls ported vacuum to EGR valve through use of a solenoid valve. The ECM uses coolant temperature, throttle position and manifold pressure signals to compute vacuum solenoid operation. During cold engine operation and idle, solenoid valve is grounded by ECM. This blocks vacuum to EGR valve. During warm engine operation and at speeds greater than idle, solenoid is not grounded and vacuum is allowed through to open EGR valve. Some models use an integrated electronic control EGR valve. This valve incorporates control solenoid and EGR valve position sensor. This sensor is monitored by ECM (similar to a TPS; .3 volt fully closed, 5.0 volts fully open). The ECM controls EGR flow on this valve by pulsing the signal to the EGR solenoid. This allows a more regulated EGR flow than conventional ported EGR valves. To check function of EGR system, perform functional check of system. See SYSTEMS & COMPONENT TESTING article in this section. NOTE:

Some vehicles may use integral EGR/ILC/RVB, TCC/EGR, or EGR/CP solenoid valves.

Pulse Width Modulated EGR System

This type EGR system is controlled entirely by the ECM. The ECM controls the flow rate by controlling an electrical signal to a solenoid vacuum valve. The ECM controlled vacuum solenoid valve is located in series between vacuum source and EGR valve. The solenoid is pulsed at a rate of up to 32 times per second. The ECM uses a ported vacuum signal to determine the flow rate signal to the solenoid. Integrated Electronic EGR System

The integrated electronic EGR valve functions similar to a ported EGR valve with a remote vacuum regulator. The internal solenoid is normally open, which causes the vacuum signal to be vented off to the atmosphere when EGR is not controlled by the ECM. This EGR valve has a sealed cap. The solenoid valve opens and closes the vacuum signal, which controls the amount of vacuum vented to atmosphere. This controls the amount of vacuum applied to the diaphragm. The electronic EGR valve contains a voltage regulator, which converts ECM signal and regulates current to the solenoid. The ECM controls EGR flow with a pulse width modulated signal based on airflow, Throttle Position Sensor (TPS), and RPM. This system also contains a pintle position sensor, which works similar to a TPS sensor. As EGR flow is increased, the sensor output increases. Digital EGR System

The digital EGR valve is designed to accurately supply EGR to engine, independent of intake manifold vacuum. The valve controls EGR flow from exhaust to intake manifold through 3 orifices, to produce 7 different combinations. When a solenoid is energized, the armature with attached shaft and swivel pintle is lifted to open the orifice.

Exhaust Backpressure EGR System

Two types of backpressure EGR valves are used, a positive or negative backpressure valve. These valves may be identified by the letter in the last position of part number. Letter "P" designates a positive backpressure valve and letter "N" a negative backpressure valve. Some 5.0L and 5.7L V8 models have backpressure EGR valves with a temperature sensor built into valve base. On these models, ECM monitors EGR valve base temperature. If EGR valve does not open, base temperature will be cool. Temperature sensor will then signal ECM to turn on SERVICE ENGINE SOON light. 



Positive Backpressure EGR Valve A control valve, located in EGR valve, acts as a vacuum regulator valve. Control valve regulates amount of vacuum to EGR diaphragm chamber by bleeding vacuum to atmosphere during certain operating conditions. When control valve receives a backpressure signal, through the hollow shaft of EGR valve, pressure on bottom of control valve closes control valve. When control valve closes, maximum vacuum signal is applied directly to EGR valve allowing exhaust gas recirculation. Negative Backpressure EGR Valve Vacuum is applied to upper EGR diaphragm via a hose connected intake manifold vacuum. Manifold vacuum is also applied to lower EGR diaphragm (through intake port at base of EGR valve). When manifold vacuum in lower chamber is insufficient to overcome spring tension on lower diaphragm, bleed valve will be closed, allowing vacuum in upper chamber to open EGR valve. With engine at idle, or under light load, high manifold vacuum applied to lower chamber opens air bleed valve in lower diaphragm. This bleeds off vacuum in upper chamber, keeping the EGR valve closed.

EVAPORATIVE EMISSION CONTROL (EEC) Carbon canister storage is used for evaporative fuel control on all vehicles. The function of evaporative emission control system is to store gasoline fumes from fuel tank (and carburetor float bowl) in a carbon canister until fumes can be drawn into engine for burning during combustion process. There are 4 basic components used in evaporative emission system.    

Activated carbon canister (may be sealed or open at top or bottom for fresh air intake). Vacuum operated canister control valve (mounted on canister or remotely). ECM-controlled solenoid (may be mounted on canister or remotely). Tank pressure control valve (may be mounted internal or external of fuel tank).

Carbureted models use a thermal bowl vent valve installed in the fuel bowl vent hose. For specific component application and vacuum hose routing, see VACUUM DIAGRAMS article in this section. Carbon Canister

Evaporative fumes from the fuel tank and fuel bowl (carbureted models) are vented through hose(s) into a canister containing activated carbon. The activated carbon absorbs and holds fuel vapors when the engine is not operating. When the engine is started and engine speed is greater than idle (purge at idle would cause too rich a mixture), engine vacuum draws fuel vapors from the canister into the engine. Regulation of vapors through this purge line may be controlled by a vacuum canister purge valve, an ECM-controlled solenoid, or both.

Carbon canisters are either open or closed in design. When the engine is started on open canister models, engine vacuum draws outside air into canister either through the top or through a filter in bottom of canister. This helps to purge vapors from the activated carbon. Canister Control Valve (CCV)

There are 2 types of vacuum operated canister control valves. In some applications, more than one type may be used on the same system. The Type 1 control valve is vacuum operated and is an integral part of the carbon canister (Y body). When the engine is not running, vapor from the fuel tank is stored in the carbon canister. When the vehicle is started, vacuum to the upper port will draw in the internal vacuum diaphragm, opening the port between the canister and purge vacuum. The Type 2 control valve is similar to the Type 1 valve, except it is located in the canister purge lines itself (5.0L VIN Y). When vacuum is applied to the upper port of valve, diaphragm is lifted, opening port between purge vacuum and accumulated vapors. When engine is off, valve diaphragm is closed by internal spring pressure, preventing vapor from venting to atmosphere. Purge Solenoid Valve

Purge solenoid valve is controlled by the Electronic Control Module (ECM). Current is supplied to solenoid when the ignition is on. Solenoid is energized when ECM provides a ground circuit for solenoid. When energized, purge solenoid valve opens, allowing purge. When de-energized, valve closes, blocking purge. The ECM will energize the canister purge solenoid when engine has been running for more than one minute, coolant temperature is above 176°F (80°C), vehicle speed is greater than 5 MPH and throttle is off idle. This solenoid is located in the purge line on Cutlass Supreme, Grand Prix, Lumina and Regal, and on the canister on all other models. Fuel Tank Pressure Control Valve

Fuel tank pressure control valve is a vacuum regulated/pressure control valve located in the fuel tank, or in the vapor delivery hose between fuel tank and carbon canister. When engine is not running and tank pressure is less than .9 psi (.06 kg/cm2 ), internal spring pressure holds valve in the closed position. This causes fuel tank lowpressure vapors to be vented through a restriction in valve. This restriction will retain most of fuel tank vapors in fuel tank. When tank pressure rises and overrides spring tension, fumes are vented to the carbon canister. When engine is running, vacuum is applied to upper port of valve, opening passage between fuel tank and carbon canister, which is purged by engine vacuum. NOTE:

Models without fuel tank pressure control valves may utilize a special pressure/vacuum relief fuel tank filler cap or other external relief device.

Thermal Bowl Vent Valve (TBVV)

The thermal bowl vent valve (located in the bowl vent hose) permits fuel bowl vapors to be directed to carbon canister for storage. When engine temperature is less than 90°F (32°C), valve will be in closed position, blocking bowl venting. Valve will open when engine temperature is greater than 120°F (49°C).

POSITIVE CRANKCASE VENTILATION (PCV) The PCV system is used to provide for more effective elimination of crankcase vapors. Fresh air from the air filter housing is supplied to the crankcase where it is mixed with blow-by gases and passed through a PCV valve into the intake manifold. This mixture is then passed into the combustion chamber and burned. The PCV valve provides primary control in this system by metering the flow of the blow-by vapors, according to manifold vacuum. When manifold vacuum is high (at idle) the PCV restricts the flow to maintain a smooth idle condition. Under conditions where abnormal amounts of blow-by gases are produced (such as worn cylinders or rings), the system is designed to allow the excess gases to flow back through crankcase vent hose into the air inlet and be consumed during normal combustion. THERMOSTATIC AIR CLEANER (TAC) Many models are equipped with a system for preheating the air entering the carburetor or the fuel injection unit during cold engine operation. This system maintains incoming air temperature to a point where the carburetor or fuel injection system can maintain lean air/fuel ratios to reduce hydrocarbon (HC) and carbon monoxide (CO) emissions, and reduces carburetor icing. This system consists of an air cleaner assembly with integral air control door, vacuum control temperature sensor, vacuum motor, heat shroud (on exhaust manifold), heated air tube and vacuum hoses. Vacuum Control Temperature Sensor

The vacuum control temperature sensor controls the operation of the air control door. During initial start-up situations, this valve directs engine vacuum to the air control vacuum motor. The motor closes the air intake door, allowing the intake of heated manifold air. When the intake air temperature reaches a precalibrated value, this valve opens, allowing the intake of cooler outside air. Air Control Door

The air control door temperature sensor closes when the temperature of air entering the air cleaner is less than the calibrated temperature of the temperature sensor. This allows engine vacuum to operate the air control door vacuum motor, and warm manifold air to be routed to the carburetor. Vacuum Motor

When engine vacuum is applied to the vacuum motor, the air control door closes off the intake of outside air. Air is then drawn into the air cleaner from around the exhaust manifold. As air inside the air cleaner warms, the temperature sensor begins to open, bleeding off vacuum to the vacuum motor. As vacuum to vacuum motor decreases, the air control door begins to open. As air control door opens, outside air is allowed to enter air cleaner assembly. When air entering air cleaner

reaches a predetermined temperature, the air control door opens completely, and closes off the intake of heated air.

SELF-DIAGNOSTIC SYSTEM The ECM is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, ECM will illuminate the SERVICE ENGINE SOON light located on instrument panel. When malfunction is detected and light is turned on, a corresponding trouble code will be stored in ECM memory. Malfunctions are designated as either "hard failures" or as "intermittent failures". To retrieve stored codes, see appropriate SELF-DIAGNOSTICS article in this section. "Hard Failures"

Hard failures cause SERVICE ENGINE SOON light to glow and remain on until the malfunction is repaired. On models using digital display on dash to indicate codes, when recalled, codes may be accompanied by a "current" or "history" indication for intermittent and hard codes. If light comes on and remains on during vehicle operation, cause of malfunction must be determined using diagnostic charts located in SELFDIAGNOSTICS article. If a sensor fails, ECM will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but loss of good driveability will most likely be encountered. "Intermittent Failures"

Intermittent failures cause SERVICE ENGINE SOON light to flicker or illuminate and go out about 10 seconds after the intermittent fault goes away. The corresponding trouble code, however, will be retained in ECM memory. On models using digital display on dash to indicate codes, when recalled, codes may be accompanied by a "current" or "history" indication for intermittent and hard codes. If related fault does not reoccur within 50 engine restarts, related trouble code will be erased from ECM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See TESTS W/O CODES article in this section. SERVICE ENGINE SOON LIGHT On carbureted models, a SERVICE ENGINE SOON light driver module is installed in wiring harness from ECM to SERVICE ENGINE SOON light. This driver turns on light when ignition is turned on. When vehicle starts, ECM turns light off. If ECM malfunctions or senses a malfunction, light will turn back on. On fuel injected models, driver is an integral part of ECM and is not serviceable. As a bulb and system check, SERVICE ENGINE SOON light will glow when ignition switch is turned to ON position and engine is not running. When engine is started, light should go out. If not, a malfunction has been detected in the computerized engine control system or SERVICE ENGINE SOON light circuit is faulty. Light may be used on some models to display stored trouble codes. To access codes using Scan or Non-Scan methods, see appropriate TESTS W/CODES article in this section. See the table below. VEHICLE-TO-G - TESTS W/CODES ARTICLE MENU Application Brougham, Caprice, Custom Cruiser Corvette

Go To: See TESTS W/CODES CARBURETED See TESTS W/CODES

DeVille & Fleetwood Eldorado & Seville Reatta & Riviera ECM Code Tests BCM Code Tests 2.3L PFI Beretta, Cutlass Calais, Cutlass Supreme, Grand Am, Grand Prix, Skylark 3.1L PFI Beretta, Camaro, Cavalier, Celebrity, Corsica, Cutlass Supreme, Firebird Grand Prix, Lumina, Regal, 6000 3.3L PFI Century, Cutlass Calais, Cutlass Ciera, Skylark 3.8L Bonneville, Electra, LeSabre, Ninety-Eight, Toronado, Trofeo, 88 5.0L & 5.7L Camaro & Firebird

See TESTS W/CODES See TESTS W/CODES See TESTS W/CODES - ECM See TESTS W/CODES - BCM See TESTS W/CODES 2.3L PFI See TESTS W/CODES 3.1L PFI See TESTS W/CODES 3.3L PFI See TESTS W/CODES 3.8L PFI See TESTS W/CODES V8 PFI

SERIAL DATA ECM is equipped with a serial data line. Serial date is a stream of electrical impulses which can be interpreted by special testers of other control modules. On some models, serial data must be accessed using special Scan testers connected to the Assembly Line Data Link (ALDL). Update intervals and information contained within the data stream vary with model application. On models utilizing an ECM and Body Control Module (BCM), serial data may be accessed using the Driver Information Center (DIC) and Climate Control Panel (CCP). On these models, serial data may be shared with BCM, A/C controller, supplemental restraint controller, anti-lock brake controller, or even cruise control unit.

MISCELLANEOUS ECM CONTROLS NOTE:

Although not considered true "Engine Performance" related systems, some controlled devices may affect driveability if they malfunction.

A/C CLUTCH On many models ECM regulates operation of the A/C clutch through an ECM controlled relay. This allows the ECM to disengage the A/C compressor when compressor load on engine may cause driveability problems (i.e. during hot restart, idle, low speed steering maneuvers, and wide open throttle operation), or if A/C freon pressure drops below or rises above normal operating levels. Freon pressure sensing may be accomplished through the monitoring of high and low pressure switches or a pressure sensor which will register either high or low pressure levels. Power steering load is monitored through a power steering pressure switch. Hot restart is monitored through the coolant temperature sensor. For component application and related wiring, see wiring schematics in MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section.

A/C Pressure Sensor

A/C high and low pressure switches may be used in the A/C compressor clutch or compressor clutch relay circuit. Switches are normally closed, completing the circuit which energizes the compressor clutch. When system freon pressure increases beyond a certain point, high side switch will open, causing compressor clutch to disengage. If system freon level decreases, causing freon pressure to drop, low side pressure switch will open, causing compressor clutch to disengage and preventing compressor damage. A/C Clutch WOT Cut-Out Relay (5.0L VIN Y)

The Wide Open Throttle (WOT) cut-out relay is used on 5.0L carbureted models. Relay delivers A/C compressor clutch power (from A/C fuse) through a set of normally closed contacts. Relay contacts are opened when the ECM energizes the relay by supplying a ground circuit for the relay winding. ECM will energize the relay during wide open throttle operation, during overheat conditions and momentarily during engine start-up on a warm engine. For wiring reference, see MISCELLANEOUS ECM CONTROLS in SYSTEMS & COMPONENT TESTING article in this section. COOLING FAN On many models ECM regulates operation of the electric cooling fan through an ECM controlled relay which controls the ground circuit or power circuit for the cooling fan. This allows the ECM to operate the cooling fan based upon engine temperature. Most systems will engage the electric cooling fan whenever the A/C clutch is engaged, regardless of engine temperature. As a back-up system, many models utilize a coolant override switch which will also engage the cooling fan in the event that the ECM fails to energize the cooling fan relay, or the cooling fan relay malfunctions. A malfunction of the cooling fan will cause engine overheating and possible detonation. Some models utilize more than one cooling fan. The second fan may function as an auxiliary cooling device when A/C is engaged, or (on models utilizing freon temperature sensors or high pressure switches) during periods of engine overheating or high A/C freon pressures. For component application and related wiring, see wiring schematics in MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section. HOT LIGHT OR COOLANT TEMP LIGHT When engine coolant temperature sensor input indicates temperature exceeds prespecified range, the ECM will turn on the TEMP or HOT light by providing a ground for the light circuit. As a bulb check, the ECM also supplies a ground to turn on light when the ignition is first turned on.

LOW COOLANT LIGHT On vehicles equipped with a coolant level sensor (located in the side radiator tank), ECM will turn on the low coolant light when the coolant level sensor indicates coolant level is below sensor probes. As a bulb check, the ECM also supplies a ground to turn on light when the ignition is first turned on.

TRANSMISSION Converter Clutch

The purpose of the transmission/transaxle converter clutch feature is to eliminate power loss of torque converter stage when vehicle is in a cruise condition. This allows convenience of automatic transmission/transaxle and fuel economy of a manual transmission. Fused battery ignition is supplied to converter solenoid through a brake switch. On some models, 2nd, 3rd and 4th gear hydraulic apply switches (located within the transmission) may also be in series with solenoid power or ground circuit. On other models, switch status may only be monitored by the ECM, without sharing power or ground with the converter solenoid. For wiring reference, see MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section. Converter clutch will engage when vehicle is moving greater than a precalibrated speed, engine is at normal operating temperature, throttle position sensor output is not changing (indicating a steady road speed), transmission 3rd gear or high gear switch is closed (if equipped), and brake switch is closed. When vehicle speed is great enough (about 20-45 MPH as indicated by the vehicle speed sensor), ECM energizes converter clutch solenoid mounted in transmission. This allows torque converter to directly connect engine to the transmission. When operating conditions indicate that transmission should operate as normal, converter clutch solenoid is de-energized. This allows transmission to return to normal automatic operation. Since power for the converter solenoid is delivered through the brake switch, transmission will also return to normal automatic operation when brake pedal is depressed. To check function of converter clutch system, perform functional check of system. See MISCELLANEOUS ECM CONTROLS in SYSTEMS & COMPONENT TESTING article in this section. Shift Light (Except Corvette)

The shift light is used on vehicles equipped with manual transmission. Light indicates the best transmission shift point for maximum fuel economy. Power for light is supplied through the GAUGES fuse. Light is illuminated when the ECM supplies a ground circuit for the bulb. For wiring reference, see MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section. 1-4 Shift Light (Corvette)

The shift light is used on vehicles equipped with manual transmission. Light indicates when driver should shift transmission from first gear to fourth gear for maximum fuel economy. Power for light is supplied through the 10-amp AIR BAG fuse. Light is illuminated when the ECM supplies a ground circuit for the bulb. For wiring reference, see MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section. 1-4 Shift Light Relay (Corvette)

Power for the relay winding is supplied by the GAUGES fuse. When ECM determines that driver should shift transmission from first gear to fourth gear for maximum fuel economy, ECM will provide a ground for the 1-4 upshift relay. When relay is energized, voltage supplied by the TURN/BACK-UP fuse will pass through relay and energize the 1-4 upshift solenoid mounted in the transmission. When solenoid is energized, transmission is locked out from shifting from first gear into any gear other than fourth. For wiring reference, see MISCELLANEOUS ECM CONTROLS in SYSTEM/COMPONENT TESTS article in this section.

ENGINE OIL PAN REMOVAL ENGINES General Motors Corp. Oil Pan Removal

IDENTIFICATION BODY IDENTIFICATION Body A B C D E F H J K L N W Y

Models Celebrity, Century, Cutlass Ciera, Cutlass Cruiser Wagon, 6000 Caprice, Custom Cruiser, Estate Wagon DeVille, Electra, Fleetwood, Ninety-Eight, Park Avenue Touring Sedan Brougham Eldorado, Reatta, Riviera, Toronado, Trofeo Camaro, Firebird Bonneville, Delta 88, LeSabre Cavalier, Sunbird Seville Beretta, Corsica Cutlass Calais, Grand Am, Skylark Cutlass Supreme, Grand Prix, Lumina, Regal Corvette

TROUBLE SHOOTING NOTE:

To trouble shoot engine mechanical components, see appropriate table in TROUBLE SHOOTING article in GENERAL INFORMATION.

REMOVAL & INSTALLATION 4-CYLINDER MODELS - 2.0L & 2.0L TURBO "J" Body

1. Disconnect negative battery cable. Raise and support vehicle. Remove right front wheel and front splash shield. Position jack stands at jack points. 2. Drain crankcase. Remove exhaust pipe from exhaust manifold or wastegate. Remove flexplate cover bolts. Remove bolts and oil pan. 4-CYLINDER MODELS - 2.2L "J" & "L" Bodies

1. Disconnect negative battery cable. Disconnect exhaust pipe shield and remove. Raise and support vehicle. Drain crankcase. Remove A/C brace at starter and at A/C bracket.

2. Remove starter bracket at block. Remove starter and lay aside. Remove flexplate cover and A/C brace. Remove right suspension support bolts to gain clearance to remove oil pan. Lower suspension support slightly to gain clearance for oil pan removal. Remove oil filler and extension on A/T models. Remove oil pan bolts and oil pan. 4-CYLINDER MODELS - 2.3L "L", "N" & "W" Bodies

Disconnect negative battery cable. Raise and support vehicle. Drain engine oil. Remove transaxle flexplate cover. Remove splash shield-to-suspension support bolt. Disconnect exhaust manifold brace (on M/T only). Remove radiator outlet pipe-to-oil pan bolt, transaxle-to-oil pan bolt and stud. Pry spacer from between oil pan and transaxle. Remove bolt connecting oil pan to transaxle. Remove oil pan and gasket. Rotate crankshaft to obtain clearance for removal (if necessary). 4-CYLINDER MODELS - 2.5L "A" & "W" Bodies

1. Disconnect negative battery cable. Remove coolant reservoir and engine torque strut. Remove drive belt, dipstick assembly, air cleaner and air inlet. Remove A/C compressor and wire out of way. Install Engine Support Fixture (J-28467-A). 2. Raise and support vehicle. Drain crankcase. Remove flexplate covers, starter and bracket. Remove engine wiring harness under right and left sides of oil pan. Remove right side engine splash shield. 3. Remove front engine mount bracket bolts and engine mount nuts. Remove transaxle mount nuts. Using engine support fixture, raise engine approximately 2". Remove front engine mount and bracket. Loosen frame bolts. Remove oil pan bolts and oil pan. "N" Body

Disconnect negative battery cable. Raise and support vehicle. Drain crankcase. Disconnect exhaust pipe at manifold and hanger and wire out of way. Remove starter and flexplate access cover. Remove starter. Remove oil pan bolts and oil pan. V6 MODELS - 3.1L "A", "J", "L" & "W" Bodies

Disconnect negative battery cable. Raise and support vehicle. Drain crankcase. Remove flexplate access cover and starter. Support engine and remove engine mount bolts. Remove oil pan bolts. Raise engine and remove oil pan. "F" Body

1. Disconnect negative battery cable. Remove air cleaner and distributor cap. Remove upper half of fan shroud. Raise vehicle and drain crankcase. 2. Remove flexplate access cover and starter. Disconnect exhaust pipe at manifold. Remove engine mount

through bolts and raise engine. Remove oil pan bolts. Remove oil pan. V6 MODELS - 3.3L & 3.8L "A", "C", "E", "H" & "N" Bodies

Disconnect negative battery cable. Raise and support vehicle. Drain crankcase and remove oil filter. Remove flexplate access cover and crossover pipe (if equipped). Disconnect engine mounts. Raise and support engine. Remove oil pan bolts and oil pan. V8 MODELS - 4.5L "C", "E" & "K" Bodies

Disconnect negative battery cable. Raise vehicle and drain crankcase. Remove both flexplate access covers. Disconnect exhaust "Y" pipe at manifolds. Remove bolts from catalytic converter and lower exhaust. Remove oil pan bolts and oil pan. V8 MODELS - 5.0L & 5.7L (VIN 7) "B" & "D" Bodies

1. Disconnect negative battery cable and remove air cleaner and fan shroud. Raise vehicle and drain crankcase. Remove cruise control servo bracket (if equipped). 2. Remove Air Injection Reaction (AIR) hose-to-catalytic converter pipe. Remove AIR pipe-to-exhaust manifold. Remove the exhaust crossover pipe at manifold and converter. Remove starter and flexplate access cover. Disconnect transmission line bracket at oil pan. Remove engine mount through bolts. 3. Remove oil pan bolts and lower pan. Position front crankshaft throw and/or counterweight on horizontal plane so it does not interfere with oil pan removal. Raise engine, reinstall through bolts and remove oil pan. V8 MODELS - 5.0L & 5.7L (VIN 8) "F" Body

1. Disconnect negative battery cable. Remove air cleaner, fan shroud and distributor cap. Raise vehicle and drain crankcase. Disconnect exhaust pipe at manifold, Air Injection Reaction (AIR) pipe clamp and catalytic converter hanger bolts. 2. Remove front starter brace, starter and flexplate access cover. On models with M/T, it may be necessary to remove oil filter for access to flywheel cover bolts. 3. Remove engine mount through bolts and oil pan bolts. Raise engine and lower pan. Position front crankshaft throw and/or counterweights as to clear oil pan. Remove oil pan. V8 MODELS - 5.7L (VIN 8) "Y" Body

1. Disconnect negative battery cable. Raise vehicle and drain crankcase. Remove oil filter. Remove oil filter adapter at block. On A/T models, remove flexplate cover. On M/T models, remove starter and bellhousing cover. 2. On all models, remove oil cooler pipe at oil pan. Remove Electronic Spark Control (ESC) shield. Remove front crossmember braces. Remove oil pan bolts. Remove oil pan.

TORQUE SPECIFICATIONS 4-CYLINDER TORQUE SPECIFICATIONS (4-CYLINDER) Application Oil Pan 2.0L & 2.2L Front Bolts Rear Bolts Stud Nuts All Other Bolts 2.3L 6-mm Bolts 8-mm Bolts Stud Nut 2.5L (1) Tighten nut to 41 ft. lbs. (56 N.m).

INCH Lbs. (N.m)

88-159 (10-18) 133-212 (15-24) 62-88 (7-10) 53-106 (6-12) 106 (12) 212 (24) (1)

54 (6)

V6 TORQUE SPECIFICATIONS (V6) Application Oil Pan 3.1L 6-mm Bolts 8-mm Bolts 3.3L & 3.8L

INCH Lbs. (N.m)

71-106 (8-12) 168-266 (19-30) 168 (19)

V8 TORQUE SPECIFICATIONS (V8) Application Oil Pan 4.5L 5.0L & 5.7L (Except "Y" Body)

INCH Lbs. (N.m) 132 (15)

1/4" Bolts & Nuts 5/16" Bolts & Nuts 5.7L ("Y" Body)

80 (9) 168 (19) 192 (22)

GENERAL INFORMATION Engine Overhaul Procedures

* PLEASE READ THIS FIRST * NOTE:

Examples used in this article are general in nature and do not necessarily relate to a specific engine or system. Illustrations and procedures have been chosen to guide mechanic through engine overhaul process. Descriptions of processes of cleaning, inspection, assembly and machine shop practice are included. Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired.

DESCRIPTION Examples used in this article are general in nature and do not necessarily relate to a specific engine or system. Illustrations and procedures have been chosen to guide mechanic through engine overhaul process. Descriptions of cleaning, inspection, and assembly processes are included.

ENGINE IDENTIFICATION Engine may be identified from Vehicle Identification Number (VIN) stamped on a metal tab. Metal tab may be located in different locations depending on manufacturer. Engine identification number or serial number is located on cylinder block. Location varies with each manufacturer.

INSPECTION PROCEDURES * PLEASE READ THIS FIRST * NOTE:

GENERAL NOTE:

of cleaning, inspection, assembly and machine shop practice are included. Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Engine components must be inspected to meet manufacturer's specifications and tolerances during overhaul. Proper dimensions and tolerances must be met to obtain proper performance and maximum engine life. Micrometers, depth gauges and dial indicator are used for checking tolerances during engine overhaul. Magnaflux, Magnaglo, dye-check, ultrasonic and x-ray inspection procedures are used for parts inspection. MAGNETIC PARTICLE INSPECTION NOTE:

Magnaflux & Magnaglo

Magnaflux is an inspection technique used to locate material flaws and stress cracks. Component is subjected to a strong magnetic field. Entire component or a localized area can be magnetized. Component is coated with either a wet or dry material that contains fine magnetic particles. Cracks which are outlined by the particles cause an interruption of magnetic field. Dry powder method of Magnaflux can be used in normal lighting and crack appears as a bright line. Fluorescent liquid is used along with a Black light in the Magnaglo Magnaflux system. Darkened room is required for this procedure. The crack will appear as a glowing line. Complete demagnetizing of component upon completion is required on both procedures. Magnetic particle inspection applies to ferrous materials only. PENETRANT INSPECTION NOTE:

Zyglo

The Zyglo process coats material with a fluorescent dye penetrant. Component is often warmed to expand cracks that will be penetrated by the dye. Using darkened room and Black light, component is inspected for cracks. Crack will glow brightly. Developing solution is often used to enhance results. Parts made of any material, such as aluminum cylinder heads or plastics, may be tested using this process. Dye Check

Penetrating dye is sprayed on the previously cleaned component. Dye is left on component for 5-45 minutes, depending upon material density. Component is then wiped clean and sprayed with a developing solution. Surface cracks will show up as a bright line. ULTRASONIC INSPECTION NOTE:

If an expensive part is suspected of internal cracking, ultrasonic testing is used. Sound waves are used for component inspection. X-RAY INSPECTION NOTE:

This form of inspection is used on highly stressed components. X-ray inspection may be used to detect internal and external flaws in any material. PRESSURE TESTING NOTE:

Examples used in this article are general in nature and do not necessarily relate to a specific engine or system. Illustrations and procedures have been chosen

to guide mechanic through engine overhaul process. Descriptions of processes of cleaning, inspection, assembly and machine shop practice are included. Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Cylinder heads can be tested for cracks using a pressure tester. Pressure testing is performed by plugging all but one of the holes of cylinder head and injecting air or water into the open passage. Leaks are indicated by the appearance of wet or damp areas when using water. When air is used, it is necessary to spray the head surface with a soap solution. Bubbles will indicate a leak. Cylinder head may also be submerged in water heated to specified temperature to check for cracks created during heat expansion.

CLEANING PROCEDURES * PLEASE READ THIS FIRST * NOTE:

GENERAL NOTE:

All components of an engine do not have the same cleaning requirements. Physical methods include bead blasting and manual removal. Chemical methods include solvent blast, solvent tank, hot tank, cold tank and steam cleaning of components. BEAD BLASTING NOTE:

Examples used in this article are general in nature and do not necessarily relate to a specific engine or system. Illustrations and procedures have been chosen

to guide mechanic through engine overhaul process. Descriptions of processes of cleaning, inspection, assembly and machine shop practice are included. Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Manual removal of deposits may be required prior to bead blasting, followed by some other cleaning method. Carbon, paint and rust may be removed using bead blasting method. Components must be free of oil and grease prior to bead blasting. Beads will stick to grease or oil soaked areas causing area not to be cleaned. Use air pressure to remove all trapped residual beads from component after cleaning. After cleaning internal engine parts made of aluminum, wash thoroughly with hot soapy water. Component must be thoroughly cleaned as glass beads will enter engine oil resulting in bearing damage. CHEMICAL CLEANING NOTE:

Solvent tank is used for cleaning oily residue from components. Solvent blasting sprays solvent through a siphon gun using compressed air. The hot tank, using heated caustic solvents, is used for cleaning ferrous materials only. DO NOT clean aluminum parts such as cylinder heads, bearings or other soft metals using the hot tank. After cleaning, flush parts with hot water. A non-ferrous part will be ruined and caustic solution will be diluted if placed in the hot tank. Always use eye protection and gloves when using the hot tank. Use of a cold tank is for cleaning aluminum cylinder heads, carburetors and other soft metals. A less caustic and unheated solution is used. Parts may be left in the tank for several hours without damage. After cleaning, flush parts with hot water. Steam cleaning, with boiling hot water sprayed at high pressure, is recommended as the final cleaning process when using either hot or cold tank cleaning.

COMPONENT CLEANING * PLEASE READ THIS FIRST *

NOTE:

SHEET METAL PARTS NOTE:

Examples of sheet metal parts are rocker covers, front and side covers, oil pan and bellhousing dust cover. Glass bead blasting or hot tank may be used for cleaning. Ensure all mating surfaces are flat. Deformed surfaces should be straightened. Check all sheet metal parts for cracks and dents. INTAKE & EXHAUST MANIFOLDS NOTE:

Using solvent cleaning or bead blasting, clean manifolds for inspection. If intake manifold has an exhaust crossover, all carbon deposits must be removed. Inspect manifolds for cracks, burned or eroded areas, corrosion and damage to fasteners. Exhaust heat and products of combustion cause threads of fasteners to corrode. Replace studs and bolts as necessary. On "V" type intake manifolds, sheet metal oil shield must be removed for proper cleaning and inspection. Ensure all manifold parting surfaces are flat and free of burrs.

CYLINDER HEAD REPLACEMENT

* PLEASE READ THIS FIRST * NOTE:

REMOVAL NOTE:

Remove intake and exhaust manifolds and valve cover. Cylinder head and camshaft carrier bolts (if equipped) should be removed only when engine is cold. On many aluminum cylinder heads, removal while hot will cause cylinder head warpage. Mark rocker arm or overhead cam components for location. Remove rocker arm components or overhead cam components. Components must be installed in original location. Individual design rocker arms may utilize shafts, ball-type pedestal mounts or no rocker arms. For all design types, wire components together and identify according to corresponding valve. Remove cylinder head bolts. Note length and location. Some applications require cylinder head bolts be removed in proper sequence to prevent cylinder head damage. See Fig. 1. Remove cylinder head. INSTALLATION NOTE:

Ensure all surfaces and head bolts are clean. Check that head bolt holes of cylinder block are clean and dry to prevent block damage when bolts are tightened. Clean threads with tap to ensure accurate bolt torque.

Install head gasket on cylinder block. Some manufacturers may recommend sealant be applied to head gasket prior to installation. Note that all holes are aligned. Some gasket applications may be marked so that certain area faces upward. Install cylinder head using care not to damage head gasket. Ensure cylinder head is fully seated on cylinder block. Some applications require head bolts be coated with sealant prior to installation. This is done if head bolts are exposed to coolant passages. Some applications require head bolts be coated with light coat of engine oil. Install head bolts. Head bolts should be tightened in proper steps and sequence to specification. See Fig. 1. Install remaining components. Tighten all bolts to specification. Adjust valves if required. See VALVE ADJUSTMENT. NOTE:

Some manufacturers require that head bolts be retightened after specified amount of operation. This must be done to prevent head gasket failure.

Fig. 1: Typical Cylinder Head Tightening or Loosening Sequence VALVE ADJUSTMENT NOTE:

Engine specifications will indicate valve train clearance and temperature at which adjustment is to be made on most models. In most cases, adjustment will be made with a cold engine. In some cases, both a cold and a hot clearance will be given for maintenance convenience. On some models, adjustment is not required. Rocker arms are tightened to specification and valve lash is automatically set. On some models with push rod actuated valve train, adjustment is made at push rod end of rocker arm while other models do not require adjustment. Clearance will be checked between tip of rocker arm and tip of valve stem in proper sequence using a feeler gauge. Adjustment is made by rotating adjusting screw until proper clearance is obtained. Lock nut is then tightened. Engine will be rotated to obtain all valve adjustments to manufacturer's specifications. Some models require hydraulic lifter to be bled down and clearance measured. Push rods of different length can be used to obtain proper clearance. Clearance will be checked between tip of rocker arm and tip of valve stem in proper sequence using a feeler gauge. Overhead cam engines designed without rocker arms actuate valves directly on a cam follower. A hardened, removable disc is installed between the cam lobe and lifter. Clearance will be checked between cam heel and adjusting disc in proper sequence using a feeler gauge. Engine will be rotated to obtain all valve adjustments. On overhead cam engines designed with rocker arms, adjustment is made at valve end of rocker arm. Ensure valve to be adjusted is riding on heel of cam on all engines. Clearance will be checked between tip of rocker arm and tip of valve stem in proper sequence using a feeler gauge. Adjustment is made by rotating adjusting screw until proper clearance is obtained. Lock nut is then tightened. Engine will be rotated to obtain all valve adjustments to manufacturer's specifications.

CYLINDER HEAD OVERHAUL * PLEASE READ THIS FIRST * NOTE:

CYLINDER HEAD DISASSEMBLY NOTE:

section for complete overhaul procedures and specifications for the vehicle being repaired. Mark valves for location. Using valve spring compressor, compress valve springs. Remove valve locks. Carefully release spring compressor. Remove retainer or rotator, valve spring, spring seat and valve. See Fig. 2.

Fig. 2: Exploded View of Valve Assemblies CYLINDER HEAD CLEANING & INSPECTION NOTE:

Clean cylinder head and valve components using approved cleaning methods. Inspect cylinder head for cracks, damage or warped gasket surface. Place straightedge across gasket surface. Determine clearance at center of straightedge. Measure across both diagonals, longitudinal center line and across cylinder head at several points. See Fig. 3.

On cast iron cylinder heads, if warpage exceeds .003" (.08 mm) in a 6" span, or .006" (.15 mm) over total length, cylinder head must be resurfaced. On most aluminum cylinder heads, if warpage exceeds .002" (.05 mm) in any area, cylinder head must be resurfaced. Warpage specification may vary by manufacturer. If warpage exceeds specification on some cylinder heads, cylinder head must be replaced. Cylinder head thickness should be measured to determine amount of material which can be removed before replacement is required. Cylinder head thickness must not be less than the manufacturer's specification. If cylinder head required resurfacing, it may not align properly with intake manifold. On "V" type engines, misalignment is corrected by machining intake manifold surface that contacts cylinder head. Cylinder head may be machined on surface that contacts intake manifold. Using oil stone, remove burrs or scratches from all sealing surfaces.

Fig. 3: Checking Cylinder Head for Warpage VALVE SPRINGS NOTE:

Inspect valve springs for corroded or pitted valve spring surfaces which may lead to breakage. Polished spring ends caused by a rotating spring indicate that spring surge has occurred. Replace springs showing evidence of these conditions. Inspect valve springs for squareness using a 90-degree straightedge. See Fig. 4. Replace valve spring if out-ofsquare exceeds manufacturer's specification.

Fig. 4: Checking Valve Spring Squareness Using vernier caliper, measure free length of all valve springs. Replace springs if not within specification. Using valve spring tester, test valve spring pressure at installed and compressed heights. See Fig. 5. Usually compressed height is installed height minus valve lift. Replace valve spring if not within specification. It is recommended to replace all valve springs when overhauling cylinder head. Valve springs may need to be installed with color coded end or small coils at specified area according to manufacturer.

Fig. 5: Checking Valve Spring Pressure VALVE GUIDE NOTE:

Measuring Valve Guide Clearance

Check valve stem-to-guide clearance. Ensure valve stem diameter is within specification. Install valve in valve guide. Install dial indicator assembly on cylinder head with tip resting against valve stem just above valve

guide. See Fig. 6.

Fig. 6: Measuring Valve Stem-to-Guide Clearance Lower valve approximately 1/16" below valve seat. Push valve stem against valve guide as far as possible. Adjust dial indicator to zero. Push valve stem in opposite direction and note reading. Clearance must be within specification. If valve guide clearance exceeds specification, valves with oversize stems may be used and valve guides are reamed to larger size or valve guide must be replaced. On some applications, a false guide is installed, then reamed to proper specification. Valve guide reamer set is used to ream valve guide to obtain proper clearance for new valve.

Reaming Valve Guide

Select proper reamer for size of valve stem. Reamer must be of proper length to provide clean cut through entire length of valve guide. Install reamer in valve guide and rotate to cut valve guide. See Fig. 7.

Fig. 7: Reaming Valve Guides

Replacing Valve Guide

Replace valve guide if clearance exceeds specification. Valve guides are either pressed, hammered or shrunk in place, depending upon cylinder head design and type of metal used. Remove valve guide from cylinder head by pressing or tapping on a stepped drift. See Fig. 8. Once valve guide is installed, distance from cylinder head to top of valve guide must be checked. This distance must be within specification. Aluminum heads are often heated before installing valve guide. Valve guide is sometimes cooled in dry ice prior to installation. Combination of a heated cylinder head and cooled valve guide ensures a tight guide fit upon assembly. The new guide must be reamed to specification.

Fig. 8: Typical Valve Guide Remover & Installer VALVES & VALVE SEATS NOTE:

Valve Grinding

Valve stem O.D. should be measured in several areas to indicate amount of wear. Replace valve if not within specification. Valve margin area should be measured to ensure that valve can be ground. See Fig. 9. If valve margin is less than specification, the valves will be burned. Valve must be replaced. Due to minimum margin dimensions during manufacture, some new type valves cannot be reground. Some manufacturers use stellite coated valves that must NOT be machined. Valves can only be lapped into valve seat.

CAUTION: Some valves are sodium filled. Extreme care must be used when disposing of damaged or worn sodium-filled valves.

Fig. 9: Measuring Valve Head Margin Resurface valve to proper angle specification using valve grinding machine. Follow manufacturer's instructions for valve grinding machine. Specifications may indicate a different valve face angle than seat angle. Measure valve margin after grinding. Replace valve if not within specification. Valve stem tip can be refinished using valve grinding machine. Valve Lapping

During valve lapping of recently designed valves, be sure to follow manufacturer's recommendations. Surface hardening and materials used with some valves do not permit lapping. Lapping process will remove excessive amounts of the hardened surface. Valve lapping is done to ensure adequate sealing between valve face and seat. Use either a hand drill or lapping stick with suction cup attached. Moisten and attach suction cup to valve. Lubricate valve stem and guide. Apply a thin coat of fine valve grinding compound between valve and seat. Rotate lapping tool between the palms or with hand drill. Lift valve upward off the seat and change position often. This is done to prevent grooving of valve seat. Lap valve until a smooth polished seat is obtained. Thoroughly clean grinding compound from components. Valveto-valve seat concentricity should be checked. See VALVE SEAT CONCENTRICITY.

CAUTION: Valve guides must be in good condition and free of carbon deposits prior to valve seat grinding. Some engines contain an induction hardened valve seat. Excessive material removal will damage valve seats. Valve Seat Grinding

Select coarse stone of correct size and angle for seat to be ground. Ensure stone is true and has a smooth surface. Select correct size pilot for valve guide dimension. Install pilot in valve guide. Lightly lubricate pilot shaft. Install stone on pilot. Move stone off and on the seat approximately 2 times per second during grinding operation. Select a fine stone to finish grinding operation. Various angle grinding stones are used to center and narrow the valve seat as required. See Fig. 10.

Fig. 10: Adjusting Valve Seat Width Valve Seat Replacement

Replacement of valve seat inserts is done by cutting out the old insert and machining an oversize insert bore. Replacement oversize insert is usually cooled and the cylinder head is sometimes warmed. Valve seat is pressed into the head. This operation requires specialized machine shop equipment.

Valve Seat Concentricity

Using dial gauge, install gauge pilot in valve guide. Position gauge arm on the valve seat. Adjust dial indicator to zero. Rotate arm 360 degrees and note reading. Runout should not exceed specification. To check valve-to-valve seat concentricity, coat valve face lightly with Prussian Blue dye. Install valve and rotate it on valve seat. If pattern is even and entire seat is coated at valve contact point, valve is concentric with the valve seat. CYLINDER HEAD REASSEMBLY NOTE:

Valve Stem Installed Height

Valve stem installed height must be checked when new valves are installed or when valves or valve seats have been ground. Install valve in valve guide. Measure distance from tip of valve stem to spring seat. See Fig. 11. Distance must be within specification to allow sufficient clearance for valve operation. Remove valve and grind valve stem tip if height exceeds specification. Valve tips are surface hardened. DO NOT remove more than .010" (.25 mm) from tip. Chamfer sharp edge of reground valve tip. Recheck valve stem installed height.

Fig. 11: Measuring Valve Stem Installed Height VALVE STEM OIL SEALS NOTE:

Valve stem oil seals must be installed on valve stem. See Fig. 2. Seals are needed due to pressure differential at the ends of valve guides. Atmospheric pressure above intake guide, combined with manifold vacuum below guide, causes oil to be drawn into the cylinder. Exhaust guides also have pressure differential created by exhaust gas flowing past the guide, creating a low pressure area. This low pressure area draws oil into the exhaust system. Some manufacturers require that special color code or specified height valve stem oil seal be installed in

designated area. Replacement (On-Vehicle)

Mark rocker arm or overhead cam components for location. Remove rocker arm components or overhead cam components. Components must be installed in original location. Remove spark plugs. Valve stem oil seals may be replaced by holding valves against seats using air pressure. Air pressure must be installed in cylinder using an adapter for spark plug hole. An adapter can be constructed by welding air hose connection to spark plug body with porcelain removed. Rotate engine until piston is at top of stroke. Install adapter in spark plug hole. Apply a minimum of 140 psi (9.8 kg/cm2 ) line pressure to adapter. Air pressure should hold valve closed. If air pressure does not hold valve closed, check for damaged or bent valve. Cylinder head must be removed for service. Using valve spring compressor, compress valve springs. Remove valve locks. Carefully release spring compressor. Remove retainer or rotator and valve spring. Remove valve stem oil seal. If oversize valves have been installed, oversize oil seals must be used. Coat valve stem with engine oil. Install protective sleeve over end of valve stem. Install new oil seal over valve stem and seat on valve guide. Remove protective sleeve. Install spring seat, valve spring and retainer or rotator. Compress spring and install valve locks. Remove spring compressor. Ensure valve locks are fully seated. Install rocker arms or overhead cam components. Tighten all bolts to specification. Adjust valves if required. Remove adapter. Install spark plugs, valve cover and gasket. VALVE SPRING INSTALLED HEIGHT NOTE:

Valve spring installed height should be checked during reassembly. Measure height from lower edge of valve spring to the upper edge. DO NOT include valve spring seat or retainer. Distance must be within specification. If valves and/or seats have been ground, a valve spring shim may be required to correct spring height. See Fig. 12.

Fig. 12: Measuring Valve Spring Installed Height ROCKER ARMS & ASSEMBLIES NOTE:

Rocker Studs

Rocker studs are either threaded or pressed in place. Threaded studs are removed by locking 2 nuts on the stud. Unscrew the stud by turning the jam nut. Coat new stud threads with Loctite and install. Tighten to specification. Pressed-in stud can be removed using a stud puller. Ream stud bore to proper specification and press in a new oversize stud. Pressed-in studs are often replaced by cutting threads in the stud bore to accept a threaded stud. Rocker Arms & Shafts

Mark rocker arms for location. Remove rocker arm retaining bolts. Remove rocker arms. Inspect rocker arms, shafts, bushings and pivot balls (if equipped) for excessive wear. Inspect rocker arms for wear in valve stem

contact area. Measure rocker arm bushing I.D. Replace bushings if excessively worn. The rocker arm valve stem contact point may be reground, using special fixture for valve grinding machine. Remove minimum amount of material as possible. Ensure all oil passages are clear. Install rocker arm components in original location. Ensure rocker arm is properly seated in push rod. Tighten bolts to specification. Adjust valves if required. See VALVE ADJUSTMENT. PUSH RODS NOTE:

Remove rocker arms. Mark push rods for location. Remove push rods. Push rods can be steel or aluminum, solid or hollow. Hollow push rods must be internally cleaned to ensure oil passage to rocker arms is cleaned. Check push rods for damage, such as loose ends on steel tipped aluminum types. Check push rod for straightness. Roll push rod on a flat surface. Using feeler gauge, check clearance at center. Replace push rod if bent. The push rod can also be supported at each end and rotated. A dial indicator is used to detect a bent area in the push rod. Lubricate ends of push rod and install push rod in original location. Ensure push rod is properly seated in lifter. Install rocker arm. Tighten bolts to specification. Adjust valves if required. See VALVE ADJUSTMENT. LIFTERS NOTE:

Hydraulic Lifters

Before replacing a hydraulic lifter for noisy operation, ensure noise is not caused by worn rocker arms or valve tips. Also ensure sufficient oil pressure exists. Hydraulic lifters must be installed in original location. Remove rocker arm assembly and push rod. Mark components for location. Some applications require intake manifold, cylinder head or lifter cover removal. Remove lifter retainer plate (if used). To remove lifters, use a hydraulic lifter remover or magnet. Different type lifters are used. See Fig. 13.

On sticking lifters, disassemble and clean lifter. DO NOT mix lifter components or positions. Parts are selectfitted and are not interchangeable. Inspect all components for wear. Note amount of wear in lifter body-tocamshaft contact area. Surface must have smooth and convex contact face. If wear is apparent, carefully inspect cam lobe. Inspect push rod contact area and lifter body for scoring or signs of wear. If body is scored, inspect lifter bore for damage and lack of lubrication. On roller type lifters, inspect roller for flaking, pitting, loss of needle bearings and roughness during rotation. Measure lifter body O.D. in several areas. Measure lifter bore I.D. Ensure components or oil clearance is within specification. Some models offer oversize lifters. Replace lifter if damaged. If lifter check valve is not operating, obstructions may be preventing it from closing or valve spring may be broken. Clean or replace components as necessary. Check plunger operation. Plunger should drop to bottom of the body by its own weight when assembled dry. If plunger is not free, soak lifter in solvent to dissolve deposits. Lifter leak-down test can be performed on lifter. Lifter must be filled with special test oil. New lifters contain special test oil. Using lifter leak-down tester, perform leak-down test following manufacturer's instructions. If leak-down time is not within specifications, replace lifter assembly. Lifters should be soaked in clean engine oil several hours prior to installation. Coat lifter base, roller (if equipped) and lifter body with ample amount of Molykote or camshaft lubricant. See Fig. 13. Install lifter in original location. Install remaining components. Valve lash adjustment is not required on most hydraulic lifters. Preload of hydraulic lifter is automatic. Some models may require adjustment. NOTE:

Some manufacturers require that a crankcase conditioner be added to engine oil and engine operated for specified amount of time to aid in lifter break-in procedure if new lifters or camshaft are installed.

Fig. 13: Typical Hydraulic Valve Lifter Assemblies Mechanical Lifters

Lifter assemblies must be installed in original locations. Remove rocker arm assembly and push rod. Mark components for location. Some applications require intake manifold or lifter cover removal. Remove lifter retainer plate (if used). To remove lifters, use lifter remover or magnet.

Inspect push rod contact area and lifter body for scoring or signs of wear. If body is scored, inspect lifter bore for damage and lack of lubrication. Note amount of wear in lifter body-to-camshaft contact area. Surface must have smooth and convex contact face. If wear is apparent, carefully inspect cam lobe. Coat lifter base, roller (if equipped) and lifter body with ample amount of Molykote or camshaft lubricant. Install lifter in original location. Install remaining components. Tighten bolts to specification. Adjust valves. See VALVE ADJUSTMENT.

PISTONS, CONNECTING RODS & BEARINGS * PLEASE READ THIS FIRST * NOTE:

RIDGE REMOVAL NOTE:

Ridge in cylinder wall must be removed prior to piston removal. Failure to remove ridge prior to removing pistons will cause piston damage in piston ring lands or grooves. With piston at bottom dead center, place rag in bore to trap metal chips. Install ridge reamer in cylinder bore. Adjust ridge reamer using manufacturer's instructions. Remove ridge using ridge reamer. DO NOT remove an excessive amount of material. Ensure ridge is completely removed. PISTON & CONNECTING ROD REMOVAL NOTE:

Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Note top of piston. Some pistons may contain a notch, arrow or be marked FRONT. Piston must be installed in proper direction to prevent damage with valve operation. Check that connecting rod and cap are numbered for cylinder location and which side of cylinder block the number faces. Proper cap and connecting rod must be installed together. Connecting rod cap must be installed on connecting rod in proper direction to ensure bearing lock procedure. Mark connecting rod and cap if necessary. Pistons must be installed in original location. Remove cap retaining nuts or bolts. Remove bearing cap. Install tubing protectors on connecting rod bolts. This protects cylinder walls from scoring during removal. Ensure proper removal of ridge. Push piston and connecting rod from cylinder. Connecting rod boss can be tapped with a wooden dowel or hammer handle to aid in removal. PISTON & CONNECTING ROD NOTE:

Disassembly

Using ring expander, remove piston rings. Remove piston pin retaining rings (if equipped). Note direction of piston installation on connecting rod. On pressed type piston pins, special fixtures and procedures according to manufacturer must be used to remove piston pins. Follow manufacturer's recommendations to avoid piston distortion or breakage. Cleaning

Remove all carbon and varnish from piston. Pistons and connecting rods may be cleaned in cold type chemical tank. Using ring groove cleaner, clean all deposits from ring grooves. Ensure all deposits are cleaned from ring grooves to prevent ring breakage or sticking. DO NOT attempt to clean pistons with wire brush. Inspection

Inspect pistons for nicks, scoring, cracks or damage in ring areas. Connecting rod should be checked for cracks using Magnaflux procedure. Piston diameter must be measured in manufacturer's specified area. Using telescopic gauge and micrometer, measure piston pin bore of piston in 2 areas, 90 degrees apart. This is

done to check diameter and out-of-round. Install proper bearing cap on connecting rod. Ensure bearing cap is installed in proper location. Tighten bolts or nuts to specification. Using inside micrometer, measure inside diameter in 2 areas, 90 degrees apart. Connecting rod I.D. and out-of-round must be within specification. Measure piston pin bore I.D. and piston pin O.D. All components must be within specification. Subtract piston pin diameter from piston pin bore in piston and connecting rod to determine proper fit. Connecting rod length must be measured from center of crankshaft journal inside diameter to center of piston pin bushing using proper caliper. Connecting rods must be the same length. Connecting rods should be checked on an alignment fixture for bent or twisted condition. Replace all components which are damaged or not within specification. PISTON & CYLINDER BORE FIT NOTE:

Ensure cylinder is checked for taper, out-of-round and properly honed prior to checking piston and cylinder bore fit. See CYLINDER BLOCK. Using dial bore gauge, measure cylinder bore. Measure piston skirt diameter at 90 degree angle to piston pin at specified area by manufacturer. Subtract piston diameter from cylinder bore diameter to determine piston-to-cylinder clearance. Clearance must be within specification. Mark piston for proper cylinder location. ASSEMBLING PISTON & CONNECTING ROD NOTE:

Install piston on connecting rod for corresponding cylinder. Ensure reference marking on top of piston corresponds with connecting rod and cap number. See Fig. 14. Lubricate piston pin and install in connecting rod. Ensure piston pin retainers are fully seated (if equipped). On

pressed type piston pins, follow manufacturer's recommended procedure to avoid distortion or breakage.

Fig. 14: Installing Typical Piston Pin CHECKING PISTON RING CLEARANCES NOTE:

Piston rings must be checked for side clearance and end gap. To check end gap, install piston ring in cylinder in which it is to be installed. Using an inverted piston, push ring to bottom of cylinder in smallest cylinder diameter.

Using feeler gauge, check ring end gap. See Fig. 15. Piston ring end gap must be within specification. Ring breakage will occur if insufficient ring end gap exists. Some manufacturers permit correcting insufficient ring end gap by using a fine file while other manufacturers recommend using another ring set. Mark rings for proper cylinder installation after checking end gap.

Fig. 15: Checking Piston Ring End Gap For checking side clearance, install rings on piston. Using feeler gauge, measure clearance between piston ring and piston ring land. Check side clearance in several areas around piston. Side clearance must be within specification. If side clearance is excessive, piston ring grooves can be machined to accept oversize piston rings (if available). Normal practice is to replace piston. PISTON & CONNECTING ROD INSTALLATION NOTE:

of cleaning, inspection, assembly and machine shop practice are included. Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Cylinders must be honed prior to piston installation. See CYLINDER HONING under CYLINDER BLOCK. Install upper connecting rod bearings. Lubricate upper bearings with engine oil. Install lower bearings in rod caps. Ensure bearing tabs are properly seated. Position piston ring gaps according to manufacturer's recommendations. See Fig. 16. Lubricate pistons, rings and cylinder walls.

Fig. 16: Positioning Typical Piston Ring End Gap Install ring compressor. Use care not to rotate piston rings. Compress rings with ring compressor. Install plastic tubing protectors over connecting rod bolts. Install piston and connecting rod assembly. Ensure piston notch, arrow or FRONT mark is toward front of engine. See Fig. 17.

Fig. 17: Installing Piston & Connecting Rod Assembly Carefully tap piston into cylinder until rod bearing is seated on crankshaft journal. Remove protectors. Install rod cap and bearing. Lightly tighten connecting rod bolts. Repeat procedure for remaining cylinders. Check bearing clearance. See MAIN & CONNECTING ROD BEARING CLEARANCE. Once clearance is checked, lubricate journals and bearings. Install bearing caps. Ensure marks are aligned on connecting rod and cap. Tighten rod nuts or bolts to specification. Ensure rod moves freely on crankshaft. Check connecting rod side clearance. See CONNECTING ROD SIDE CLEARANCE. CONNECTING ROD SIDE CLEARANCE NOTE:

Examples used in this article are general in nature and do not necessarily relate to a specific engine or system. Illustrations and procedures have been chosen

to guide mechanic through engine overhaul process. Descriptions of processes of cleaning, inspection, assembly and machine shop practice are included. Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Position connecting rod toward one side of crankshaft as far as possible. Using feeler gauge, measure clearance between side of connecting rod and crankshaft. See Fig. 18. Clearance must be within specification. Check for improper bearing installation, wrong bearing cap or insufficient bearing clearance if side clearance is insufficient. Connecting rod may require machining to obtain proper clearance. Excessive clearance usually indicates excessive wear at crankshaft. Crankshaft must be repaired or replaced.

Fig. 18: Measuring Connecting Rod Side Clearance MAIN & CONNECTING ROD BEARING CLEARANCE NOTE:

Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Plastigage Method

Plastigage method may be used to determine bearing clearance. Plastigage can be used with an engine in service or during reassembly. Plastigage material is oil soluble. Ensure journals and bearings are free of oil or solvent. Oil or solvent will dissolve material and false reading will be obtained. Install small piece of Plastigage along full length of bearing journal. Install bearing cap in original location. Tighten bolts to specification. CAUTION: DO NOT rotate crankshaft while Plastigage is installed. Bearing clearance will not be obtained if crankshaft is rotated. Remove bearing cap. Compare Plastigage width with scale on Plastigage container to determine bearing clearance. See Fig. 19. Rotate crankshaft 90 degrees. Repeat procedure. This is done to check journal eccentricity. This procedure can be used to check oil clearance on both connecting rod and main bearings.

Fig. 19: Measuring Bearing Clearance Micrometer & Telescopic Gauge Method

A micrometer is used to determine journal diameter, taper and out-of-round dimensions of the crankshaft. See CLEANING & INSPECTION under CRANKSHAFT & MAIN BEARINGS in this article. With crankshaft removed, install bearings and caps in original location on cylinder block. Tighten bolts to specification. On connecting rods, install bearings and caps on connecting rods. Install proper connecting rod cap on corresponding rod. Ensure bearing cap is installed in original location. Tighten bolts to specification. Using a telescopic gauge and micrometer or inside micrometer, measure inside diameter of connecting rod and main bearings bores. Subtract each crankshaft journal diameter from the corresponding inside bearing bore diameter. This is the bearing clearance.

CRANKSHAFT & MAIN BEARINGS * PLEASE READ THIS FIRST * NOTE:

REMOVAL NOTE:

Ensure all main bearing caps are marked for location on cylinder block. Some main bearing caps have an arrow stamped on them. The arrow must face timing belt or timing chain end of engine. Remove main bearing cap bolts. Remove main bearing caps. Carefully remove crankshaft. Use care not to bind crankshaft in cylinder block during removal. CLEANING & INSPECTION

NOTE:

Thoroughly clean crankshaft using solvent. Dry with compressed air. Ensure all oil passages are clear and free of sludge, rust, dirt and metal chips. Inspect crankshaft for scoring and nicks. Inspect crankshaft for cracks using Magnaflux procedure. Inspect rear seal area for grooving or damage. Inspect bolt hole threads for damage. If pilot bearing or bushing is used, check pilot bearing or bushing fit in crankshaft. Inspect crankshaft gear for damaged or cracked teeth. Replace gear if damaged. Ensure oil passage plugs are tight (if equipped). Using micrometer, measure all journals in 4 areas to determine journal taper, out-of-round and undersize. See Fig. 20. Some crankshafts can be reground to the next largest undersize, depending on the amount of wear or damage. Crankshafts with rolled fillet cannot be reground and must be replaced.

Fig. 20: Measuring Crankshaft Journals Crankshaft journal runout should be checked. Install crankshaft in "V" blocks or bench center. Position dial indicator with tip resting on the main bearing journal area. See Fig. 21. Rotate crankshaft and note reading. Journal runout must not exceed specification. Repeat procedure on all main bearing journals. Crankshaft must be replaced if runout exceeds specification.

Fig. 21: Measuring Crankshaft Main Bearing Journal Runout INSTALLATION NOTE:

Install upper main bearing in cylinder block. Ensure lock tab is properly located in cylinder block. Install bearings in main bearing caps. Ensure all oil passages are aligned. Install rear seal (if removed). Ensure crankshaft journals are clean. Lubricate upper main bearings with clean engine oil. Carefully install crankshaft. Check each main bearing clearance using Plastigage method. See MAIN & CONNECTING ROD BEARING CLEARANCE. Once clearance is checked, lubricate lower main bearing and journals. Install main bearing caps in original location. Install rear seal in rear main bearing cap (if removed). Some rear main bearing caps require sealant to be applied in corners to prevent oil leakage. Install and tighten all bolts except thrust bearing cap to specification. Tighten thrust bearing cap bolts finger tight only. Some models require that thrust bearing be aligned. On most applications, crankshaft must be moved rearward then forward. Procedure may vary with manufacturer. Thrust bearing cap is then tightened to specification. Ensure crankshaft rotates freely. Crankshaft end play should be checked. See CRANKSHAFT END PLAY.

CRANKSHAFT END PLAY NOTE:

Dial Indicator Method

Crankshaft end play can be checked using dial indicator. Mount dial indicator on rear of cylinder block. Position dial indicator tip against rear of crankshaft. Ensure tip is resting against flat surface. Pry crankshaft rearward. Adjust dial indicator to zero. Pry crankshaft forward and note reading. Crankshaft end play must be within specification. If end play is not within specification, check for faulty thrust bearing installation or worn crankshaft. Some applications offer oversize thrust bearings. Feeler Gauge Method

Crankshaft end play can be checked using feeler gauge. Pry crankshaft rearward. Pry crankshaft forward. Using feeler gauge, measure clearance between crankshaft and thrust bearing surface. See Fig. 22.

Fig. 22: Checking Crankshaft End Play Crankshaft end play must be within specification. If end play is not within specification, check for faulty thrust bearing installation or worn crankshaft. Some applications offer oversize thrust bearings. CYLINDER BLOCK NOTE:

Block Cleaning

Only cast cylinder blocks should be hot tank cleaned. Aluminum cylinder blocks should be cleaned using cold tank method. Cylinder block is cleaned in order to remove carbon deposits, gasket residue and water jacket

scale. Remove oil gallery plugs, freeze plugs and cam bearings before cleaning block. Block Inspection

Visually inspect the block. Check suspected areas for cracks using the Dye Penetrant inspection method. Block may be checked for cracks using the Magnaflux method. Cracks are most commonly found at the bottom of cylinders, main bearing saddles, near expansion plugs and between cylinders and water jackets. Inspect lifter bores for damage. Inspect all head bolt holes for damaged threads. Threads should be cleaned using tap to ensure proper head bolt torque. Consult machine shop concerning possible welding and machining (if required). Cylinder Bore Inspection

Inspect bore for scoring or roughness. Cylinder bore is dimensionally checked for out-of-round and taper using dial bore gauge. For determining out-of-round, measure cylinder parallel and perpendicular to the block center line. Difference in the 2 readings is the bore out-of-round. Cylinder bore must be checked at top, middle and bottom of piston travel area. Bore taper is obtained by measuring bore at the top and bottom. If wear has exceeded allowable limits, block must be honed or bored to next available oversize piston dimension. Cylinder Honing

Cylinder must be properly honed to allow new piston rings to properly seat. Cross-hatching at correct angle and depth is critical to lubrication of cylinder walls and pistons. A flexible drive hone and power drill are commonly used. Drive hone must be lubricated during operation. Mix equal parts of kerosene and SAE 20W engine oil for lubrication. Apply lubrication to cylinder wall. Operate cylinder hone from top to bottom of cylinder using even strokes to produce 45 degree cross-hatch pattern on the cylinder wall. DO NOT allow cylinder hone to extend below cylinder during operation. Recheck bore dimension after final honing. Wash cylinder wall with hot soapy water to remove abrasive particles. Blow dry with compressed air. Coat cleaned cylinder walls with lubricating oil. Deck Warpage

Check deck for damage or warped gasket surface. Place a straightedge across gasket surface of the deck. Using feeler gauge, measure clearance at center of straightedge. Measure across width and length of cylinder block at several points. If warpage exceeds specifications, deck must be resurfaced. If warpage exceeds manufacturer's maximum tolerance for material removal, replace block. NOTE:

Some manufacturers recommend that a total amount of material (cylinder head and cylinder block) can only be removed before components must be replaced.

Deck Height

Distance from crankshaft center line to block deck is called the deck height. Measure and record front and rear main journals of crankshaft. To compute this distance, install crankshaft and retain with center main bearing and cap only. Measure distance from crankshaft journal to block deck, parallel to cylinder center line. Add one half of main bearing journal diameter to distance from crankshaft journal to block deck. This dimension should be checked at front and rear of cylinder block. Both readings should be the same. If difference exceeds specification, cylinder block must be repaired or replaced. Deck height and warpage should be corrected at the same time. Main Bearing Bore & Alignment

For checking main bearing bore, remove all bearings from cylinder block and main bearing caps. Install main bearing caps in original location. Tighten bolts to specification. Using inside micrometer, measure main bearing bore in 2 areas 90 degrees apart. Determine bore size and out-of-round. If diameter is not within specification, block must be align-bored. For checking alignment, place a straightedge along center line of main bearing saddles. Check for clearance between straightedge and main bearing saddles. Block must be align-bored if clearance exists. Expansion Plug Removal

Drill hole in center of expansion plug. Remove with screwdriver or punch. Use care not to damage sealing surface. Expansion Plug Installation

Ensure sealing surface is free of burrs. Coat expansion plug with sealer. Using wooden dowel or pipe of slightly smaller diameter, install expansion plug. Ensure expansion plug is evenly located. Oil Gallery Plug Removal

Remove threaded oil gallery plugs using appropriate wrench. Soft press-in plugs are removed by drilling into plug and installing a sheet metal screw. Remove plug with slide hammer or pliers. Oil Gallery Plug Installation

Ensure threads or sealing surface is clean. Coat threaded oil gallery plugs with sealer and install. Replacement soft press-in plugs are installed with a hammer and drift.

CAMSHAFT * PLEASE READ THIS FIRST * NOTE:

Examples used in this article are general in nature and do not necessarily relate

to a specific engine or system. Illustrations and procedures have been chosen to guide mechanic through engine overhaul process. Descriptions of processes of cleaning, inspection, assembly and machine shop practice are included. Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. CLEANING & INSPECTION NOTE:

Clean camshaft with solvent. Ensure all oil passages are clear. Inspect cam lobes and bearing journals for pitting, flaking or scoring. Using micrometer, measure bearing journal O.D. Support camshaft at each end with "V" blocks. Position dial indicator with tip resting on center bearing journal. Rotate camshaft and note camshaft runout reading. If reading exceeds specification, replace camshaft. Check cam lobe lift by measuring base circle of camshaft using micrometer. Measure again at 90-degree angle to tip of cam lobe. Cam lift can be determined by subtracting base circle diameter from tip of cam lobe measurement. Different lift dimensions are given for intake and exhaust cam lobes. Reading must be within specification. Replace camshaft if cam lobes or bearing journals are not within specification. Inspect camshaft gear for chipped, eroded or damaged teeth. Replace gear if damaged. On camshafts using thrust plate, measure distance between thrust plate and camshaft shoulder. Replace thrust plate if not within specification. CAMSHAFT BEARINGS NOTE:

Removal & Installation

Remove camshaft rear plug. Camshaft bearing remover is assembled with shoulder resting against bearing to be removed according to manufacturer's instructions. Tighten puller nut until bearing is removed. Remove remaining bearings, leaving front and rear bearings until last. These bearings act as a guide for camshaft bearing remover. To install new bearings, puller is rearranged to pull bearings toward the center of block. Ensure all lubrication passages of bearing are aligned with cylinder block. Coat new camshaft rear plug with sealant. Install camshaft rear plug. Ensure plug is even in cylinder block. CAMSHAFT INSTALLATION NOTE:

Lubricate bearing surfaces and cam lobes with ample amount of Molykote or camshaft lubricant. Carefully install camshaft. Use care not to damage bearing journals during installation. Install thrust plate retaining bolts (if equipped). Tighten bolts to specification. On overhead camshafts, install bearing caps in original location. Tighten bolts to specification. On all applications, check camshaft end play. CAMSHAFT END PLAY NOTE:

Using dial indicator, check camshaft end play. Position dial indicator on front of engine block or cylinder head. Position indicator tip against camshaft. Push camshaft toward rear of cylinder head or engine and adjust indicator to zero. Move camshaft forward and note reading. Camshaft end play must be within specification. End play may be adjusted by relocating gear, shimming thrust plate or replacing thrust plate depending on each manufacturer.

TIMING CHAINS & BELTS

* PLEASE READ THIS FIRST * NOTE:

TIMING CHAINS NOTE:

Timing chains will stretch during operation. Limits are placed upon amount of stretch before replacement is required. Timing chain stretch will alter ignition timing and valve timing. To check timing chain stretch, rotate crankshaft to eliminate slack from one side of timing chain. Mark reference point on cylinder block. Rotate crankshaft in opposite direction to eliminate slack from remaining side of timing chain. Force other side of chain outward and measure distance between reference point and timing chain. See Fig. 23. Replace timing chain and gears if not within specification.

Fig. 23: Measuring Timing Chain Stretch Timing chains must be installed so timing marks on camshaft gear and crankshaft gear are aligned according to manufacturer. See Fig. 24.

Fig. 24: Typical Gear Timing Mark Alignment TIMING BELTS NOTE:

Cogged tooth belts are commonly used on overhead cam engines. Inspect belt teeth for rounded corners or cracking. Replace belt if it is cracked, damaged, missing teeth or oil soaked. Used timing belt must be installed in original direction of rotation. Inspect all sprocket teeth for wear. Replace all worn sprockets. Sprockets are marked for timing purposes. Engine is positioned so that crankshaft sprocket mark will be upward. Camshaft sprocket is aligned with reference mark on cylinder head or timing belt cover and then timing belt can be installed. See Fig. 25.

Fig. 25: Typical Camshaft Belt Sprocket Alignment TENSION ADJUSTMENT NOTE:

If guide rails are used with spring loaded tensioners, ensure at least half of original rail thickness remains. Spring loaded tensioner should be inspected for damage. Ensure all timing marks are aligned. Adjust belt tension using manufacturer's recommendations. Belt tension may require checking using tension gauge. See Fig. 26.

Fig. 26: Adjusting Typical Timing Belt Tension

TIMING GEARS * PLEASE READ THIS FIRST *

NOTE:

TIMING GEAR BACKLASH & RUNOUT NOTE:

On engines where camshaft gear operates directly on crankshaft gear, gear backlash and runout must be checked. To check backlash, install dial indicator with tip resting on tooth of camshaft gear. Rotate camshaft gear as far as possible. Adjust indicator to zero. Rotate camshaft gear in opposite direction as far as possible and note reading. To determine timing gear runout, mount dial indicator with tip resting on face edge of camshaft gear. Adjust indicator to zero. Rotate camshaft gear 360 degrees and note reading. If backlash or runout exceeds specification, replace camshaft and/or crankshaft gear. REAR MAIN OIL SEAL INSTALLATION NOTE:

One-Piece Type Seal

For one-piece type oil seal installation, coat block contact surface of seal with sealer if seal is not factory coated. Ensure seal surface is free of burrs. Lubricate seal lip with engine oil and press seal into place using proper oil seal installer. See Fig. 27.

Fig. 27: Installing Typical One-Piece Oil Seal Rope Type Seal

For rope type rear main oil seal installation, press seal lightly into seat area. Using seal installer, fully seat seal in bearing cap or cylinder block. Trim seal ends even with cylinder block parting surface. Some applications require sealer to be applied on main bearing cap before installing. See Fig. 28.

Fig. 28: Installing Typical Rope Seal Split-Rubber Type Seal

Follow manufacturer's procedures when installing split-rubber type rear main oil seals. Installation procedures vary with manufacturer and engine type. See Fig. 29.

Fig. 29: Installing Typical Split-Rubber Seal

OIL PUMP * PLEASE READ THIS FIRST * NOTE:

ROTOR TYPE NOTE:

Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Mark oil pump rotor locations before removing. See Fig. 30. Remove outer rotor and measure thickness and diameter. Measure inner rotor thickness. Inspect shaft for scoring or wear. Inspect rotors for pitting or damage. Inspect cover for grooving or wear. Replace worn or damaged components. Measure outer rotor-to-body clearance. Replace pump assembly if clearance exceeds specification. Measure clearance between rotors. See Fig. 31. Replace shaft and both rotors if clearance exceeds specification. Install rotors in pump body. Position straightedge across pump body. Using feeler gauge, measure clearance between rotors and straightedge. Pump cover wear is measured using a straightedge and feeler gauge. Replace pump if clearance exceeds specification.

Fig. 30: Typical Rotor Type Oil Pump

Fig. 31: Measuring Rotor Clearance GEAR TYPE NOTE:

Mark oil pump gear location before removing. See Fig. 32. Remove gears from pump body. Inspect gears for pitting or damage. Inspect cover for grooving or wear. Measure gear diameter and length. Measure gear housing cavity depth and diameter. See Fig. 33. Replace worn or damaged components. Pump cover wear is measured using a straightedge and feeler gauge. Replace pump or components if warpage or wear exceeds specification, or mating surface of pump cover is scratched or grooved.

Fig. 32: Typical Gear Type Oil Pump

Fig. 33: Measuring Oil Pump Gear Cavity

BREAK-IN PROCEDURE * PLEASE READ THIS FIRST * NOTE:

ENGINE PRE-OILING

NOTE:

Pre-oil engine prior to operation to prevent engine damage. Lightly oiled oil pump will cavitate unless oil pump cavities are filled with engine oil or petroleum jelly. Engine pre-oiling can be done using pressure oiler (if available). Connect pressure oiler to cylinder block oil passage such as oil pressure sending unit. Operate pressure oiler long enough to ensure correct amount of oil has filled crankcase. Check oil level while pre-oiling. If pressure oiler is not available, disconnect ignition system. Remove oil pressure sending unit and replace with oil pressure test gauge. Using starter motor, rotate engine starter until gauge shows normal oil pressure for several seconds. DO NOT crank engine for more than 30 seconds to avoid starter motor damage. Ensure oil pressure has reached the most distant point from the oil pump. NOTE:

If new lifters or camshaft are installed, some manufacturers require that a crankcase conditioner be added to engine oil. The engine should be operated for specified amount of time to aid in lifter break-in procedure.

INITIAL START-UP NOTE:

Start engine and operate engine at low speed while checking for coolant, fuel and oil leaks. Stop engine. Recheck coolant and oil level. Adjust if necessary. CAMSHAFT NOTE:

Always refer to appropriate engine overhaul article, if available, in the ENGINES section for complete overhaul procedures and specifications for the vehicle being repaired. Break-in procedure is required when new or reground camshaft has been installed. Operate and maintain engine speed between 1500-2500 RPM for approximately 30 minutes. Procedure may vary due to manufacturer's recommendations. PISTON RINGS NOTE:

Piston rings require a break-in procedure to ensure seating of rings to cylinder walls. Serious damage may occur to rings if correct procedures are not followed. Extremely high piston ring temperatures are obtained during break-in process. If rings are exposed to excessively high RPM or high cylinder pressures, ring damage can occur. Follow piston ring manufacturer's recommended break-in procedure. FINAL ADJUSTMENTS NOTE:

Check or adjust ignition timing and dwell (if applicable). Adjust valves (if necessary). Adjust idle speed and mixture. Retighten cylinder heads (if required). If cylinder head or block is aluminum, retighten bolts when engine is cold. Follow the engine manufacturer's recommended break-in procedure and maintenance schedule for new engines. NOTE:

Some manufacturers require that head bolts be retightened after specified amount of operation. This must be done to prevent head gasket failure.

ENGINE REMOVAL ENGINES General Motors Corp. Removal & Installation

IDENTIFICATION BODY IDENTIFICATION Body A B C D E F H J K L N W Y

Models Celebrity, Century, Cutlass Ciera, Cutlass Cruiser, 6000 Caprice, Custom Cruiser, Estate Wagon DeVille, Electra, Fleetwood, Ninety-Eight, Park Avenue Brougham Eldorado, Reatta, Riviera, Toronado, Trofeo Camaro, Firebird Bonneville, Delta 88, LeSabre Cavalier, Sunbird Seville Beretta, Corsica Cutlass Calais, Grand Am, Skylark Cutlass Supreme, Grand Prix, Lumina, Regal Corvette

REMOVAL & INSTALLATION 4-CYLINDER MODELS - 2.0L CAUTION: Relieve fuel pressure. On TBI models, remove fuel pump fuse. Start and run engine until engine dies from lack of fuel. Engage starter for an additional 3 seconds. On PFI models, install Fuel Pressure Gauge (J34730-1) on fuel rail service valve. Place bleed hose into approved container and bleed fuel system. NOTE:

Engine and transaxle are removed as an assembly from bottom of vehicle.

Removal ("J" Body)

1. Disconnect battery cables. Drain cooling system and remove radiator hoses. Remove air cleaner. Disconnect electrical harness at firewall. Disconnect electrical connector at brake master cylinder. 2. Disconnect wiring at Electronic Control Module (ECM), temperature switch at thermostat housing, and A/C relay cluster switches. Disconnect vacuum hoses at Manifold Absolute Pressure (MAP) sensor, canister, and Electronic Fuel Injection (EFI). 3. Remove power steering hoses at pump return port and cut-off switch. Disconnect accelerator cable at bracket and EFI. Disconnect shift linkage or cable at transaxle. Raise and support vehicle.

4. Remove speedometer cable and bracket. Disconnect exhaust pipe from hangers and manifold and move aside. Remove heater hoses and fuel lines. Remove A/T transaxle cooler lines (if equipped). 5. Remove both front wheels. Remove front brake calipers and support with wire. Remove right and left tie rod ends. 6. Disconnect electrical connections at A/C compressor. Discharge refrigerant from A/C system. Remove A/C lines from compressor. Remove 3 suspension attaching bolts from each side of engine compartment and loosen the last 2 bolts (one on each side). CAUTION: Be sure to support vehicle, engine and transaxle weight during following steps. 7. On A/T models, remove rear transaxle lateral strut. On all models, remove front transaxle strut. Lower vehicle. Support front of vehicle by placing 2 jack stands under radiator core support. Position jack at rear of cowl with 4" x 4" x 6' timber spanning vehicle width. 8. Raise and support vehicle enough to remove jack stands. Position 4-wheel dolly under transaxle assembly with three 4" x 4" x 12" blocks as support. Lower vehicle onto 4-wheel dolly. Remove right and left side suspension attaching bolts loosened in step 6). NOTE:

Engine and transaxle are removed as an assembly from bottom of vehicle.

9. Remove transaxle mounting bolts. Remove front and rear engine mounting bolts. Remove steering knuckle-to-strut bolts on both sides. Scribe steering knuckle-to-strut position to preserve camber adjustment. Raise and support vehicle, letting engine, transaxle, and suspension rest on 4-wheel dolly. Installation

To install, reverse removal procedure. Fill coolant recovery reservoir to FULL COLD mark. With engine off, fill thermostat housing until level is even with thermostat seat. Install cap. Run engine until upper radiator hose is hot. Check coolant level in reservoir tank. Add coolant to FULL COLD mark. 4-CYLINDER MODELS - 2.2L CAUTION: Relieve fuel pressure. Disconnect battery cables to prevent accidental discharge of fuel. Loosen fuel filler cap. The TBI system has an automatic internal pressure bleed. No further action is required. NOTE:

Engine and transaxle are removed as an assembly from bottom of vehicle.

Removal ("J" & "L" Bodies)

1. Disconnect battery cables. Remove battery. Disconnect hood wires and remove hood. Drain cooling system and disconnect radiator and heater hoses. Remove air cleaner and throttle body intake duct. 2. Disconnect all vacuum hoses at engine. Remove alternator top bracket and wiring. Disconnect upper engine electrical wiring and position out of way. Discharge A/C system. Remove A/C compressor-toaccumulator and compressor-to-condenser lines.

3. Raise vehicle. Remove left splash shield, exhaust system and lower engine wiring. Remove flexplate inspection cover and front wheels. Remove front brake calipers and support with wire. 4. Lower vehicle and on M/T models, remove clutch slave cylinder. Disconnect fuel lines. Disconnect transaxle linkage at transaxle. Disconnect accelerator cruise control at throttle body. On A/T models, disconnect TV cables at throttle body and cooling lines at transaxle. 5. On all models, disconnect power steering hoses from pump. Remove center carriage bolts. Position 4wheel dolly under frame and lower vehicle onto dolly. Add support under engine and rear of vehicle. NOTE:

Engine and transaxle are removed as an assembly from bottom of vehicle.

6. Remove upper transaxle mount, upper strut bolts and nuts. Remove front and rear engine mounts. Remove rear carriage bolts. Remove front carriage bolts, and wire holes together to prevent axle separation. Raise vehicle and remove engine/transaxle assembly. Installation

To install, reverse removal procedure. With engine off, fill radiator until level is even with filler neck. Run engine until upper radiator hose is hot. Add coolant as necessary. After 5 minutes, add coolant to base of filler neck and install cap. Add coolant to recovery reservoir to HOT mark. Install cap. 4-CYLINDER MODELS - 2.3L CAUTION: Relieve fuel pressure. Install Fuel Pressure Gauge (J-34730-1) on fuel rail service valve. Place bleed hose into approved container and bleed fuel system. NOTE:

Except on "W" body, engine and transaxle are removed as an assembly from bottom of vehicle. On "W" body, engine only is lifted from engine compartment.

Removal ("L" Body)

1. Disconnect negative battery cable. Drain coolant. Remove front wheel and tire assemblies. Remove air cleaner assembly, heater hoses, upper radiator hose and cooling fan. Remove oil filter. NOTE:

On "L" body, engine and transaxle are removed as an assembly from bottom of vehicle.

support retaining bolts. Remove rear engine mount bracket and ground strap from block. 5. Remove engine mount body bracket. Remove transaxle through bolt. Position jack below engine and lower car onto support. Raise vehicle off engine and transaxle assembly. Separate engine from transaxle. Installation

1. Disconnect negative battery cable. Drain coolant. Remove air cleaner assembly, heater hoses, upper radiator support and cooling fan. Remove oil filter. NOTE:

On "N" body, engine and transaxle are removed as an assembly from bottom of vehicle.

2. On A/C equipped models, discharge A/C system. Remove coupled hose assembly at A/C compressor and discard "O" rings. On all models, disconnect and label all linkage, hoses, vacuum lines and electrical wiring that will interfere with engine removal. Remove negative battery cable from block. 3. Remove power steering pivot bolt, pump, and drive belt. Position power steering pump aside. Disconnect clutch actuator, fuel lines, engine oil cooler lines and exhaust heat shield. Disconnect exhaust manifold and front engine mount. Install Engine Support (J-28467). Raise vehicle. 4. Remove front right wheel assembly. Remove right lower splash shield and radiator air deflector. Separate ball joints from steering knuckles. Support suspension crossmember and stabilizer shaft. Remove suspension support retaining bolts. 5. Remove suspension supports, crossmember and stabilizer shaft as an assembly. Install Axle Boot Protector (J-34754) on drive axle boots. Remove axle shafts from transaxle. 6. Remove nut from transaxle mount through bolt and rear engine mount through bolt. Remove engine mount body bracket. Position jack below engine and lower car onto support. 7. Remove transaxle through bolt. Mark support fixture hooks so that positioning can be duplicated when reinstalling engine. Remove engine support fixture. Raise vehicle off engine and transaxle assembly. Separate engine from transaxle. Installation

To install, reverse removal procedure. When tightening transaxle mount through bolt, ensure related gaps are equal and within .08" (2 mm) of each other. Check all fluid levels. With engine off, fill radiator until level is even with filler neck. Run engine until upper radiator hose is hot. Add coolant as necessary. After 5 minutes, add coolant to base of filler neck and install cap. Add coolant to recovery reservoir to HOT mark. Install cap. Removal ("W" Body)

1. Disconnect battery cables. Remove hood. Drain cooling system and disconnect upper radiator hoses. Disconnect heater hoses at thermostat housing and heater core. Remove air cleaner to throttle body duct.

NOTE:

On "W" body, only engine is lifted from engine compartment.

2. Disconnect engine injector wiring harness connector. Disconnect ground connection at front of engine. Disconnect electrical connectors from alternator, A/C compressor, coolant sensors, oil pressure switch, knock sensor, oxygen sensor and throttle position sensor. 3. Remove electrical connection at starter solenoid. Position harness aside. Disconnect vacuum hoses. Recover A/C refrigerant and disconnect A/C hoses at compressor. Remove A/C compressor. 4. Remove throttle cable and bracket. Remove power steering belt and through bolt. Remove power steering pump with brackets and hoses attached and position aside. Release fuel pressure. Disconnect fuel lines. Remove torque strut mounts. 5. Remove A/T fill tube (if equipped). Remove exhaust heat shield and exhaust pipe-to-manifold bolts. Remove transaxle-to-block attaching bolts. Raise vehicle. Remove transaxle-to-block attaching bolts from under vehicle. 6. Disconnect lower radiator hose. Remove torque converter cover (if equipped), scribe marks on converterto-flexplate for reassembly reference. Remove transaxle-to-engine brace and lower engine mount. Lower vehicle. Support transaxle. Install engine hoist. Remove engine assembly. Installation

1. To install, reverse removal procedure. Leave heater hose outlet disconnected. Fill radiator with coolant until coolant flows from outlet. Install heater hose. 2. With engine off, fill radiator until level is even with filler neck. Run engine until upper radiator hose is hot. Add coolant as necessary. After 5 minutes, add coolant to base of filler neck and install cap. Add coolant to recovery reservoir to HOT mark. Install cap. 4-CYLINDER MODELS - 2.5L CAUTION: Relieve fuel pressure. Remove fuel pump fuse. Start and run engine until engine dies from lack of fuel. Engage starter for an additional 3 seconds. Removal ("A" Body)

1. Disconnect battery cables. Remove hood. Drain cooling system and disconnect radiator hoses. Remove air cleaner. Disconnect engine wiring harness connector. Disconnect vacuum and heater hoses. Remove A/C compressor with hoses attached and place aside. NOTE:

On "A" Body, engine only is lifted from engine compartment.

2. Remove front reaction rod/strut. Disconnect throttle and transaxle linkage. Remove transaxle-to-engine bolts, except 2 upper bolts. Remove front mount-to-cradle nuts. Remove forward exhaust pipe. Remove converter housing cover or flywheel inspection cover. Remove converter-to-flexplate bolts, on A/T models. On all models, remove starter motor. 3. Remove power steering pump with hoses attached and position aside (if equipped). Remove rear transaxle support bracket bolts. Disconnect fuel line at fuel filter. 4. Position jack with wood block under transaxle and raise engine and transaxle until front engine mount

studs clear cradle. Support engine weight with lift equipment. Remove upper transaxle-to-engine bolts. Remove engine. Installation

To install, reverse removal procedure. With engine off, fill radiator until level is even with filler neck. Run engine until upper radiator hose is hot. Add coolant as necessary. After 5 minutes, add coolant to base of filler neck and install cap. Allow engine to cool, then add coolant to recovery reservoir to ADD or FULL COLD mark. Install cap. Removal ("N" Body)

1. Disconnect battery cables. Drain cooling system and disconnect radiator hoses. Remove air cleaner. Disconnect ECM connectors, route through firewall and lay harness across engine. Disconnect vacuum, radiator and heater hoses. NOTE:

On "N" Body, engine and transaxle assembly are removed from below vehicle.

2. Recover refrigerant from A/C system. Hoist vehicle. Remove A/C compressor and brackets. Remove power steering pump with hoses attached and wire out of way. Remove front and rear transaxle struts. Remove fuel lines. 3. Remove shift linkage. On A/T models, disconnect transaxle cooler lines, and downshift cable. On all models, disconnect throttle cable at throttle body. Disconnect engine ground cable. Remove multiple relay bracket. Remove power steering line bracket. Remove tire and wheel assembly. Remove brake calipers and rotors. 4. Remove knuckle-to-strut bolts. Disconnect exhaust pipe from manifold and hangers and wire out of way. Remove body-to-frame bolts at lower control arm and loosen remaining body-to-frame bolts. Remove bolts from frame, leaving one in each corner. 5. Support front of vehicle by placing 2 jack stands under front of body. Move hoist back to body pan and place a 4" x 4" block between hoist and vehicle. Raise hoist and remove jack stands. 6. Position 4-wheel dolly under transaxle assembly with 4" x 4" x 12" blocks as support. Lower vehicle and engine/transaxle to rest on dolly. Remove engine mount bolts and right front bracket. Remove remaining frame-to-body bolts. Raise vehicle from engine/transaxle assembly. Separate engine from transaxle. Installation

To install, reverse removal procedure. Check all fluid levels. With engine off, fill surge tank until level is even with base of filler neck. Run engine until upper radiator hose is hot. Stop engine and observe coolant level in surge tank. If not above FULL line, carefully remove pressure cap and add coolant as necessary. Install cap. Removal ("W" Body)

1. Disconnect battery cables. Drain coolant. Remove air cleaner assembly. Remove hood. Disconnect engine harness connector. Disconnect vacuum, radiator and heater hoses. Remove A/C compressor with hoses attached and position aside.

NOTE:

On "W" Body, engine only is lifted from engine compartment. Transaxle is removed separately from below vehicle.

2. Remove alternator and bracket. Remove engine torque strut. Disconnect throttle and transaxle linkage. Remove engine-to-transaxle bolts, except 2 upper bolts. 3. Install Engine Support Fixture (J-28467-A) and Engine Support Adapter (J-36462). Raise vehicle. Remove engine mount-to-frame nuts. Disconnect exhaust pipe and position aside. Remove torque converter cover. Remove torque flexplate-to-torque converter bolts. Remove starter motor. Remove power steering pump with hoses attached and position aside. Disconnect fuel line. 4. Support transaxle. Remove 2 remaining engine-to transaxle bolts and rear support bracket. Remove transaxle from engine. Lower vehicle. Attach engine hoist and remove engine. Installation

To install, reverse removal procedure. With engine off, fill thermostat housing until level is even with base of radiator neck. Install radiator cap. Continue to fill thermostat housing until level is 1/2" below top of thermostat housing. Install thermostat and thermostat housing cap. Fill coolant recovery reservoir to 1 1/4" above HOT mark. Run engine 5 minutes. Check coolant level in reservoir tank. Add coolant to HOT mark. V6 MODELS - 3.1L CAUTION: Relieve fuel pressure. Install Fuel Pressure Gauge (J-34730-1) on fuel rail service valve. Place bleed hose into approved container and bleed fuel system. Removal ("A", "J", "L" & "W" Bodies)

1. Disconnect battery cables. Remove air cleaner. Drain cooling system. Remove engine strut bracket from radiator support and position to rear. Remove A/C compressor from engine, leaving rear mounting bracket attached and hang from body. NOTE:

On "A", "J", "L" & "W" Bodies, engine and transaxle assembly are removed from below vehicle.

2. Disconnect vacuum hoses. Disconnect accelerator cable and TV cable (if equipped). Disconnect engine harness from ECM and pull connector through front of dash. Disconnect engine harness from junction block at left side of dash panel. 3. Disconnect radiator and heater hoses from engine. Remove power steering pump and bracket from engine and lay aside (if equipped). Disconnect fuel lines at rubber hose connections on left side of engine compartment. 4. Raise and support vehicle. Remove tire and wheel assemblies. Remove right side splash shield and oil filter. Remove lower engine wiring. Remove exhaust down pipe from crossover pipe. Remove brake calipers and rotors. Remove tie rods from struts. 5. Lower vehicle enough to support engine/transaxle on engine/transaxle table. Remove remaining engine/transaxle-to-frame bolts. Lower table and raise vehicle. Separate engine from transaxle.

Installation

To install, reverse removal procedure. With engine off, fill radiator until level is even with base of radiator neck. Ensure air bleeds on thermostat housing and bypass pipe are tightly closed. Start engine and let idle for 5 minutes, adding coolant as necessary to maintain level. Install radiator cap. Add coolant to recovery reservoir level HOT mark. Removal ("F" Body)

1. Disconnect battery cables. Remove air cleaner. Mark hinges for installation and remove hood. Drain cooling system. Remove lower radiator hose. Remove upper fan shroud. Remove upper radiator hose and coolant recovery hose. NOTE:

On "F" Body, only the engine is lifted from engine compartment.

2. Discharge A/C system and disconnect A/C lines. Disconnect transmission cooler lines at radiator (if equipped). Remove radiator. Remove fan assembly. Remove heater hoses. 3. Disconnect throttle and cruise control detent linkages from throttle valve. Disconnect all vacuum lines and wiring to engine. Remove distributor cap. 4. Remove power steering pump and position aside with hoses connected. Raise and support vehicle. Remove exhaust pipes at manifolds. Remove transmission torque converter cover. Match mark and remove flexplate-to-converter bolts. Disconnect starter wires. 5. Remove transmission-to-engine bolts. Remove motor mount through bolts. Lower vehicle. Support transmission with jack. Install engine lift. Remove engine, disconnecting wire from bracket at left rear of engine. Installation

To install, reverse removal procedure. With engine off, fill radiator until level is even with base of radiator neck. Add coolant to recovery reservoir COLD FILL mark. Start engine and let idle until upper radiator hose becomes hot. Add coolant as necessary to maintain level. Install radiator cap. V6 MODELS - 3.3L CAUTION: To depressurize fuel system, raise vehicle and disconnect fuel tank electrical connection to disable fuel pump. Start and run engine until fuel is exhausted and engine will not restart. Removal ("A" & "N" Bodies)

1. Remove hood. Depressurize fuel system. Remove negative battery cable. Disconnect fuel lines from fuel rail. Disconnect air intake duct. Drain cooling system. Disconnect radiator and heater hoses. Remove engine cooling fan. Raise and support vehicle. NOTE:

On "A" & "N" Bodies, only engine is lifted from engine compartment.

2. Disconnect electrical connections and vacuum hoses. Disconnect cables and bracket at throttle body. Remove drive belt. Remove power steering pump and set aside. Remove upper transaxle-to-engine bolts. 3. Raise vehicle on hoist. Disconnect A/C compressor and set aside (if equipped). Remove rear engine mount-to-mount bracket bolts. Remove flexplate cover. Match mark flexplate-to-torque converter relationship to ensure proper reassembly. Remove flexplate-to-torque converter bolts. 4. Remove lower transaxle-to-engine bolts. One bolt is located between transaxle case and engine block and is installed in opposite direction. Lower vehicle. Disconnect front engine mount to bracket bolts. Using engine lift, remove engine. Installation

To install, reverse removal procedure. With engine off, fill surge tank until level is even with base of filler neck. Run engine until upper radiator hose is hot. Stop engine and observe coolant level in surge tank. If not above FULL line, carefully remove pressure cap and add coolant as necessary. Install cap. V6 MODELS - 3.8L CAUTION: Relieve fuel pressure. Install Fuel Pressure Gauge (J-34730-1) to fuel rail service valve. Place bleed hose into approved container and bleed fuel system. Removal ("C", "E" & "H" Bodies)

1. Remove negative battery cable. Remove airflow sensor wiring. Disconnect air intake duct. Drain cooling system. Disconnect upper engine strut. Raise and support vehicle. NOTE:

On "C", "E" & "H" Bodies, engine only is lifted from engine compartment.

2. Disconnect exhaust pipe. Disconnect engine mount bolts. Remove starter wiring and starter. Disconnect A/C compressor and set aside (if equipped). 3. Remove lower transaxle-to-engine bolts. One bolt is located between transaxle case and engine block and is installed in opposite direction. Remove flexplate cover. Match mark flexplate-to-torque converter relationship to ensure proper reassembly. Remove flexplate-to-torque converter bolts. 4. Disconnect engine support bracket at transaxle. Lower vehicle. Remove radiator hoses. Disconnect heater hoses at engine. Remove alternator. Disconnect engine wiring harness. Remove remaining transaxle-toengine bolts. Remove engine. Installation

To install, reverse removal procedure. Fill radiator to base of filler neck. Start engine. Place heater-A/C control in A/C mode and at highest temperature setting. Run engine to 3000 RPM and back to idle 5 times to expel any trapped air in system. Refill radiator as necessary. Install radiator cap. Allow engine to cool. Check coolant level in reservoir. Add coolant as necessary to bring level to ADD or FULL COLD mark. V8 MODELS - 4.5L

CAUTION: Relieve fuel pressure. Install Fuel Pressure Gauge (J-34730-1) to fuel rail service valve. Place bleed hose into approved container and bleed fuel system. Removal ("C", "E" & "K" Bodies)

1. Disconnect battery cables. Drain cooling system. Remove air cleaner. Mark hinges for reassembly reference and remove hood. Disconnect A/C hose strap from right strut tower. Disconnect A/C accumulator from bracket and move aside. 2. Disconnect canister hose and ground wire from A/C accumulator bracket. Disconnect A/C accumulator bracket from wheelwell. Remove cooling fan. Remove accessory drive belt and heater hose. Remove upper radiator hose. 3. Disconnect engine wiring. Disconnect cables at throttle lever. Disconnect cruise control diaphragm with bracket and set aside. Disconnect vacuum hoses. Disconnect exhaust crossover pipe. 4. Disconnect oil cooler lines from oil filter adapter. Disconnect oil cooler line bracket at transaxle and move lines aside. Remove air cleaner bracket. 5. Disconnect fuel lines at throttle body. Disconnect fuel line bracket at transaxle and move fuel lines aside. Remove Air Injection Reaction (AIR) valve with bracket. Remove pulley idler. 6. Remove power steering hose strap from stud bolt. Remove stud bolt. Remove AIR pipe clip. Remove power steering pump and belt tensioner with bracket and move aside. Raise and support vehicle. 7. Remove both flexplate covers. Remove starter and flexplate-to-converter bolts. Remove A/C compressor lower dust shield. Remove right front tire and wheel assembly. Remove outer wheelhouse plastic shield. 8. Remove A/C compressor mounting bolts and lower compressor aside. Remove lower radiator hose. Remove driveline vibration damper with brackets from lower right front of engine and cradle. Pull alternator wire with plastic cover down, out of way. Remove right front engine-to-transaxle bracket bolts. 9. Remove exhaust pipe-to-manifold bolts and springs. Remove the AIR pipe-to-converter bracket from the exhaust manifold stud. Remove lower right transaxle-to-engine bolt. Lower vehicle and support engine. 10. Remove upper transaxle-to-engine bolts. Remove left front engine mount bracket-to-engine bolts. See Fig. 1. Remove engine.

Fig. 1: Identifying Engine & Transmission Mounts Installation

To install, reverse removal procedure. Fill radiator to base of filler neck. Start engine. Place heater control in DEF mode and at 90 degree temperature setting. Run engine at 2000 RPM for 10 minutes. Refill radiator as

necessary. Install radiator cap. Stop engine. Check coolant level in reservoir. Add coolant as necessary to bring level to FULL mark. V8 MODELS - 5.0L & 5.7L (VIN 7) CAUTION: To relieve fuel pressure on TBI models (except TBI model 220 with internal bleed). Remove fuel pump fuse. Start and run engine until engine dies from lack of fuel. Engage starter for an additional 3 seconds. On TBI model 220, remove gas cap to relieve tank pressure. No further procedures necessary. On PFI models, install Fuel Pressure Gauge (J-34730-1) on fuel rail service valve. Place bleed hose into approved container and bleed fuel system. Removal ("B", "D" & "F" Bodies)

1. Disconnect battery and remove air cleaner. Drain radiator. Disconnect radiator hoses and remove upper fan shroud. Remove fan assembly. Disconnect heater hoses at engine. 2. Remove power steering pump and lay aside. Remove A/C compressor and lay aside. Disconnect accelerator and throttle valve cable. Disconnect cooler lines at radiator (if equipped). Remove radiator. 3. Disconnect vacuum hoses. Disconnect Computer Command Control (CCC) wiring harness. Disconnect Air Injection Reaction (AIR) hose at pipe from converter. Remove washer bottle. Disconnect engine wiring harness at bulkhead. Disconnect necessary wires. Remove hood. 4. Remove distributor cap. Disconnect cruise control cable. Disconnect positive battery cable. Disconnect negative battery cable at A/C hose bracket and alternator bracket. Raise and support vehicle. 5. Remove crossover pipe and catalytic converter as an assembly. Remove flexplate cover. Remove torque converter bolts. Remove motor mount bolts. Disconnect fuel hose at fuel pump (carbureted) or at in-line filter (TBI) or at fuel rail (PFI). Disconnect torque converter clutch wiring at transmission. 6. Disconnect transmission cooler lines at clip on engine pan. Remove transmission-to-engine bolts. Lower vehicle. Support transmission. Install lifting device and remove engine. Installation

To install, reverse removal procedure. With engine off, fill radiator until level is even with base of filler neck. Fill coolant recovery reservoir to COLD FILL mark. Install coolant recovery reservoir cap. Run engine until radiator inlet hose is hot. With engine at idle, add coolant to radiator until level is even with base of filler neck. Install cap. V8 MODELS - 5.7L (VIN 8) CAUTION: Install Fuel Pressure Gauge (J-34730-1) on fuel rail service valve. Place bleed hose into approved container and bleed fuel system. Removal ("F" & "Y" Bodies)

1. Disconnect negative battery cable. Drain coolant. Remove air cleaner. Remove serpentine belt. Remove braces at back of A/C compressor. Disconnect wires at A/C compressor.

2. Remove plenum extension (if equipped). Disconnect fuel lines at front fuel hose-to-fuel line connection. Remove A/C compressor mounting bracket nuts and bolts. Disconnect heater hoses. Disconnect upper radiator hose at thermostat outlet. 3. Remove A/C compressor-to-mounting bracket bolt and move compressor aside. Remove mounting bracket. Disconnect Port Fuel Injection (PFI) harness at engine. Disconnect cruise, detent and accelerator cables. 4. Remove distributor cap and wires from spark plugs and remove as an assembly. Disconnect detent cable bracket at intake. Remove distributor. Remove cowl screen. Remove nut from wiper motor and remove wiper motor. Disconnect wires at oil pressure sending unit. Disconnect vacuum hoses. 5. Remove power steering pump and wire aside. Remove crankshaft pulley. Disconnect bulkhead connector and necessary connectors. Disconnect Air Injection Reaction (AIR) hose at converter check valve. Move fuel lines out of way. 6. Disconnect radiator hose at water pump. Disconnect upper radiator hose at power steering reservoir bracket. Raise and support vehicle. Drain engine oil and remove oil filter. Remove oil cooler adapter at engine. Disconnect AIR pipe at exhaust manifold. Remove AIR converter pipe. 7. Disconnect "Y" pipe hanger. Disconnect heat shields at "Y" pipe and converter. Disconnect oxygen sensor wire. Remove "Y" pipe. Remove flexplate/flywheel cover. On A/T models, remove torque converter bolts. On M/T models, remove transmission-to-bellhousing bolts. 8. On all models, loosen motor mount through bolts. Remove motor mount-to-engine block bolts. On A/T models, remove bellhousing bolts and lower vehicle. On all models, disconnect knock sensor wire. Disconnect ground cable at engine. Disconnect positive battery cable at battery and harness. 9. Lower vehicle. Support transmission with floor jack. Install engine lift. Carefully lift engine out of vehicle, disconnecting wire from bracket at left rear of engine. Installation ("F" Body)

To install, reverse removal procedure. With engine off, fill radiator until level is even with base of filler neck. Fill coolant recovery reservoir to COLD FILL. Install coolant recovery reservoir cap. Run engine until radiator inlet hose is hot. With engine at idle, add coolant to radiator until level is even with base of filler neck. Install cap. Installation ("Y" Body)

To install, reverse removal procedure. With engine off, fill radiator until level is even with base of filler neck. Fill coolant recovery reservoir to COLD mark. Add coolant to high fill reservoir to base of filler neck. Install coolant recovery reservoir cap. Run engine until radiator inlet hose is hot. Add coolant to high fill reservoir to maintain level at base of filler neck. Add 2 Cooling System Sealer Pellets GM (1051687). Install cap. Fill coolant recovery reservoir to HOT mark.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS (4-CYLINDER) Application 2.0L Flexplate-to-Converter Bolts

Ft. Lbs. (N.m) 31 (42)

Left Front Engine Mount Bolts Right Rear Engine Mount Bolts Right Rear Mount-to-Frame Bolts Transaxle-to-Engine Bolts 2.2L Flexplate-to-Converter Bolts Front Engine Mount-to-Engine Bolts Lower Engine Mount-to-Engine Bolts Engine Mount-to-Frame Bolts Starter-to-Engine Bolts Transaxle-to-Engine Bolts 2.3L Flexplate-to-Converter Bolts Engine Mounts-to-Engine Bolts Transaxle-to-Engine Bolts M10 M12 2.5L Flexplate-to-Converter Bolts Engine Mount-to-Engine Bolts Engine Mount-to-Frame Bolts Starter-to-Engine Bolts Transaxle-to-Engine Bolts TORQUE SPECIFICATIONS (V6) Application 3.1L Eng. Mntg. Brkt.-to-Engine Bolts Eng. Mntg. Torque Strut Brkt. Bolts Flexplate-to-Converter Bolts Starter-to-Engine Bolts Transaxle-to-Engine Bolts 3.3L & 3.8L Flexplate-to-Converter Bolts Engine Mount-to-Engine Bolts Engine Mount-to-Frame Bolts Starter-to-Engine Bolts Transaxle-to-Engine Bolts TORQUE SPECIFICATIONS (V8) Application

18 (24) 38 (52) 38 (52) 42 (57) 31 (42) 25-35 (34-47) 15-20 (20-27) 35-45 (47-61) 26-37 (35-50) 48-63 (65-85) 46 (61) 55 (76) 41 (56) 71 (96) 31 (42) 35 (47) 35 (47) 31 (42) 55 (75)

Ft. Lbs. (N.m) 70-92 (95-125) 30-40 (41-54) 25-35 (34-47) 26-37 (35-50) 55 (75) 35 (47) 66 (89) 66 (89) 35 (47) 35 (47)

Ft. Lbs. (N.m)

4.5L Flexplate-to-Converter Bolts Engine Mount-to-Engine Bolts Engine Mount-to-Frame Bolts Starter-to-Engine Bolts Transaxle-to-Engine Bolts Transaxle-to-Engine Bracket Bolts 5.0L & 5.7L Except 5.7L VIN 8 ("F" & "Y" Bodies) Crankshaft Pulley Bolts Flexplate-to-Converter Bolts Engine Mount-to-Engine Bolts Engine Mount-to-Frame Bolts Engine Mount Through Bolts Starter-to-Engine Bolts Transmission-to-Engine Bolts 5.7L VIN 8 ("F" & "Y" Bodies) Crankshaft Pulley Bolt Center Outer Crankshaft Torsional Damper Bolt Flexplate-to-Converter Bolts Engine Mount-to-Engine Bolts Engine Mount Through Bolts Torque Converter-to-Flexplate Bolts Transmission-to-Bellhousing Bolts (M/T) Transmission-to-Engine Bolts (A/T)

46-48 (62-65) 33 (45) 65 (88) 30 (41) 55 (74) 33 (45)

43 (58) 35 (47) 47 (64) 47 (64) 55 (75) 30 (41) 35 (47)

70 (95) 32 (43) 60 (81) 35 (47) 41 (56) 40 (54) 46 (62) 37 (50) 35 (47)

FUSES & CIRCUIT BREAKERS Fuses & Circuit Breakers Cadillac RWD

FUSES & CIRCUIT BREAKERS ACCESSORY FUSE & RELAY PANEL ID (CADILLAC)

Fig. 1: Accessory Fuse & Relay Panel ID (Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Circuit Breaker Identification         

1 - Blank 2 - Relay Electronic Level Control 3 - Relay (5.7L) Fuel Pump; Blank (5.0L) 4 - Blank 5 - Relay Park/Neutral 6 - Relay Antenna 7 - Relay Horn 8 - Blank; Relay (1991-92) Starter Interrupt 9 - Relay Rear Window Defogger

        

10 - Relay Parking Lights, Running Lights; Blank (1992) 11 - 3 Amp Fuse (5.7L) Crank Signal; Blank (5.0L) 12 - 10 Amp Fuse (5.7L) Fuel Pump; Blank (5.0L) 13 - Blank 14 - 7.5 Amp Fuse (5.7L) Fuel Injection System; Blank (5.0L) 15 - Blank 16 - 15 Amp Fuse Ignition System 17 - 3 Amp Fuse ECM 18 - 3 Amp Fuse (5.0L) Anti-Diesel Solenoid; Blank (5.7L); Blank (1991-92)

FUSE PANEL IDENTIFICATION ( CADILLAC)

Fig. 2: Fuse Panel Identification ( Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Circuit Breaker Identification 

  

1 - 10 Amp Engine Compartment Light (), Front Ashtray Light, E.C.C. Head, Radio, Theft Deterrent, Turn/Hazard, Front Marker, Park Turn Lights, Instrument Panel Cluster (1990) 2 - 3 Amp Cruise Control, Instrument Panel Lights (1990) 3 - 30 Amp (Circuit Breaker) Power Windows, Trunk Release, Sun Roof 4 - 20 Amp Air Conditioning (1989), A/C Compressor Clutch, Electronic Climate Control, Instrument

  



    



 

Panel (1989), NO CHARGE Warning Light (1990), Rear Defogger Relay, Alternator (1990) 5 - 10 Amp Power Antenna 6 - 20 Amp Hazard Flasher, Brakelights, Electronic Climate Control 7 - 30 Amp (Circuit Breaker) Horn, Power Seats, Power Door Locks, Power Seat Recliners, Trunk Lid Pull-Down 8 - 20 Amp Gear Selector Switch, Rear Quarter Lights, Vanity Mirror Lights, Power Mirrors, Rear Compartment Lights, Door Lock Switches (1990), Instrument Courtesy Lights, Electronic Level Control, Instrument Panel Lights, Cigarette Lighter, Glove Box Light, Key Warning Buzzer, Illuminated Entry, Door Locks 9 - 10 Amp Anti-Lock Braking System (1990) 10 - 25 Amp Rear Window Defogger 11 - 25 Amp Windshield Wiper/Washer 12 - 10 Amp Radio 13 - 20 Amp Automatic Door Locks, Illuminated Entry, Trans. Converter Clutch Brake Switch, Seat Belt Reminder (1989), Anti-Lock Brake System (1990), Theft Deterrent, Electronic Level Sensor Relay, Emission Control Solenoid (1990), Instrument Panel Warning Lights, Audio Alarm, CHECK ENGINE Light (1989) 14 - 20 Amp Front Cigarette Lighter, Glove Box Light, Radio, Engine Compartment Light (1989), Passive Restraint Belts Module 1990), Audio Alarm, Instrument Panel Cluster 15 - 20 Amp Turn Signal Flasher 16 - 20 Amp Twilight Sentinel Module, Headlight Switch, Headlight Dimmer Switch (1989), Instrument Panel Dimming Control (1990), Left Opera Light, License Plate Light, Rear Taillights, Stoplights & Turn Lights 17 - 10 Amp Back-Up Lights (1990), Gear Selector Switch, Automatic Mirror 18 - 5 Amp Instrument Panel (1989), Wiper/Washer (1989), Electronic Climate Control (1989), Cruise Control (1989), Radio (1989), Light Switch Light (1989), Audio Alarm Module (1989), Light Switch (1989), Dimmable Instrument Panel Lights (1990)

FUSE PANEL IDENTIFICATION (1991-92 CADILLAC)

Fig. 3: Fuse Panel Identification (1991-92 Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Circuit Breaker Identification 

  

1 - 10 Amp Radio, Instrument Panel Cluster, Ashtray Light, Engine Compartment Light, Cornering, Side Marker & Front Park Lights 2 - 3 Amp Cruise Control, EVO Module, Instrument Panel Cluster 3 - Circuit Breaker Power Windows, Trunk Release, Astroroof 4 - 20 Amp A/C Cut-Out Relay, Electronic Climate Control, No Charge Tell-Taillight, Alternator, Rear

   

    



 

Defogger Relay 5 - 10 Amp Power Antenna 6 - 20 Amp Hazard Flasher, Brakelight, Electronic Climate Control Head 7 - Circuit Breaker Horn, Power Seats, Power Door Locks, Power Seat Recliners, Trunk Lid Pull-Down 8 - 20 Amp Electronic Level Control, Illuminated Entry, Power Door Locks, Courtesy Lights, Gear Select Switch, Rear Quarter Lights, Lighted Vanity Mirrors, Power Mirrors, Rear Compartment Light, Right Front & Rear Doors Cigarette Lighter, Door Latch Switches, Passive Restraint 9 - 10 Amp Anti-Lock Braking System 10 - 25 Amp Rear Window Defogger 11 - 25 Amp Windshield Wiper/Washer 12 - 10 Amp Radio 13 - 20 Amp Automatic Door Locks, Illuminated Entry, Transmission Converter Clutch Brake Switch, Anti-Lock Brake System, Theft Deterrent, Electronic Level Sensor, Instrument Panel Tell-Tails Audio Alarm Chime, Electronic Level Control Relay 14 - 20 Amp Front Cigarette Lighter, Glove Box Light, Radio, Passive Restraint Belts Module, Audio Alarm Chime, Instrument Panel Cluster 15 - 20 Amp Turn Signal Flasher 16 - 20 Amp Twilight Sentinel Module, Headlight Switch, Instrument Panel Dimming Control, Left Opera Light, License Plate Light, Park/See Park Fuse 17 - 10 Amp Back-Up Lights, Gear Selector Switch, Automatic Day Night/Mirror 18 - 5 Amp Dimmable Instrument Panel Illumination

CAUTIONS & WARNINGS ANTI-LOCK BRAKE SYSTEM On models equipped with anti-lock brake systems, ALWAYS observe the following cautions: 



DO NOT attempt to bleed hydraulic system without first referring to appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES Section. DO NOT mix tire sizes. As long as tires remain close to the original diameter, increasing the width is acceptable. Rolling diameter must be identical for all 4 tires. Some manufacturers recommend tires of the same brand, style and type. Failure to follow this precaution may cause inaccurate wheel speed readings. Use ONLY recommended brake fluids. DO NOT use silicone brake fluids in an ABS-equipped vehicle.

SUPPLEMENTAL RESTRAINT (AIR BAG) SYSTEM CAUTION: The Diagnostic Energy Reserve Module (DERM) can maintain enough voltage to cause a deployment of the inflator module for up to 10 minutes after the ignition switch is turned off and the battery is disconnected. Many of the service procedures require disconnection of the inflator module to avoid an accidental deployment.

HEADLIGHTS - AUTOMATIC ACCESSORIES & EQUIPMENT General Motors Headlights - Automatic Twilight Sentinel

DESCRIPTION & OPERATION DESCRIPTION The twilight sentinel system automatically controls on-off operation of headlights, taillights, and instrument panel lights in response to ambient light. A time delay control allows lights to remain on for a preselected period after ignition is turned off. A photocell is mounted face up under speaker or defroster grille. An amplifier unit is mounted on lower instrument panel brace. A time delay and on-off switch is attached to light switch behind the light switch knob. AUTOMATIC OPERATION Twilight sentinel system will operate automatically when ignition switch is in ON position or headlight switch is in OFF position and the control ring pointer is turned on. System will automatically activate lights when level of available light corresponds to dusk. At daybreak, system will turn lights off. Sudden changes in lighting such as passing through tunnels or under bright lights will not cause system to cycle, due to a 10-60 second delay before amplifier switches system on or off. A variable time-delay switch control permits the driver to select a delay period before the headlights turn off. This can be a few seconds to a maximum of 4 1/2 minutes after ignition switch is turned off. Additional lighting may be provided (during this period) by turning on cornering lights (if equipped). All lights will turn off automatically at end of time-delay period selected by driver. MANUAL OPERATION If lights are to be used during daylight hours, 2 methods may be used. If photocell assembly is covered, lights will turn on. This allows lights to be turned off in normal manner when ignition is off. Lights can also be turned on using regular light switch after turning time-delay switch to OFF position.

TROUBLE SHOOTING LIGHTS DO NOT TURN ON IN DARKNESS Loose connection at light switch or amplifier connector. Open wiring between fusible link and light switch. Inoperative light switch (circuit breaker). Open ground path through on-off switch of time delay control assembly. Inoperative photocell or amplifier. LIGHTS DO NOT TURN OFF IN DAYLIGHT

Amplifier sensitivity control out of adjustment. Inoperative photocell or amplifier. Poor contact between photocell and socket, or socket disengaged from mounting hole. LIGHTS DO NOT TURN OFF AFTER IGNITION IS OFF Ignition switch wire has power with key off. Fuse blown. Inoperative time delay control. Open wiring in circuit. Inoperative amplifier. Malfunctioning photocell. LIGHTS DO NOT STAY ON PROPER TIME SPAN AFTER IGNITION IS OFF Inoperative time delay control assembly. Blown taillight fuse. Improper resistance at amplifier connector. Short in wiring circuit. Inoperative amplifier. WARNING CHIME WILL NOT OPERATE Open wire in chime circuit. Inoperative door jam switch. Poor connection at light switch. Inoperative amplifier. Blown fuse. Time delay control malfunction. WARNING CHIME SOUNDS WHEN IT SHOULD NOT Open wire to ignition light switch. Open ground wire to chime module. Malfunctioning amplifier.

TESTING SYSTEM TEST NOTE:

With time-delay control in ON position and headlight knob in OFF position, check that photocell is not obstructed. Lighting system will work properly when manually operated. Check all fuses for continuity.

1. With sentinel in OFF position, check for proper operation of parking lights, headlights and taillights, using light switch. Place light switch in manual ON position with ignition off. Open a door. Warning chime should operate. Turn lights off. 2. Turn sentinel on after covering photocell. With ignition on, lights should come on automatically within 10-30 seconds. Remove cover and shine a bright light onto photocell. 3. Light should turn off after a 10-60 second delay. Cover photocell and wait for light to turn on. Wait 15 seconds and turn ignition off. Lights should turn off after a few seconds when control is in off position and after 1 1/2 - 4 1/2 minutes when control is in maximum position. 4. Satisfactory performance of steps 1) through 3), indicates unit is operating properly. If unit is operating properly but turn-on time is incorrect, make minor sensitivity adjustment (Toronado only).

REMOVAL & INSTALLATION AMPLIFIER & PHOTOCELL Remove instrument panel top cover, photocell mounting bracket and electrical connector. Remove photocell. To

remove amplifier, remove lower left sound absorbing panel. Remove amplifier module from air duct. Remove electrical connectors. To install, reverse removal procedure.

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

A/C-HEATER SYSTEM - AUTOMATIC AUTOMATIC A/C-HEATER SYSTEMS General Motors Passenger Cars

A/C SYSTEM SPECIFICATIONS A/C SYSTEM SPECIFICATIONS Application Compressor Type Compressor Belt Tension New Used Refrigerant (R-12) Capacity System Oil Capacity System Operating Pressures (1) High

Specification Harrison R-4 (4-Cyl.) 167 lbs. (76 kg) 112 lbs. (51 kg) Information Not Available 6.0 oz. (177 cc) 165-200 psi (12-14 kg/cm2 )

22-29 psi (1.5-2.0 kg/cm2 ) (1) Approximate operating pressures with ambient temperature of 80°F (27°C). Low

WIRING DIAGRAM

Fig. 1: Brougham Climate Control A/C-Heater Wiring Diagram

DESCRIPTION CAUTION: When discharging air conditioning system, use only approved refrigerant recovery/recycling equipment. Make every attempt to avoid discharging refrigerant into the atmosphere. The Electronic Climate Control (ECC) is used on all Brougham models. System automatically regulates and maintains driver selected in-car temperatures from 60째F (16째C) maximum cool to 90째F (32째C) maximum heat regardless of changes in outside temperature. A control panel is used in selecting an in-car comfort level. Other main components comprising the climate control system are: The Electronic Control Module (ECM), programmer, power module, temperature sensors, and refrigeration system.

OPERATION CONTROL PANEL

The control panel is located in the center of instrument panel. Control panel contains a microprocessor providing central control over system components. All system switches and sensors are monitored by the control panel. See Fig. 2 . Based on system inputs and program instructions contained within control panel memory, microprocessor calculates proper outputs to provide accurate control of ECC system.

Fig. 2: Brougham Control Panel Courtesy of GENERAL MOTORS CORP. TEMPERATURE & MODE SETTINGS To change temperature settings, press "WARMER" or "COOLER" button until temperature setting is displayed. When a temperature of 65°F (18°C) is selected and "COOLER" button is pressed again, system will go into maximum cool 60°F (16°C). When a temperature of 85°F (29°C) is selected and "WARMER" button is pressed again, system will go into maximum heat 90°F (32°C). Maximum cool or heat will continue until another temperature setting is selected. "OFF" Mode

In this mode, blower motor and A/C compressor will not run. System will still try to reach temperature range selected. However, it cannot cool vehicle colder than outside temperature. "ECON" Mode

In this mode, A/C compressor will not run. Blower motor speed and air outlet positions are automatically controlled by various inputs. All incoming air into A/C-heater module is from outside air. The ECC system will

adjust to temperature range selected. However, it cannot cool vehicle colder than outside temperature. "AUTO" Mode

In this mode, ECC system is controlled automatically by various A/C system inputs. System has the capability to control blower motor speed and air inlet or outlet position to maintain selected temperature. Defrost Mode

In this mode, ECC system is controlled automatically as in "AUTO" mode, except that air is always delivered out defroster grille on top of instrument panel. TEMPERATURE SENSOR INPUT There are 4 temperature inputs monitored by control panel to provide control of ECC system. These temperature values are sent to control panel via thermistors, which decrease in resistance as they get hotter. In-Car Temperature Sensor

This sensor is located on far right side of instrument panel. A small amount of in-car air is drawn into sensor housing and over thermistor. The air movement is accomplished by using an aspirator mounted on top of A/Cheater module. Airflow from A/C-heater module creates a slight vacuum at one end of aspirator. This vacuum draws in-car air through temperature sensor housing. The resistance value of the sensor is sent to control panel. Outside Temperature Sensor

This thermistor-type sensor has no effect on in-car temperature. It is used only to monitor outside air temperature, which is then displayed on control panel. It is located in a small protective housing, just rear of radiator grille. To display outside temperature, press "OUTSIDE TEMP" button. Coolant Temperature Sensor

Coolant temperature sensor is located in a coolant passage of intake manifold. On models equipped with 5.0L engine, thermistor resistance is monitored by control panel. On models with 5.7L engine, Electronic Control Module (ECM) monitors temperature and sends the value to control panel via ALDL circuit. A/C Low Side Temperature Sensor

This sensor is located in low pressure refrigerant line between orifice tube and evaporator. The control panel monitors this sensor to determine A/C low side pressure. LOW REFRIGERANT PRESSURE SWITCH Low refrigerant pressure switch is located at rear head of A/C compressor. Switch is closed when pressurized and allows compressor clutch relay to engage. If pressure drops below approximately 25 psi (1.76 kg/cm2 ), switch opens and cuts off voltage to compressor clutch. On 5.7L engine, control panel monitors state of switch during compressor clutch operation and diagnostic purposes. On 5.0L engine, ECM monitors switch.

PROGRAMMER The programmer is attached to A/C-heater module behind glove box. Programmer can be identified by electrical and vacuum connectors attached to it. An electrical circuit board inside programmer accepts data signals from control panel and responds to these signals to provide controls for temperature regulation. Included in programmer is a DC motor, vacuum solenoids and circuit board. Circuit board is an amplifier and logic board. Programmer accepts electrical signals from sensors and mode push buttons in control panel and provides output control signals. A reversible DC motor located inside programmer actuates a rotary shaft to drive air-mix door link. Signals from circuit board actuate vacuum solenoids within programmer. These solenoids control heater control valve, air door, mode door and defroster door positions. AIR-MIX DOOR LINKAGE Linkage consists of a plastic crank arm integral with programmer output shaft, a serrated nylon retainer and a threaded rod. One end is connected to air-mix door. Opposite end is retained by serrations in nylon retainer. POWER MODULE Transistorized power module is mounted on top of evaporator-blower assembly. It receives signals from control panel to cycle A/C compressor clutch. Power module amplifies signals to provide variable blower speeds. A heat sink, which protrudes into airflow in evaporator case, prevents module from overheating. PROGRAM NUMBER Program number is a number calculated by control panel to express the amount of heating or cooling required to meet desired inside temperature. The variables this program number is based on are: Set temperature on control panel, outside temperature and in-car temperature. The calculated program number is used to determine proper air delivery mode and blower speed. Program number is also a factor in determining air-mix valve position. A program number of "0" represents maximum system cooling and "255" (100 percent) represents maximum system heating. As in-car temperature nears desired set temperature, program number will begin to approach a value appropriate for maintaining comfort based on certain ambient conditions. Program number can be observed when in diagnostic mode. A self-diagnostic feature allows technician to manually override calculation of program number to observe system operation throughout working range. AIR-MIX DOOR POSITION Proper air-mix door position is determined by control panel. In order to provide proper mix of warm and cool air, control panel monitors these variables: In-car temperature, outside temperature, low side temperature, and coolant temperature.

Based on these inputs and depending on current program number, control panel can send a signal to position air-mix valve for appropriate blend of air through evaporator core and heater core. By monitoring feedback potentiometer on programmer DC motor, control panel commands programmer to move air-mix valve until desired position is achieved. COMPRESSOR CLUTCH CONTROL On 5.0L engine, compressor clutch is controlled by Electronic Control Module (ECM) based on inputs to control panel and ECM. On 5.7L engine, the ECC system has direct control of compressor clutch. Inputs to ECM are: Engine coolant temperature, throttle position sensor and power steering pressure switch. Inputs to control panel are: In-car temperature, vehicle speed (5.0L), A/C low side (evaporator inlet), outside air temperature, refrigerant low pressure switch (5.7L), and engine coolant temperature. The voltage source to compressor clutch is from 20-amp A/C fuse, which is switched through a relay controlled by IGN-3 signal. Inputs to ECM used for compressor clutch control are: A/C cycling signal (5.0L), A/C request input from control panel, engine coolant temperature (5.7L), vehicle speed (5.7L), and engine RPM (5.7L). When all inputs to control panel are within calibration values, compressor clutch will engage if these parameters are met: Coolant temperature is less than 248°F (120°C), ECC is set to "AUTO" or defrost, outside temperature is greater than 43°F (6°C), and evaporator inlet temperature is greater than 48°F (9°C). When compressor clutch is enabled during any of the above conditions, it will remain on for a minimum of 4 seconds. During compressor on cycle, these conditions will force control panel to disengage compressor clutch: Ambient temperature is less than 39°F (4°C), A/C low pressure switch is open, A/C low side temperature is less than 30° F (-1°C), coolant temperature is greater than 258°F (125°C), and open or shorted A/C low side sensor circuit. When compressor is disabled for any of the above conditions, compressor clutch will remain off for a minimum of 4 seconds.

ADJUSTMENTS AIR-MIX DOOR LINKAGE 1. Remove glove box and set temperature on control panel to 90°F. Allow 1 or 2 minutes for programmer arm to travel to maximum heat position. Snap threaded rod from plastic retainer on programmer arm. See Fig. 3 . 2. Check air-mix door for free travel from full cold to full heat position. Preload in maximum heat position by pulling on threaded rod. Programmer output arm should align with arrow on programmer case. 3. Snap threaded rod into retainer on programmer arm. Set temperature to 60°F (16°C) and check for airmix door travel to maximum cool air position.

Fig. 3: Programmer & Air-Mix Door Linkage Courtesy of GENERAL MOTORS CORP.

TROUBLE SHOOTING NOTE:

Complete trouble shooting information was not available from manufacturer.

SELF-DIAGNOSTICS In the process of controlling A/C system, control panel continually monitors operating conditions for possible system malfunctions. By comparing system conditions against standard operating limits, certain circuit and component malfunctions can be detected. A 2 digit numerical trouble code is stored in computer memory when a problem is detected by self-diagnostic system. If a particular malfunction results in unacceptable system operation, self-diagnostics will attempt to minimize effect by taking FAILSOFT action. Failsoft action refers to any specific attempt by computer system to compensate for detected problem. A typical failsoft action would be the substitution of a fixed input value when

a sensor is detected to be open or shorted. ENTERING SELF-DIAGNOSTICS NOTE:

If any control panel segments do not illuminate after entering self-diagnostics, replace control panel.

1. To enter diagnostic mode, turn ignition to "ON." Press "OFF" and "WARMER" buttons on control panel simultaneously. Hold buttons until all control panel segments illuminate. Ensure all segments illuminate. This indicates beginning of diagnostic readout. See Fig. 4 . 2. After entering self-diagnostic mode, any trouble codes stored in computer memory will be displayed. If trouble codes are present, they will be displayed on control panel.

Fig. 4: Self-Diagnostic Basic Operation Courtesy of GENERAL MOTORS CORP. CLEARING TROUBLE CODES

Trouble codes can be cleared by entering self-diagnostic mode. Press "OFF" and "LO" buttons on control panel simultaneously and hold buttons until "00" appears. See Fig. 5 .

Fig. 5: Control Panel Status Display Lights Courtesy of GENERAL MOTORS CORP. CLIMATE CONTROL DIAGNOSTIC MODE OPERATION When in diagnostic mode, the ECC will operate in whatever mode is being commanded just prior to pressing "OFF" and "WARMER" buttons simultaneously. Even if display changes to "OFF" mode as buttons are pushed, prior operating mode is remembered and will resume after diagnostic mode is entered. STATUS DISPLAY LIGHTS When in diagnostic mode, the mode indicators on control panel are used to indicate status of certain system operating modes. See Fig. 5 . The different modes of operation are indicated by status lights either being turned ON or OFF. A brief summary of each status light is provided below: "OUTSIDE TEMP" Status Light

Status light is turned on when the A/C clutch is enabled or disabled by control panel. "째F" Status Light

Status light is turned ON when control panel senses refrigerant low pressure switch is open. This light will come on when ambient temperature falls to less than -5째F (-20째C) due to temperature pressure relationship of refrigerant. If A/C system is fully charged, this light should remain OFF. "째C" Status Light

Status light is turned ON when control panel is commanding heater water valve to block coolant flow through heater core. This light should remain OFF, except when air-mix valve is being commanded to maximum A/C ("0") position. "LO FAN" Status Light

Status light is turned ON when control panel is commanding A/C-heater mode valve to divert airflow to A/C outlets. Status light will be OFF when ECC system is in heater, heater/defrost, or defrost modes. "HI FAN" Status Light

Status light is turned on when control panel is commanding defroster/heater mode valve to divert airflow away from heater outlet to defrost outlet. Status light will be OFF when ECC system is in heater mode. CLIMATE CONTROL DATA DISPLAY CODES To display climate control parameter data information, proceed as follows: 1. Press and release "OUTSIDE TEMP" button on control panel. Electronic Climate Control (ECC) parameter series begins as display switches from "CODE DISPLAY" to parameter number display. It is possible to leave ECC parameter series anytime and return to parameter "-00" by clearing ECC codes. 2. To advance parameter display, press "HI" button on control panel. To return to lower number parameter or jump directly to end of parameter list, press "LO" button on control panel. 3. Switch between parameter code display (distinguished by a preceding minus sign) and parameter value display by pressing "OUTSIDE TEMP" button on control panel. 4. When trouble shooting a malfunction, data display codes can be used to compare vehicle problems with a vehicle functioning properly. Below is a list of climate control data display codes. Code "-02"

The ECC program number is read in counts between "0" and "255." Code "-10"

Ignition voltage (battery) is read in volts. Code "-11"

The ECC program number is read in percentage between "0" and "100." When in this display, ECC program override may be initiated. Code "-12"

Vehicle speed is displayed in MPH between "0" and "199." Code "-19"

Actual blower voltage is displayed in volts. Code "-20"

Commanded blower voltage is displayed in volts. Code "-21"

Coolant temperature is displayed in degrees Celsius (째C). Code "-22"

Commanded air-mix valve position is displayed in counts ("0" to "255"). A value close to "200" represents a cold air-mix valve position and a value close to "0" represents a warm air-mix valve position. Code "-23"

Actual air-mix valve position is displayed in counts ("0" to "255"). This value should follow commanded airmix valve position ("-22"), except when valve is commanded beyond its mechanical limit of travel. Code "-24"

Air delivery mode is displayed as a number from "0" to "6." Each number is a code representing air delivery mode. See AIR DELIVERY MODE CODES table. Code "-25"

In-car temperature sensor will be displayed in degrees Celsius (째C). Code "-26"

Actual outside temperature is displayed in degrees Celsius (째C). This value represents actual sensor temperature and is not restricted by features used to minimize engine heat effects on customer display value. Code "-28"

Low side temperature (evaporator inlet) is displayed in degrees Celsius (째C). Code "-29"

This parameter is used to distinguish ECC's version (5.0L or 5.7L). The 5.0L engine application will display "00". The 5.7L engine application will display "01." Code "-30"

Ignition cycle counter value is the number of times ignition is cycled from "OFF" to "START" since a trouble code was last detected. After 199 ignition cycles without any malfunction detected, all ECC codes are cleared and counter is reset to "0."

Code "-31"

Control panel calibration is displayed as a number up to 3 digits long and can be used to verify proper A/Cheater module calibration is installed in control panel. CLIMATE CONTROL DATA DISPLAY CODES Code -00 -01 -02 -10 -11 -12 -19 -20 -21 -22 -23 -24 -25 -26 -28 -29 -30 -31 NOTE:

Description ECC System Faults ECM Faults Program Number (In Counts) Ignition Voltage Program Number (In Percent) Vehicle Speed Actual Blower Voltage Commanded Blower Voltage Engine Coolant Temperature Commanded Mix Valve Position Actual Mix Valve Position Air Delivery Mode In-Car Temperature Outside Air Temperature Evaporator Inlet Temperature 5.0L or 5.7L Engine ("00" 5.0L) ("01" 5.7L) Ignition Cycle Counter A/C-Heater Calibration Identification

Because this article only covers climate control system, ECM codes and their descriptions are not supplied.

CLIMATE CONTROL DIAGNOSTIC CODES Code 00 10 12 13 19 32 40 48

Circuit Affected No ECC System Fault Outside Temperature Sensor Fault Evaporator Inlet Sensor Circuit Fault In-Car Temperature Sensor Circuit Fault Blower Motor Problem ECM/ECC Data Problem (5.7L) Air-Mix Valve Problem (1) Very Low A/C Refrigerant Pressure

Condition (5.7L) 49

(1) High Engine Temperature (5.7L)

Shorted Coolant Temperature Sensor (5.0L)

(1) Compressor off.

AIR DELIVERY MODE CODES Code 0 1 2 3 4 5 6

Mode Max A/C A/C Heater/Defroster Heater Defrost Delay Off

PROGRAM OVERRIDE During display of ECC program number on control panel, it will display a 2-digit number representing ECC program number. This number represents various levels of heating and cooling effort. As parameter "-02" or "11" appear on control panel, it will begin displaying program number currently being used by ECC system. As operating conditions change, this number will automatically change in response. Automatic calculation of program number can be by-passed by a manual override feature using "WARMER" or "COOLER" buttons. When in this display, pressing the "WARMER" button will force program number to increase at a controlled rate until maximum value is realized (maximum heat mode). Pressing "COOLER" button will force program number to decrease until value of "0" is reached (maximum A/C mode). Manual override of automatic program number calculation will continue until exiting from diagnostic mode. This allows technician to control program number to any number from maximum A/C to maximum heat and simultaneously observing reaction of any ECC parameter values. EXITING SELF-DIAGNOSTICS To exit self-diagnostic mode, press "AUTO" button or turn ignition switch to "OFF" for 10 seconds. Trouble codes are not erased when this is done. Temperature setting will reappear on control panel.

REMOVAL & INSTALLATION CONDENSER Removal & Installation

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Drain and remove radiator. Disconnect condenser inlet and outlet pipes and cap openings. Remove mounting screws, brackets and insulators from top of condenser. Remove condenser from vehicle. 2. To install, reverse removal procedure. Add 1 oz. refrigerant oil to new condenser. Use new "O" rings lubricated with refrigerant oil at connections. Evacuate and recharge system.

POWER MODULE Removal & Installation

Disconnect negative battery cable. Disconnect power module connector and ground wire. Remove screws attaching power module to A/C-heater module cover. Remove power module. To install, reverse removal procedure. EVAPORATOR CORE Removal & Installation

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect electrical leads from blower motor, thermostatic switch, power module and radio. Position wiring harness to side. See Fig. 6 . 2. Remove screws from compressor cycling switch, remove insulation, loosen hose clamps and remove switch. Remove right windshield washer nozzle. Remove screws to secondary inlet screen. 3. Remove attaching screw on right side and partially remove rubber molding above plenum. Remove remaining screws and remove primary inlet screen. Remove blower motor. Disconnect evaporator to accumulator connection at top of accumulator. 4. Remove screw and partially remove accumulator bracket. Remove all screws from top of evaporator case cover and remove cover. Disconnect condenser to evaporator connection. Remove evaporator core by lifting straight up and out. 5. Remove old sealer from surface of module cover and replace with new sealer. To install, position evaporator core in module and connect lines using new "O" rings. Add 3 oz. new refrigerant oil to new evaporator. Reverse removal procedure to complete installation.

Fig. 6: A/C-Heater Module Assembly Courtesy of GENERAL MOTORS CORP. HEATER CORE Removal & Installation

1. Disconnect negative battery cable. Partially drain cooling system. Disconnect electrical connectors from blower motor, compressor cycling switch, power module and radio connectors. Position wiring harness out of way. 2. Remove right windshield washer nozzle. Remove right secondary air inlet screen from plenum. Partially remove rubber molding above plenum. Remove screws and remove primary inlet screen. 3. Remove blower motor. Remove screws securing thermostatic switch to A/C-heater module and carefully reposition switch off of module cover. Remove 16 fasteners and A/C-heater module cover. 4. Clamp heater hoses to prevent leakage and disconnect hoses from core. Remove screw and retainer at top of core. With temperature door in maximum heat position, reach through housing and push lower forward

corner of core away from housing. 5. Rotate core parallel to housing to snap core out of clamp. Remove core. Remove old sealer from module cover and replace with new sealer. To install, reverse removal procedure. ORIFICE TUBE Removal & Installation

1. Discharge A/C system, using approved refrigerant recovery/recycling equipment, and disconnect evaporator inlet line. Remove as much impacted residue as possible and cap line and orifice opening. Remove orifice tube and "O" ring from inlet tube with needle nose pliers. 2. To install, coat new "O" ring with refrigerant oil and position on new orifice tube. Insert short end of orifice tube into inlet line first. Push until tube reaches a firm stop to seat "O" ring. Add 1 oz. refrigerant oil to system. Connect evaporator line. Evacuate and recharge system. LOW PRESSURE SWITCH Removal & Installation

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove air cleaner. Remove electrical connector at rear of compressor. Remove snap ring. Using pliers, remove switch from cavity. 2. Lubricate cavity with clean refrigerant oil and replace "O" ring. Install switch and snap ring. Pressurize compressor and check that switch is actuated between 20-30 psi (1.4-2.1 kg/cm2 ). Evacuate and recharge system. ACCUMULATOR Removal & Installation

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Clean all dirt and grease from system connection points. Loosen evaporator-to-accumulator and accumulator-to-compressor fittings. Cap openings to prevent moisture from entering system. 2. Remove mounting clamp and accumulator. Drain and measure refrigerant oil in accumulator. Remove caps from evaporator fittings and install accumulator. Use new "O" rings, lubricated with refrigerant oil. Add 2 oz. more oil than drained during removal. Reverse removal procedure to complete installation. IN-CAR TEMPERATURE SENSOR Removal & Installation

1. Remove screws from ends, front edge and in defroster ducts of dash top cover. Remove top cover. Remove screws and right instrument driver information panel. 2. After disconnecting aspirator hose and electrical connector, remove screws and sensor from driver information panel. To install, reverse removal procedure. Sensor must be positioned with electrical connector toward right side of vehicle.

CONTROL PANEL Removal & Installation

Disconnect battery ground cable. Remove center trim plate from dash. Remove screws attaching control panel to dash. Pull control panel out. Disconnect electrical leads and remove control panel. To install, reverse removal procedure. PROGRAMMER Removal & Installation

1. Disconnect battery ground cable. Remove glove box liner. Remove right side hush panel and ECM. Remove left hush panel. 2. Snap programmer arm from clip. Disconnect electrical and vacuum connectors. Remove screws and programmer. To install, reverse removal procedure. OUTSIDE TEMPERATURE SENSOR Removal & Installation

Disconnect battery ground cable. Remove plastic retainers across top of radiator support and remove front panel fillers. Disconnect 2-pin connector behind right headlight. Remove screw and temperature sensor. To install, reverse removal procedure.

OIL CIRCUIT DIAGRAMS Hydra-Matic 4L60

Fig. 1: Engine Running - Park

Fig. 2: Reverse Gear

Fig. 3: Engine Running - Neutral

Fig. 4: Overdrive - D4

Fig. 5: Part Throttle 4-3 & Modulated Downshifts

Fig. 6: 3rd Gear - D4 (Converter Clutch Applied)

Fig. 7: 2nd Gear - D4

Fig. 8: 1st Gear - D4

Fig. 9: Detent Downshifts (Valves Shown In 2nd Gear Position)

Fig. 10: Manual 3rd Gear

Fig. 11: Manual 2nd Gear

Fig. 12: Manual Low Gear

OIL CIRCUIT DIAGRAMS Hydra-Matic 200-4R

Fig. 1: Park - Engine Running

Fig. 2: Neutral - Engine Running

Fig. 3: Drive Range - 1st Gear

Fig. 4: Drive Range - 2nd Gear

Fig. 5: Drive Range - 2nd Gear, Converter Clutch Applied

Fig. 6: Drive Range - 3rd Gear

Fig. 7: Drive Range - Overdrive

Fig. 8: Valves In 3rd Gear Position - Part Throttle 4-3 & Modulated Downshifts

Fig. 9: Valves In 2nd Gear Position-Detent Downshifts

Fig. 10: Manual 3rd Gear

Fig. 11: Manual 2nd Gear

Fig. 12: Manual Low Gear

Fig. 13: Reverse Gear

OIL CIRCUIT DIAGRAMS Hydra-Matic 700R4

Fig. 1: Park - Engine Running

Fig. 2: Neutral - Engine Running

Fig. 3: 1st Gear - "D4" Range

Fig. 4: 2nd Gear - "D4" Range

Fig. 5: 3rd Gear - Converter Clutch Applied - "D4" Range

Fig. 6: Overdrive - "D4" Range

Fig. 7: Part Throttle & Modulated Downshifts, Valves In 3rd Gear Position

Fig. 8: Detent Downshift Valves Shown In 2nd Gear Position

Fig. 9: Manual 3rd Gear

Fig. 10: Manual 2nd Gear

Fig. 11: Manual Low Gear

Fig. 12: Reverse Gear

INSTRUMENT PANEL - ELECTRONIC ACCESSORIES & EQUIPMENT General Motors Electronic Instrument Panel

DESCRIPTION & OPERATION DESCRIPTION The electronic instrument panel cluster uses vacuum fluorescent displays to show vehicle speed, fuel level, turn signal arrows, high beam indicators and odometer information. The instrument panel cluster consists of a display panel and a microcomputer that processes sensor information. Using the sensor information, the microcomputer operates the electronic instrument cluster. The display panel consists of a speedometer, 2 odometers, a fuel gauge, a high beam indicator light, an ENG/MET button, a TRIP SET button and turn signal indicators.

Fig. 1: Electronic Instrument Cluster Courtesy of GENERAL MOTORS CORP. SPEEDOMETER OPERATION Speedometer displays speed information based on input from the vehicle speed sensor through the vehicle speed sensor buffer. Speedometer display is limited to a maximum of 85 MPH (137 KM/H). Any speed over 85 MPH (137 KM/H) will cause speedometer to flash 85 (137) until vehicle speed is brought below 85 MPH (137

KM/H). Speedometer will display either MPH or KM/H by depressing ENG/MET button. MPH or KM/H will be illuminated below speedometer depending on which mode the speedometer is in. ENG/MET BUTTON OPERATION The ENG/MET button changes the speedometer display from English (MPH) to Metric (KM/H) or Metric to English. TRIP SET BUTTON OPERATION The TRIP SET button resets the trip odometer to zero. FUEL GAUGE OPERATION Displays amount of fuel remaining in the fuel tank based on input from the fuel tank unit. Fuel tank unit has an operating range from empty to full of 0-90 ohms. POWER-UP SEQUENCE OPERATION When ignition is turned on, instrument cluster will light entire display to check all light segments. After initial segment check, display will light up at normal operating intensity and gauges will indicate condition of the engine at that time. TELLTALE WARNING LIGHTS OPERATION The telltale warning lights are located along a horizontal line above the instrument cluster. The warning lights are: CHECK ENGINE, SECURITY SYSTEM, NO CHARGE, FASTEN BELTS, RIDE LEVEL, ANTILOCK, BRAKE, and STOP ENGINE OIL PRESSURE. These lights should come on briefly when the ignition switch is turned to the ON position.

SYSTEM TESTING SYSTEM TEST A - DIGITAL CLUSTER 1. Turn ignition switch to RUN position. Check digital instrument panel cluster display. If display does not illuminate, go to step 2). If display illuminates, go to step 5). 2. Disconnect instrument cluster connector C3. Connect a test light from terminal A8 to chassis ground. See Fig. 2 . If test light comes on, go to step 3). If test light does not come on, repair open in Pink/White wire (circuit No. 350).

Fig. 2: Instrument Cluster Connector C3 Courtesy of GENERAL MOTORS CORP. 3. Connect a digital multimeter from instrument cluster connector C3 terminal B1 to chassis ground. See Fig. 2 . Measure resistance. If resistance is less than 0.3 ohms, go to step 4). If resistance is more than 0.3 ohms, repair Black ground wire (circuit No. 151). 4. Connect a digital multimeter from instrument cluster connector C3 terminal A11 to chassis ground. See Fig. 2 . Measure resistance. If resistance is less than 0.3 ohms, replace digital instrument panel cluster. If resistance is more than 0.3 ohms, repair Black ground wire (circuit No. 151). 5. Check speedometer operation. If speedometer operates normally, go to next step. If speedometer does not operate, go to step 14). 6. Check odometer operation. If odometer operates normally, go to next step. If odometer does not operate normally, replace digital instrument panel cluster. 7. Check trip odometer operation. If trip odometer operates normally, go to step 8). If trip odometer does not operate, replace digital instrument panel cluster. If trip odometer resets to zero when ignition is turned off, repair open in Orange wire (circuit No. 40). 8. Press TRIP SET button. If trip odometer resets to zero, go to step 9). If trip odometer does not reset to zero, go to step 16). 9. Press ENG/MET button. If readout changes from English to Metric or Metric to English, go to step 10). If readout does not change, replace digital instrument panel cluster. 10. Turn ignition switch to RUN position. Pull headlight switch to PARK position. If digital instrument panel cluster display dims, go to step 11). If digital instrument panel cluster display does not dim, turn ignition switch to OFF position and push headlight switch to OFF position. Go to step 18). 11. With ignition switch in RUN position and headlight switch in PARK position, adjust headlight switch dimmer function up and down. If digital instrument panel cluster display brilliance varies with dimmer, go to next step. If digital instrument panel cluster display brilliance does not vary with dimmer, go to step

20). 12. Turn ignition switch to OFF position. If digital instrument panel cluster display blanks out, go to step 13). If digital instrument panel cluster display continues to illuminate, repair short to battery voltage in Pink/ White wire (circuit No. 350). 13. Disconnect connector C301. See Fig. 3 . Connect a J 24156 Fuel Tester or equivalent from terminal "A" to terminal "B". Connectors on vehicles with 5.0L engines have only 2 terminals. See Fig. 3 . Turn ignition switch to RUN position. Set tester dial to zero ohms and then to 90 ohms while checking fuel gauge. Fuel gauge should read "F" and then "E". Wait one minute for fuel gauge to respond. If fuel gauge responds correctly to both tester and fuel level, system is functioning normally. If fuel gauge responds correctly to tester only, replace fuel tank unit. If fuel gauge does not respond correctly, go to step 23).

Fig. 3: Connector C301 (5.7L VIN 7) Courtesy of GENERAL MOTORS CORP. 14. Disconnect instrument cluster connector C3. Connect a digital multimeter from terminal B1 to chassis ground. See Fig. 2 . Measure resistance. If resistance is less than 0.3 ohms, go to step 15). If resistance is more than 0.3 ohms, repair Black ground wire (circuit No. 151). 15. Connect a digital multimeter from instrument cluster connector C3 terminal B1 to chassis ground. See Fig. 2 . Measure resistance. If resistance is less than 0.3 ohms, correct speed sensor problem before continuing. If resistance is more than 0.3 ohms, repair Black ground wire (circuit No. 151). 16. Connect a digital multimeter from instrument cluster connector C3 terminal B1 to chassis ground. See Fig. 2 . If resistance is less than 0.3 ohms, go to step 17). If resistance is more than 0.3 ohms, repair Black ground wire (circuit No. 151). 17. Connect a digital multimeter from instrument cluster connector C3 terminal A11 to chassis ground. See Fig. 2 . Measure resistance. If resistance is less than 0.3 ohms, replace digital instrument panel cluster. If resistance is more than 0.3 ohms, repair Black ground wire (circuit No. 151). 18. Disconnect instrument cluster connector C3. Connect a test light from terminal A1 to chassis ground. See

19.

20.

21.

22.

23.

24.

25.

Fig. 2 . Turn ignition switch to RUN position and pull headlight switch to PARK position. If test light does not light, go to step 19). If test light comes on, replace digital instrument panel cluster. With ignition switch in RUN position and headlight switch in PARK position, check taillight operation. If taillights operate normally, repair open in Brown wire (circuit No. 9). If taillights do not operate, service taillight problem before proceeding. Backprobe headlight switch connector C1 with a test light from terminal D (Gray wire) to chassis ground. If test light comes on, go to step 21). If test light does not come on, repair open in Gray wire (circuit No. 8). Backprobe headlight switch connector C2 with a test light from terminal A to chassis ground. Adjust headlight switch dimmer function up and down. If test light brilliance varies with dimmer adjustment, go to step 22). If test light does not light, or brilliance does not vary with dimmer adjustment, replace headlight switch. Disconnect instrument cluster connector C3. Connect a test light from terminal A2 to chassis ground. See Fig. 2 . Turn headlight switch dimmer to HI position. If test light does not come on, repair open in Gray wire (circuit No. 8). If test light comes on, replace digital instrument panel cluster. Connect a digital multimeter from connector C301 terminal "A" (5.0L VIN Y) or terminal "D" (5.7L VIN 7) to chassis ground. See Fig 3. Measure resistance. If resistance is less than 0.3 ohms, go to step 24). If resistance is more than 0.3 ohms, repair Black/White ground wire (circuit No. 353). Disconnect instrument cluster connector C3. Connect a digital multimeter from connector C301 terminal "B" to chassis ground. See Fig. 2 . Measure resistance. If resistance is more than 0.3 ohms, go to step 25). If resistance is less than 0.3 ohms, repair short to ground in Purple wire (circuit No. 30). Connect a fused jumper from connector C301 terminal "B" to chassis ground. See Fig. 3 . Measure resistance. If resistance is less than 0.3 ohms, replace digital instrument panel cluster. If resistance is more than 0.3 ohms, repair open in Purple wire (circuit No. 30).

SYSTEM TEST B - INDICATOR CLUSTER 1. Turn ignition switch to RUN position. Check instrument panel. If STOP ENGINE oil pressure warning indicator light comes on, leave ignition switch in RUN position and go to step 2). If STOP ENGINE oil pressure warning indicator light does not come on, go to step 5). 2. Check instrument panel. If COOLANT TEMP warning indicator light does not come on, go to step 3). If COOLANT TEMP warning indicator light comes on (with engine cool), leave ignition switch in RUN position and go to step 8). 3. Turn ignition switch to BULB TEST position. If COOLANT TEMP warning indicator light comes on, go to step 4). If COOLANT TEMP warning indicator light does not come on, go to step 10). 4. Start engine. If STOP ENGINE oil pressure warning indicator light remains lit, go to step 12). If STOP ENGINE oil pressure warning indicator light goes out, system is functioning normally. 5. Disconnect engine oil pressure switch connector. Connect a fused jumper from connector terminal (connector terminal "A" on 5.7L VIN 7) to chassis ground. If STOP ENGINE oil pressure warning indicator light does not come on, go to step 6). If STOP ENGINE oil pressure warning indicator light comes on, replace engine oil pressure switch. 6. Disconnect instrument cluster connector C1. Connect a test light from terminal No. 1 to chassis ground. See Fig. 4 . Turn ignition switch to RUN position. If test light comes on, leave instrument cluster connector C1 removed and go to step 7). If test light does not come on, repair open in Pink/Black wire (circuit No. 39).

Fig. 4: Instrument Cluster Connector C1 Courtesy of GENERAL MOTORS CORP. 7. Connect a test light between terminals No. 1 and 5 of instrument cluster connector C1. Turn ignition switch to BULB TEST position. If test light comes on, repair open in instrument panel printed circuit. If test light does not come on, repair open in Tan wire (circuit No. 31). 8. Disconnect temperature indicator switch connector. If COOLANT TEMP warning indicator light remains lit, go to step 9). If COOLANT TEMP warning indicator light goes out, replace temperature indicator switch. 9. Disconnect ignition switch connector C1. If COOLANT TEMP warning indicator light remains lit, repair short to ground in Dark Green wire (circuit No. 35) or instrument panel printed circuit. If COOLANT TEMP warning indicator light goes out, replace ignition switch. 10. Disconnect temperature indicator switch connector. Disconnect instrument cluster connector C1. Connect a fused jumper from temperature indicator switch connector terminal No. 6 (connector terminal "B" on 5.7L VIN 7) to chassis ground. Connect a test light between terminals No. 1 and 6 of instrument cluster connector C1. See Fig. 4 . If test light does not light, leave light connected and go to step 11). If test light comes on, repair open in Dark Green wire (circuit No. 35) between connector C100 and ignition switch or instrument panel printed circuit. 11. Turn ignition switch to BULB TEST position. If test light comes on, repair open in Dark Green wire (circuit No. 35) between connector C100 and temperature indicator switch. If test light does not come on, repair open in Dark Green wire (circuit No. 35) between connector C100 and instrument cluster connector C1. 12. Check oil pressure with a mechanical gauge. If oil pressure is normal, turn ignition switch to OFF position and go to step 13). If oil pressure is below 6 psi (41 kPa), service oil pressure problem before proceeding. 13. Disconnect engine oil pressure switch connector. Start engine. If STOP ENGINE oil pressure warning indicator light is not lit, replace engine oil pressure switch. If STOP ENGINE oil pressure warning indicator light remains lit, repair short to ground in Tan wire (circuit No. 31) or in instrument panel printed circuit.

REMOVAL & INSTALLATION DIGITAL INSTRUMENT CLUSTER Removal

1. Disconnect negative battery cable. Remove left side trim panel. See LEFT SIDE TRIM PANEL under REMOVAL & INSTALLATION in this article. Place gear selector in PARK and remove shift indicator clip from steering column. 2. Remove 4 screws retaining cluster. See Fig. 5 . Pull cluster out of instrument panel and disconnect electrical connector from cluster. Move gear selector out of PARK and tilt steering wheel down to facilitate cluster removal. Installation

1. Install cluster into housing, connecting electrical connector. Install 4 screws securing instrument cluster. Position gear selector in NEUTRAL and install shift indicator clip to steering column. Adjust clip around steering column to center pointer on "N" position. 2. Move gear selector from PARK to "1" to be sure that full indication travel is possible. Install left side trim panel. Refer to LEFT SIDE TRIM PANEL under REMOVAL & INSTALLATION in this article. Reconnect negative battery cable.

Fig. 5: Removing Electronic Instrument Cluster Courtesy of GENERAL MOTORS CORP.

HEADLIGHT SWITCH Removal

1. Disconnect negative battery cable. Remove left side trim panel. See LEFT SIDE TRIM PANEL under REMOVAL & INSTALLATION in this article. Remove 3 screws retaining headlight switch to instrument panel. Remove 2 screws retaining cruise control switch and slide it forward (if equipped). 2. Disconnect 2-piece electrical connector from switch. Disconnect Twilight Sentinel wiring (if equipped). See Fig. 6 . Depress retaining button while pulling switch rod from switch. Remove retaining nut and headlight switch from housing. Installation

1. Thread switch onto lens housing. Install switch rod into switch. Connect Twilight Sentinel wiring (if equipped). Connect 2-piece electrical connector to switch. Install 3 screws securing headlight switch to instrument panel. 2. Reposition and install cruise control switch (if equipped). Install left side trim panel. See LEFT SIDE TRIM PANEL under REMOVAL & INSTALLATION in this article. Connect negative battery cable. Check for proper switch function.

Fig. 6: Exploded View of Headlight Switch Courtesy of GENERAL MOTORS CORP. INSTRUMENT PANEL TOP COVER Removal

1. Remove screws at each end of instrument panel. Remove top cover retaining screw through access hole above instrument cluster. Remove screw through access hole in top of glove box. 2. Remove 4 screws in defroster grilles attaching top cover to cowl. Remove top cover by pulling panel up and out of retaining clips. Installation

1. Install top cover to instrument panel, engaging retaining clips. Install 4 screws securing top cover to cowl. Install top cover retaining screw through access hole in top of glove box. 2. Install top cover retaining screw through access hole above instrument cluster. Install side retaining screws (one each side). LEFT SIDE TRIM PANEL Removal

Remove outlet grille directional knob. Loosen 1/16 inch Allen key on bottom of knob and remove. Remove 2 screws and lower column cover. Remove 6 screws retaining trim panel. Place gear selector out of PARK to facilitate trim panel removal. Remove trim panel from instrument cluster. Installation

Install trim panel to instrument panel. Secure with 6 screws. Install outlet grille directional knob and secure with one screw. Install lower column cover and secure with 2 screws. TELLTALE WARNING LIGHT HOUSING Removal

1. Remove negative battery cable. Remove instrument panel top cover. See INSTRUMENT PANEL TOP COVER under REMOVAL & INSTALLATION in this article. 2. Disconnect electrical connectors. Remove 5 screws retaining light housing to instrument panel. Remove telltale warning light housing from vehicle. Installation

1. Install warning light housing and secure with 5 retaining screws. Connect electrical connectors. 2. Install instrument panel top cover. See, under REMOVAL & INSTALLATION in this article INSTRUMENT PANEL TOP COVER . Connect negative battery cable.

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

JACKING AND HOISTING General Motors Corp

JACKING & HOISTING FLOOR JACK FWD Models

When supporting vehicle with floor jack, the support should be placed at suspension lift points or frame lift points. Floor jacks may be placed under front crossmember on most models. See Fig. 1-Fig. 6 . RWD Models

Floor jack may be used under rear axle or front suspension lower control arms while observing following precautions:  

 

Never use jack on any part of underbody. DO NOT raise entire vehicle at side rail, with jack midway between front and rear wheels, or permanent body damage may result. DO NOT allow lifting plate fingers to contact axle cover plate when lifting at rear axle housing. If vehicle is equipped with a stabilizer bar, DO NOT lift at rear axle housing. See Fig. 1-Fig. 6 .

BUMPER JACK Bumper jack should be used only on models that are supplied as original equipment and only to change flat tire. If vehicle is not supplied with a bumper type jack, DO NOT lift vehicle by the bumper at any time. NOTE:

Always follow hoist manufacturer's instructions. DO NOT allow hoist or adapters to contact suspension, exhaust or steering components. Frame contact must be made. Use adapters if necessary. Lift vehicle as shown in illustrations. Corvette illustration not available.

AXLE CONTACT HOIST Hoist should contact lower control arms or front crossmember, and rear axle as shown in illustrations. FRAME CONTACT HOIST Hoist adapters must contact vehicle in specified areas. See Fig. 1-Fig. 6 . Adapters must be positioned to distribute load and support vehicle in a stable manner. DO NOT allow lift pads to contact exhaust system components. On Corvette, position frame contact hoist on the frame rails just forward of the rear wheels and just rearward of the front wheels. CAUTION: If removing rear axle, fuel tank, spare tire or liftgate and single post hoist

is used, anchor vehicle to hoist. Place jack stands under vehicle or add weight on rear end of vehicle to prevent tipping when center of gravity changes.

Fig. 1: Lifting Points ("A" Body) Courtesy of General Motors Corp.

Fig. 2: Lifting Points ("B" & "D" Bodies) Courtesy of General Motors Corp.

Fig. 3: Lifting Points ("C", "H" & "W" Bodies) Courtesy of General Motors Corp.

Fig. 4: Lifting Points ("E" & "K" Bodies) Courtesy of General Motors Corp.

Fig. 5: Lifting Points ("F" Body) Courtesy of General Motors Corp.

Fig. 6: Lifting Points ("J", "N" & "L" Bodies) Courtesy of General Motors Corp.

REMINDER INDICATOR RESET PROCEDURES GM - Buick / Cadillac / Chevrolet / GMC / Olds / Pontiac - 1980-14

CHANGE TRANS FLUID MESSAGE NOTE:

To determine the appropriate reset procedure, refer to CHANGE TRANS FLUID MESSAGE RESET INDEX. Only the vehicles listed in this index have a CHANGE TRANS FLUID MESSAGE reset.

CHANGE TRANS FLUID MESSAGE RESET INDEX Model & Year Reset Procedure Aurora 1995-99 Change Trans Fluid Message Reset - Procedure 4 Concours 1994-98 Change Trans Fluid Message Reset - Procedure 1 1999 Change Trans Fluid Message Reset - Procedure 2 CTS 2003 Change Trans Fluid Message Reset - Procedure 3 2004 Change Trans Fluid Message Reset - Procedure 2 DeVille 1992-97 Change Trans Fluid Message Reset - Procedure 1 1998-04 Change Trans Fluid Message Reset - Procedure 2 Eldorado 1992-98 Change Trans Fluid Message Reset - Procedure 1 1999-00 Change Trans Fluid Message Reset - Procedure 2 2001-02 Change Trans Fluid Message Reset - Procedure 1 Seville 1992-97 Change Trans Fluid Message Reset - Procedure 1 1998-04 Change Trans Fluid Message Reset - Procedure 2 SRX 2004 Change Trans Fluid Message Reset - Procedure 2 CHANGE TRANS FLUID MESSAGE RESET - PROCEDURE 1 This message will appear on the Driver Information Center (DIC) when transaxle fluid change is due. Change fluid in both the oil pan and side cover. 1. To reset display, turn ignition ON with engine OFF. 2. On the climate control panel, press and hold OFF and REAR DEFOG buttons until TRANS FLUID RESET message appears in DIC (about 5-20 seconds). CHANGE TRANS FLUID MESSAGE RESET - PROCEDURE 2

The CHANGE TRANS FLUID message will appear on the Driver Information Center (DIC) when transaxle fluid change is due. Percentage of transaxle fluid life remaining may be checked at any time by pressing INFO button several times until TRANS FLUID LIFE message appears. 1. To reset display, turn ignition key ON with engine OFF. 2. Press the INFO button until TRANS FLUID LIFE message appears. 3. Press and hold INFO RESET button until display shows 100 percent TRANS FLUID LIFE. Transaxle fluid life index is now reset. CHANGE TRANS FLUID MESSAGE RESET - PROCEDURE 3 Resetting With Base Audio System

Press CLR button located to the right of the DIC display to acknowledge the CHANGE TRANS FLUID message. This will clear the message from the display and reset it. To reset transmission fluid life indicator, press up or down arrow on INFO button located to the right of the DIC display to access the DIC menu. Once percentage TRANS FLUID LIFE menu item is highlighted, press and hold CLR button. Percentage will return to 100, and transmission fluid life indicator will be reset. Repeat if percentage does not return to 100. Resetting With Navigation System

Press multifunction button located to the right of the DIC display, next to the OK prompt to acknowledge the CHANGE TRANS FLUID message. This will clear the message form the display and reset it. To reset transmission fluid life indicator, turn system on by pressing PWR/VOL knob once. PWR/VOL knob is located to the lower left of the DIC display. Press INFO button located to the left of the DIC display to access the VEHICLE INFO menu. Turn TUNE/SEL knob located to the lower right of the DIC display until TRANS FLUID LIFE is highlighted. Press knob once to select it. Once percentage TRANS FLUID LIFE is displayed, press multifunction button next to the RESET prompt in the upper right corner of the display. Percentage will return to 100, and transmission fluid life indicator will be reset. Repeat if percentage does not return to 100. CHANGE TRANS FLUID MESSAGE RESET - PROCEDURE 4 1. The Driver Information Center (DIC) displays estimated percentage of the remaining useful life of transaxle fluid. When remaining fluid life is 0 percent, the display will show CHANGE TRNS FLUID NOW. After changing transaxle fluid, reset oil life display. 2. To reset the display, turn ignition on with engine off. Press ENG button to select the TRNS FLUID LIFE percentage display. Then, press and hold in RESET for at least 5 seconds. 3. The word RESET will appear. Then, TRNS FLUID 100 will be displayed.

CHECK ENGINE LIGHT NOTE:

To determine the appropriate reset procedure, refer to CHECK ENGINE LIGHT RESET INDEX. Only vehicles listed in this index have a check engine light reset.

CHECK ENGINE LIGHT RESET INDEX Model & Year

Reset Procedure

Geo Tracker 1989-94

Check Engine Light Reset - Procedure 1

CHECK ENGINE LIGHT RESET - PROCEDURE 1 Federal Emissions

1. CHECK ENGINE light functions as a service reminder indicator and emission system service. CHECK ENGINE light will come on each 50,000 miles (PCV and EGR), each 80,000 miles (oxygen sensor) and each 100,000 miles (charcoal canister) to indicate needed emission system service. 2. After servicing and/or replacing components, reset CHECK ENGINE light by sliding cancel switch to its opposite position. See CHECK ENGINE LIGHT RESET SWITCH LOCATION (GEO TRACKER) for switch location. CHECK ENGINE LIGHT RESET SWITCH LOCATION (GEO TRACKER) Application Location 1989-91 Behind Access Panel, Directly Below Steering Column (1) Behind Instrument Panel, Next To Left Speaker 1992-94 (1) See Fig. 1.

Fig. 1: Check Engine Light Reset Switch Location (1992-94 Geo Tracker - Federal Emissions) Courtesy of GENERAL MOTORS CORP.

California Emissions

CHECK ENGINE light indicates when it is necessary to have emission system serviced, regardless of mileage. CHECK ENGINE light comes on briefly when starting as a bulb check. If light does not come on or stays on constantly, repair as necessary.

FUEL FILTER LIFE NOTE:

To determine the appropriate reset procedure, refer to Fuel Filter Life Reset Index. Only vehicles listed in this index have a fuel filter life reset.

FUEL FILTER LIFE RESET INDEX Application Some Models NOTE:

Reset Procedure Fuel Filter Life Reset - Procedure 1

ALWAYS reset the FUEL FILTER LIFE system (if equipped) after a fuel filter change.

"FUEL FILTER LIFE" message will appear when a reset is performed either by using the steering wheel controls or performing manual reset procedure. FUEL FILTER LIFE RESET - PROCEDURE 1 1. On vehicles with steering wheel controls, press and hold the select button for 5 seconds while the FUEL FILTER LIFE message is displayed. This message will appear on the Driver Information Center (DIC) for 10 seconds. 2. On vehicles without steering wheel controls, go to next step. 3. Without pressing the pedals, turn the ignition key to the ON position, engine off. Wait 5 seconds. 4. Completely depress the brake and accelerator pedals simultaneously and hold for 10 seconds. The system is now reset. Turn ignition key OFF. 5. On all vehicles, the next time engine is started, the message will no longer be displayed.

OIL CHANGE REMINDER NOTE:

Most 1981-88 General Motors vehicles do not use a Service Reminder Indicator (SRI).

NOTE:

To determine the appropriate reset procedure, refer to Oil Change Reminders Reset Index. Only vehicles listed in this index have an oil change reminder reset.

OIL CHANGE REMINDERS RESET INDEX Model & Year Alero

Reset Procedure

1999-03 2004 Acadia 2007-10 2011-15 Allante 1989-93 ATS 2013-14 Aurora 1995-99 2001-03 Avalanche 2002-06 2007-13 Aveo 2009-11 Aztek 2001-05 Bravada 2002-04 Bonneville 2003-05 Brougham 1992 Camaro 1998-02 2010-14 Canyon 2004-12 Caprice 1994 1995-96 2011-14 Captiva Sport 2012-15 Classic 2005 Cobalt & G5 Pursuit (Canadian) 2005-09 Colorado

Oil Change Reminder Reset - Procedure 1 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 16 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 23 Oil Change Reminder Reset - Procedure 33 Oil Change Reminder Reset - Procedure 27 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 11 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 1 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 10 Oil Change Reminder Reset - Procedure 2 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 4 Oil Change Reminder Reset - Procedure 4

Oil Change Reminder Reset - Procedure 10 Concours 1994-96 1997-99 Corvette -96 1997-13 2014 Cruze 2011-14 CTS 2003-04 2005-08 2009 2010-11

Oil Change Reminder Reset - Procedure 19 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 5 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 33 Oil Change Reminder Reset - Procedure 18

Oil Change Reminder Reset - Procedure 20 Oil Change Reminder Reset - Procedure 22 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 or Oil Change Reminder Reset - Procedure 19 2012-14 Oil Change Reminder Reset - Procedure 6 Cutlass Calais, Cutlass Supreme, Cutlass Ciera, Cutlass Cruiser & Touring Sedan 1990-91 Oil Change Reminder Reset - Procedure 28 DeVille 1991-93 Oil Change Reminder Reset - Procedure 25 1994-99 Oil Change Reminder Reset - Procedure 19 2000-05 Oil Change Reminder Reset - Procedure 16 DTS 2006-11 Oil Change Reminder Reset - Procedure 6 Eighty Eight & Ninety Eight 1990-91 Oil Change Reminder Reset - Procedure 28 1992-94 Oil Change Reminder Reset - Procedure 29 1995-97 Oil Change Reminder Reset - Procedure 30 Eldorado 1989-91 Oil Change Reminder Reset - Procedure 24 1992-93 Oil Change Reminder Reset - Procedure 26 1994-97 Oil Change Reminder Reset - Procedure 19 1997-02 Oil Change Reminder Reset - Procedure 6 ELR 2014 Oil Change Reminder Reset - Procedure 33 Enclave 2008-15 Oil Change Reminder Reset - Procedure 16 Encore 2013-14 Oil Change Reminder Reset - Procedure 18 Envoy/ XL

2002-06 2007-09 Equinox 2005-09 2011-14 Escalade Series 2002-06 2007-14 2015 Express/ Cutaway/ RV 2003-14 Firebird 1998-02 Fleetwood 1991-92 1993-96 Grand Am 1999-02 2003-05 Grand Prix 1998-03 2004-08 GTO 2004-06 G5 2007-09 G6 2005-10 G8 2008-09 HHR 2006-11 Impala 2000-06 2007-13 2014-15 Impala Limited 2014 Intrigue 1998-02 LaCrosse & Allure

Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 4 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 33 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 25 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 2 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 4 Oil Change Reminder Reset - Procedure 32 Oil Change Reminder Reset - Procedure 9 Oil Change Reminder Reset - Procedure 4 Oil Change Reminder Reset - Procedure 8 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 33 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3

Oil Change Reminder Reset - Procedure 18 LeSabre 1994-99 2000-05 Lucerne 2006-10 2011 Lumina 1997-01 Malibu 2004-07 2008-12 2013-15 Montana 2000-05 2006 Monte Carlo 1997-99 2000-06 2007 Park Avenue 1991-94 1995-96 1997-05 Pickup/Cab & Chassis (C/K) 1996-00 Rainier 2004-07 Regal 1997-04 2011-14 Rendezvous 2002-07 Roadmaster 1994 1995-96 Savana/ Cutaway/ RV 2003-14 Seville 1989-91

Oil Change Reminder Reset - Procedure 12 Oil Change Reminder Reset - Procedure 14 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 13 Oil Change Reminder Reset - Procedure 4 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 8 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 15 Oil Change Reminder Reset - Procedure 12 Oil Change Reminder Reset - Procedure 14 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 17 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 17 Oil Change Reminder Reset - Procedure 15 or Oil Change Reminder Reset - Procedure 2 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 24

1992-93 1994-97 1998-04 Sierra 1500/ 2500/ 3500 1999-06 2007-15 Silhouette 2000-01 2002-04 Silverado 1500/ 2500/ 3500 2001-06 2007-15 Solstice 2006-10 Sonic 2012-14 Spark 2013-14 SRX 2004 2005-06 2007-09 2010-12 2013-15 SS 2014 SSR 2004 2005-06 STS 2005-11 Suburban 2000-06 2007-15 Tahoe 2000-06 2007-15 Terrain 2011-14 Toronado 1989-92

Oil Change Reminder Reset - Procedure 26 Oil Change Reminder Reset - Procedure 19 Oil Change Reminder Reset - Procedure 16 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 4 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 20 Oil Change Reminder Reset - Procedure 22 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 33 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 7 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 31

2006-09 Trailblazer 2002-09 Traverse 2009-14 Uplander, Montana SV6 (Canadian) 2005-08 Venture 2000-04 2005 Verano 2012-14 Volt 2011-14 XLR 2004 2005-09 XTS 2013-14 Yukon/ XL 2000-06 2007-13

Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 11 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 18 Oil Change Reminder Reset - Procedure 21 Oil Change Reminder Reset - Procedure 6 Oil Change Reminder Reset - Procedure 19 Oil Change Reminder Reset - Procedure 33 Oil Change Reminder Reset - Procedure 3 Oil Change Reminder Reset - Procedure 6

OIL CHANGE REMINDER RESET - PROCEDURE 1 1. The CHANGE OIL (or CHANGE ENGINE OIL) message is displayed when its time to change engine oil, usually between 3000 and 7500 miles since last oil change. 2. To reset the oil life monitor, turn the ignition switch to RUN position, with engine off. Press the TRIP/OIL RESET button on the instrument panel for 12 seconds. The OIL CHANGE light will start to flash to confirm that system is reset (on some models a chime will also sound). Reset is complete when OIL CHANGE light goes out. OIL CHANGE REMINDER RESET - PROCEDURE 2 Engine oil life monitor calculates engine oil temperature and RPM. It indicates when the engine oil is nearly worn out. A CHANGE OIL light on the instrument cluster is illuminated when it is time to change the engine oil. To reset CHANGE OIL light: 1. 2. 3. 4.

Remove IP fuse block cover (cover can be seen when driver's door is open). Turn ignition ON, engine OFF. Press OIL RESET button and hold for 5 seconds. If Oil Life light does not reset, repeat procedure with ignition OFF.

OIL CHANGE REMINDER RESET - PROCEDURE 3 Engine oil life monitor calculates engine oil temperature and RPM. It indicates when the engine oil is nearly worn out. A CHANGE OIL light on the instrument cluster is illuminated when it is time to change the engine oil. 1. To reset oil life monitor and turn off CHANGE OIL light, turn ignition switch to ON position with engine off. 2. Depress accelerator pedal to wide open throttle 3 times within 5 seconds. This throttle signal will inform the PCM to reset the oil life monitor and turn off the light. If light does not turn off, turn ignition off and repeat procedure. OIL CHANGE REMINDER RESET - PROCEDURE 4 When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A CHANGE ENGINE OIL SOON message will come on. Change the engine oil as soon as possible within the next 600 miles (1,000 km). It is possible that, if driving under the best conditions, the oil life system may not indicate that an oil change is necessary for over a year. However, the engine oil and filter must be changed at least once a year and at this time the system must be reset. Reset Procedure

1. Turn the ignition key to RUN with the engine OFF. 2. Press the INFO and RESET buttons on the Driver Information Center (DIC) at the same time to enter the personalization menu. 3. Press the INFO button to scroll through the available personalization menu modes until the DIC display shows OIL-LIFE RESET. 4. Press the INFO and RESET buttons at the same time for one second and release. 5. Press and hold the reset button until the DIC display shows ACKNOWLEDGED. This will tell you the system has been reset. 6. Turn the key to LOCK/OFF. Alternate Method (Some Models)

1. 2. 3. 4.

Turn ignition on. Depress ENG MET button on trip monitor and release. Within 5 seconds, depress and release ENG MET button again. Within 5 seconds, depress and hold the ENG MET or GAUGES button again. The CHANGE OIL light should flash. 5. Depress and hold the RANGE or GAUGES button until the CHANGE OIL light stops flashing and goes out. When the light goes out, the engine oil life monitor is reset. This should take about 10 seconds. NOTE:

If the light does not reset, turn ignition off and repeat the procedure.

OIL CHANGE REMINDER RESET - PROCEDURE 6 The Driver Information Center (DIC) will display a CHANGE OIL message when an oil change is due. The instrument cluster may also have a CHANGE OIL light. To reset the oil life monitor: Reset Procedure

1. Turn ignition switch to RUN position, with engine off. 2. Press the TRIP (on some models SELECT or SET/RESET) button, located on the DIC, until the OIL LIFE display appears. Message will display percentage of oil life remaining. NOTE:

On models without DIC buttons, use the TRIP/ODOMETER reset stem.

3. Press and hold SET/RESET button (on some models, the check-symbol button) on DIC for at least 5 seconds. The message will change to indicate that the Oil Life has been reset. On some models, 3 chimes will also sound. 4. Turn ignition off. 5. Turn the key to OFF. If the light or message comes back on when you start your vehicle, the oil life system has not reset. Repeat the procedure. NOTE:

On some models, if oil life system does not reset, try turning ignition OFF after displaying oil life message. Then press and hold reset button.

Alternate Method (Some Models)

CHANGE ENGINE OIL SOON message in the DIC comes on. Reset the system whenever the engine oil is changed so that the system can calculate the next engine oil change. To reset the system: 1. Press the up or down arrow to scroll the DIC to show OIL LIFE. 2. Once the XXX% ENGINE OIL LIFE menu item is highlighted, press and hold the RESET button until the percentage shows 100% OIL CHANGE REMINDER RESET - PROCEDURE 8 The CHANGE ENGINE OIL message is displayed when its time to change engine oil, usually between 3000 and 7500 miles since last oil change. The oil change interval is not based on mileage, but on engine revolutions and engine operating temperature. 1. There are 2 ways to reset the engine oil life monitor. To reset the engine oil life monitor using the accelerator pedal, go to step 4. To reset the engine oil life monitor using the radio, turn the radio off. Turn ignition to ACC or ON, with the engine off. Press and hold the DISP (on some models, TUNE DISP) button (or knob) on the radio for at least 5 seconds until SETTINGS is displayed. 2. Press the SEEK (on some models, SEEK PTYPE or SEEK PSCAN) up or down arrow to scroll through the main menu. Scroll until OIL LIFE appears on the display. Press the PREV or NEXT button to enter the sub-menu. RESET will be displayed. 3. Press the DISP/TUNE DISP button to reset. A chime will sound to verify the new setting and DONE will be displayed for one second. Once the message indicator has been reset, scroll through the menu until EXIT appears on the display. Press the DISP/TUNE DISP button to exit the program. A chime will sound to verify the exit. 4. To reset the engine oil life monitor using the accelerator pedal, turn ignition on with engine off. Fully depress and release the accelerator pedal slowly 3 times within 5 seconds. If CHANGE ENGINE OIL light flashes, oil life monitor is reset. If the CHANGE ENGINE OIL light comes back on and stays on, oil life monitor has not reset. Repeat reset procedure. OIL CHANGE REMINDER RESET - PROCEDURE 9 When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A CHANGE message will come on. Change the engine oil as soon as possible within the next 600 miles (1000 km). It is possible that, if driving under the best conditions, the oil life may not indicate that an oil change is necessary for over a year. However, the engine oil and filter must be changed at least once a year and at this time the system must be reset. To reset the Engine Oil Life System, do the following: 1. Press and hold the TRIP button on the steering wheel while turning on the ignition. Do not start the engine. 2. The instrument panel cluster will prompt to clear the service code. 3. Release the button. 4. Press and hold ENTER Switch on the left side of the steering wheel for approximately one second. 5. Turn off the ignition.

If the CHANGE ENGINE OIL SOON message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure. OIL CHANGE REMINDER RESET - PROCEDURE 10 1. Turn ignition ON, with engine off. 2. Press and release reset stem on instrument panel while OIL LIFE message is displayed. 3. Once the alternating OIL LIFE and RESET messages appear, press and hold stem in until several beeps will sound. This confirms that oil life system has been reset. Turn ignition off or full LOCK position. If CHANGE OIL messages comes back after starting engine, repeat reset procedure. OIL CHANGE REMINDER RESET - PROCEDURE 11 Reset Procedure

If vehicle is equipped with a Driver Information Center (DIC), reset oil life monitor by pressing the Driver Information Center SELECT button for 5 seconds while ENGINE OIL LIFE is displayed. Alternate Method

To reset the oil life monitor, turn ignition switch to ON or RUN position with engine off. Depress accelerator pedal slowly to wide open throttle 3 times within 5 seconds. If CHANGE ENG OIL light flashes for 5 seconds, oil life monitor is reset. If the CHANGE ENG OIL light does not flash, oil life monitor has not reset. Repeat this step. OIL CHANGE REMINDER RESET - PROCEDURE 12 1. CHANGE OIL SOON light will come on when engine oil has broken down enough to require changing. After changing oil, reset oil life display. 2. To reset light, turn ignition on. Open glove box to access oil reset button. Press and hold oil reset button in glove box for at least 5 seconds, but not longer than 60 seconds. The CHANGE OIL SOON light will flash 4 times to indicate light has been reset. OIL CHANGE REMINDER RESET - PROCEDURE 13 GM Oil Life System calculates when to change your engine oil and filter based on vehicle use. Anytime oil is changed, reset the system so it can calculate when the next oil change is required. If a situation occurs where you change your oil prior to a Change Oil Soon message being turned on, reset the system. After changing the engine oil, reset the system. 1. Display OIL LIFE RESET on the DIC. 2. Press and hold ENTER button for at least one second. An ACKNOWLEDGED display message will appear for 3 seconds or until the next button is pressed. This will tell you the system has been reset. 3. Turn key to OFF. 4. If Change Oil Soon message comes back on when you start your vehicle, engine oil life system has not reset. Repeat the procedure.

OIL CHANGE REMINDER RESET - PROCEDURE 14 1. To display this light, press the GAGE INFO or GAGES button on the Driver Information Center (DIC). When oil life index is less than 10 percent, display will show OIL LIFE INDEX CHANGE OIL. After changing oil, reset system. 2. To reset light, display OIL LIFE INDEX. Hold RESET button for more than 5 seconds. After reset, oil life will change to 100 percent. OIL CHANGE REMINDER RESET - PROCEDURE 15 1. CHANGE OIL SOON light will come on when engine oil has broken down enough to require changing. After changing oil, reset oil life display. 2. To reset light, locate reset button hole under the dash near passenger door. Use a pencil or similar object to push and hold button (inside hole) for 5 seconds. The CHANGE OIL SOON light will flash 4 times to indicate light has been reset. OIL CHANGE REMINDER RESET - PROCEDURE 16 Vehicles WITHOUT Driver Information Center (DIC) Buttons

1. Turn the ignition to ON/RUN, with the engine off. The vehicle must be in P (Park) to access this display. Press the trip odometer reset stem until OIL LIFE REMAINING displays. 2. Press and hold the trip odometer reset stem until OIL LIFE REMAINING shows "100%." Three chimes sound and the CHANGE ENGINE OIL SOON message goes off. 3. Turn the key to LOCK/OFF. If the CHANGE ENGINE OIL SOON message comes back on when the vehicle is started, the engine oil life system has not been reset. Repeat the procedure. Vehicles WITH Driver Information Center (DIC) Buttons

1. Turn the ignition to ON/RUN position, with the engine off. 2. Press the VEHICLE INFORMATION BUTTON (i) until OIL LIFE REMAINING displays. 3. Press and hold the SET/RESET button (check-mark symbol) until "100%" is displayed. Three chimes sound (on some models) and the CHANGE ENGINE OIL SOON message goes off. 4. Turn ignition to LOCK/OFF position. If the CHANGE ENGINE OIL SOON message comes back on when engine is started, repeat reset procedure. OIL CHANGE REMINDER RESET - PROCEDURE 17 Reset Procedure

1. Turn the ignition to ON, with the engine off. 2. Press the MODE button until the Driver Information Center (DIC) reads OIL LIFE LEFT/HOLD SET TO RESET. 3. Press and hold the SET button until 100% is displayed. You will hear three chimes and the CHANGE ENGINE OIL message will go off. Turn the key to OFF.

4. If the CHANGE ENGINE OIL message comes back on when engine is started, the engine oil life system has not reset. Repeat the procedure. Alternate Method (Some Models)

1. Turn the ignition key to RUN with the engine off. 2. Fully press the release the accelerator pedal 3 times within 5 seconds. Several beeps sound. This confirms the oil life system has been reset. 3. If the CHANGE/OIL message comes back on when you start the engine, the engine oil life system has not been reset. Repeat the procedure. OIL CHANGE REMINDER RESET - PROCEDURE 18 When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A CHANGE ENGINE OIL message or light will come on. Change the engine oil as soon as possible within the next 600 miles (1 000 km). It is possible that, if driving under the best conditions, the oil life system may not indicate that an oil change is necessary for over a year. However, the engine oil and filter must be changed at least once a year and at this time the system must be reset. NOTE:

Be careful not to reset the oil life display accidentally at any time other than after the oil is changed. It cannot be reset accurately until the next oil change.

Vehicles with Driver Information Center (DIC)

1. Turn the ignition to ON/RUN with the engine off. 2. Press the DIC MENU button on the turn signal lever to enter the Vehicle Information Menu. Use the thumbwheel to scroll through the menu items until you reach REMAINING OIL LIFE. See Fig. 2. 3. Press the SET/CLR button (on some models, the check-symbol button) while the oil life display is active. After a few seconds, there will be a single chime (on some models) and the oil life will be reset to 100% 4. Turn the ignition to LOCK/OFF. The system is reset when the CHANGE OIL message is off and the REMAINING OIL LIFE 100% message is displayed. NOTE:

If the CHANGE OIL message comes back on or Code 82 DIC message comes on when the vehicle is started, the engine oil life system has not been reset. Repeat the procedure.

Fig. 2: Identifying DIC Controls (Turn Signal Lever) Courtesy of GENERAL MOTORS CORP. Vehicles without DIC (Some Models)

1. With the engine OFF, turn the ignition key to RUN. 2. Fully press and release the accelerator pedal slowly three times within five seconds. 3. Turn the key to OFF, than start the vehicle. Reset Using Diagnostic Scan Tool (Some Models)

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Turn on ignition. Connect scan tool. Select Module Diagnosis. Select Engine Control Module. Select Configuration/Reset function. Select Engine Oil System Reset. Push Enter button to run function. Confirm Executed successfully. Turn ignition of and confirm. Turn ignition on and confirm.

OIL CHANGE REMINDER RESET - PROCEDURE 19 1. The Driver Information Center (DIC) will display remaining oil life as a percentage estimate of the useful life of oil. 2. When remaining oil life is 10 percent or less, the system will display CHANGE OIL SOON. When oil life expires, display will show CHANGE ENGINE OIL. After changing oil, reset oil life display. 3. To reset oil life display, press INFORMATION (or INFORMATION SKIP) button to display OIL LIFE LEFT. Press and hold RESET (or RESET NO) button until 100 OIL LIFE LEFT (0.0 OIL LIFE LEFT on some early models) is displayed.

OIL CHANGE REMINDER RESET - PROCEDURE 20 With Base Audio System

Press up or down arrow on the INFO button located to right of Driver Information Center (DIC) display to access DIC menu. Once 100 percent ENGINE OIL LIFE menu item is highlighted, press and hold the CLR button. Percentage will return to 100 and oil life indicator will be reset. Repeat procedure if the percentage does not return to 100. With Navigation System

Turn the system on by pressing PWR/VOL knob once. PWR/VOL knob is located to lower left of DIC display. Press INFO button located to left of the display to access Vehicle Information menu. Turn TUNE/SEL knob located to lower right of the display until ENGINE OIL LIFE is highlighted. Press TUNE/SEL knob once to select it. When 100 percent Engine Oil Life is displayed, press multifunction button next to reset prompt in upper right corner of the display. Percentage will return to 100 and the oil life indicator will be reset. Repeat procedure if the percentage does not return to 100. OIL CHANGE REMINDER RESET - PROCEDURE 21 1. Use the SELECT knob to select OIL LIFE on the DIC menu. 2. Press SELECT to start the OIL LIFE reset procedure. 3. The DIC menu will display "Are you sure that you want to reset?" Use SELECT to choose YES to reset oil life or NO to exit and return to the previous menu. 4. If YES is selected, the DIC menu will display RESET OIL LIFE for a short time and then 100% OIL LIFE will be display when OIL LIFE is successfully reset. OIL CHANGE REMINDER RESET - PROCEDURE 22 With Base Audio System

1. Press the CLR button located to the right of the driver information center (DIC) display to acknowledge the Change Engine Oil message. This will clear the message from the display and reset it. 2. Press the up or down arrow on the INFO button located to the right of the Driver Information Center (DIC) display to access the DIC menu. 3. Once 100% ENGINE OIL LIFE menu item is highlighted, press and hold the CLR button. The percentage will return to 100 and the oil life indicator will be reset. Repeat the steps if the percentage does not return to 100. 4. Turn OFF the key. If the Change Engine Oil message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure. Without DIC

1. With the engine OFF, turn the ignition key to RUN. 2. Fully press and release the accelerator pedal slowly three times within five seconds. 3. Turn the key to OFF, then start the vehicle.

With Navigation System

1. Press the multifunction button, next to the OK prompt in the upper right of the display to acknowledge the Change Engine Oil message. This will clear the message from the display and reset it. 2. Turn the system on by pressing the PWR/VOL knob once. The PWR/VOL knob is located to the lower left of the driver information center (DIC) display. 3. Press the INFO button located to the left of the display to access the Vehicle Information menu. 4. Turn the TUNE/SEL knob located to the lower right of the display until Engine Oil Life is highlighted. Press the knob once to select it. 5. Once the 100% Engine Oil Life is displayed, press the multifunction button next to the Reset prompt in the upper right corner of the display. The percentage will return to 100 and the oil life indicator will be reset. Repeat the steps if the percentage does not return to 100. 6. Turn OFF the key. If the Change Engine Oil message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure. OIL CHANGE REMINDER RESET - PROCEDURE 23 1. An OIL LIFE INDEX is one of the displays on Driver Information Center (DIC). It will display remaining oil life as a percentage estimate of the useful life of oil. 2. It will show 100 percent when the system is reset. When the oil life is 0 percent, the display will show CHANGE ENGINE OIL. After changing oil, reset oil life display. 3. To reset service reminder on 1989 models, press RANGE button until OIL LIFE INDEX appears on display. Depress and hold in AVG ECON and RANGE buttons for more than 5 seconds or until 100 is displayed. This will reset remaining oil life to 100 percent. 4. On 1990-93 models, press RANGE button until OIL LIFE INDEX appears on DIC display. Depress and hold in AVG SPEED and RANGE buttons for more than 5 seconds or until 100 is displayed. This will reset remaining oil life to 100 percent. OIL CHANGE REMINDER RESET - PROCEDURE 24 1. An OIL LIFE INDEX is one of 4 displays on Driver Information Center (DIC). It will display remaining oil life as a percentage estimate of the useful life of oil. 2. Display will show 100 percent when the system is reset. When remaining oil life is 10 percent or less, the system will display CHANGE OIL SOON. When the oil life expires, the display will show CHANGE ENGINE OIL. After changing oil, reset oil life display. 3. To reset oil life display, press ENG DATA button until OIL LIFE INDEX appears on DIC display. Depress and hold in ENG DATA and RANGE buttons until 100 is displayed. This will reset remaining oil life to 100 percent. OIL CHANGE REMINDER RESET - PROCEDURE 25 1. An OIL LIFE INDEX is one of the displays on Driver Information Center (DIC). It will display remaining oil life as a estimated percentage of the useful life of oil. 2. It will show 100 percent when the system is reset. When the oil life is 0 percent, the display will show CHANGE ENGINE OIL. After performing necessary services, reset service reminder.

3. To reset service reminder, turn ignition to on position. Do not start engine. Depress and hold RANGE and FUEL USED buttons until OIL LIFE INDEX appears on DIC display. Depress and hold RANGE and RESET buttons for 5-60 seconds. 4. When CHANGE OIL SOON light flashes 4 times, remaining oil life index is reset to 100 percent. If CHANGE OIL SOON comes on and stays on for 5 seconds, display did not reset. Repeat step 3. OIL CHANGE REMINDER RESET - PROCEDURE 26 1. Oil change reminder display on the Driver Information Center (DIC) is similar to 1990-91 models, but reset procedures are different. After changing oil, reset oil life display. 2. To reset, press INFORMATION button to display OIL LIFE INDEX. Press and hold STORE/RECALL button until 100 is displayed. This will reset oil life display to 100 percent. OIL CHANGE REMINDER RESET - PROCEDURE 27 1. The Driver Information Center (DIC) displays estimated percentage of the remaining useful life of engine oil or transaxle fluid. When remaining oil or fluid life is 0 percent, the display will show CHANGE OIL NOW or CHANGE TRNS FLUID NOW. After changing engine oil or transaxle fluid, reset oil life display. 2. To reset the display, turn ignition on with engine off. Press ENG button to select the OIL LIFE or TRNS FLUID LIFE percentage display. Then, press and hold in RESET for at least 5 seconds. 3. The word RESET will appear. Then, OIL LIFE 100 or TRNS FLUID 100 will be displayed. OIL CHANGE REMINDER RESET - PROCEDURE 28 1. An oil change reminder displays estimated percentage of the remaining useful life of the oil. When engine is started, a tone will sound and approximate distance to next oil change will be displayed. 2. When remaining oil life is 10 percent or less, the system will calculate distance to next oil change. When the oil life is 0 percent, the display will show CHANGE OIL NOW. After changing oil, reset oil life display. 3. To reset the display, press and hold in OIL button to select the oil life display. Then, press and hold in RESET and OIL buttons for at least 5 seconds. This will reset oil life display to 100 percent. OIL CHANGE REMINDER RESET - PROCEDURE 29 1. To reset the display, press and release the TEST button. 2. Press and release the OIL button. 3. Press and hold the RESET button for at least 7 seconds. This will reset oil life display to 100 percent. OIL CHANGE REMINDER RESET - PROCEDURE 30 1. To reset the display, press and release RESET button on Driver Information Center (DIC). 2. Press SEL button (with down arrow) to select OIL. 3. Press SEL button (with left and right arrows) to display oil life.

4. Press and hold RESET button for about 5 seconds. 5. A reset message will display, then oil life will display 100 percent. OIL CHANGE REMINDER RESET - PROCEDURE 31 With Information Center Display

OIL LIFE INDEX is one of 4 engine data displays used on models with Information Center display. It will display remaining oil life as estimated percentage of the useful life of oil. It will show 100 percent when the system is reset. After changing oil, reset oil life display. 1. To reset the display, press ENG DATA button (1989-90) or OPTIONS button (1991-92) until oil life index is displayed. 2. Then, press and hold in ENG DATA and GAGE buttons (1989) or RESET/ENTER button (1990-92) for at least 5 seconds. This will reset remaining oil life to 100 percent. With Visual Information Center

OIL LIFE is one of the displays used on models with a Visual Information Center (VIC). It will display data regarding previous oil change. A bar graph display shows full when oil is changed. Bar graph will go down as vehicle is driven and oil ages. When bar graph reaches CHANGE OIL mark, oil should be changed. After changing oil, reset oil life display. 1. To reset the display, press INFO hard key and then OIL LIFE soft key to display oil life index. 2. Press RESET soft key. 3. A reset confirmation page will appear and ask if oil has been changed. Press YES soft key to reset bar graph, and update last oil change date and mileage information. OIL CHANGE REMINDER RESET - PROCEDURE 32 When the system has calculated that oil life has been diminished, it will indicate that an oil change is necessary. A CHANGE ENGINE OIL SOON message will come on. Change the engine oil as soon as possible within the next 600 miles (1000 km). It is possible that, if driving under the best conditions, the oil life system may not indicate that an oil change is necessary for over a year. However, the engine oil and filter must be changed at least once a year and at this time the system must be reset. To reset the Engine Oil Life System, do the following: 1. With the CHANGE OIL SOON message displayed, press any of the three driver information center (DIC) buttons to clear the CHANGE OIL SOON message. 2. Display OIL LIFE RESET on the DIC. 3. Press and hold the ENTER button for at least one second. An ACKNOWLEDGED display message will appear for three seconds or until the next button is pressed. This will tell you the system has reset. 4. Turn the ignition to OFF. If the CHANGE ENGINE OIL message comes back on when you start the vehicle the Engine Oil Life System

has not reset. Repeat the procedure. OIL CHANGE REMINDER RESET - PROCEDURE 33 This vehicle has a computer system that indicates when to change the engine oil and filter. This is based on a combination of factors which include engine revolutions, engine temperature, and miles driven. Based on driving conditions, the mileage at which an oil change is indicated can vary considerably. For the oil life system to work properly, the system must be reset every time the oil is changed. To reset the system: Reset Procedure

1. Using the DIC controls on the right side of the steering wheel, display REMAINING OIL LIFE on the driver information center (DIC). 2. Press SEL on the DIC controls and hold SEL down for a few seconds to clear the CHANGE ENGINE OIL SOON message and reset the oil life at 100%. NOTE:

Be careful not to reset the oil life display accidentally at any time other than after the oil is changed. It cannot be reset accurately until the next oil change.

Alternate Method (Some Models)

OXYGEN SENSOR REMINDER FLAG NOTE:

To determine the appropriate reset procedure, refer to OXYGEN SENSOR REMINDER FLAG RESET. Only vehicles listed in this index have an oxygen sensor reminder flag reset.

OXYGEN SENSOR REMINDER FLAG RESET INDEX Model & Year Reset Procedure Some Models 1980 Oxygen Sensor Reminder Flag - Procedure 1 OXYGEN SENSOR REMINDER FLAG - PROCEDURE 1 1. Every 30,000 miles, a reminder flag appears in speedometer face, indicating service of oxygen sensor is necessary. See Fig. 3. Inspect and service oxygen sensor as necessary and reset flag. 2. To reset flag, remove instrument panel trim plate. Remove instrument cluster lens. Using pointed tool, apply light downward pressure on notches of flag until it is reset. An alignment mark will appear in left

center of odometer window when flag is fully reset.

Fig. 3: Resetting Reminder Flag Courtesy of GENERAL MOTORS CORP.

OXYGEN SENSOR WARNING LIGHT NOTE:

To determine the appropriate reset procedure, refer to OXYGEN SENSOR WARNING LIGHT RESET INDEX. Only vehicles listed in this index have an oxygen sensor warning light reset.

OXYGEN SENSOR WARNING LIGHT RESET INDEX Model & Year Reset Procedure Sprint 1985-86 Oxygen Sensor Warning Light Reset - Procedure 1 OXYGEN SENSOR WARNING LIGHT RESET - PROCEDURE 1 At 30,000 mile intervals, a SENSOR light in dash will start flashing, indicating oxygen sensor needs replacement. To reset mileage counter (after sensor replacement), locate SENSOR light cancel switch on right side of fuse box. Return cancel switch to OFF position. Start engine to ensure light remains off.

SERVICE REMINDER MESSAGE NOTE:

To determine the appropriate reset procedure, refer to Service Reminder Reset

Index. Only vehicles listed in this index have a Service Reminder reset. SERVICE REMINDER RESET INDEX Model & Year 6000 STE 1987-89 Bonneville 1988-91 Caprice 2011

Reset Procedure Service Reminder Message Reset - Procedure 1 Service Reminder Message Reset - Procedure 1 Service Reminder Message Reset - Procedure 2

SERVICE REMINDER MESSAGE RESET - PROCEDURE 1 The SERVICE REMINDER message light is used on models with a Driver Information Center (DIC). After performing necessary services, reset service reminder light. 1. To reset service reminder, push DIC button until desired service item is displayed. 2. Press and hold down the DIC button. With button pressed, the distance display will decrease in increments of 500 miles. 3. Release button when desired distance is displayed on the DIC. SERVICE REMINDER MESSAGE RESET - PROCEDURE 2 The displayed service reminder is reset using a scan tool or by the following procedure: 1. 2. 3. 4. 5.

Turn the ignition to the OFF position. Press and hold the TRIP button. Turn the ignition to the ON position. Release the TRIP button. Once in the Service Reset screen, press and hold the ENTER switch for 3-5 seconds. A confirmation beep will sound upon reset. 6. Turn the ignition to the OFF position. NOTE:

If the service reminder comes back on when you start the vehicle, the Service Reminder Display has not reset. Repeat the procedure.

TIRE PRESSURE MONITOR SYSTEM (TPMS) NOTE:

To determine the appropriate reset procedure, refer to TPMS RESET INDEX. Only vehicles listed in this index have a TPMS reset.

TPMS RESET INDEX Model

Application

Procedure

Buick Allure Century Enclave

2007 2008-09 1999-05

LaSabre

2008-12 2013-15 2013-14 2006-09 2010-12 2013-14 2002-05

Lucerne

2006

Encore LaCrosse

TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 (1) TPMS Reset - Procedure 21

TPMS Reset - Procedure 2 TPMS Reset - Procedure 9 TPMS Reset - Procedure 25 TPMS Reset - Procedure 2 TPMS Reset - Procedure 11 TPMS Reset - Procedure 26 (1) TPMS Reset - Procedure 20 (1) TPMS Reset - Procedure 22

Park Avenue

2007-11 1998-05

(1) TPMS Reset - Procedure 20

Rainier Regal

2006-07 1999-04

(1) TPMS Reset - Procedure 21

Rendezvous

2011-12 2013-14 2003-07

(1) TPMS Reset - Procedure 24

2012 2013-14

TPMS Reset - Procedure 11 TPMS Reset - Procedure 26

2013-14 2004-11 2012

TPMS Reset - Procedure 11 TPMS Reset - Procedure 31 With RPO UH3: TPMS Reset - Procedure 9 W/O RPO UH3: TPMS Reset - Procedure 10 TPMS Reset - Procedure 9 TPMS Reset - Procedure 4 TPMS Reset - Procedure 2 TPMS Reset - Procedure 11 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 9 TPMS Reset - Procedure 11 TPMS Reset - Procedure 4 TPMS Reset - Procedure 2 TPMS Reset - Procedure 11 TPMS Reset - Procedure 3

Verano Cadillac ATS CTS

Deville DTS ELR Escalade Series

Seville SRX STS

2013-14 2001-05 2006-11 2014 2004-06 2008-12 2013-14 2015 2001-04 2008-11 2012-14 2005-11

TPMS Reset - Procedure 2 TPMS Reset - Procedure 1 TPMS Reset - Procedure 11 TPMS Reset - Procedure 26

XLR XTS Chevrolet Avalanche

Aveo Camaro

Caprice Captiva Sport Cobalt Colorado Corvette

Cruze Equinox

HHR G-Series Van Impala

Impala Limited Malibu/Classic

2008 2013-14

TPMS Reset - Procedure 2 TPMS Reset - Procedure 11

2004-07 2008-11 2012 2013 2008-11

TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 3 TPMS Reset - Procedure 9

2010-11 2012 2013-14 2011-13 2014 2012-14 2008-10 2006-12 1987-96 1997-04 2005-06 2007-13 2014 2011-12 2013-14 2007 2008-11 2012 2013-14 2008-11 2008-12 2013-14 2000-02

(2) TPMS Reset - Procedure 7

TPMS Reset - Procedure 2 TPMS Reset - Procedure 11 TPMS Reset - Procedure 25 TPMS Reset - Procedure 31 TPMS Reset - Procedure 25 TPMS Reset - Procedure 2 TPMS Reset - Procedure 3 TPMS Reset - Procedure 1 (1) TPMS Reset - Procedure 20

TPMS Reset - Procedure 6 TPMS Reset - Procedure 3 TPMS Reset - Procedure 9 TPMS Reset - Procedure 8 TPMS Reset - Procedure 11 TPMS Reset - Procedure 25 TPMS Reset - Procedure 5 TPMS Reset - Procedure 2 TPMS Reset - Procedure 11 TPMS Reset - Procedure 25 TPMS Reset - Procedure 3 TPMS Reset - Procedure 2 TPMS Reset - Procedure 27

2003-05

(1) TPMS Reset - Procedure 13 (1) TPMS Reset - Procedure 14

2006-07 2008-12 2013 2014 2014 2008-11 2012 2013-14

TPMS Reset - Procedure 5 TPMS Reset - Procedure 2 TPMS Reset - Procedure 9 TPMS Reset - Procedure 28 TPMS Reset - Procedure 9 TPMS Reset - Procedure 3 TPMS Reset - Procedure 2 TPMS Reset - Procedure 25

Monte Carlo

Orlando (Canada) Silverado Series

Sonic Spark Spark EV SS Suburban

Tahoe

TrailBlazer Traverse Uplander Volt GMC Acadia

Canyon Envoy Savana Series Sierra Series

2015 2000-02

TPMS Reset - Procedure 28

2003-05

(1) TPMS Reset - Procedure 13 (1) TPMS Reset - Procedure 14

2006-07 2012 2006-07 2008-11 2012 2013 2014-15 2012 2013-14 2012-14 2014-15 2014 2004-07 2008-11 2012 2013-14 2015 2004-07 2008-11 2012 2013-14 2015 2006-07 2009-12 2013-15 2008 2011-12 2013-14

TPMS Reset - Procedure 5 TPMS Reset - Procedure 11 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 3 TPMS Reset - Procedure 27 TPMS Reset - Procedure 26 TPMS Reset - Procedure 11 TPMS Reset - Procedure 25 TPMS Reset - Procedure 29 TPMS Reset - Procedure 30 TPMS Reset - Procedure 25 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 3 TPMS Reset - Procedure 9 TPMS Reset - Procedure 26 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 3 TPMS Reset - Procedure 9 TPMS Reset - Procedure 26 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 9 TPMS Reset - Procedure 3 TPMS Reset - Procedure 11 TPMS Reset - Procedure 30

2007-11 2012 2013-15 2006-12 2006-09 2008-12 2013-14 2006-07 2008-11

TPMS Reset - Procedure 3 TPMS Reset - Procedure 2 TPMS Reset - Procedure 9 TPMS Reset - Procedure 1 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 27 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2

2012 2013 2014-15 2010-11 2012-14 2004-07 2008-11 2012 2013-14 2015

TPMS Reset - Procedure 3 TPMS Reset - Procedure 9 TPMS Reset - Procedure 26 TPMS Reset - Procedure 2 TPMS Reset - Procedure 12 TPMS Reset - Procedure 1 TPMS Reset - Procedure 2 TPMS Reset - Procedure 3 TPMS Reset - Procedure 9 TPMS Reset - Procedure 26

Oldsmobile Alero

1999-00

Aurora

2001-03

(1) TPMS Reset - Procedure 16 (1) TPMS Reset - Procedure 17

Pontiac Aztek

2003-05

Bonneville

2000-05

G3 G5 G6 G8 Grand Am

2009 2008-09 2008-10 2008-09 1999-05

Grand Prix Solstice Torrent Wave Vibe

2008 2008-10 2008-09 2008 2005-07

Terrain Yukon Series

(1) TPMS Reset - Procedure 23 (1) TPMS Reset - Procedure 15

TPMS Reset - Procedure 2 TPMS Reset - Procedure 2 TPMS Reset - Procedure 2 TPMS Reset - Procedure 2 (1) TPMS Reset - Procedure 18

TPMS Reset - Procedure 2 TPMS Reset - Procedure 2 TPMS Reset - Procedure 2 TPMS Reset - Procedure 2 (1) TPMS Reset - Procedure 19

(1) This is an Indirect TPM System. A tire sensor activation tool is not required for this procedure. (2) A tire sensor activation tool cannot be used for this procedure.

TPMS RESET - PROCEDURE 1 NOTE:

When the wheels have been rotated, or a tire pressure sensor or EGM/LGM has been replaced, retrain tire pressure sensors.

NOTE:

The DIC will display the "SERVICE TIRE MONITOR" message if one or more of the tire pressure sensors has malfunctioned or if all of the sensors have not been programmed successfully. If, after the relearn procedure, the warning indicators are still on, there is a problem in the TPM system.

NOTE:

If this procedure is performed following replacement and reprogramming of the Liftgate Module (LGM), DIC may display a low tire pressure fault and all tire pressures read 0 psi. If this problem occurs, see appropriate manufacturer service information.

NOTE:

The TPM system will cancel the learn mode if more than 2 minutes have passed and no sensors have been learned, or if the system has been in learn mode for more than 5 minutes. If the learn mode is canceled before any sensor has been learned, the EGM/LGM will remember all current sensor IDs and their locations. As soon as the first sensor ID code is learned, all other IDs are erased from the EGM/LGM's memory. On models that display the individual tire pressure on DIC, updated tire pressures will not be displayed until EGM/LGM receives 2 more valid transmissions from each sensor.

NOTE:

Before proceeding with the steps below, ensure that no other sensor learn procedure is being performed simultaneously, or that tire pressures are not being adjusted on a TPM equipped vehicle within close proximity.

1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Turn ignition ON with engine OFF. Apply parking brake. NOTE:

If Learn Mode cannot be enabled, TPM system is not enabled in EGM/LGM. See appropriate manufacturer service information.

3. To enable Learn Mode, turn headlight switch from OFF to parking lamps 4 times within 4 seconds. A double horn chirp will sound and the low tire pressure indicator will begin to flash to indicate the learn mode has been enabled. 4. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 5. After horn chirp has sounded, proceed to the next 3 sensors in the following order: right front, right rear and left rear. 6. After left rear sensor has been learned, turn ignition switch to OFF position to exit Learn Mode. 7. Test drive the vehicle above 25 mph for at least 2 minutes before viewing tire pressures on DIC. TPMS RESET - PROCEDURE 2 NOTE:

If a tire pressure sensor or the Remote Control Door Lock Receiver (RCDLR) is replaced, or if wheels have been rotated, tire pressure sensor must be retrained.

NOTE:

When the tire pressure warning light illuminates and warning message appears on DIC, immediately check air pressure of all tires and adjust to the specified pressure. If warning indicators are still on or display shows dashes instead of a value, there is a problem in the TPM system. See appropriate manufacturer service information.

NOTE:

Under the following conditions, the TPM system may not function properly:  

If one or more of the tire pressure sensors are missing or inoperable. A compact spare tire is used.

NOTE:

If a tire pressure sensor or the Remote Control Door Lock Receiver (RCDLR) is replaced, or if wheels have been rotated, tire pressure sensor must be retrained.

NOTE:

The relearn procedure must be completed within 15 minutes from when the vehicle is stationary after being driven at 20 mph (32 km/h), or greater, for 10 seconds.

NOTE:

The learn mode will cancel if the ignition is cycled to OFF or if more than 2 minutes has elapsed for any sensor that has not been learned. If the learn mode is cancelled before the first sensor is learned, the original sensor IDs will be maintained. If the learn mode is canceled after the first sensor is learned, the following will occur:   

All stored sensor IDs will be invalidated in the RCDLR memory. If equipped, the DIC will display dashes instead of tire pressures. DTC C0775 will be set.

These conditions will now require the learn procedure to be repeated for the system to function properly. IMPORTANT: Ensure that no other learn procedure is being performed simultaneously or that tire pressures are not being adjusted on another TPM equipped vehicle within close proximity. Stray signals from other TPM equipped vehicles just driving by can be inadvertently learned. If any random horn chirps are heard from the vehicle while performing the learn procedure, most likely a stray sensor has been learned and the procedure will need to be cancelled and repeated. Under these circumstances, performing the TPM Learn Procedure away from other vehicles would be highly recommended. In the event a particular sensor activation does not cause the horn to chirp, it may be necessary to rotate the wheel valve stem to a different position due to the sensor signal is being blocked by another component. 1. Turn ignition switch to ACC position. Apply parking brake. 2. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 3. To enable Learn Mode:  On vehicles equipped with keyless entry, simultaneously press the keyless entry transmitters lock and unlock buttons until a double horn chirp sounds indicating the Learn Mode has been enabled. On vehicles with DIC, a TIRE LEARN message may be displayed. The left front turn signal will

4. 5. 6. 7.

also be illuminated. ď Ź On vehicles not equipped with keyless entry, press and release the driver information center (DIC) INFO button until the TIRE LEARN message appears on the DIC display. Press and hold the SET/RESET button until a double horn chirp sounds indicating the Learn Mode has been enabled. The left front turn signal will also be illuminated. Ignition ON. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. After horn chirp has sounded, proceed to the next 3 sensors in the following order: right front, right rear and left rear. After left rear sensor has been learned, turn ignition switch to OFF position to exit Learn Mode.

TPMS RESET - PROCEDURE 3 NOTE:

If a tire pressure sensor or the Remote Control Door Lock Receiver (RCDLR) is replaced, or if wheels have been rotated, tire pressure sensor must be relearned.

NOTE:

In vehicles without the "UH3" option, each turn signal will illuminate one at a time indicating which location is to be learn.

NOTE:

The TPM system will cancel the learn mode if more then 2 minutes have passed and no sensors have been learned, or if the ignition switch is turn to the OFF position. If the learn mode is canceled before the first ID is learned, the RCDLR will remember all previously stored IDs and their locations. As soon as the first sensor ID is learned, all other IDs are erased from the RCDLR's memory. If the learn mode is canceled after the first ID is learned, the RCDLR will store the IDs as invalid and the DIC will display dashes instead of tire pressures.

NOTE:

Before proceeding with the registration procedure, ensure that no other sensor learn procedure is being performed simultaneously, or that no tire pressures are being adjusted on another TPM equipped vehicle within close proximity.

1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Turn ignition switch to ACC position. Apply parking brake. 3. Simultaneously press the keyless entry transmitter's lock and unlock buttons until a double horn chirp sounds, indicating the Learn Mode has been enabled.

NOTE:

The left front turn signal will also illuminate to indicate the learn mode has been enabled.

If the wheels have been rotated, or tire pressure sensor or Remote Control Door Lock Receiver (RCDLR) is replaced, the TPM system needs to relearn tire pressure sensor IDs.

NOTE:

When the tire pressure warning light illuminates and warning message appears on DIC, immediately check air pressure of all tires and adjust to the specified pressure. If warning indicators are still on, there is a problem in the TPM system. See appropriate manufacturer service information.

NOTE:

The TPM system will cancel Learn Mode if ignition is turned off, if more than 1 or 2 minutes has passed and no sensors have been learned, vehicle battery voltage is less than 8 volts, all 4 sensors have been learned, or if the RCDLR has been in Learn Mode for more than 5 minutes. If Learn Mode is cancelled before any IDs are learned, the RCDLR will remember all previously stored IDs and their locations. As soon as the first sensor ID is learned, all other IDs are erased from the RCDLR's memory.

NOTE:

1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Turn ignition ON with engine OFF. NOTE:

If the TPM Learn Mode cannot be enabled, ensure the TPM option is enabled in the RCDLR. See appropriate manufacturer service information.

3. Simultaneously press the keyless entry transmitter's lock and unlock buttons until a horn chirp sounds, indicating Learn Mode has been enabled. NOTE:

If a horn chirp does not sound after 15 seconds, remove, then re-apply TPM sensor relearn magnet.

4. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 5. After the horn chirp sounds, proceed to the next 3 sensors in the following order: right front, right rear, then left rear. 6. After the left rear sensor ID is learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn the ignition switch to OFF position to exit Learn Mode. TPMS RESET - PROCEDURE 5 NOTE:

If the wheels have been rotated, or tire pressure sensor or Remote Control Door Lock Receiver (RCDLR) is replaced, the TPM system needs to relearn tire pressure sensor IDs.

NOTE:

When the tire pressure warning light illuminates and warning message appears on DIC, immediately check air pressure of all tires and adjust to the specified pressure. If warning indicators are still on, there is a problem in the TPM system. See appropriate manufacturer service information.

NOTE:

1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Turn ignition ON with engine OFF. 3. Simultaneously press the keyless entry transmitter's lock and unlock buttons until a horn chirp sounds, indicating Learn Mode has been enabled. 4. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 5. After the horn chirp sounds, proceed to the next 3 sensors in the following order: right front, right rear, then left rear. 6. After the left rear sensor ID is learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn the ignition switch to OFF position to exit Learn Mode. TPMS RESET - PROCEDURE 6 NOTE:

If the wheels have been rotated, or tire pressure sensor or Remote Control Door

Lock Receiver (RCDLR) is replaced, the TPM system needs to relearn tire pressure sensor IDs. NOTE:

When the tire pressure warning light illuminates and warning message appears on DIC, immediately check air pressure of all tires and adjust to the specified pressure. If warning indicators are still on, there is a problem in the TPM system. See appropriate manufacturer service information.

NOTE:

1. 2. 3. 4. 5.

Set the tire pressure of all wheels to pressure specified on the tire and loading information label. Turn ignition ON with engine OFF. Press RESET button on DIC in order to clear any warning messages. Press and release OPTIONS button until display is blank. Press and hold RESET button for 3 seconds. NOTE:

If the DIC does not display "TIRE TRAINING" message, ensure TPM option is enabled in the RCDLR. See appropriate manufacturer service information.

6. Press and release OPTIONS button until "TIRE TRAINING" is displayed. 7. Press and release RESET button. The DIC should display "LEARN L FRONT TIRE", verifying Learn Mode has been enabled. 8. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 9. After the horn chirp sounds, proceed to the next 3 sensors in the following order: right front, right rear, then left rear. 10. Turn the ignition switch to OFF position to exit the learn mode. TPMS RESET - PROCEDURE 7 NOTE:

An OEM scan tool or Pressure Increase/Decrease Method is used to perform this procedure.

NOTE:

Before proceeding with this process, ensure that no other learn procedure is being performed simultaneously or that tire pressures are not being adjusted on another TPM equipped vehicle within close proximity. Stray signals from

other TPM equipped vehicles just driving by can be inadvertently learned. If any random horn chirps are heard from the vehicle while performing the learn procedure, most likely a stray sensor has been learned and the procedure will need to be cancelled and repeated. Under these circumstances, performing the TPM Learn Procedure away from other vehicles would be highly recommended. In the event a particular sensor activation does not cause the horn to chirp, it may be necessary to rotate the wheel valve stem to a different position due to the sensor signal is being blocked by another component. 1. Ignition ON with engine OFF, apply the parking brake. 2. Using a scan tool, initiate the TPM Learn Mode. 3. Perform the procedure by following the menu selections. A double horn chirp will sound and the IPC tire pressure monitor indicator warning lamp icon will flash indicating Learn Mode is enabled. 4. Starting with the left front tire, active the sensors by one of the following methods: ď Ź Hold the antenna of the scan tool, aimed upward, against the tire sidewall close to the wheel rim at the valve stem location. Press and release the activate button and wait for a horn chirp. Once the horn chirp has sounded, the sensor information is learned. ď Ź Increase/decrease the tire pressure for 8-10 seconds then wait for a horn chirp. The horn chirp may occur before or up to 30 seconds after the 8-10 second pressure increase/decrease time period has been reached. Once the horn chirp has sounded, the sensor information has been learned. 5. After the horn chirp has sounded, repeat step 4 for the remaining 3 sensors in the following order: Right front, Right rear, Left rear. 6. After the left rear sensor is learned, a double horn chirp will sound indicating all sensor IDs have been learned and the tire pressure module will exit the Learn mode turning OFF the IPC tire pressure monitor warning indicator lamp icon. 7. Ignition OFF, adjust all tires to the recommended pressures. Refer to the tire placard label. TPMS RESET - PROCEDURE 8 Automatic Sensor Learn Process Each TPMS sensor has a unique identification code. The identification code needs to be matched to a new tire/wheel position after rotating the tires or replacing one or more of the TPMS sensors. When a tire is installed, the vehicle must be stationary for about 20 minutes before the system recalculates. The following relearn process takes up to 10 minutes, driving at a minimum speed of 12 mph (19 km/h). A dash (-) or pressure value will display in the DIC. A warning message displays in the DIC if a problem occurs during the relearn process. TPMS RESET - PROCEDURE 9 NOTE:

If a tire pressure sensor or the Remote Control Door Lock Receiver (RCDLR) is replaced, or if wheels have been rotated, tire pressure sensor must be relearned.

NOTE:

When the tire pressure warning light illuminates and warning message appears

on DIC, immediately check air pressure of all tires and adjust to the specified pressure. If warning indicators are still on or display shows dashes instead of a value, there is a problem in the TPM system. See appropriate manufacturer service information. NOTE:

NOTE:

1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Turn ignition switch to RUN position. Apply parking brake. 3. Simultaneously press the keyless entry transmitter's lock and unlock buttons until a double horn chirp sounds, indicating the Learn Mode has been enabled. 4. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 5. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. 6. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position to exit Learn Mode. TPMS RESET - PROCEDURE 10 NOTE:

If a tire pressure sensor or the Remote Control Door Lock Receiver (RCDLR) is replaced, or if wheels have been rotated, tire pressure sensor must be relearned.

NOTE:

sensor ID is learned, all other IDs are erased from the RCDLR's memory. If the learn mode is canceled after the first ID is learned, the RCDLR will store the IDs as invalid and the DIC will display dashes instead of tire pressures. NOTE:

1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Depending on ignition type: ď Ź With standard ignition switch, place the switch in the RUN position. ď Ź With electronic keyless ignition, place the switch in the ACC position. 3. Simultaneously press the keyless entry transmitter's lock and unlock buttons until a double horn chirp sounds, indicating the Learn Mode has been enabled. 4. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 5. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. 6. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position to exit Learn Mode. TPMS RESET - PROCEDURE 11 1. 2. 3. 4. 5. 6.

8. 9.

10.

Set the tire pressure of all wheels to pressure specified on the tire and loading information label. Set the parking brake. Place the vehicle power mode in ON/RUN/START. Make sure the Tire Pressure info display option is turned on. The info displays on the DIC can be turned on and off through the Settings menu. Use the five-way DIC control on the right side of the steering wheel to scroll to the Tire Pressure screen under the DIC info page. Press and hold the SEL button located in the center of the five-way DIC control. The horn sounds twice to signal the receiver is in relearn mode and the TIRE LEARNING ACTIVE message displays on the DIC screen Start with the driver side front tire. Place a tire sensor activation tool against the tire sidewall, near the valve stem. Then press the button to activate the TPMS sensor. A horn chirp confirms that the sensor identification code has been matched to this tire and wheel position. After horn chirp has sounded, proceed to the next 3 sensors in the following order: right front, right rear and left rear. After left rear sensor has been learned, the horn sounds two times to indicate the sensor identification code has been matched to the driver side rear tire, and the TPMS sensor matching process is no longer active. The TIRE LEARNING ACTIVE message on the DIC display screen goes off. Press STOP to turn the ignition off.

TPMS RESET - PROCEDURE 12 1. 2. 3. 4. 5. 6. 7.

8. 9.

10.

Set the tire pressure of all wheels to pressure specified on the tire and loading information label. Set the parking brake. Turn the ignition to ON/RUN with the engine off. Use the MENU button (center console) to select the Vehicle Information Menu in the Driver Information Center (DIC). Use the arrow keys to scroll to the Tire Pressure screen Press the SET/CLR button to begin the sensor matching process. A message requesting acceptance of the process should display. Press the SET/CLR button again to confirm the selection. The horn sounds twice to signal the receiver is in relearn mode and the TIRE LEARNING ACTIVE message displays on the DIC screen. Start with the driver side front tire. Place a tire sensor activation tool against the tire sidewall, near the valve stem. Then press the button to activate the TPMS sensor. A horn chirp confirms that the sensor identification code has been matched to this tire and wheel position. After horn chirp has sounded, proceed to the next 3 sensors in the following order: right front, right rear and left rear. After left rear sensor has been learned, the horn sounds two times to indicate the sensor identification code has been matched to the driver side rear tire, and the TPMS sensor matching process is no longer active. The TIRE LEARNING ACTIVE message on the DIC display screen goes off. Turn the ignition to LOCK/OFF.

TPMS RESET - PROCEDURE 13 LOW TIRE PRESSURE light comes on if air pressure in one tire drops to 12 psi (kPa) less than the other 3 tires, if tires are rotated, if tire(s) are repaired or replaced, if air pressure is adjusted or when vehicle battery is disconnected. Light will stay on until ignition is turned off or RESET button is pressed. Check and adjust air pressure in all 4 tires before resetting system. 1. There are 2 ways to reset the tire inflation monitor. To reset the tire inflation monitor using the exterior or interior lamp controls, go to step 4. To reset tire inflation monitor using the radio, turn the radio off. Turn ignition to ACC or ON, with the engine OFF. Press and hold the TUNE DISP button on the radio for at least 5 seconds until settings is displayed. 2. To scroll through the main menu:  On Impala, press the SEEK PTYPE up or down arrow.  On Monte Carlo, press the SEEK PSCAN up or down arrow. On all models, scroll until TIRE MON appears on the display. Press the 1 PREV or 2 NEXT button to enter the sub-menu. RESET will be displayed. 3. Press the TUNE DISP button to reset. A chime will sound to verify the new setting and DONE will be displayed for one second. Once the message has been reset, scroll through the menu until EXIT appears on the display. Press the TUNE DISP button to exit the program. A chime will sound to verify the exit. 4. Reset the tire inflation monitor:  On Impala, using the interior lighting controls, turn the switch from OFF to ON position 3 times with ignition switch in ON position.

ď Ź

On Monte Carlo, using the exterior lighting controls, turn the switch from OFF to parking lamps 3 times with ignition switch in ON position.

TPMS RESET - PROCEDURE 14 NOTE:

There are 3 different ways to reset the Tire Pressure Monitor (TPM) system. After resetting, the TPM system requires up to 30 minutes of straight line driving in each of the 3 speed ranges to complete the calibration process.

Using Exterior Lamp Switch

1. 2. 3. 4.

Adjust all tire pressures to the recommended kPa/psi. Turn ignition ON with engine OFF. Cycle the exterior lamp switch from OFF to parking lamps 3 times within 5 seconds. Use the scan tool in order to clear the TPM DTC.

Using RDS Radio, If Equipped

1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Adjust all tire pressures to the recommended kPa/psi. Turn the ignition to ACC or ON, with the engine OFF. Turn the radio OFF. Press and hold the DISP button until SETTINGS is displayed. Press the SEEK up or down arrows until TIRE MON is displayed. Press the PREV or NEXT button to enter the sub-menu. RESET will be displayed. Press the DISP button, A chime will sound and DONE will be displayed. Scroll until EXIT is displayed. Press the DISP button to exit the TPM reset mode. A chime will sound to verify exit. Use the scan tool in order to clear the TPM DTC.

Using Scan Tool

1. 2. 3. 4. 5. 6. 7.

Adjust all tire pressures to the recommended kPa/psi. Install the scan tool. Turn ignition ON with engine OFF. With the scan tool select Special Functions. Select TIM Reset. Press the Reset soft key. Use the scan tool in order to clear the TPM DTC.

TPMS RESET - PROCEDURE 15 CHECK TIRE PRESSURE or TIRE PRESS message will come on if air pressure in one tire is lower than the

other 3 tires, if tires are rotated, if tire(s) are repaired or replaced, or if air pressure is adjusted. Message will stay on until system is recalibrated. Check and adjust air pressure in all 4 tires before recalibrating system. NOTE:

If vehicle is equipped with Systems Monitor, go to step 2.

1. To recalibrate vehicle equipped with Driver Information Center (DIC), turn ignition ON with engine OFF. Using the MODE and SELECT button on DIC, change display until TIRE PRESSURE appears. Press and hold RESET button for 5 seconds. TIRE PRESSURE RESET should now appear on display. If TIRE PRESSURE RESET does not appear on display after 5 seconds, repair system as necessary. Using a scan tool, clear TPM DTC. 2. To recalibrate vehicle equipped with Systems Monitor, turn ignition ON with engine OFF. Press and hold TIRE PRESS RESET button for 5 seconds. TIRE PRESS light on the Systems Monitor should begin to flash. Release the TIRE PRESS RESET button. TIRE PRESS light should go out and system is now reset. If TIRE PRESS light does not begin to flash after 5 seconds, repair system as necessary. Using a scan tool, clear TPM DTC. TPMS RESET - PROCEDURE 16 CHECK TIRE PRESSURE light comes on if air pressure in one tire drops to 12 psi (kPa) less than the other 3 tires, if tires are rotated, if tire(s) are repaired or replaced, or if air pressure is adjusted. Light will stay on until ignition is turned off or RESET button is pressed. Check and adjust air pressure in all 4 tires before resetting system. 1. To reset tire inflation monitor, turn ignition ON with engine OFF. Press and release the RESET button. RESET button is located inside of driver's side instrument panel fuse block (left end of instrument panel). The CHANGE OIL indicator light will begin to flash. 2. Press and release the RESET button again. The CHANGE OIL indicator light will turn off, and the CHECK TIRE PRESSURE indicator light will begin to flash. While the CHECK TIRE PRESSURE indicator light is flashing, press and hold the RESET button until the chime sounds indicating system is reset. If CHECK TIRE PRESSURE light does not go out, repeat reset procedure. If system still will not reset, repair system as necessary. TPMS RESET - PROCEDURE 17 NOTE:

When a spare tire is mounted, a wheel is replaced or rotated, or tire pressure has been adjusted, TPM system will need to be recalibrated.

NOTE:

When the low tire pressure warning messages appear, immediately check air pressure of all tires and adjust to the specified pressure. If warning messages are still displayed, there is a malfunction in the TPM system. See appropriate manufacturer service information.

NOTE:

Under the following conditions, the system may not function properly: ď Ź

More than one tire is low.

       

Only one tire is replaced with a new tire during service. Vehicle is moving faster than 65 mph (105 km/h). The system is not yet calibrated. Tire treadwear is uneven. Compact spare tire is installed. Tire chains are being used. Vehicle is being driven on a rough or frozen road. If ABS warning light is on.

CAUTION: DO NOT recalibrate TPM system until all problems are fixed and tire pressure in all 4 tires has been adjusted. If recalibration is done when tire pressures are incorrect, TPM system will not work properly and may not set an alert when a tire pressure is low or high. NOTE:

There are 2 ways to recalibrate the Tire Pressure Monitor (TPM) system:  

Using DIC Reset Button (if no scan tool is available) Using Scan Tool (if an OBD-II compatible scan tool is available).

Using DIC Reset Button

1. 2. 3. 4. 5. 6. 7. 8.

Turn ignition switch to OFF position. Ensure all tire pressures are adjusted to the pressure recommended on tire pressure label. Turn ignition ON with engine OFF. Press SELECT right arrow button until "GAGE" is displayed. Press SELECT down arrow button until "TIRE PRESSURE" is displayed. Press and hold RESET button until "TIRE PRESSURE RESET" is displayed. Release RESET button. DIC should display "TIRE PRESSURE NORMAL". After resetting, the TPM system requires up to 30 minutes of straight line driving in each of the following speed ranges to complete calibration process:  15-40 mph (24-64 km/h).  40-70 mph (64-113 km/h).  70-90 mph (113-145 km/h). NOTE:

The EBCM learns tire pressure calibration for each speed range independently. In Monitor Mode 1, EBCM has only partially learned tire pressure calibration for speed range and has limited detection capability for a tire pressure condition. In Monitor Mode 2, EBCM has fully learned tire pressure calibration for speed range and has full detection capability for a tire pressure condition.

NOTE:

Learning process does not need to be completed during a single trip.

Using Scan Tool

1. 2. 3. 4. 5. 6. 7. 8.

Turn ignition switch to OFF position. Ensure all tire pressures are adjusted to the pressure recommended on tire pressure label. Connect scan tool. Turn ignition ON with engine OFF. Using scan tool, select "SPECIAL FUNCTIONS". Select "TIRE PRESSURE RESET". Press RESET soft key. A "TIRE PRESSURE NORMAL" message should appear on display. If necessary, use scan tool to clear any TPM Diagnostic Trouble Codes (DTCs). After resetting, the TPM system requires up to 30 minutes of straight line driving in each of the following speed ranges to complete calibration process:  15-40 mph (24-64 km/h).  40-70 mph (64-113 km/h).  70-90 mph (113-145 km/h). NOTE:

NOTE:

Learning process does not need to be completed during a single trip.

TPMS RESET - PROCEDURE 18 The Tire Pressure Monitor (TPM) system alerts the driver when a large change in the pressure of one tire exists, while the vehicle is being driven. The TPM system uses the Electronic Brake Control Module (EBCM), ABS wheel speed sensor inputs, class 2 serial data circuit, and the Driver Information Center (DIC) to perform the system functions. The EBCM contains software to calculate relative tire pressure differences. The software requires approximately 30 minutes of straight line driving in 3 different speed ranges to complete the calibration process to have full capability for detecting a tire pressure condition. The speed ranges are 15-40 mph, 40-70 mph and 70-90 mph. 1. LOW TIRE PRESSURE light comes on if air pressure in one tire drops to 12 psi less than the other 3 tires, if tires are rotated, if tire(s) are repaired or replaced, if air pressure is adjusted or if vehicle battery is disconnected. Light will stay on until ignition is turned off or RESET button is pressed. Check and adjust air pressure in all 4 tires before resetting system. 2. To reset tire inflation monitor, turn ignition ON with engine OFF. Press and release the RESET button. RESET button is located inside of driver's side instrument panel fuse block (left end of instrument panel). The CHANGE OIL indicator light will begin to flash. 3. Press and release the RESET button again. The CHANGE OIL indicator light will turn off, and the LOW

TIRE PRESSURE indicator light will begin to flash. While the LOW TIRE PRESSURE indicator light is flashing, press and hold the RESET button until the chime sounds indicating system is reset. If the LOW TIRE PRESSURE indicator light does not go out, repeat reset procedure. If system still will not reset, repair system as necessary. TPMS RESET - PROCEDURE 19 NOTE:

After resetting, the tire pressure monitoring (TPM) system requires 60 minutes or more of driving at a speed of 30 km/h (19 mph) or above to complete the calibration process to have full capability for detecting a tire pressure condition.

1. Adjust all tire pressures to the recommended kPa/psi. 2. Turn ignition ON with engine OFF. 3. Press and hold the tire pressure warning reset switch until the tire pressure warning indicator blinks 3 times at one second intervals. 4. If the tire pressure warning indicator does not blink, repeat the procedure starting at step 2. 5. Drive the vehicle for 60 minutes or more at a speed of 30 km/h (19 mph). 6. Verify the system has initialized. Turn ignition ON with engine OFF and observe the tire pressure warning indicator.  System Initialized: light on for 3 seconds.  System not initialized: light on for 4 seconds. TPMS RESET - PROCEDURE 20 NOTE:

When a spare tire is mounted, a wheel is replaced or rotated, or tire pressure has been adjusted, TPM system will need to be recalibrated. CAUTION: DO NOT recalibrate TPM system until all problems are fixed and tire pressure in all 4 tires has been adjusted. If recalibration is done when tire pressures are incorrect, TPM system will not work properly and may not set an alert when a tire pressure is low or high.

NOTE:

When the tire pressure warning message appears on DIC, immediately check air pressure of all tires and adjust to the specified pressure. If warning message is still displayed, there is a malfunction in the TPM system. See appropriate manufacturer service information.

NOTE:

Under the following conditions, the system may not function properly:   

More than one tire is low. Vehicle is moving faster than 65 mph (105 km/h). The system is not yet calibrated.

    

NOTE:

Tire treadwear is uneven. Compact spare tire is installed. Tire chains are being used. Vehicle is being driven on a rough or frozen road. If ABS warning light is on.

There are 2 ways to recalibrate the Tire Pressure Monitor (TPM) system:  

Using DIC Reset Button (if no scan tool is available) Using Scan Tool (if an OBD-II compatible scan tool is available).

Using DIC Reset Button

1. 2. 3. 4.

Turn ignition switch to OFF position. Ensure all tire pressures are adjusted to the pressure recommended on tire pressure label. Turn ignition ON with engine OFF. Press and hold appropriate button (located on left side of steering column) until "TIRE PRESSURE" message appears on display:  1997-99 models: Press and hold GAGES button  2000-05 models: Press and hold GAGES INFO button 5. Press and hold RESET button for 5 seconds. After 5 seconds, "TIRE PRESSURE RESET" message should appear on display. 6. Release RESET button. A "TIRE PRESSURE NORMAL" message should appear on display. 7. After resetting, the TPM system requires up to 30 minutes of straight line driving in each of the following speed ranges to complete calibration process:  15-40 mph (24-64 km/h).  40-70 mph (64-113 km/h).  70-90 mph (113-145 km/h). NOTE:

NOTE:

Learning process does not need to be completed during a single trip.

Using Scan Tool

1. Turn ignition switch to OFF position. 2. Ensure all tire pressures are adjusted to the pressure recommended on tire pressure label.

3. 4. 5. 6. 7. 8.

Connect scan tool. Turn ignition ON with engine OFF. Using scan tool, select SPECIAL FUNCTIONS. Select TIM RESET. Press RESET soft key. A "TIRE PRESSURE NORMAL" message should appear on display. If necessary, use scan tool to clear any TPM Diagnostic Trouble Codes (DTCs). After resetting, the TPM system requires up to 30 minutes of straight line driving in each of the following speed ranges to complete calibration process:  15-40 mph (24-64 km/h).  40-70 mph (64-113 km/h).  70-90 mph (113-145 km/h). NOTE:

NOTE:

Learning process does not need to be completed during a single trip.

TPMS RESET - PROCEDURE 21 Using Reset Button (1999-05 Models)

1. Adjust all tire pressures to the recommended Psi (kPa). See vehicle's Loading Information Label for recommended tire pressure. Turn ignition ON with engine OFF. 2. Press and hold the red RESET button located in the passenger side instrument panel fuse block. 3. The LOW TIRE indicator will flash 3 times, then turn off. 4. Use scan tool to clear the TPM DTC. Using Scan Tool (2003-05 Models)

1. Adjust all tire pressures to the recommended Psi (kPa). See vehicle's Loading Information Label for recommended tire pressure. Turn ignition ON with engine OFF. 2. Install scan tool. Turn ignition ON with engine OFF. 3. With scan tool, select Special Functions. 4. Select TIM Reset. 5. Press Reset soft key. 6. LOW TIRE indicator will flash 3 times, then turn OFF. 7. Clear the TPM DTC. TPMS RESET - PROCEDURE 22

NOTE:

1. 2. 3. 4.

Turn ignition switch to OFF position. Ensure all tire pressures are adjusted to the pressure recommended on tire pressure label. Turn ignition ON with engine OFF. Press and hold the MODE button until DIC display reads "LOW TIRE PRESSURE HOLD SET TO RESET". 5. Press and hold SET button chime sounds and "TIRE PRESSURE RESET" is displayed and a chime sounds 3 times. 6. Release SET button and DIC will display "TIRE PRESSURE NORMAL". NOTE:

If low tire pressure warning message is still set, TPM system has not reset. Repeat procedure. If it does not work after two tries, refer to appropriate service information.

7. After resetting, the TPM system requires up to 5 miles of driving in each of the following speed ranges to complete the calibration process:  25-40 mph (40-64 km/h).  40-60 mph (65-96 km/h).  60-85 mph (96-136 km/h). NOTE:

Learning process does not need to be completed during a single trip.

TPMS RESET - PROCEDURE 23 1. Check and adjust air pressure in all 4 tires before resetting system. Refer to tire placard located on the inside edge of the driver's door. Turn ignition ON, with engine OFF. 2. Press the MODE button on the Driver Information System until LOW TIRE PRESSURE HOLD SET TO RESET is displayed. 3. Press and hold the SET button until a chime sounds and TIRE PRESSURE RESET is displayed and a chime sounds 3 times. 4. Release the SET button and TIRE PRESSURE NORMAL will be displayed. TPMS RESET - PROCEDURE 24 NOTE:

When a spare tire is mounted, a wheel is replaced or rotated, or tire pressure has been adjusted, TPM system will need to be recalibrated.

Turn ignition switch to OFF position. Ensure all tire pressures are adjusted to the pressure recommended on tire pressure label. Turn ignition ON with engine OFF. Press and hold the MODE button until DIC display reads "LOW TIRE PRESSURE HOLD SET TO RESET". 5. Press and hold SET button until a chime sounds and "TIRE PRESSURE RESET" is displayed. 6. System will now sound a chime 3 times, and DIC will display "TIRE PRESSURE NORMAL". NOTE:

If low tire pressure warning message is still set, TPM system has not reset. Repeat procedure.

7. After resetting, the TPM system requires up to 5 miles (8 km) of flat, smooth road, straight line driving in each of the 4 speed ranges (about 10-20 minutes in each range) to complete the calibration process:  19-40 mph (31-65 km/h).  40-59 mph (65-95 km/h).  59-74.5 mph (95-120 km/h).  74.5-90 mph (120-145 km/h). NOTE:

The EBCM learns tire pressure calibration for each speed range independently. In Calibration Mode, EBCM has only partially learned tire pressure calibration for speed range and has limited detection capability for a tire pressure condition. In Detection Mode, EBCM has fully learned tire pressure calibration for speed range and has full detection capability for a tire pressure condition.

NOTE:

Learning process does not need to be completed during a single trip.

TPMS RESET - PROCEDURE 25 1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Set the parking brake. 3. Turn the ignition to ON/ RUN with the engine OFF or place the vehicle power mode in ON/ RUN/ START. See Fig. 4. 4. Use the MENU button to select the VEHICLE INFORMATION MENU in the Driver Information Center (DIC). See Fig. 5. 5. Use the thumbwheel (or up and down arrows) to scroll to the TIRE PRESSURE MENU item screen. 6. Press the SET/CLR button to begin the sensor matching process. A message requesting acceptance of the

7. 8. 9. 10.

process should display. Press the SET/CLR button again to confirm the selection. The horn sounds twice to signal the receiver is in relearn mode and the TIRE LEARNING ACTIVE message displays on the DIC screen. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position to exit Learn Mode.

Fig. 4: Ignition Positions (Key & Keyless) Courtesy of GENERAL MOTORS CORP.

Fig. 5: Identifying DIC Controls (Turn Signal Lever)

Courtesy of GENERAL MOTORS CORP. TPMS RESET - PROCEDURE 26 1. 2. 3. 4. 5.

7. 8. 9. 10.

Set the tire pressure of all wheels to pressure specified on the tire and loading information label. Set the parking brake. Turn the ignition to ON/RUN with the engine OFF. Up-level Driver Information Center (DIC) Only: Make sure the TIRE PRESSURE INFO page option is turned on. The info pages on the DIC can be turned on and off through the SETTINGS menu. If the vehicle has an up-level DIC, use the DIC controls (arrow buttons) on the right side of the steering wheel to scroll to the TIRE PRESSURE screen under the DIC info page. If the vehicle has a base-level DIC, use the TRIP ODOMETER RESET stem to scroll to the TIRE PRESSURE screen. If the vehicle has an up-level DIC, press and hold the SET/RESET button (check-mark symbol) located in the center of the DIC controls. If the vehicle has a base-level DIC, press and hold the TRIP ODOMETER RESET stem for about five seconds. A message asking if the process should begin should appear. Select YES and press the TRIP ODOMETER RESET stem to confirm the selection. The horn sounds twice to signal the receiver is in relearn mode and the TIRE LEARNING ACTIVE message displays on the DIC screen. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position to exit Learn Mode.

TPMS RESET - PROCEDURE 27 1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Turn ignition switch to ON/RUN position, with engine OFF. 3. Simultaneously press the keyless entry transmitter's lock and unlock buttons until a horn chirp sounds, indicating Learn Mode has been enabled. The TIRE LEARNING ACTIVE message displays on the DIC screen. NOTE:

If the vehicle does not have RKE, press the Driver Information Center (DIC) vehicle information button until the PRESS (check mark symbol) TO RELEARN TIRE POSITIONS message displays. The horn sounds twice to signal the receiver is in relearn mode and TIRE LEARNING ACTIVE message displays on the DIC screen. If the vehicle does not have RKE or DIC buttons, press the trip odometer reset stem on the instrument cluster until the PRESS (check mark symbol) TO RELEARN TIRE POSITIONS message displays. The horn sounds twice to signal the receiver is in relearn mode and TIRE LEARNING ACTIVE message displays on the DIC screen.

4. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 5. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. 6. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position to exit Learn Mode. TPMS RESET - PROCEDURE 28 1. Set the tire pressure of all wheels to pressure specified on the tire and loading information label. 2. Set the parking brake. 3. Turn the ignition to ON/ RUN with the engine OFF or place the vehicle power mode in ON/ RUN/ START. See Fig. 4. 4. Make sure the Tire Pressure info page option is turned on. The info pages on the Driver Information Center (DIC) can be turned on and off through the Settings menu. 5. Use the DIC controls on the right side of the steering wheel to scroll to the Tire Pressure screen under the DIC info page. 6. Press and hold the SET/RESET button (check mark symbol) located in the center of the DIC controls. 7. The horn sounds twice to signal the receiver is in relearn mode and the TIRE LEARNING ACTIVE message displays on the DIC screen. 8. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 9. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. 10. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position to exit Learn Mode. TPMS RESET - PROCEDURE 29 1. 2. 3. 4. 5. 6. 7.

Set the tire pressure of all wheels to pressure specified on the tire and loading information label. Set the parking brake. Turn the ignition to ON/RUN with the engine OFF. Press the MENU button once on the Driver Information Center (DIC). Press the up or down arrow button until the Tire Learn screen is displayed. Press and hold the SET/CLR button to begin the sensor matching process. The horn sounds twice to signal the receiver is in relearn mode and the TIRE LEARNING ACTIVE message displays on the DIC screen. 8. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. 9. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. 10. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have

been learned. Turn ignition switch to OFF position to exit Learn Mode. TPMS RESET - PROCEDURE 30 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

Set the tire pressure of all wheels to pressure specified on the tire and loading information label. Set the parking brake. Put the vehicle in ON/ RUN and place the vehicle in P (Park). If the Driver Information Center (DIC) display is minimized, press the SELECT knob to maximize it. Use the SELECT knob to scroll to the Tire Pressure display screen. Press and hold the SELECT knob for five seconds to begin the sensor matching process. A message displays confirming to begin the process. Use the SELECT knob to select YES with the highlighted selection, and press the SELECT knob again to confirm the selection. The horn sounds twice to signal the receiver is in relearn mode and the TIRE LEARNING ACTIVE message displays on the DIC screen. Starting with left front tire, hold a tire sensor activation tool against the side wall of the tire, within 3 inches of the valve stem. Activate tool until a horn chirp sounds. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. After left rear sensor has been learned, a double horn chirp will sound, indicating all 4 sensor IDs have been learned. Turn ignition switch to OFF position to exit Learn Mode.

TPMS RESET - PROCEDURE 31 NOTE:

1. 2. 3. 4.

You have two minutes to match the first tire/wheel position, and five minutes overall to match all four tire/wheel positions. If it takes longer, the matching process stops and must be restarted.

Set the tire pressure of all wheels to pressure specified on the tire and loading information label. Set the parking brake. Turn the ignition to ON/RUN with the engine off. Enter the learn sequence from the TPM Learn screen, located under the Customization Menu in the instrument panel cluster. Press SRCE button until you see Customize Options and then press ENTER (left pointing arrow). Move the thumbwheel up or down to scroll through the available options. Press ENTER to select an item. To exit the current menu, or go back, use the thumbwheel to select BACK (left arrow) at the top of the screen and then press ENTER. 5. Start with the driver side front tire. The driver side front indicator lamp also comes on to indicate that corner's sensor is ready to be learned. Place a tire sensor activation tool against the tire sidewall, near the valve stem. Then press the button to activate the TPMS sensor. A horn chirp confirms that the sensor identification code has been matched to this tire and wheel position 6. After horn chirp has sounded and the right turn signal has illuminated, proceed to the next 3 sensors in the following order: right front, right rear and left rear. 7. After the driver side rear TPMS sensor has been learned the horn chirps two times. The driver side rear

indicator lamp turns off and the TPMS sensor matching process is done. Turn the ignition switch to LOCK/OFF.

Fig. 6: Identifying DIC Controls Courtesy of GENERAL MOTORS CORP.

MAINTENANCE INFORMATION (RWD) 1983-93 MAINTENANCE General Motors Corp. - Maintenance Information

MODEL IDENTIFICATION VIN LOCATION The Vehicle Identification Number (VIN) is located on the left side of the dash panel at the base of the windshield. The VIN chart explains the code characters. VIN CODE ID EXPLANATION Numbers preceding the explanations in the legend below refer to the sequence of characters as listed on VIN identification label. See VIN example below.

Fig. 1: VIN Code ID Explanation

MAINTENANCE SERVICE INFORMATION SEVERE & NORMAL SERVICE DEFINITIONS

NOTE:

Use the Severe Service schedule if the vehicle to be serviced is operated under ANY (one or more) of these conditions:

Service is recommended at mileage intervals based on vehicle operation. Service schedules are based on the following primary operating conditions: Severe Service      

Short Trips (4 Miles Or Less) When Most Trips Are Less Than 10 Miles And Outside Temperatures Remain Below Freezing. Towing Or Heavily Loaded Severe Dust Conditions Hot Weather, Stop-And-Go Driving Extensive Idling Conditions (Taxi Or Delivery Type Service)

Normal Service  

Driven More Than 10 Miles Daily No Severe Service Operating Conditions

SERVICE POINT LOCATIONS

Fig. 2: Service Point Locations (Typical) Courtesy of GENERAL MOTORS CORP.

Fig. 3: Lift Point Locations Courtesy of GENERAL MOTORS CORP. NOTE:

For more information regarding jacking or hoisting the vehicle, refer to the JACKING & HOISTING article in the WHEEL ALIGNMENT section.

SERVICE LABOR TIMES NOTE:

For and newer vehicles, labor times are provided, where available, within appropriate SERVICE INTERVAL table in SCHEDULED SERVICES article.

WHEEL & TIRE SPECIFICATIONS TIRE INFLATION The tire specification decal is located on rear of the driver's door. WHEEL TIGHTENING All standard wheel lug nuts are tightened to 100 ft. lbs. (136 N.m).

BATTERY SPECIFICATIONS CAUTION: When battery is disconnected, vehicles equipped with computers may lose memory data. When battery power is restored, driveability problems may exist on some vehicles. These vehicles may require a relearn procedure. See COMPUTER RELEARN PROCEDURES article in the GENERAL

INFORMATION section. All models use Group 75 batteries with a 630 amp cold crank rating.

CAUTIONS & WARNINGS SUPPLEMENTAL RESTRAINT SYSTEM (AIR BAG) NOTE:

See the AIR BAGS article in the ACCESSORIES/SAFETY EQUIPMENT Section.

Modifications or improper maintenance, including incorrect removal and installation of the Supplemental Restraint System (SRS), can adversely affect system performance. DO NOT cover, obstruct or change the steering wheel horn pad in any way, as such action could cause improper function of the system. Use only plain water when cleaning the horn pad. Solvents or cleaners could adversely affect the air bag cover and cause improper deployment of the system. WARNING: To avoid injury from accidental air bag deployment, read and carefully follow all warnings and service precautions. See appropriate AIR BAGS article in ACCESSORIES/SAFETY EQUIPMENT. Modification to the air bag system component or wiring can adversely affect system performance and possibly cause injury. CAUTION: The Diagnostic Energy Reserve Module (DERM) can maintain enough voltage to cause a deployment of the inflator module for up to 10 minutes after the ignition switch is turned off and the battery is disconnected. Many of the service procedures require disconnection of the inflator module to avoid an accidental deployment. CAUTION: Disconnect negative battery cable before servicing any air bag system, steering column or passenger side dash component. After any repair, turn ignition key to the ON position from passenger's side of vehicle in case of accidental air bag inflation ANTI-LOCK BRAKE SYSTEM The anti-lock brake system contains electronic equipment that can be susceptible to interference caused by improperly installed or high output radio transmitting equipment. Since this interference could cause the possible loss of the anti-lock braking capability, such equipment should be installed by qualified professionals. On models equipped with anti-lock brake systems, ALWAYS observe the following cautions: ď Ź

ď Ź

DO NOT attempt to bleed hydraulic system without first referring to the appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES Section. DO NOT mix tire sizes. As long as tires remain close to the original diameter, increasing the width is



acceptable. Rolling diameter must be identical for all 4 tires. Some manufacturers recommend tires of the same brand, style and type. Failure to follow this precaution may cause inaccurate wheel speed readings. Use ONLY recommended brake fluids. DO NOT use silicone brake fluids in an ABS-equipped vehicle.

BATTERY DO NOT test battery if it shows any signs of freezing, leaking, loose posts or low electrolyte level; an explosive condition could result. BATTERY WARNING WARNING: When battery is disconnected, vehicles equipped with computers may lose memory data. When battery power is restored, driveability problems may exist on some vehicles. These vehicles may require a relearn procedure. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION section. REPLACING BLOWN FUSES Before replacing a blown fuse, remove ignition key, turn off all lights and accessories to avoid damaging the electrical system. Be sure to use fuse with the correct indicated amperage rating. The use of an incorrect amperage rating fuse may result in a dangerous electrical system overload. BRAKE PAD WEAR INDICATOR Indicator will cause a squealing or scraping noise, warning that brake pads need replacement. CATALYTIC CONVERTER Continued operation of vehicle with a severe malfunction could cause converter to overheat, resulting in possible damage to converter and vehicle. COOLANT (PROPYLENE-GLYCOL FORMULATIONS) CAUTION: To avoid possible damage to vehicle use only ethylene-glycol based coolants with a mixture ratio from 44-68% anti-freeze. DO NOT use 100% anti-freeze as it will cause the formation of cooling system deposits. This results in coolant temperatures of over 300° F (149°C) which can melt plastics. 100% anti-freeze has a freeze point of only -8° F (-22°C). CAUTION: Propylene-Glycol Mixtures has a smaller temperature range than EthyleneGlycol. The temperature range (freeze-boil) of a 50/50 Anti-Freeze/Water Mix is as follows: Propylene-Glycol -26° F (-32°C) - 257° F (125°C) EthyleneGlycol -35° F (-37°C) - 263° F (128°C) CAUTION: Propylene-Glycol/Ethylene-Glycol Mixtures can cause the destabilization

of various corrosion inhibitors. Also Propylene-Glycol/Ethylene-Glycol has a different specific gravity than Ethylene-Glycol coolant, which will result in inaccurate freeze point calculations. DIESEL FUEL ANTI-FUNGAL ADDITIVES CAUTION: If fuel contamination due to fungi or other microorganisms is suspected a fuel additive with a biocide may be used. Follow the manufacturers dosage as recommended on product label. Use biocides ONLY when necessary, excessive use can may cause other fuel system problems. DIESEL FUEL CONTAMINATION WARNING: Diesel fuel system may be contaminated with fungi or other microorganisms. Keep contaminated fuel away from open skin cuts or sores to prevent skin irritation or infection. DIESEL FUEL REQUIREMENTS CAUTION: All diesel engines are to use Diesel Fuel #2 when the outside temperature is above 20째F (-7째C). In temperatures that are below 20째F (-7째C) use Diesel Fuel #1, this will reduce the chance of the fuel thickening and forming wax. NOTE:

A Diesel Fuel #1 & #2 combination (Blended Fuel) may be used, and is recommended for mild winter driving.

ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS WARNING: Many solid state electrical components can be damaged by static electricity (ESD). Some will display a warning label, but many will not. Discharge personal static electricity by touching a metal ground point on the vehicle prior to servicing any ESD sensitive component. ENGINE OIL CAUTION: Never use non-detergent or straight mineral oil.

FUEL CONDITIONER (DIESEL ENGINES) Allowing water to remain in fuel conditioner could result in extensive damage to or failure of fuel injection system. Diesel fuel can damage asphalt and other surfaces. Always place a drain pan under fuel conditioner to collect fuel, and dispose of fuel properly. FUEL SYSTEM SERVICE

WARNING: Relieve fuel system pressure prior to servicing any fuel system component (fuel injection models). HALOGEN BULBS WARNING: Halogen bulbs contain pressurized gas which may explode if overheated. DO NOT touch glass portion of bulb with bare hands. Eye protection should be worn when handling or working around halogen bulbs. RADIATOR CAP CAUTION: Always disconnect the fan motor when working near the radiator fan. The fan is temperature controlled and could start at any time even when the ignition key is in the OFF position. DO NOT loosen or remove radiator cap when cooling system is hot. RADIATOR FAN WARNING: Keep hands away from radiator fan.

TAILGATE (COMMERCIAL MODELS) DO NOT drive vehicle with tailgate open, as carbon monoxide can enter vehicle.

WARRANTY INFORMATION CAUTION: Due to the different warranties offered in various regions and the variety of after-market extended warranties available, please refer to the warranty package that came with the vehicle to verify all warranty options. BASIC NEW CAR WARRANTY Everything is covered for 12 months or 12,000 miles, whichever occurs first. POWER TRAIN WARRANTY Begins at 12 months or 12,000 miles and lasts for 6 years or 60,000 miles, whichever occurs first. Covers all moving internal and external parts, including seals and water pump on engine and clutch cover and "U" joints on transaxle. Items not covered include, accessory drive belts, clutch discs and brake pads. SUPPLEMENTAL INFLATABLE RESTRAINT COVERAGE Begins at Warranty Start Date and lasts 3 years regardless of mileage.

CORROSION COVERAGE Begins at Warranty Start Date and lasts 6 years or 100,000 miles, whichever occurs first. Covers any holes in body sheet metal caused by corrosion. EMISSIONS PERFORMANCE WARRANTY Begins at Warranty Start Date and lasts for 5 years or 50,000 miles, whichever occurs first. Applies only in states that require EPA emission performance testing. Coverage is limited to fewer components after 2 years or 24,000 miles.

FUSES & CIRCUIT BREAKERS ACCESSORY FUSE & RELAY PANEL ID (1983-89 CADILLAC)

Fig. 4: Accessory Fuse & Relay Panel ID (1983-89 Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Relay Identification      

1 - Relay - E.L.C. (1983) Blank (1983) 2 - Relay - E.L.C. (1984-89) Blank (1983) 3 - Relay - Park/Neutral (1983) Blank (1984-89) 4 - Relay - Diesel Wait Timer (1983) Blank (1984-85) Park/Neutral Relay (1986-89) 5 - Blank 6 - Relay - Antenna

           

7 - Relay - Horn 8 - Relay - Cold Advance Altitude Relay Blank (1983, 85-89) 9 - Relay - Rear Window Defogger 10 - Relay - Fuel Pump Relay (1983-85) Blank (1986-89) 11 - 20 Amp Fuse - ECM (1983-85) Blank (1986-89) 12 - 25 Amp Fuse - Fuel Pump (1986-89) Blank (1983-85) 13 - 3 Amp Fuse - Crank Signal (1983-85) Blank (1986-89) 14 - 15 Amp Fuse - Ignition System 15 - 3 Amp Fuse - Fuel Injector (1983-85) Blank (1986-89) 16 - 10 Amp Fuse - DFI Fuel Pump (1983-85) Blank (1986-89) 17 - 3 Amp Fuse - Fuel Injection (1983-85) Blank (1986-89) 18 - 10 Amp Fuse - Emission Control Solenoid, Ignition System (1984-85) Blank (1986-89)

ACCESSORY FUSE & RELAY PANEL ID (CADILLAC)

Fig. 5: Accessory Fuse & Relay Panel ID (1991-92 Brougham) Courtesy of GENERAL MOTORS CORP.

Fig. 6: Accessory Fuse & Relay Panel ID ( Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Relay Identification               

1 - Blank 2 - Relay - Electronic Level Control 3 - Relay (5.7L) - Fuel Pump Blank (5.0L) 4 - Blank 5 - Relay - Park/Neutral 6 - Relay - Antenna 7 - Relay - Horn 8 - Blank Relay (1991-92) - Starter Interrupt 9 - Relay - Rear Window Defogger 10 - Relay - Parking Lights, Running Lights Blank (1992) 11 - 3 Amp Fuse (5.7L) - Crank Signal Blank (5.0L) 12 - 10 Amp Fuse (5.7L) - Fuel Pump Blank (5.0L) 13 - Blank 14 - 7.5 Amp Fuse (5.7L) - Fuel Injection System Blank (5.0L) 15 - Blank

    

16 - 15 Amp Fuse - Ignition System 17 - 3 Amp Fuse - ECM 18 - 3 Amp Fuse (5.0L) - Anti-Diesel Solenoid Blank (5.7L) Blank (1991-92)

FUSE PANEL IDENTIFICATION (1983-88 CADILLAC)

Fig. 7: Fuse Panel Identification (1983-88 Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Circuit Breaker Identification  

1 - 10 Amp - Ashtray Light, Side Marker Lights, Cornering Lights, Door Ashtray Lights 2 - 3 Amp - Cruise Control (DFI Release Switch)

 

         

    

3 - 30 Amp (Circuit Breaker) - Power Windows 4 - 20 Amp - A/C Compressor Clutch Feed, Electronic Climate Control Programmer & Power Module, Alternator Warning Light, Rear Defogger Relay 5 - 10 Amp - Power Antenna Motor 6 - 20 Amp - Hazard Flasher, Brakelights, Electronic Climate Control, Control Head 7 - 30 Amp (Circuit Breaker) - Horn 8 - 20 Amp - Electronic Level Control (Where Applicable) 9 - 20 Amp - Courtesy Lights, Cigarette Lighters, Electronic Level Control Height Sensor 10 - 10 Amp - Electronic Level Control Exhaust 11 - 25 Amp - Rear Window Defogger 12 - 25 Amp - Windshield Wipers & Washers 13 - 10 Amp - Radio Antenna Relay Coil 14 - 20 Amp - Instrument Panel Lights, Engine Temperature Warning, Instrument Panel Cigarette Lighter, Key Warning Buzzer, Glove Box Light 15 - 20 Amp - Gauges, Warning Lights, 16 - 20 Amp - Opera Lights, License Plate Light, Taillights, Side Marker Lights 17 - 20 Amp - Directional Signal Lights 18 - 10 Amp - Back-Up Lights 19 - 5 Amp - Rheostat-Controlled Instrument Panel Lights

FUSE PANEL IDENTIFICATION (1989-90 CADILLAC)

Fig. 8: Fuse Panel Identification (Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Circuit Breaker Identification 

  

1 - 10 Amp - Engine Compartment Light (1990), Front Ashtray Light, E.C.C. Head, Radio, Theft Deterrent, Turn/Hazard, Front Marker, Park & Turn Lights, Instrument Panel Cluster (1990) 2 - 3 Amp - Cruise Control, Instrument Panel Lights (1990) 3 - 30 Amp (Circuit Breaker) - Power Windows, Trunk Release, Sun Roof 4 - 20 Amp - Air Conditioning (1989), A/C Compressor Clutch, Electronic Climate Control, Instrument

  



    



 

Panel (1989), NO CHARGE Warning Light (1990), Rear Defogger Relay, Alternator (1990) 5 - 10 Amp - Power Antenna 6 - 20 Amp - Hazard Flasher, Brakelights, Electronic Climate Control 7 - 30 Amp (Circuit Breaker) - Horn, Power Seats, Power Door Locks, Power Seat Recliners, Trunk Lid Pull-Down 8 - 20 Amp - Gear Selector Switch, Rear Quarter Lights, Vanity Mirror Lights, Power Mirrors, Rear Compartment Lights, Door Lock Switches (1990), Instrument Courtesy Lights, Electronic Level Control, Instrument Panel Lights, Cigarette Lighter, Glove Box Light, Key Warning Buzzer, Illuminated Entry, Door Locks 9 - 10 Amp - Anti-Lock Braking System (1990) 10 - 25 Amp - Rear Window Defogger 11 - 25 Amp - Windshield Wiper/Washer 12 - 10 Amp - Radio 13 - 20 Amp - Automatic Door Locks, Illuminated Entry, Trans. Converter Clutch Brake Switch, Seat Belt Reminder (1989), Anti-Lock Brake System (1990), Theft Deterrent, Electronic Level Sensor & Relay, Emission Control Solenoid (1990), Instrument Panel Warning Lights, Audio Alarm, CHECK ENGINE Light (1989) 14 - 20 Amp - Front Cigarette Lighter, Glove Box Light, Radio, Engine Compartment Light (1989), Passive Restraint Belts Module (1990), Audio Alarm, Instrument Panel Cluster 15 - 20 Amp - Turn Signal Flasher 16 - 20 Amp - Twilight Sentinel Module, Headlight Switch, Headlight Dimmer Switch (1989), Instrument Panel Dimming Control (1990), Left Opera Light, License Plate Light, Rear Taillights, Stoplights & Turn Lights 17 - 10 Amp - Back-Up Lights (1990), Gear Selector Switch, Automatic Mirror 18 - 5 Amp - Instrument Panel (1989), Wiper/Washer (1989), Electronic Climate Control (1989), Cruise Control (1989), Radio (1989), Light Switch Light (1989), Audio Alarm Module (1989), Light Switch (1989), Dimmable Instrument Panel Lights (1990)

FUSE PANEL IDENTIFICATION (1991-92 CADILLAC)

Fig. 9: Fuse Panel Identification (1991-92 Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Circuit Breaker Identification 

  

1 - 10 Amp - Radio, Instrument Panel Cluster, Ashtray Light, Engine Compartment Light, Cornering, Side Marker & Front Park Lights 2 - 3 Amp - Cruise Control, EVO Module, Instrument Panel Cluster 3 - Circuit Breaker - Power Windows, Trunk Release, Astroroof 4 - 20 Amp - A/C Cut-Out Relay, Electronic Climate Control, No Charge Tell-Taillight, Alternator, Rear

  



    



 

Defogger Relay 5 - 10 Amp - Power Antenna 6 - 20 Amp - Hazard Flasher, Brakelight, Electronic Climate Control Head 7 - Circuit Breaker - Horn, Power Seats, Power Door Locks, Power Seat Recliners, Trunk Lid PullDown 8 - 20 Amp - Electronic Level Control, Illuminated Entry, Power Door Locks, Courtesy Lights, Gear Select Switch, Rear Quarter Lights, Lighted Vanity Mirrors, Power Mirrors, Rear Compartment Light, Right Front & Rear Doors Cigarette Lighter, Door Latch Switches, Passive Restraint 9 - 10 Amp - Anti-Lock Braking System 10 - 25 Amp - Rear Window Defogger 11 - 25 Amp - Windshield Wiper/Washer 12 - 10 Amp - Radio 13 - 20 Amp - Automatic Door Locks, Illuminated Entry, Transmission Converter Clutch Brake Switch, Anti-Lock Brake System, Theft Deterrent, Electronic Level Sensor, Instrument Panel Tell-Tails Audio Alarm Chime, Electronic Level Control Relay 14 - 20 Amp - Front Cigarette Lighter, Glove Box Light, Radio, Passive Restraint Belts Module, Audio Alarm Chime, Instrument Panel Cluster 15 - 20 Amp - Turn Signal Flasher 16 - 20 Amp - Twilight Sentinel Module, Headlight Switch, Instrument Panel Dimming Control, Left Opera Light, License Plate Light, Park/See Park Fuse 17 - 10 Amp - Back-Up Lights, Gear Selector Switch, Automatic Day Night/Mirror 18 - 5 Amp - Dimmable Instrument Panel Illumination

FUSE PANEL IDENTIFICATION (1993 CADILLAC)

Fig. 10: Fuse Panel Identification (1993 Cadillac) Courtesy of GENERAL MOTORS CORP. Fuse & Circuit Breaker Identification     

1 - Not Used 2 - Not Used 3 - Not Used 4 - Not Used 5 - Not Used

       

    

                      

6 - 15 Amp - Park/Neutral/Back-Up Switch, Electric Turn Flasher 7 - 10 Amp - Electronic Brake Control 8 - 25 Amp - Retained Accessory Power 9 - 10 Amp - Radio 10 - 25 Amp - Windshield Wiper/Washer 11 - 10 Amp - DERM, Low Coolant, Instrument Panel Cluster Indicators 12 - Not Used 13 - 10 Amp - Chime Module, Defogger Relay, Speed Sensor Buffer, TCC Disable Relay, Auto. Day/Night Mirror 14 - 10 Amp - Central Control Module, TPS Sensor, Electronic Level Control 15 - 10 Amp - Air Bag Dual Pole Arming Sensor 16 - 10 Amp - Generator, Cruise Control 17 - 10 Amp - Driver Memory Seat, Heated Front Seats 18 - 10 Amp - Central Control Module, Instrument Cluster, Remote Keyless Entry, Theft Deterrent Receiver 19 - 10 Amp - Retained Accessory Power 20 - 10 Amp - HVAC Solenoid Module, HVAC Control Head, Instrument Cluster 21 - 25 Amp - Retained Accessory Power, Wiper Relay 22 - 25 Amp - HVAC Power Module 23 - 10 Amp - Trunk Lid Release Switch 24 - 10 Amp - Starter Enable Relay, DERM 25 - 10 Amp - Side Mirror Defoggers 26 - 20 Amp - Trunk Light, Power Antenna 27 - 15 Amp - Delayed Interior Lights 28 - 10 Amp - Front Cigar Lighter 29 - 20 Amp - Rear Cigar Lighters 30 - 10 Amp - HVAC Control Assembly 31 - 25 Amp - ELEC. Brake/Traction Control Module 32 - Not Used 33 - 10 Amp - Chime, Instrument Cluster, Low Engine Oil, Headlight Switch, Radio 34 - 10 Amp - Central Control Module 35 - 10 Amp - Power Door Locks, Power Mirrors, Power Lumbar Seats 36 - 15 Amp - Trunk Lid Pull-Down 37 - 20 Amp - Hazard Warning Flasher 38 - 15 Amp - Front Seats Recliner Switch 39 - 20 Amp - Power Lumbar Seat Motor Control 40 - 15 Amp - Front Heated Seats Control Module 41 - 10 Amp - Instrument Cluster, Radio Control Head, Cornering Lights

        

42 - 10 Amp - Headlight Switch, Dimming, Interior Lights 43 - 10 Amp - Rear Tail/Side Marker Lights, License Light 44 - 20 Amp - Stop Light Brake Switch, Brake/Transmission Shift Interlock 45 - 20 Amp - Power Door Lock Relay 46 - Not Used 47 - 30 Amp Circuit Breaker - Retained Acc. Power Relay 48 - 25 Amp Circuit Breaker - Power Seat Switches, Memory Seat Module 49 - 30 Amp Circuit Breaker - Rear Defogger Relay 50 - 30 Amp Circuit Breaker - Headlight Relay, Daytime Running Lights (Canada)

MIRRORS - POWER ACCESSORIES & SAFETY EQUIPMENT General Motors Power Mirrors

DESCRIPTION & OPERATION On all models except Brougham, Caprice, Custom Cruiser and Estate Wagon, one mirror control switch adjusts both left (driver side) and right (passenger side) mirrors. Mirror select switch setting determines whether left or right mirror is adjusted. Brougham, Caprice, Custom Cruiser and Estate Wagon models do not use mirror select switch. Two separate mirror control switches control left and right mirrors. Each power mirror assembly contains 2 reversible motors: an up/down motor and a left/right motor. Mirror control switch reverses polarity of motor circuit to change direction of mirror movement. Each motor contains a self-resetting circuit breaker which opens when mirror reaches its mechanical limit of travel.

TESTING SYSTEM TESTING 1. Check fuse. If fuse is okay, go to step 2). If fuse is open, replace fuse. Operate power mirrors. If fuse blows, repair short to ground in power mirror circuit. 2. Remove mirror switch. Check for voltage on Orange wire at mirror switch connector. If voltage is present, go to step 3). If voltage is not present, repair open condition in Orange wire. 3. Connect ohmmeter between ground and Black wire at mirror switch connector. If there is continuity, go to step 4). If there is no continuity, repair Black wire between mirror switch and ground. 4. Test operation of mirror motors. See appropriate table under TESTING in this article MIRROR MOTOR TEST . 5. If mirror motors operate in all directions, go to step 7). If mirror motors do not operate in all directions, check for open condition in wiring between mirror switch and mirror motors. 6. If wiring is okay, replace mirror motor. See, under REMOVAL & INSTALLATION in this article, MIRROR MOTOR . 7. Test operation of mirror switch. See appropriate table under DIAGNOSIS & TESTING in this article, MIRROR SWITCH TEST . If mirror switch fails test, replace mirror switch. MIRROR MOTOR TEST 1. To perform mirror motor test, remove mirror switch. Disconnect electrical connector. Using a 12-volt source, connect positive lead to one wire terminal and negative lead to other wire terminal as listed under TERMINALS in appropriate table. 2. Reverse positive and negative leads on these wire terminals. Reverse leads again. Mirror motor should move UP and DOWN. Follow same procedure to test operation of LEFT/RIGHT motor. NOTE:

On most models with mirror select switch, duplicate wire colors are used in

circuit between mirror switch and mirror motors: one set of wires leads to driver's side mirror motors, other set leads to passenger's side mirror motors. When testing mirror motors on models with duplicate wire colors, connect battery positive lead to one wire terminal and battery negative lead to other wire terminal as specified in table. If mirror motor does not operate, leave positive lead connected. Disconnect negative lead and connect to other wire terminal of same color. If mirror motor does not operate, leave negative lead connected. Disconnect positive lead and connect to other wire terminal of the same color. MIRROR MOTOR TEST SPECIFICATIONS Application Terminals Both Sides YEL & LT GRN (1) LT BLU & WHT (1) (1) WHT/BLK on Cutlass Supreme, Grand Prix and Regal.

Mirror Movement UP/DOWN LEFT/RIGHT

MIRROR SWITCH TEST 1. To perform mirror switch test, remove mirror switch. Leave electrical connector connected. Place mirror select switch in LEFT position. (On vehicles with separate mirror switches, test applies to LEFT and RIGHT mirror switches). 2. Hold mirror directional switch in positions specified in table. Check voltage at terminals specified in table. See appropriate MIRROR SWITCH TEST table. Place mirror select switch in RIGHT position. Repeat voltage test. 3. Disconnect mirror switch connector. Place mirror select switch in LEFT position. Hold mirror directional switch in positions specified in table. Using an ohmmeter, check continuity of mirror switch by probing both terminals as specified in table. Place mirror select switch in RIGHT position. Repeat continuity test. NOTE:

On most models with mirror select switch, duplicate wire colors are used in circuit between mirror switch and mirror motors: one set of wires leads to driver mirror motors, other set leads to passenger mirror motors. When checking for voltage on models with duplicate wire colors, probe wire terminal as specified in table. If voltage is not present, probe other wire terminal of same color. When checking continuity, connect ohmmeter positive lead to one switch terminal and ohmmeter negative lead to other switch terminal as specified in table. If there is no continuity, leave positive lead connected. Disconnect negative lead and connect to other switch terminal of same color. If there is no continuity, leave negative lead connected. Disconnect positive lead and connect to other switch terminal of the same color.

MIRROR SWITCH TEST SPECIFICATIONS Mirror Select Sw. Mirror Directional Sw. Position Position Volts At This Terminal UP YEL Both Sides (1) "

DOWN

LT GRN

Continuity At Terminals LT GRN & BLK YEL & BLK

LEFT

LT BLU

(2) WHT & BLK

RIGHT

(2) WHT

LT BLU & BLK

(1) Same test for both switches on Brougham, Caprice, Custom Cruiser and Estate Wagon. (2) WHT/BLK on Cutlass Supreme, Grand Prix and Regal.

REMOVAL & INSTALLATION CAUTION: On some models, momentary actuation of power window switch can cause window to move directly to fully open position. When working inside door, leave ignition off whenever possible. MIRROR GLASS Removal

Cover door to avoid damage to painted surface. Tape mirror, then break mirror glass. Remove broken glass and fiber pad from mirror frame. Wipe inside of mirror frame clean. Installation

Remove paper backing from service mirror and center mirror in frame. Press mirror firmly to ensure adhesion of mirror to mirror frame. MIRROR MOTOR Removal (All Others)

Cover door to avoid damage to painted surface. Remove mirror by taping mirror and breaking mirror glass. Remove broken glass, mirror frame attaching screw and mirror frame. Remove motor attaching screws. Lift motor out of housing and disconnect wiring harness. Installation

Connect wiring harness to motor and install motor to housing using screws. Position new mirror frame to motor and install attaching screw. Remove paper backing from service mirror and center mirror in frame. Press mirror firmly to ensure adhesion of mirror to mirror frame.

Fig. 1: Typical Power Mirror Assembly Courtesy of GENERAL MOTORS CORP. MIRROR ASSEMBLY Remove door trim panel and disconnect wiring harness at connector. Peel back insulator pad and water deflector enough to gain access to wire harness. Detach harness from any retaining tabs in door. Remove attaching nuts from mirror case and remove mirror and harness from door. To install, reverse removal

procedure.

WIRING DIAGRAMS Refer to appropriate chassis diagram in WIRING DIAGRAMS.

POWER STEERING GENERAL SERVICING STEERING General Motors Corp. Power Steering General Servicing

TROUBLE SHOOTING Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

BELT TENSION SERVICING SERPENTINE BELT Belt tension is adjusted automatically. For more information, see SERPENTINE BELT ROUTING in DRIVE BELT ROUTING article in the ENGINE COOLING section. CONVENTIONAL BELT Use a belt tension gauge to check belt tension. See POWER STEERING BELT TENSION SPECIFICATIONS table. POWER STEERING BELT TENSION SPECIFICATIONS Application New: Lbs. (kg) 2.0L 135 (61) 1.8L, 2.3L & 2.5L 165 (75) 2.8L, 3.0L, 3.1L 3.8L & 4.5L 135 (61) 5.0L & 5.7L 125 (57)

Used: Lbs. (kg) 70 (32) 100 (45) 73 (33) 75 (34)

TESTING NOTE:

Before testing power steering system, check fluid level, belt tension, pump pulley, tire pressure and engine idle speed.

1. Remove high pressure line from pump and attach Adapter Fitting (J-5176-11) to pump. Using Pressure Gauge (J-5176-02) and Adapter (J-5176-12), connect gauge to hose. 2. Open valve fully. Run engine until fluid reaches normal operating temperature. Check fluid level and add as necessary. With engine at operating temperature, pressure reading should be 80-125 psi (5.6-8.8 kg/cm2 ). If pressure is more than 200 psi (14 kg/cm2 ), inspect system for restrictions or faulty flow control valve. CAUTION: To prevent pump damage, DO NOT hold valve closed for more than 5 seconds in step 3). 3. Alternately close and open gauge valve fully 3 times while recording highest pressure obtained. Each

reading should be at least 1000 psi (70.3 kg/cm2 ) or 1250 psi (87.9 kg/cm2 ) on TC series pumps. TC series pumps can be identified by a square shaped reservoir on side of pump. 4. If recorded pressures are all within 50 psi (3.5 kg/cm2 ), pump is okay. If pressures are high and not within 50 psi (3.5 kg/cm2 ) of each other, flow control valve is sticking. 5. If pressure readings are less than 1000 psi (70.3 kg/cm2 ) or 1250 psi (87.9 kg/cm2 ) on TC series pumps, replace flow control valve and retest pump pressure. 6. If pump meets specification, leave valve open. Turn steering wheel from stop to stop. Record and compare highest pressure with maximum pump pressure. 7. If pressure at both stops is not similar to maximum pressure, steering gear is leaking internally. POWER STEERING PUMP PRESSURE TEST SPECS Application 4.5L Idle Relief 5.0L & 5.7L Idle Relief 5.0L Commercial Idle Relief All Other Engines (TC Series Pump) Idle Relief

Pressure: psi (kg/cm2 ) 80-125 (5.6-8.8) 1350-1450 (94.9-101.9) 80-125 (5.6-8.8) 1000-1250 (70.3-84.7) 80-100 (5.6-7.0) 1000-1250 (70.3-84.7) 80-125 (5.6-8.8) 1000-1250 (70.3-84.7)

POWER STEERING PUMP FLOW TEST SPECIFICATIONS Application 4.5L Minimum Maximum All Other Engines (TC Series Pump)

Flow: Gals./Min. (L/Min.) 1.32 (5.0) 3.10 (11.8) (1)

(1) Information not available from manufacturer.

LUBRICATION SERVICE INTERVAL Check fluid level every 7500 miles. If vehicle is driven less than 12,000 miles a year, check fluid every 3000 miles. Clean dirt and grease from filler cap area to avoid contaminating fluid. Check fluid level with engine off. Manufacturer recommends General Motors Power Steering Fluid (1050017) or equivalent to G.M. Specification

No. 9985010. CHECKING FLUID LEVEL Maintain fluid between FULL and ADD marks on dipstick. BLEEDING & REFILLING SYSTEM 1. Fill reservoir and operate engine until power steering fluid reaches operating temperature. Stop engine and recheck fluid level. Add fluid as necessary. Repeat procedure until fluid level stabilizes. 2. Raise and support vehicle so front wheels are off ground. Start engine. Turn steering wheel from side-toside several times. Avoid hitting stops or holding wheel in full left or right position. Fluid level should remain visible. 3. Return wheels to center position. Operate engine for 2-3 minutes. Road test vehicle. Recheck fluid level. Fluid containing air will have a milky appearance. All air should be eliminated to obtain normal steering.

POWER STEERING PUMP STEERING General Motors Power Steering Saginaw Pump With Reservoir

DESCRIPTION The Saginaw vane power steering pump is a constant displacement, vane type pump with an integral fluid reservoir. Shaft-driven pumping vanes move the fluid from the intake to cam ring pressure cavities. As the rotor turns, the vanes pick up residual fluid. The rotor forces the fluid into a high pressure area. Fluid is then forced into the cavities of the thrust plate through 2 crossover holes in the cam ring and pressure plate. The crossover holes empty into a high pressure area between the pressure plate and housing end cover. When pressure exceeds set limits, the flow control pressure relief valve opens and allows fluid to return to the inlet side of the pump. Under normal conditions, both pressure relief and flow control valves are closed.

TROUBLE SHOOTING Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

LUBRICATION & TESTING See POWER STEERING GENERAL SERVICING article in the STEERING section.

REMOVAL & INSTALLATION POWER STEERING PUMP Removal & Installation

Place container under vehicle. Disconnect power steering hoses and plug fittings. Remove drive belt. Remove pump mounting hardware and pump. Because of different engines and air conditioning configurations, it may be necessary to remove additional components. On some models, power steering pump pulley may be removed to ease removal of pump. To install, reverse removal procedure. NOTE:

On some models, it may be necessary to remove pump bracket with pump. Also, bracket mounting bolts may extend into water jacket.

Fig. 1: Exploded View of Power Steering Pump Courtesy of GENERAL MOTORS CORP. POWER STEERING PUMP PULLEY Removal & Installation

To remove pulley, use PULLEY REMOVER (J-25034-B) See Fig. 2 . To install pulley, use PULLEY INSTALLER (J-25033-B). See Fig. 3 . Clamp pump in vise at mounting bracket or front hub. Avoid clamping front hub too tightly.

Fig. 2: Removing Power Steering Pump Pulley Courtesy of GENERAL MOTORS CORP.

Fig. 3: Installing Power Steering Pump Pulley Courtesy of GENERAL MOTORS CORP. DRIVE SHAFT SEAL Removal & Installation

Remove pump and remove pump pulley. Protect pump shaft with shim stock. Using a chisel, cut and remove seal. To install, coat shaft seal with power steering fluid. Using a socket, drive new seal in place until it bottoms on shoulder. RESERVOIR Removal

1. Remove pump from vehicle and drain fluid. Mount pump in vise with shaft facing down. DO NOT allow vise jaws to contact reservoir. 2. Remove reservoir-to-pump mounting studs at rear of pump. Remove pressure line union bolt. Using a soft mallet, tap on filler neck of reservoir. Move reservoir back and forth until free of pump. Installation

1. Use new "O" rings. Lubricate and install pump housing "O" ring, 2 pump-to-reservoir stud "O" rings and outlet fitting "O" ring. Slide reservoir over pump. Ensure reservoir is seated properly. 2. Install pump-to-reservoir mounting studs and tighten to 26 ft. lbs. (35 N.m). Install union bolt and tighten to 35 ft. lbs (47 N.m). Install pump in vehicle, adjust belt tension, refill and bleed pump.

OVERHAUL

POWER STEERING PUMP CAUTION: When clamping pump in vise or mounting fixture, DO NOT exert excessive force on front hub as housing may be distorted. Disassembly

1. Remove pulley from shaft. Remove brackets from pump. Drain reservoir. Clean exterior of pump. Clamp pump in a soft-jawed vise, shaft down, between square boss and shaft housing. 2. Remove union bolt and "O" ring seal. Remove mounting studs. Rock filler tube back and forth gently to loosen. Work reservoir off pump housing. Remove and discard all "O" rings. 3. Using a punch, tap end cover retainer ring until one end of ring is near hole in pump housing. Insert punch in hole far enough to disengage ring from groove in pump bore. Pry ring out of pump housing. 4. Tap end cover with plastic hammer to jar it loose. Spring located under end cover should push it up. Remove pump housing from vise. Place pump in an inverted position on a clean, flat surface. 5. Tap end of drive shaft with plastic hammer to loosen pressure plate, rotor and thrust plate assembly from housing. Lift pump housing off rotor assembly. 6. Flow control valve and control valve spring should slide out of bore. See Fig. 4 . Remove and discard end cover and pressure cover "O" rings. Remove drive shaft oil seal.

Fig. 4: Exploded View of Flow Control Valve Courtesy of GENERAL MOTORS CORP. 7. Lift pressure plate and cam ring from rotor. Remove 10 vanes from slots. See Fig. 1 . Clamp drive shaft in soft-jawed vise with rotor and thrust plate upward.

8. Remove and discard rotor lock ring. Use care to avoid nicking rotor end face. Slide rotor and thrust plate off drive shaft. Remove drive shaft from vise. NOTE:

Individual flow control valve parts are not available. Replace flow control valve as an assembly if worn or damaged. If pump is being overhauled because of contamination in system, valve can be disassembled for cleaning.

Cleaning & Inspection

1. Clean all parts in solvent. Inspect flow control valve for wear or damage. Inspect seal bore in housing for burrs, nicks or scoring. Inspect fit of vanes in rotor. Vanes must slide freely into slots of rotor without binding. 2. Excessively loose vanes require replacement of rotor and/or vanes. Examine inner surface of cam ring for heavy scuff or chatter marks. Inspect flat surfaces of pressure and thrust plates for wear or scoring. 3. Light scoring can be removed by lapping on a flat surface. Inspect pump housing drive shaft bushing for excessive wear. Replace pump housing and bushing as an assembly if badly worn or scored. Replace any damaged or worn parts. NOTE:

If pump is equipped with magnet, ensure all residue is cleaned from magnet.

Reassembly

1. Lubricate all "O" ring seals and seal areas with power steering fluid. Place pump housing on flat surface. Drive new shaft seal into bore with a 7/8" or 15/16" socket until seal bottoms on shoulder. DO NOT use excessive force as seal can be distorted. 2. Clamp pump housing in vise with shaft down. Install end cover and pressure plate "O" rings in grooves in pump cavity. With drive shaft clamped, splined shaft up, install thrust plate on drive shaft with ported side up. See Fig. 5 .

Fig. 5: Installing Thrust Plate Courtesy of GENERAL MOTORS CORP. 3. Slide rotor over splines with counterbore of rotor facing down. Install rotor lock ring. Insert both dowel pins in holes of pump cavity. Rotor must move freely on splines. Install drive shaft assembly in pump body, ensuring dowel pins are properly engaged in thrust plate. 4. Slide cam ring over rotor on dowel pins with arrow facing up. See Fig. 6 . Install 10 vanes in rotor slots. Position pressure plate on dowel pins with plate spring groove facing upward. Place a 1 1/4" socket in groove of pressure plate. Seat entire assembly on "O" ring in pump cavity by pressing down with both thumbs.

Fig. 6: Installing Cam Ring Courtesy of GENERAL MOTORS CORP. 5. Place pressure plate spring in groove in pressure plate. Position end cover lip edge up over spring. Press end cover down below retainer ring groove with thumb. Install retainer ring. Ensure ring is seated in groove. Use care to avoid cocking end cover in bore or distorting assembly. 6. Install flow control valve, if removed, in pump bore with control valve spring and hex end of valve facing interior of bore. Using a punch, tap retainer ring end around groove until opening is opposite flow control valve bore. This is important for maximum retention of retainer ring. 7. Replace reservoir "O" ring seal, 2 mounting stud "O" ring seals and flow control valve "O" ring seal on pump housing. Carefully position reservoir on pump housing. Visually align mounting stud holes until studs can be started in threads. 8. Press reservoir down on pump to seat on pump housing. Place new seal on union bolt. Install union bolt in flow control valve bore. Tighten mounting studs. Install pump pulley.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS Application Flow Control Valve High Pressure Line-to-Union Fitting High Pressure Union Bolt Fitting Mounting Bracket Bolts Reservoir Mounting Stud Flow Control Valve Plug

Ft. Lbs. (N.m) 55 (75) 30 (41) 35 (47) 30 (41) 26 (35) INCH Lbs. (N.m) 4 (.45)

SEATS - POWER ACCESSORIES & SAFETY EQUIPMENT General Motors Power Seats

DESCRIPTION & OPERATION DESCRIPTION Power seats operate by toggle switches located on the seat side or in the door arm rest. Seat adjusters are powered by a 12-volt reversible motor with an internal circuit breaker. A 30-ampere plug-in circuit breaker also protects power seat wiring and mounts on fuse panel. 6-WAY POWER SEATS Two types are used. One type has 3 reversible motors that operate the seats. Front and back parts of the seat are operated by different motors and can be raised and lowered independently. The third motor controls forwardbackward movement. Drive cables connect motors to gearnuts, which turn jack screws and adjusters at each side of seat. In the second type, each seat uses a single motor with 3 solenoids, 6 drive cables and a transmission. One solenoid controls front vertical movement, one controls rear vertical movement and the other controls horizontal movement. The motor then moves the seat. Releasing the switch disengages the drive motor from the cables. An optional memory device is available on both types. POWER RECLINING SEAT BACK This feature is not available on all models. The system includes a motor under the seat, drive cable, actuator and control switch. The switch is on the seat edge or in the armrest. Power seat backs operate independently of other power seat adjustments. SPORT SEAT The sport seat is similar to the base seat except it can be adjusted to fit driver's body contour. The backrest lateral restraints (side bolsters) are power adjusted 15 degrees in or out. Lumbar support can be pneumatically adjusted from soft to firm by inflating the 3 compartments located in seatback cushion. Inflation of 3 compartment bladders is controlled by a pressure pump, 3 bleed down valves and a control located on the right bolster. The seatback angle is power adjustable over a 12 degree travel by a control in the left bolster. The sport seat is available with a manual fore and aft adjustment or a 6-way power adjustment.

ADJUSTMENTS HORIZONTAL ACTUATOR ADJUSTMENT 1. Chucking can be corrected by adjusting the horizontal actuator and pinion gear to full mesh with the lower adjuster lower track rack gear. Operate seat to full up position and about 3/4 forward. Loosen

horizontal actuator screws. See Fig. 1 .

Fig. 1: Adjusting Horizontal Actuator Courtesy of GENERAL MOTORS CORP. 2. Using a large screwdriver, apply outward pressure on horizontal actuator (about 15-25 lbs.) and energize horizontal switch to move seat slightly fore and aft. This helps seat the horizontal actuator pinion gear teeth tight to the lower track rack gear teeth and eliminate free play between gear teeth. Tighten screws while maintaining outward pressure against horizontal actuators. SEAT ADJUSTER PHASING When installing power seat adjusters (except at back recliner), each pair of adjusters must be in phase with each other. When adjusters are out of phase, one adjuster will reach its maximum travel before the other, resulting in improper seat travel.

HORIZONTAL TRAVEL ADJUSTMENT Operate seat until one adjuster reaches full forward position. Detach horizontal drive cable from adjuster which has reached full forward position. Now operate seat forward until other adjuster reaches full forward position. Reconnect drive cable of first adjuster. Adjusters are now in phase. VERTICAL TRAVEL (FRONT OR REAR) ADJUSTMENT 1. Operate seat until one adjuster has reached fully raised position at both front and rear vertical travel limits. Disconnect both front and rear vertical drive cables from adjuster which has reached fully raised position. 2. Operate seat until other adjuster reaches fully raised position. Now reconnect previously removed front and rear vertical drive cables. Seat should now be in phase. If not, repeat above procedure.

TROUBLE SHOOTING JERKY HORIZONTAL OPERATION 1. Improper lubrication of adjuster shoes and channels. To correct operation, lubricate adjuster upper channel and adjuster shoes. 2. Adjuster horizontal actuator gear too tight to rack gear. See HORIZONTAL ACTUATOR under ADJUSTMENTS. HORIZONTAL CHUCK OR LOOSENESS Horizontal actuator improperly adjusted. Refer to, under ADJUSTMENTS, HORIZONTAL ACTUATOR . ONE ADJUSTER WILL NOT OPERATE HORIZONTALLY 1. Horizontal drive cable damaged or disconnected. To correct operation, check horizontal drive cables, replace if damaged. 2. Horizontal actuator inoperative. To correct operation, replace horizontal actuator assembly. ONE ADJUSTER WILL NOT OPERATE VERTICALLY 1. Vertical drive cable disconnected or damaged. To correct operation, check vertical drive cables, replace if damaged. 2. Vertical gearnut inoperative. To correct operation, replace vertical actuator assembly. BOTH ADJUSTERS WON'T OPERATE HORIZONTALLY AND/OR VERTICALLY Inoperative horizontal and/or vertical solenoid in transmission. Damaged, broken or inoperable solenoid plunger, shaft, gear or drive gear. To correct operation, replace damaged or defective parts. VERTICAL CHUCK OR LOOSENESS

Excessive clearance at vertical gearnut tension spring. To correct looseness, grind down top of vertical gearnut shoulder nut .016-3.64" (.40-92.4 mm). POWER SEAT BACK MOTOR OPERATES, BUT SEAT BACK DOES NOT MOVE Drive cable disconnected or broken. Damaged or broken reclining actuator gearnut. Reclining actuator disconnected from arm of the seat back lock or support. Incorrect seat back lock or support. POWER SEAT BACK OPERATION JERKY Kink or damage to drive cable. Bind in reclining hinge arm. Damaged or bent jack screw. Damaged actuator gearnut. Insufficient lubrication. Jack screw stop nut is loose. INOPERATIVE ADJUSTER MOTOR Check for shorted or open circuit between power source, switch or motor. Check for a defective adjuster motor. Motor Operates But Adjusters Will Not Operate Check for a shorted or open circuit between switch and solenoid. Check solenoid for defects. MOTOR WORKS BUT ADJUSTERS/RECLINER ONLY OPERATE ONE DIRECTION Check for a shorted or open circuit between one of the motor fields and control switch. Check for a defective field coil.

REMOVAL & INSTALLATION BASIC SEAT ASSEMBLY 1. Remove seat belt-to-floor anchor plate attaching bolts. Where required, remove door sill plates and turn carpet to gain access to adjuster-to-floor attaching bolts. Operate seat to full forward and up position. At rear of adjusters, remove adjuster-to-floor rear attaching bolts. 2. Operate seat to full rearward and full rear tilt position. Remove front adjuster-to-floor pan nuts. Disconnect electrical wire harness under seat and remove seat. To install, reverse removal procedure.

Fig. 2: 6-Way Seat Adjuster Mechanism Courtesy of GENERAL MOTORS CORP. SEAT ADJUSTER ASSEMBLY 1. Remove seat as previously outlined. Place seat upside down on bench. Disconnect drive cables at adjuster being removed. Squeeze the oblong connector to remove. On bucket seats, remove the motor support-toadjuster bolt. 2. Remove adjuster-to-seat bottom attaching bolts and remove seat adjuster. Note location of spacers (if equipped). To install, reverse removal procedure and check that seats are in phase. SEAT BACK RECLINING ACTUATOR Remove seat and place upside down. Remove trim on outside of seat for access to actuator. Unscrew reclining back drive cable from reclining actuator and detach cable from actuator. Remove pin securing reclining actuator coupling-to-hinge arm. Remove actuator. To install, reverse removal procedure. DRIVE MOTOR (6-WAY SEAT) 1. Remove front seat assembly and place upside down on clean surface. Disconnect wiring. On single-motor seats, remove transmission-to-support screws and cable end plate screws on transmission ends. Separate

motor and transmission and disengage rubber coupling. 2. On 3-motor seats, remove motor support-to-motor mounting bracket screw. Disconnect drive cables from adjusters, remove nut from motor retaining rod and remove motor. To install, reverse removal procedure and check phasing. BACK ANGLE OR SIDE BOLSTER SWITCH Disconnect battery ground cable. Remove seat cushion. Remove 2 screws retaining left side control panel escutcheon (face plate). Pull face plate with switches attached out of armrest to gain access to connector. Remove defective switch. To install, reverse removal procedure. LUMBAR CONTROL ASSEMBLY OR VALVE BODY 1. Disconnect battery ground cable. Remove seat cushion and release bail clip from frame panel. Disconnect pneumatic tubing and electrical connector to lumbar control assembly. Remove hog ring at underside of seat to access control. 2. Remove escutcheon (face) plate and remove control assembly through bottom of seat cushion. Also, if necessary, the valve body can be replaced at this time. To install, reverse removal procedure. LUMBAR MOTOR & PUMP ASSEMBLY 1. Disconnect battery ground cable. Remove seat cushion. Remove 4 bolts retaining cushion frame panel to adjuster. Disconnect electrical connector and remove seat from vehicle. 2. Disconnect electrical and pneumatic harness connectors at motor. Remove motor and pump assembly to frame attaching parts. Remove motor from seat cushion frame. To install, reverse removal procedure. Check operation of motor and pump.

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

SERVICE INDICATOR & WARNING LIGHTS (RWD) 1983-92 MAINTENANCE General Motors Service Indicator & Warning Lights

SERVICE INDICATOR & WARNING LIGHTS

Fig. 1: Gauges & Warning Lights (1983-84 DeVille & 1983-90 Fleetwood Brougham) Courtesy of GENERAL MOTORS CORP.

Fig. 2: Electronic Dash Gauges & Warning Lights (1991-92 Brougham) Courtesy of GENERAL MOTORS CORP.

Fig. 3: Dash Warning Lights (Oldsmobile 98/Regency 1983-84) Courtesy of GENERAL MOTORS CORP. STOP ENGINE OIL WARNING LIGHT Indicates low oil pressure. Does not indicate amount of oil in engine. ANTI-LOCK BRAKE WARNING LIGHT Will illuminate when parking brake is applied, and also if fluid is low in service brake system. EGR WARNING LIGHT

Light indicates need for periodic maintenance service. ALTERNATOR WARNING LIGHT Comes on briefly during engine start as a bulb check. If it remains on or comes on while driving, it indicates a problem with the alternator system. GATE OPEN WARNING LIGHT Indicates rear lift gate is not closed. SERVICE ENGINE SOON/CHECK ENGINE WARNING LIGHT Indicates engine control system problem which may affect driveability or emissions.

MESSAGE LIGHTS LEVEL RIDE LIGHT Indicates ride level system is operating. SECURITY SYSTEM LIGHT This light will stay lit until the ignition key is inserted into the ignition. TRUNK LIGHT Indicates the trunk lid is open. WASHER FLUID LIGHT Indicates low fluid level in windshield washer reservoir. STOP ENGINE COOLANT TEMPERATURE LIGHT Indicates excessive coolant temperature. FASTEN BELTS LIGHT Indicates lap belts are not fastened. WAIT LIGHT (DIESEL) Indicates need to wait for glow plugs to warm-up prior to starting diesel engines. WATER IN FUEL LIGHT (DIESEL)

Indicates water in fuel system on diesel engine vehicles. CHOKE LIGHT Indicates choke operation, on some gasoline engine vehicles.

STARTER ELECTRICAL Starters - Delco-Remy

DESCRIPTION The starter motor is part of the cranking circuit, which consists of the battery, ignition switch and related wiring. When the ignition switch is turned to the START position, the starter solenoid windings are energized. This causes the plunger to move the shift lever, which engages the pinion with the engine flywheel ring gear. The movement of the plunger also closes the main contacts, applying battery voltage to the starter motor. When the engine starts, the pinion will overrun, protecting the armature from excessive speed and the flywheel from damage. When the ignition switch is released, the plunger return spring disengages the pinion.

TROUBLE SHOOTING STARTER PERFORMANCE TEST - STARTER IS NOISY NOTE:

Never operate starter for periods of more than 15 seconds. Excessive cranking can cause starter to overheat. Allow starter to cool for at least 2 minutes after each time it is operated.

1. A high-pitched whine, heard while cranking (before engine starts), indicates excessive distance between starter pinion and flywheel. If high-pitched whine is heard after engine starts and key is released, distance between starter pinion and flywheel is too small. 2. If loud, siren-like "whoop" sound is heard after the engine starts, clutch is likely defective. If "rumble", "growl" or "knock" is present as starter is coasting to a stop after starting engine, starter armature is either bent or unbalanced. 3. If diagnosis indicates pinion should be closer to flywheel, remove one double .015" shim or add a single .015" shim to the outer bolt only. If the noise condition persists, continue removing shims or adding shims to outside bolt as required. Refer to REMOVAL & INSTALLATION in this article. 4. If diagnosis indicates pinion should be moved away from flywheel, add one .015" shim. If condition is not corrected, another .015" shim may be added. DO NOT exceed .045" shim thickness. See REMOVAL & INSTALLATION in this article. NOTE:

For additional trouble shooting information, refer to the TROUBLE SHOOTING BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

ON-VEHICLE TESTING SOLENOID WINDING TESTS NOTE:

To prevent overheating, perform solenoid tests in a minimum of time with leads disconnected. Manufacturer does not provide Corvette specifications.

Hold-In Windings

Connect an ammeter in series with 12-volt battery and terminal "S" on solenoid. See Fig. 1. Connect a voltmeter between solenoid terminal "S" and ground. Connect a carbon pile rheostat across battery. Adjust voltage to 10 volts and check amperage reading. See HOLD-IN WINDINGS SPECIFICATIONS. HOLD-IN WINDINGS SPECIFICATIONS Starter Motor 0G195 SD200 SD210 SD250 SD300

Amperage At 10 Volts 14.5-16.5 14.5-16.5 14.5-16.5 13-19 13-19

Pull-In Windings

Connect test equipment as previously described. See Fig. 1. Ground terminal "M" of solenoid. Adjust voltage to 10 volts and note ammeter reading. See PULL-IN WINDINGS SPECIFICATIONS. NOTE:

Current will decrease as windings heat up.

PULL-IN WINDINGS SPECIFICATIONS Starter Motor 0G195 SD200 SD210 SD250 SD300

Amps @ 10 Volts 41-47 41-47 41-47 55-80 55-80

Test Results

If current draw reads greater than specification, short or ground is present in windings of solenoid. Low current draw indicates excessive resistance. If no current is present, there is an open circuit. Check connections. Replace starter solenoid as necessary.

Fig. 1: Solenoid Winding Test Connections Courtesy of GENERAL MOTORS CORP. STARTER NO-LOAD TEST

1. Connect test equipment to starter. See Fig. 2. Close switch and compare RPM, amperage and voltage readings with specifications.

Fig. 2: Starter No-Load Connections Courtesy of GENERAL MOTORS CORP. DELCO-REMY STARTER NO-LOAD TEST SPECIFICATIONS Part Number Amps @ 10 Volts RPM 199548 50-75 6000-11,900 1998579 70-110 6500-10,700 1998580 70-110 6500-10,700 1998591 70-110 6500-10,700 10455004 50-75 6000-11,900 10455006 45-74 8600-12,900 10455007 50-75 6000-11,900 10455010 50-75 6000-11,900

10455016 10455019 10455021 10455022 10455024 10455044 10455702 10455704

50-75 50-75 55-85 55-85 45-74 52-76 45-90 45-90

6000-11,900 6000-11,900 6000-12,000 6000-12,000 8600-12,900 6000-12,000 3500-5000 3500-5000

CAUTION: DO NOT apply more voltage than specified. Excessive voltage may cause armature to throw windings due to excessive speed. 2. If current draw and RPM meet specification, starter motor is okay. If test indicates low free speed and high current draw, unit may have tight, dirty or worn bearings, shorted armature, grounded armature, or grounded fields. 3. Failure to operate with high current draw indicates direct ground in terminal fields or frozen bearings. Failure to operate with no current draw indicates an open field circuit, open armature coils, or broken brush springs. 4. Low RPM and low current draw indicates high internal resistance due to poor connections, defective leads, or dirty commutator. High free speed and high current draw indicate shorted fields.

BENCH TESTING PRELIMINARY CHECKS Remove starter from vehicle. See REMOVAL & INSTALLATION in this article. Ensure pinion moves freely on screw shaft. Ensure armature rotates freely by prying pinion. If armature does not turn freely, motor must be disassembled for inspection. If armature rotates freely, motor should be given a no-load test before disassembly. ARMATURE BENCH TEST 1. Test armature for shorted coils with growler. Check for grounded coils with test light. Place one lead on armature shaft and the other lead on commutator. Test light should not illuminate. If test light illuminates, armature is grounded and must be replaced. 2. Turn commutator in lathe if it is rough, worn, or has protruding insulation. DO NOT turn to less than 1.65" (41.9 mm) diameter. Sand commutator lightly with 240 grit emery cloth and clean slots. CAUTION: Some starters have a molded type commutator. Insulation must not be undercut as it may cause serious damage to commutator. SERIES COIL OPEN BENCH TEST Using self-powered test light, place one lead on series coil terminal connection and other lead on insulated brush. See Fig. 3. If test light fails to illuminate, series coil is open and requires repair or replacement. Repeat

test for each insulated brush.

Fig. 3: Testing Series Coil For Open Courtesy of GENERAL MOTORS CORP. SERIES COIL GROUND BENCH TEST On starters with shunt coil, separate series and shunt coil strap terminals during test. Using test light, place one

lead on grounded brush holder and the other lead on either insulated brush. See Fig. 4. If test light glows, a grounded series coil is indicated and it must be repaired or replaced.

Fig. 4: Testing Series Coil For Ground Courtesy of GENERAL MOTORS CORP. CHECKING BRUSHES, SPRINGS & HOLDERS Replace brushes if worn to 1/2 of original length or if oil-soaked or pitted. Check brush spring tension and replace springs if weak or distorted.

OVERRUNNING CLUTCH CHECK Clutch pinion should turn freely in one direction only. Check pinion teeth for chips, cracks, or excessive wear. Chipped teeth may indicate defective ring gear. PINION CLEARANCE CHECK 1. Disconnect motor field coil at solenoid terminal "M" and insulate field connector. Connect 12 volts to solenoid terminal "S". Momentarily touch jumper lead from solenoid terminal "M" to starter frame, shifting pinion into cranking position. 2. Push pinion away from stop retainer as far as possible. Using a feeler gauge, ensure there is .010.140" (.25-3.6 mm) clearance between pinion and retainer. On SD300 starter only, clearance should be .010-.160 (.25-4.06 mm). See Fig. 5. NOTE:

Pinion clearance is not adjustable. If clearance is not within specification, motor must be disassembled and rechecked.

Fig. 5: Checking Pinion Clearance Courtesy of GENERAL MOTORS CORP.

Fig. 6: Typical Cranking Circuit Courtesy of GENERAL MOTORS CORP.

REMOVAL & INSTALLATION REMOVAL 1. Disconnect negative battery cable. Raise and support vehicle. As required, remove nuts from A/C compressor and engine brace, adjacent to starter motor. Remove other items that may interfere with removal of starter motor. 2. If necessary, remove nut from engine cross brace. Using pry bar between upper engine mount and engine, pry rearward and support engine. 3. If necessary, remove oil filter. Disconnect wiring at starter and note position. Remove starter mounting bolts and any shims. Remove starter. See Fig. 7 and Fig. 9. INSTALLATION Prior to installation, measure pinion-to-flywheel clearance. See Fig. 10. Clearance should be .020" (0.5 mm). Add or subtract shims as necessary. To complete installation, reverse removal procedure.

Fig. 7: Starter Mounting 2.5L Courtesy of GENERAL MOTORS CORP.

Fig. 8: Starter Mounting 5.0L & 5.7L Courtesy of GENERAL MOTORS CORP.

OVERHAUL NOTE:

DO NOT clean starter in degreasing tank or with grease dissolving solvents. This will remove lubricant from clutch mechanism.

Starter motors do not require lubrication, except during overhaul. The roll type overrunning clutch requires no lubrication. The drive assembly, however, should be wiped clean and lubricated with silicon grease on the shaft, underneath the overrunning clutch assembly.

Fig. 9: Exploded View Of Delco-Remy Starter Motor Courtesy of GENERAL MOTORS CORP.

Fig. 10: Measuring Pinion-To-Flywheel Clearance Courtesy of GENERAL MOTORS CORP.

STARTER REMOVAL & INSTALLATION STARTER REMOVAL General Motors

REMOVAL & INSTALLATION 2.3L "QUAD-4" (VIN D) 1. Disconnect cable from battery negative terminal. Remove air cleaner-to-throttle body duct. Disconnect electrical connectors from TPS, IAC and MAP sensor and secure harness to the side. 2. Disconnect vacuum harness assembly from intake manifold and secure to the side. Disconnect MAP sensor hose from intake manifold. Remove coolant fan shroud retaining bolts and remove shroud along with MAP sensor. 3. Remove coolant fan-to-upper radiator support bolt. Remove remaining support bolt and upper radiator support. Disconnect electrical connector from coolant fan and lift fan assembly out from the 2 lower insulators. 4. Rotate bracket so that 2 lower bracket legs point upward. Move fan assembly toward drivers side until fan blade overlaps the radiator-to-core seam by approximately one inch. Pull fan assembly up, and out the top to remove. NOTE:

Because of the low clearance, special care must be taken not to damage the lock tang on the TPS with the fan bracket.

5. Remove harness retaining clip from engine mount bracket stud. Remove starter mounting bolts. Tilt rear of starter toward radiator, pull starter out and rotate solenoid toward radiator to gain access to electrical connections. CAUTION: DO NOT damage crank sensor mounted directly to the rear of the starter. If it is damaged, replacement will be required. 6. Disconnect electrical connections at starter terminals and move starter toward drivers side of vehicle. Remove starter from top and note if any shims have been used. 4.5L (VIN 5) 1. Disconnect negative battery cable. Raise and support vehicle. Remove starter motor shield. Remove exhaust front and rear pipe assembly. 2. Remove flexplate inspection cover. Disconnect solenoid wires and battery cables. Remove starter motor. 3. To install reverse, removal procedure.

Fig. 1: Starter Mounting (4.5L VIN 5) Courtesy of GENERAL MOTORS CORP. ALL OTHERS 1. Disconnect negative battery cable. Raise and support vehicle. Remove starter braces, shields, flywheel cover etc., that might interfere with removal of starter. 2. On 2.5L VIN R, 2.8L VIN W, 3.1L VIN V and 3.3L VIN N, remove bolt from engine cross brace. Using pry bar between upper engine mount and engine, pry rearward and support engine. 3. On models with engine oil cooler, remove oil filter and position oil cooler line away from starter. Disconnect wiring at starter and note position. Remove starter mounting bolts and any shims. Remove starter.

Fig. 2: Starter Mounting (2.5L VIN R) Courtesy of GENERAL MOTORS CORP.

Fig. 3: Starter Mounting (2.8 VIN S, 5.0 VIN F, 5.7 VIN 8, 5.0 VIN E) Courtesy of GENERAL MOTORS CORP.

Fig. 4: Starter Mounting (2.8L VIN W & 3.1L VIN T) Courtesy of GENERAL MOTORS CORP.

STEERING COLUMN SWITCHES STEERING General Motors Corp. Steering Column Switches

DESCRIPTION Description not used for this article.

SERVICE PRECAUTION WARNING: If vehicle is equipped with an air bag, it should be disabled before doing steering column work, see appropriate AIR BAGS article in the ACCESSORIES/SAFETY EQUIPMENT Section.

TROUBLE SHOOTING Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

REMOVAL & INSTALLATION PRECAUTIONS Steering column must be lowered or removed for access to ignition switch on some vehicles. Steering wheel, directional signal and other components must be removed to gain access to lock cylinder retaining screw, or retaining tab (if equipped) for lock cylinder removal. HORN BUTTON Removal & Installation

Disconnect battery ground cable. On models with sport wheel, lift off horn button, remove 3 screws and take off contact, insulator eyelet and spring. On all other models, remove screws from underside of wheel, partially lift off horn button. Unplug electrical connectors. Remove horn button. To install, reverse removal procedure. STEERING WHEEL Removal

1. Disconnect battery ground cable. Remove horn button. On models with tilt and telescoping columns, remove screws securing locking lever and flange to steering wheel hub. On all models, remove steering wheel nut. On Camaro and Firebird, use Steering Wheel Puller (J-2927) to remove steering wheel. 2. Use Steering Wheel Puller (BT-61-9 or J-1859-03) to remove steering wheel. Installation

Align steering wheel hub and shaft index marks. Install retainer and nut. To complete installation, reverse removal procedure.

Fig. 1: Exploded View of Steering Column Assembly Courtesy of GENERAL MOTORS CORP. TURN SIGNAL SWITCH Removal & Installation

1. Disconnect battery ground cable. Remove steering wheel, retaining ring, and shaft lock cover. Using Lock Plate Compressors (J-23653-4 and J-23653), remove lock plate. Remove canceling cam assembly, upper bearing preload spring, and turn signal lever. 2. Push hazard switch in and unscrew knob. Remove actuator arm assembly and switch mounting screws, wrap a piece of tape around upper part of wires. Remove switch by pulling straight up. To install, reverse removal procedure. CRUISE CONTROL SWITCH

Removal

1. With turn signal switch assembly removed, remove lower trim panel. Unplug switch harness connector. Connect 24" follower wire to end of switch harness connector. Disconnect turn signal lever from spring retainer. 2. Pull turn signal lever (cruise control lever) straight out of column. Remove lever and harness by pulling from column. Leave follower wire in column to guide new wire harness back into column. Installation

Connect new harness to follower wire. Pull harness into column. Align key on turn signal lever with slot in turn signal switch. Push lever in until seated in spring retainer. To complete installation, reverse removal procedure. LOCK CYLINDER Removal

Remove turn signal switch as previously described. Turn lock cylinder to ON position. Remove key warning buzzer switch and lock cylinder attaching screw. Remove lock cylinder. Installation

Turn lock cylinder to STOP position. Align lock cylinder in housing and install retaining screw. Turn lock cylinder to ON position. Install key warning buzzer switch. To complete installation, reverse removal procedure.

Fig. 2: Lock Cylinder Mechanism Courtesy of GENERAL MOTORS CORP. IGNITION SWITCH Removal

1. Steering column must be lowered (removed on some models) to gain access to ignition switch. Steering wheel removal is not required. Place lock cylinder in OFF position. 2. If lock cylinder has already been removed, pull actuator rod up until it stops. Back off actuator rod 2 detents. Remove switch retaining screw and stud. Lift switch from column. Detach actuator rod. Installation

1. Place lock cylinder in OFF position. Place switch in OFF position by moving selector to top of switch and then backing off 2 detents. 2. On fixed columns, fit actuator rod into slider hole. Install switch onto steering column. Tighten attaching stud and screw. 3. On tilt or telescoping columns, install switch. Lightly push switch down on column to take up free play in actuator rod. Tighten attaching stud and screw. Connect wiring harness. Check operation of ignition switch.

DIMMER SWITCH Removal

1. Disconnect battery ground cable. Remove lower steering column cover. Remove 2 steering column-toupper mounting bracket nuts. 2. Lower column. Remove nut and screw securing dimmer switch. Disconnect electrical connections. Remove switch. Installation

1. Position switch on steering column and loosely install fasteners. Install electrical connectors. Insert one 3/32" drill through locating hole securing dimmer switch to connector body. 2. Connect actuator arm and slide dimmer switch up to remove lash. Tighten fasteners. Remove drill bit. Reverse removal procedure to complete installation. WINDSHIELD WIPER/WASHER SWITCH Removal & Installation

1. Remove turn signal switch as previously described. Remove ignition switch, dimmer switch and lock cylinder. 2. Remove steering column housing attaching screws. Remove pivot pin, horn contact, bearing and washer/wiper switch from column housing. To install, reverse removal procedure.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Steering Wheel Retaining Nut

Ft. Lbs. (N.m) 30-35 (41-47)

STEERING COLUMN STEERING General Motors Corp. Steering Columns - Fixed & Tilt

DESCRIPTION Steering columns are either floor shift or column shift. Construction and maintenance of both columns is the same except for addition of shift lever, tube and related components on column shift models. Column shift and floor shift steering columns are each available in 3 configurations: fixed column, tilt column and tilt/telescopic column. See Fig. 7 -Fig. 10 . Steering column design is basically the same for all columns, with the main differences involving the addition of column shifters and tilt or tilt/telescopic mechanisms. Steering columns use an integral ignition lock switch. This lock secures the steering wheel and shift linkage (column shift). Columns have a 2-piece telescoping gear shift tube (column shift), interconnected by plastic inserts and shear pins, and a 2-piece telescoping steering shaft with upper and lower sections connected by plastic collars and pins. CAUTION: Columns must be handled with care to avoid stresses. Use only fasteners of the same or equivalent part number if replacement is necessary. Improper fasteners or tightening could result in failure.

REMOVAL & INSTALLATION STEERING COLUMN CAUTION: Applying excessive pressure, or causing impact to mainshaft during service, may cause the column to collapse. Removal

1. Disconnect battery ground cable. On column shift models, disconnect transmission linkage rod from lever on steering column. 2. Remove dust cover from steering shaft coupler at steering gear. Remove shaft coupler clamp bolt. Mark steering shaft coupler and steering gear shaft for reassembly reference. 3. Remove steering column floor plate mounting bolts. Remove lower trim panel. Unplug electrical connectors from steering column. Remove steering column bracket mounting nuts. Remove steering column. Installation

To install, reverse removal procedure. Check for proper operation. Ensure there is at least 1/16-1/8" (1.6-3.2 mm) clearance between steering shaft and steering gear flanges.

NOTE:

For information on ignition and turn signal switch replacement, see STEERING COLUMN SWITCHES article in the STEERING section.

OVERHAUL STEERING COLUMN Preparation

Steering column removal is not necessary for lock plate cover, lockplate, steering shaft snap ring, canceling cam, turn signal switch, upper bearing preload spring or lock cylinder service. For the remaining components, steering column must be removed. Disassembly procedure for the tilt/telescopic steering column is similar to the tilt steering column and typical of all variations. Disassembly (Non-Tilt Steering Column)

1. Disconnect battery ground cable. Remove steering column. See STEERING COLUMN in in REMOVAL & INSTALLATION in this article. Remove horn pad, steering wheel and combination switch. See STEERING COLUMN SWITCHES article in the STEERING section. 2. Remove lock plate cover. Remove lock plate snap ring using Spring Compressor (J-23653). See Fig. 1 . Remove lock plate, horn cam and spring.

Fig. 1: Removing Retainer Snap Ring Courtesy of GENERAL MOTORS CORP. 3. Remove combination switch. Remove key buzzer switch. Remove ignition lock retaining screw. Remove ignition lock. Remove housing assembly. 4. Remove ignition switch and dimmer switch. Remove steering shaft retaining ring. Remove steering shaft through lower end of column. Disassembly (Tilt Steering Column)

1. Disconnect battery ground cable. Remove steering column. See STEERING COLUMN in REMOVAL

2. 3. 4. 5.

& INSTALLATION in this article. Remove tilt lever. Remove hazard warning knob and ignition key light. Remove wiper switch knob. Remove wiper switch tube mounting screws. Remove wiper switch tube. Rotate shaft fully clockwise. Remove shaft by pulling straight out. Carefully remove plastic cover from lock plate. Using Compressor (J-23653), remove lock plate retaining ring from shaft. See Fig. 1 . Remove lock plate, canceling cam and upper bearing spring. Remove turn signal switch and actuator arm. Place ignition lock cylinder in LOCK position. Using a thin screwdriver, depress ignition lock cylinder tab retainer (if equipped) or remove lock retaining screw. Remove ignition lock cylinder. See Fig. 3 . Remove housing cover from column.

Fig. 2: Removing Tilt Spring Courtesy of GENERAL MOTORS CORP. 6. Place column in fully up position. Remove tilt spring retainer and spring. See Fig. 2 . Remove dimmer switch. Remove steering shaft inner race seat and race. Remove ignition switch and back-up light switch.

Fig. 3: Removing Lock Cylinder Courtesy of GENERAL MOTORS CORP. 7. Using Pivot Pin Remover (J-21854-1), remove pivot pins. See Fig. 4 . Pull tilt lever to unlock shoes.

Remove housing. Remove actuator rods.

Fig. 4: Removing Pivot Pin Courtesy of GENERAL MOTORS CORP. 8. Remove lower coupling roll pin. Remove steering shaft assembly from upper end. Remove support from lock plate. Remove shift tube retaining ring. 9. Remove thrust washer. Using screwdriver, disengage plastic shift tube from lower end of jacket. Using Puller (J-23072), pull shift tube from bowl. 10. Inserting bushing on end of tool in shift tube, force bowl from shift tube. Remove shift tube through lower end. Remove jacket mounting plate and wave washer. Remove bowl from jacket. Inspection (All Steering Columns)

1. Check for separation of the 2 break-away capsules. If capsules have moved more than 1/16" (1.6 mm), some column collapse may have occurred. Check for damaged steering shaft components. 2. Inspect jacket section of column for looseness, bends, collapsed mesh or bellows section. Check for mast jacket collapse by measuring for proper dimensions. See Fig. 5 . Also see appropriate STEERING COLUMN COLLAPSE MEASUREMENTS . 3. On column shift models, check operation of shift lever. If lever can be moved to PARK position without raising lever, upper shift tube plastic bearing is broken. 4. Inspect intermediate and steering column shafts for sheared plastic pins. If the shafts rattle when tapped

lightly from side, pins are sheared. Replace any collapsed or damaged parts. Reassembly (All Steering Columns)

1. Install key release lever and spring into shroud. Install retainer plate. Using an arbor press, install bearings into housing (if removed). Using a .180" (4.5 mm) pin to align shoes, install lock shoe springs, lock shoes and shoe pin into housing. Relieve tension on release lever. 2. Install spring, release lever, and pin into bearing housing. Install drive shaft into housing. Lightly tap sector onto shaft, far enough to bottom on drive shaft. Install lock bolt. 3. Engage lock bolt with sector cam surface. Install rack and spring. Block tooth on rack should engage block tooth on sector. Install tilt release lever. Install lock bolt spring, and spring retaining screw. Tighten screw to 35 INCH lbs. (4 N.m). 4. On all models, slide bowl onto jacket. Position wave washer and mounting plate in place. 5. Work jacket mounting plate into notches in jacket by tipping jacket mounting plate toward bowl hub at 12 o'clock position and under jacket opening. Slide jacket mounting plate into notches in jacket. 6. Install shift tube into lower end of jacket. Align key in tube with keyway in bowl. Using Installer (J23073), pull shift tube into bowl. See Fig. 6 . Do not tap on end of shift tube. 7. Pulling up bowl to compress wave washer, install thrust washer and retaining ring. Slide dimmer switch actuator rod through hole in support. Aligning "U" in support with "U" notch in jacket, install support. 8. Insert 4 screws through support into lock plate. Tighten screws to 60 INCH lbs. (7 N.m). Drive lower bearing approximately 3/16" into tube. Slide ignition actuator rod between bowl and jacket. 9. Install centering spheres and anti-lash spring into upper steering shaft. Install lower steering shaft from same side of spheres that ends protrude. Ensure that master serration of upper shaft aligns with master serration of lower shaft. 10. Place shift bowl in PARK position. Holding lock shoes in disengaged position, install bearing housing over steering shaft until pivot pin holes align with holes in support. Ensure rack has engaged ignition switch actuator rod. 11. Install pivot pins. Use hand pressure to prevent damaging support pivot holes. Using small hammer and drift, tap in pins to complete installation. Place housing in the fully up position. 12. Install guide and peg onto support. Install tilt spring and spring retainer. Using a screwdriver turn retainer counterclockwise to engage. Install inner bearing race and seat. Install tilt lever opening shield in housing. 13. Remove tilt release lever. Install housing cover. Seat screw at 12 o'clock position. Install and tighten 3 screws to 100 INCH lbs. (11 N.m). Install buzzer/chime switch to spring clip with spring bowed away from switch on side opposite contact. 14. Push switch and spring into hole in cover with contacts toward lock cylinder. Install key light (if equipped). Install turn signal switch. Feed wires and connector through cover, bearing housing and shift bowl. 15. Install hazard warning knob. Install canceling cam, cam spring and shaft lock plate. Using Compressor (J23653) to depress lock plate, install new retaining ring. 16. Reinstall tilt release lever and turn signal switch lever. Install upper shift lever. Drive in pivot pin. Position shaft lock cover over lock. Snap shaft lock cover into position by pressing on outer edges. 17. To install ignition lock, turn key to LOCK position. Remove key. Buzzer operating lever should retract into cylinder. Slide ignition switch to LOCK position (second detent from bottom).

18. Insert cylinder into housing far enough to contact drive shaft. Press inward while moving ignition switch actuator rod up and down to align parts. When properly aligned, cylinder will move in and spring loaded retainer will snap into place locking the cylinder into housing. 19. Push ignition switch lightly up column, toward lock housing, to remove lash in actuator rod. Tighten mounting screws to 35 INCH lbs. (4 N.m). Install wire protector. Seat actuator rod on dimmer switch. 20. Depress dimmer switch until one 3/32" drill bit can be inserted into adjusting pin hole. See Fig. 11 . Reposition upper end of actuator rod in pocket of washer/wiper switch. With light upward pressure on switch to remove lash, install and tighten 2 screws on switch. Remove drill bit. 21. Ensure that switch clicks as lever is lifted. Check for proper operation of ignition lock, wiper/washer switch, dimmer switch and steering mechanism. STEERING COLUMN COLLAPSE MEASUREMENTS STEERING COLUMN COLLAPSE MEASUREMENTS (STANDARD COLUMN) Body "A" Body "B" Body "C" Body "D" Body "F" Body "H" Body "J" Body "K" Body "L" Body "N" Body Column Shift "N" Body Floor Shift "W" Body "Y" Body (1) See Fig. 5 .

(1) In. (mm)

(D) 5-5 3/32 (127-129) (A) 3 1/2 (89.35) (A) 3 1/2 (89.35) (A) 4 1/64 (102) (B) 7 15/64 (184) (D) 7 17/64 (184.6) (E) 5 1/32-5 1/8 (128-130) (F) 5 15/64 (133) (D) 5 19/64 (134.6) (D) 4 15/32-4 17/32 (114-116) (E) 5 5/32 (127-129) (H) 4 1/16 (103.2) (C) 5 43/64 (144)

STEERING COLUMN COLLAPSE MEASUREMENTS (TILT COLUMN) Body "A" Body "B" Body Tilt "B" Body Telescopic "C" Body "D" Body "E" Body (Eldorado) "E" Body (Toronado Column Shift) "E" Body (Toronado Floor Shift) "E" Body (Riviera)

(1) In. (mm)

(D) 5 1/32-5 1/8 (128-130) (A) 4 1/64 (102) (A) 3 3/8 (85.47) (A) 4 1/64 (102) (A) 4 1/64 (102) (F) 5 15/64 (133) (D) 4 13/16 (123) (D) 4 13/16 (123) (D) 5 25/64-5 15/32 (137-139)

(1) See Fig. 5 .

NOTE:

The STEERING COLUMN COLLAPSE MEASUREMENTS tables refer to the letter designation of the body series. See MODEL IDENTIFICATION table for proper identification.

Fig. 5: Steering Column Collapse Measurement Courtesy of GENERAL MOTORS CORP. MODEL IDENTIFICATION Body Type & GM Division "A" Body Buick Chevrolet Oldsmobile Pontiac "B" Body Buick Chevrolet

Model Name Century Celebrity Cutlass Ciera & Cutlass Cruiser Wagon 6000 Estate Wagon Caprice

Oldsmobile "C" Body Buick Cadillac Oldsmobile Pontiac "D" Body (Cadillac) "E" Body Buick Cadillac Oldsmobile "F" Body Chevrolet Pontiac "H" Body Buick Pontiac Oldsmobile "J" Body Chevrolet Pontiac "K" Body (Cadillac) "L" Body (Chevrolet) "N" Body Buick Oldsmobile Pontiac "W" Body Buick Chevrolet Oldsmobile Pontiac "Y" Body (Chevrolet)

Custom Cruiser Electra & Park Avenue DeVille & Fleetwood Ninety-Eight Touring Sedan Brougham Reatta & Riviera Eldorado Toronado & Trofeo Camaro Firebird LeSabre Bonneville Delta 88 Cavalier Sunbird Seville Beretta & Corsica Skylark Cutlass Calais Grand Am Regal Lumina Cutlass Supreme Grand Prix Corvette

Fig. 6: Installing Shift Tube Courtesy of GENERAL MOTORS CORP.

Fig. 7: Non-Tilt Steering Column Assembly (Except "L" & "W" Bodies) Courtesy of GENERAL MOTORS CORP.

Fig. 8: Tilt Steer Column Assembly (Except "L" & "W" Bodies) Courtesy of GENERAL MOTORS CORP.

Fig. 9: Non-Tilt Steer Column Assembly ("L" & "W" Bodies) Courtesy of GENERAL MOTORS CORP.

Fig. 10: Tilt Steer Column Assembly ("L" & "W" Bodies) Courtesy of GENERAL MOTORS CORP.

Fig. 11: Aligning Dimmer Switch Courtesy of GENERAL MOTORS CORP.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Bracket-to-Column Nuts Bracket-to-Instrument Panel Stud Nuts Flexible Coupling Nuts Intermediate Shaft-to-Steering Shaft Bolt Lower Intermediate Shaft-to-Steering Gear Box

Ft. Lbs. (N.m) 22 (30) 22 (30) 20 (27) 35 (47) 35 (47)

Steering Wheel Nut Upper Intermediate Shaft-to-Steering Column

30 (42) 44 (60)

STEERING GEAR - POWER STEERING Rotary Valve Steering Gear

DESCRIPTION Saginaw rotary valve integral power steering gear contains a control valve which directs hydraulic pressure to either side of the rack piston. The rack piston converts hydraulic pressure into mechanical force.

TROUBLE SHOOTING Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

LUBRICATION See POWER STEERING GENERAL SERVICING article in the STEERING section.

TESTING See POWER STEERING GENERAL SERVICING article in the STEERING section.

ADJUSTMENTS NOTE:

If complete wheel alignment is necessary, refer to WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES article in the WHEEL ALIGNMENT section.

WORM BEARING PRELOAD NOTE:

Adjust worm bearing preload first, then adjust pitman shaft over-center turning torque.

1. Remove steering gear from vehicle. See STEERING GEAR removal nd installation in this article. Using Spanner Wrench (J-7624), seat adjuster plug firmly in housing. Approximately 20 ft. lbs. (27 N.m) torque is required to seat adjuster plug. Index mark gear housing opposite one hole in adjuster plug. 2. Measure back (counterclockwise) 1/2" (13 mm) from index mark and make another index mark on housing. Turn adjuster plug counterclockwise until hole in plug is aligned with second mark on housing. 3. Install adjuster plug nut and torque to specification. Hold adjuster plug to maintain alignment and use a punch to stake nut in place. PITMAN SHAFT OVER-CENTER TURNING TORQUE (LASH ADJUSTMENT) 1. Remove steering gear. Rotate pinion shaft back and forth to drain power steering fluid. Rotate pitman shaft adjusting screw counterclockwise until fully extended, then tighten one full turn. See Fig. 1 . Rotate pinion shaft from stop to stop and count number of turns.

2. To center gear, start at either stop and turn pinion shaft back 1/2 the total number of turns. Once centered, flat on pinion shaft should face upward, parallel with side cover and master spline on pitman shaft should line up with adjuster screw. 3. Using an INCH lb. torque wrench with handle facing upward, rotate pinion shaft 45 degrees each side of center. Record highest turning torque measured on or near center. 4. To adjust over-center turning torque, loosen adjusting screw lock nut and turn pitman shaft adjuster screw clockwise until correct drag torque is obtained. On new steering gears (less than 400 miles), add 6-10 INCH lbs. (.7-1.1 N.m) to previously measured worm bearing preload. DO NOT exceed total steering gear preload of 18 INCH lbs. (2 N.m). 5. On used steering gears (400 miles or more), add 4-5 INCH lbs. (.5-.6 N.m) torque to previously measured worm bearing preload. DO NOT exceed total steering gear preload of 13 INCH lbs. (1.5 N.m). Prevent adjusting screw from turning and tighten adjusting screw lock nut to 37 ft. lbs. (50 N.m).

Fig. 1: Adjusting Pitman Shaft Over-Center Courtesy of GENERAL MOTORS CORP.

REMOVAL & INSTALLATION PITMAN SHAFT SEAL Removal

1. Remove pitman arm. Clean exposed end of pitman shaft and end of housing. Remove pitman shaft and side cover. Remove dust seal (if present), and retaining ring.

2. Two different types of seal assemblies may be used. Either remove 2 washers, single lip seal and double lip seal or remove only one washer and seal. Use care not to score housing bore when prying out seals and washers. 3. Check housing for burrs and remove as necessary. Insert Pitman Shaft Bearing Remover (J-6278) through hole in top of housing and drive out needle bearing. Installation

1. Lubricate new shaft seal with power steering fluid. Apply a single layer of tape to pitman arm shaft to avoid damaging seals. 2. Using Seal Installer (J-6219), install single lip seal and back-up washer. Ensure there is clearance for remaining double lip seal, back-up washer, and retaining ring. DO NOT allow seal to bottom in end of counter bore. 3. Install double lip seal and back-up washer. Provide clearance for retaining ring when installing seal. Install retaining ring, ensuring it is properly seated. STEERING GEAR Removal & Installation

1. Disconnect negative battery cable. Remove pressure and return hoses from steering gear. Raise hoses to prevent fluid leakage. Remove intermediate shaft from steering gear. Remove pitman arm. Remove steering gear bolts and washers. Remove steering gear from vehicle. 2. To install, reverse removal procedure. Ensure steering gear is aligned as straight as possible with intermediate shaft. Tighten attaching bolts to 70 ft. lbs. (95 N.m).

Fig. 2: Exploded View of Power Steering Gear

Courtesy of GENERAL MOTORS CORP.

OVERHAUL STEERING GEAR Disassembly

1. Remove steering gear from vehicle. Clean gear exterior and drain fluid. Mount gear in soft-jawed vise with pitman shaft facing down. Remove pitman shaft adjusting screw lock nut. Remove side cover bolts. Rotate pinion shaft to center gear. Remove pitman shaft nut and spring washer. Remove side cover, gasket and pitman shaft assembly. 2. Remove housing end plug retaining ring. Remove plug and "O" ring seal. Rotate pinion shaft counterclockwise until rack piston begins to come out of housing. Remove rack piston plug. Insert Rack Piston Arbor (J-21552) into bore of rack piston. Hold tool firmly against worm shaft while turning pinion counterclockwise to force piston from housing. Remove rack piston, rack piston balls and tool from housing. 3. Remove pinion shaft, valve body and worm shaft as an assembly. Remove worm bearing and races. Lightly tap pinion shaft on a wood block to loosen shaft cap. Pull out cap and valve spool from valve body approximately 1/4" and disengage pinion shaft pin from hole in valve spool. Remove valve spool from valve body. Remove valve spool "O" ring seal, Teflon rings and "O" rings. NOTE:

DO NOT disassemble valve body. If valve body is defective, replace entire valve body assembly.

Cleaning & Inspection

Clean housing and lubricate all internal components with power steering fluid. Replace steering gear housing if bore is damaged. Replace any worn or damaged components. Reassembly

1. Lubricate valve spool and "O" ring with power steering fluid. Install valve spool "O" ring seal to valve spool. Install valve spool to valve body until hole in valve spool for pinion shaft pin is accessible from opposite end of valve body. 2. Install pinion shaft to valve spool and insert retaining pin. Ensure notch in pinion shaft cap fully engages valve body pin and seats against valve body shoulder. Lubricate "O" ring seals and Teflon rings with power steering fluid and install on valve body. Install worm bearing and races to worm shaft. Install pinion shaft and valve assembly to worm shaft. Ensure pin on pinion shaft aligns with slot in valve assembly. Install pinion shaft, valve assembly and worm shaft into housing. 3. Using Adjuster Plug Bearing Remover and Installer (J-6221), install needle bearing in adjuster plug. Ensure identification mark on needle bearing faces tool during installation. Using same tool, install lip seal and dust seal. Install "O" ring seal, large bearing race, worm bearing, small bearing race and bearing spacer to adjuster plug. Install worm bearing retainer to adjuster plug. Install adjuster plug in housing, using care not to cut seals. 4. Install worm shaft to rack piston. Align worm shaft groove with rack piston ball return guide hole.

Alternately install Black and Silver balls into rack piston and ball guide while turning worm shaft counterclockwise. Use grease to retain balls in place and install ball guide to rack piston. Install ball guide clamp and screws. 5. Insert Rack Piston Arbor (J-21552) into bore while turning rack piston counterclockwise. Rack piston will be forced onto tool and will hold balls in place. Using same arbor, install rack piston to worm shaft, using Ring Compressor (J-8947) to compress seals. Hold arbor against worm shaft and turn pinion shaft clockwise until rack piston is seated on worm shaft. Install rack piston plug and housing end plug seal, plug and retaining ring. Ensure open end of retaining ring is approximately 1" (25 mm) from housing access hole. 6. Turn pinion shaft until rack piston center groove is aligned with center of pitman shaft bearing bore. Lubricate side cover gasket and install on side cover. Thread cover onto adjusting screw until cover bottoms against pitman shaft. If removed, install pitman shaft bearing. 7. Install pitman shaft so long center sector tooth meshes with rack piston center groove. Install side cover and gasket on housing. Install and tighten side cover bolts to 45 ft. lbs. (61 N.m). Thread adjusting screw lock nut halfway on adjusting screw. Prevent screw from turning with Allen wrench while installing nut. Adjust steering gear. See ADJUSTMENTS in this article. Install pitman shaft seal assembly.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Flexible Coupling Pinch Bolt Pitman Arm Retaining Nut Pitman Shaft Adjuster Lock Nut Rack Piston Plug Steering Gear Mounting Bolts Steering Gear Side Cover Bolts

Ft. Lbs. (N.m) 30 (41) 185 (251) 37 (50) 75 (102) 70 (95) 45 (61)

STEERING LINKAGE STEERING General Motors Corp. Steering Linkage

DESCRIPTION GENERAL INFORMATION DO NOT weld, heat or bend steering linkage to repair or straighten. When installing cotter pins, tighten nut to lower specified torque, then tighten nut to next slot that lines up with stud hole. Use new cotter pins during reassembly. DO NOT hammer on ball studs. Ensure threads are clean and lubricated before tightening.

TROUBLE SHOOTING Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the GENERAL TROUBLE SHOOTING section.

REMOVAL & INSTALLATION TIE RODS NOTE:

  

For removal and installation procedures for rack and pinion type steering gear, see appropriate STEERING GEARS article in the STEERING section below.

STEERING GEAR - POWER (Brougham, Camaro, Caprice, Custom Cruiser, Estate Wagon & Firebird) STEERING GEAR - POWER (Celebrity, Century, Cutlass Ciera, Cutlass Cruiser Wagon & 6000) STEERING GEAR - POWER (all others)

Removal

1. Raise and support vehicle. Remove cotter pins and castle nuts from inner and outer tie rod ends. Using a puller, separate tie rod ends from steering knuckle and center link. 2. Remove tie rod ends from adjusting sleeve by loosening clamp bolts. Unscrew tie rod ends, noting number of turns necessary for reassembly reference. Installation

1. Apply penetrating oil to clamps, tie rod threads and adjusting sleeve. Wipe threads clean. Lubricate threads with EP chassis lube. Install adjusting sleeve clamps. 2. Thread tie rod ends same number of turns required during removal. Ensure both ends are equal distance (within 3 threads) into sleeve. 3. Install castle nuts and NEW cotter pins. Properly position adjusting sleeve clamps. Lower vehicle and adjust toe-in. See appropriate WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES article in WHEEL ALIGNMENT as listed below. Tighten clamp bolts.  WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Cutlass Supreme, Grand Prix,



 

Lumina & Regal) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Brougham, Caprice, Corvette, Custom Cruiser & Estate Wagon) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Bonneville, 88, DeVille, Electra, Fleetwood, LeSabre, Ninety-Eight & Park Avenue) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Eldorado, Reatta, Riviera, Seville, Toronado & Trofeo) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Camaro & Firebird) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for all Others)

CENTER LINK Removal & Installation

Raise and support vehicle. Remove cotter pins and castle nuts. Using a puller, separate inner tie rod ends, idler arm and pitman arm from center link. Remove center link from vehicle. To install, reverse removal procedure. Ensure idler arm stud seal is in place. Lower vehicle. Adjust toe-in. IDLER ARM Removal

1. Raise vehicle. Separate center link from idler arm. Remove 2 idler arm mounting bolts. If idler arm support is disconnected from frame for other work, wire support to idler arm to prevent rotation if equipped with a threaded type bushing. 2. Idler arm should be replaced when a vertical force of 25 lbs. (11 kg) is applied at center link end of idler arm, and vertical lash exceeds .13" (3.3 mm). Installation

To install, reverse removal procedure. On models equipped with threaded bushing, thread idler arm support into bushing until the distance between the center line of the lower mounting hole on the support and the upper face of the idler arm is 2.31-2.41" (58.7-61.2 mm). See Fig. 1. Idler arm must freely rotate 90 degrees in both directions from straight ahead.

Fig. 1: Idler Arm Positioning Courtesy of GENERAL MOTORS CORP. PITMAN ARM Removal & Installation

1. Raise and support vehicle. Mark pitman arm-to-steering shaft for reassembly reference. 2. Remove center link ball joint stud cotter pin and nut. Using a puller, separate center link from pitman arm. DO NOT hammer on end of puller. 3. Remove pitman arm retaining nut. Using a puller, separate pitman arm from steering gear. To install, reverse removal procedure.

WHEEL ALIGNMENT After performing appropriate service procedures, refer to appropriate WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES article in the WHEEL ALIGNMENT section as listed below. 



WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Cutlass Supreme, Grand Prix, Lumina & Regal) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Brougham, Caprice, Corvette, Custom Cruiser & Estate Wagon)



 

WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Bonneville, 88, DeVille, Electra, Fleetwood, LeSabre, Ninety-Eight & Park Avenue) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Seville) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Eldorado, Reatta, Riviera, Toronado & Trofeo) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for Camaro & Firebird) WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (for all Others)

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Idler Arm-to-Center Link Nut Idler Arm-to-Frame Pitman Arm-to-Center Link Nut Tie Rod End Castle Nut Tie Rod End Lock Nut

Ft. Lbs. (N.m) 40 (54) 60 (81) 40 (54) 35-45 (47-61) 30 (41)

ACCESSORIES & SAFETY EQUIPMENT Sun Roofs - Power

DESCRIPTION & OPERATION DESCRIPTION Sun roofs have a sliding glass panel and sliding sunshade. The glass panel is controlled by sun roof switch on front center area of roof. The sunshade can be opened or closed by hand. OPERATION All models are operated by an electric motor located in headliner, above windshield. A reversible motor opens and closes sliding glass panel. In case of electrical failure, the sun roof can be operated manually by removing rubber plug in headliner. Use hand crank (in glove box) to turn driving gear and close or open panel.

ADJUSTMENTS GLASS HEIGHT ADJUSTMENT 1. Open glass panel. Unsnap deflector arms from side tracks. Remove 2 screws securing wind deflector assembly to forward track. Remove deflector assembly. 2. Close glass and slide sunshade fully rearward. Remove 3 screws from front edge of halo. Slide halo fully rearward. Loosen 3 attaching screws on each side of glass. Adjust glass height so front and rear edge of glass is at specified height. All Except "C" & "H" Bodies  

1/32" (.8 mm) below flush at front of roof. 1/32" (.8 mm) above flush at rear of glass.

"C" & "H" Bodies  

3/8" (1.0 mm) below flush at front of roof. 3/8" (1.0 mm) above flush at rear of glass.

Ensure gap at front and rear seal of glass is correct before tightening screws. Front glass seal-to-roof opening should be zero (just touching). Rear glass seal-to-roof opening should be .020" (.5 mm). Reassemble halo to glass and reinstall deflector assembly. MOTOR SYNCHRONIZATION ADJUSTMENT Release gear synchronization lever from notch on motor casting and rotate lever in direction of arrow on casting. Using a 4 mm Allen wrench, manually rotate small cam until hole in large cam is aligned with centerline of cams. See Fig. 1 . Return synchronization lever to notched position.

NOTE:

To fully synchronize sun roof, lifter arms and guidance ramps must also be aligned. See LIFTER ARM installation. Both motor and track assembly must be synchronized for proper sun roof operation.

Fig. 1: Sun Roof Motor Synchronization Courtesy of GENERAL MOTORS CORP.

TESTING SWITCH TEST 1. Place switch in neutral position. Using a self-powered test light, check for continuity between terminals No. 1-3, and 2-5-6. See Fig. 2 .

Fig. 2: Sun Roof Switch Testing Courtesy of GENERAL MOTORS CORP. 2. Position switch lever rearward. Continuity should exist between terminals No. 2-4-5 and between terminals No. 1-3. Terminal No. 6 should be disconnected from any other terminal. 3. Position switch lever forward. Continuity should exist between terminals No. 2-3-5, and between terminals No. 4-6. Terminal No. 1 should be disconnected from any other terminal.

REMOVAL & INSTALLATION SUN ROOF, HALO & CABLE ASSEMBLY Removal

1. Protect painted surfaces at roof opening. Open glass panel. Unsnap and remove air deflector arms to expose rivets at front of assembly. Tape over exposed cable to prevent metal shavings from entering track. 2. Using a 3/8" drill with drill stop, drill out rivets securing track assembly to sun roof housing. Ensure all rivet heads and metal shavings are cleaned from sun roof track. 3. Close glass panel. Pull lace from around sun roof opening. Partially withdraw headliner material (if necessary). Remove overhead map light console. Remove screws securing motor to track assembly.

Lower motor leaving wire harness attached. Lift and slide sun roof assembly from vehicle. Disassembly & Reassembly

Remove "E" clip from guide ramp retaining pin. Disengage lifter arm from guide ramp. Withdraw plastic slide on forward portion of lifter arm from track slot. Remove cable assembly from track. To reassemble, reverse disassembly procedure. Installation

1. Install sunshade to track before installing sun roof. Lower and slide sun roof assembly into roof opening. Synchronize motor and cables. See MOTOR SYNCHRONIZATION under ADJUSTMENTS. 2. Install screws securing motor to track assembly. Open glass panel. Install rivets. Adjust glass height. See GLASS HEIGHT under ADJUSTMENTS. Install air deflector, lace and headliner material (if removed). To complete installation, reverse removal procedure. LIFTER ARM Removal

Remove glass panel. See GLASS PANEL & SUNSHADE . Remove sun roof motor. Raise lifter arm to vent position by holding plastic slide in track and pushing guide bracket forward to stop. Hold lifter arm and remove "E" clips with needle-nose pliers. Pull lifter arm off guidance ramp retaining pin and slide out of track. Installation

To install, reverse removal procedure. Synchronize both cables by aligning lifter arms and guidance ramp holes with track slots. Install a 4 mm Allen wrench into slots. See Fig. 3 . Ensure wrench bottoms out against slot in lifter arms. Make sure lifter arm is fully rearward.

Fig. 3: Sun Roof Track Synchronization Courtesy of GENERAL MOTORS CORP. MOTOR Removal

1. Remove sun visors. Remove lace from front of sun roof opening and headliner material (as required). Release hook and loop retainer strips securing underside of headliner to header. 2. Partially lower headliner. Depress release tabs on side of switch and pull switch downward. Remove screws securing motor to track assembly and housing roof bracket.

3. Partially withdraw motor. Remove relay from housing roof bracket. Disconnect motor wiring harness. Remove motor. Installation

To install, reverse removal procedure. Ensure motor is synchronized prior to installation. See MOTOR SYNCHRONIZATION in this article. GLASS PANEL & SUNSHADE Removal

1. Slide sunshade fully rearward. Remove 3 screws securing halo to glass panel. Remove halo exposing 6 glass-to-lifter screws (3 at each side). Remove 6 screws and remove glass panel. 2. Slide halo and sun shade forward to middle of opening. Lift halo to clear sunshade and push halo fully rearward. Push sunshade fully forward. Deflect center of sunshade upward to disengage guides from track. Remove sunshade. Installation

Position sunshade so both front and one rear guide are in track. Flex sunshade upward and insert remaining guide into track. Check that guides are properly seated in track. Slide halo forward of sunshade. Slide halo and sunshade fully rearward. To install glass panel, reverse removal procedure. Adjust glass panel height. See, under ADJUSTMENT, GLASS HEIGHT .

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

SUSPENSION - FRONT SUSPENSION General Motors Front Suspension

DESCRIPTION System is an independent coil-spring suspension with upper and lower control arms and ball joints, shock absorbers, steering knuckles and a stabilizer bar.

ADJUSTMENTS CASTER & CAMBER See appropriate ALIGNMENT SPECIFICATIONS article. RIDING HEIGHT See RIDING HEIGHT SPECIFICATIONS article. WHEEL BEARINGS Raise vehicle and support at lower control arm. Remove wheel, dust cap and cotter pin. Tighten steering knuckle nut to 12 ft. lbs. (16 N.m) while rotating wheel by hand. Back off nut until barely loose, then hand tighten until snug. Back off about 1/2 hex, so cotter pin may be inserted. Adjustment should provide .001.005" (.03-.13 mm) end play. Install new cotter pin and dust cap. Lower vehicle.

INSPECTION BALL JOINTS Lower Ball Joint

1. Vehicle must be supported by wheels to properly load ball joints. Lower ball joint has a visual wear indicator. Wear is indicated by the protrusion of nipple into which grease fitting is threaded. See Fig. 1 .

Fig. 1: Inspecting Lower Ball Joint Courtesy of GENERAL MOTORS CORP. 2. On new ball joints, this round nipple projects .050" (1.27 mm) beyond the surface of ball joint cover. If fitting is flush or recessed, replace ball joint. Upper Ball Joint

1. Ensure wheel bearings are properly adjusted. Raise vehicle. Position floor stands under lower control arm as near as possible to ball joint. Upper control arm bumpers must NOT contact frame. 2. Position dial indicator against lowest point of wheel rim. Grasp wheel at top and bottom, moving it in and out. Check indicator reading. If measurement is more than .13" (3.2 mm), replace ball joint.

REMOVAL & INSTALLATION UPPER BALL JOINT Removal

1. Raise vehicle and remove wheel. Remove caliper and support out of way. Remove cotter pin from upper ball joint stud. Loosen stud nut about one turn but DO NOT remove. Install Ball Joint Separator (J23742 ) and turn threaded end until stud is free of steering knuckle. NOTE:

Lower control arm must be supported so coil spring cannot force arm down.

2. Remove upper ball joint stud nut. Swing steering knuckle out of the way. Lift and support upper control arm with block of wood between frame and arm. Use a drill and punch to remove rivets from control arm. Installation

1. Install new ball joint in arm and attach with bolts (supplied in kit). Insert bolts from bottom of control arm. Cotter pin hole in stud should run parallel with wheel. 2. Remove wood support from upper control arm and clean tapered hole in steering knuckle. Attach ball joint to steering knuckle. Install caliper. Lubricate ball joint and install wheel assembly. Lower vehicle and check alignment. LOWER BALL JOINT Removal

1. Raise vehicle and remove wheel assembly. Loosen stud nut one turn but DO NOT remove. Using Ball Joint Separator (J-23742 ) between studs, turn threaded end of ball joint separator until stud is free of steering knuckle. NOTE:

Lower control arm must be supported so coil spring cannot force arm down.

2. Remove lower stud nut. Pull outward on bottom of tire and at same time push wheel assembly upward to free knuckle from ball joint stud. Lift upper control arm, with steering knuckle and hub assembly attached, and place a wood block between frame and upper control arm. 3. Remove tie rod end from steering knuckle (if necessary). Place Ball Joint Remover/Installer (J-9519-03 and J-9519-7 ) over ball joint. Turn hex nut bolt until lower ball joint is pushed out of control arm. Installation

1. Position ball joint in lower control arm with bleed vent in boot facing inward. Using ball joint remover/installer, turn down hex head bolt until joint is seated. Remove ball joint remover/installer. Cotter pin hole in stud should run parallel with wheel. 2. Remove wood support from upper control arm. Inspect tapered hole in steering knuckle and clean. Connect lower joint stud to steering knuckle and install stud nut. Install new cotter pin. NOTE:

DO NOT back off nut for cotter pin installation. Turn nut 1/6 turn maximum to install cotter pin.

3. Lubricate ball joint. Install tie rod end (if removed). Install wheel assembly. Check wheel alignment. UPPER CONTROL ARM Removal

1. Raise vehicle and support at lower control arm. Remove wheel assembly. Separate upper arm ball joint stud from steering knuckle. 2. Remove nuts securing control arm shaft to frame bracket and remove assembly. Mark shims for reassembly. Bushing Replacement

With upper control arm removed from vehicle, remove bushing nuts. Using "C" Clamp (J-22269-5 ) and Adapters J-24770-2 and J-24770-3 ), remove bushings. See Fig. 2 . Install bushings using "C" Clamp (J-222695 ) and Adapter (J-24770-1 ). See Fig. 3 .

Fig. 2: Removing Upper Control Arm Bushing Courtesy of GENERAL MOTORS CORP.

Fig. 3: Installing Upper Control Arm Bushing Courtesy of GENERAL MOTORS CORP. Installation

1. Position new upper control arm attaching bolts loosely in frame. Install control arm cross shaft on attaching bolts. Using a free running nut, instead of lock nut, tighten both nuts until serrated bolts seat. 2. Remove free running nuts. Install lock nuts. Install same number of shims to each bolt as removed. Tighten mounting nuts. Tighten nut on thinner shim pack first for proper clamping force. Install wheel assembly and lower vehicle. Check alignment. LOWER CONTROL ARM & COIL SPRING Removal

1. Raise vehicle. Remove shock absorber lower mounting bolts. Push shock absorber through control arm and into spring. Support vehicle so control arm hangs free. 2. Place floor jack, with Adapter (J-23028-01 ) attached, into position so it cradles inner bushings of lower control arm. Adapter must be secured to jack. Remove stabilizer bar-to-lower control arm attaching bolts. 3. Raise jack to remove tension on lower control arm pivot bolts. Install a safety chain around spring and through lower control arm. Remove rear pivot bolt first, then remaining bolts and nuts. 4. Lower control arm by slowly lowering jack. When all compression is removed from spring, remove chain and spring. DO NOT use force to remove spring. Proper maneuvering of spring will allow it to be removed easily. 5. To remove lower control arm from steering knuckle, use Ball Joint Separator (J-23742 ). Remove lower control arm from vehicle.

Installation

Position spring into frame so lower end of coil covers all or part of one inspection hole in lower control arm. Second hole must be partially or completely uncovered. See Fig. 4 . To install remaining components, reverse removal procedure.

Fig. 4: Positioning Coil Spring Courtesy of GENERAL MOTORS CORP. LOWER CONTROL ARM REAR BUSHING Removal

1. Raise vehicle. Support frame with jack stands so lower control arm hangs free. Remove lower shock absorber mounting bolts. Push shock absorber through control arm into coil spring. 2. Position floor jack, with Adapter (J-23028-01 ) attached, under lower control arm so bushings seat in grooves of adapter. Install safety chain around lower control arm and through coil spring. 3. Remove lower control arm rear pivot bolt first, then remaining bolts and nuts. If bolts hang up in lower control arm, release by using pry bar. DO NOT use a hammer. Lower control arm by slowly releasing jack. 4. Assemble Hex Nut (J-21474-4 ), Adapter (J-21474-5 ), Adapter (J-21474-8 ) and Spacer (J-21474-12 ) onto lower control arm. See Fig. 5 . Turn hex bolt and nut until bushing is removed. Installation

Assemble Hex Nut (J-21474-4 ), Lower Control Arm Bushing Flarer (J-23915 ), Adapter (J-21474-5 ), Bolt (J21474-3 ) and Spacer (J-21474-12 ) onto lower control arm. See Fig. 6 . Position new bushing and install. Turn hex bolt and nut until new bushing is seated. To complete installation, reverse removal procedure.

Fig. 5: Removing Lower Control Arm Bushing Courtesy of GENERAL MOTORS CORP.

Fig. 6: Installing & Flaring Lower Control Arm Bushing Courtesy of GENERAL MOTORS CORP. LOWER CONTROL ARM FRONT BUSHING Removal

1. Remove lower control arm. See LOWER CONTROL ARM & COIL SPRING in this article. Remove bushing flare by tapping on edge with hammer. 2. Assemble Hex Nut (J-21474-4 ), Adapter (J-21474-5 ), Adapter (J-21474-8 ) and Spacer (J-21474-12 ) onto lower control arm. See Fig. 5 . Turn hex bolt and nut until bushing is removed. Installation

1. Assemble Hex Nut (J-21474-4 ), Lower Control Arm Bushing Flarer (J-23915 ), Adapter (J-21474-5 ), Bolt (J-21474-3 ) with NEW control arm bushing, and Spacer (J-21474-12 ) onto lower control arm. Position new bushing and install. Turn hex bolt and nut until new bushing is seated. To complete installation, reverse removal procedure. 2. Remove installation adapters and install Lower Control Arm Bushing Flarer (J-23915 ). Turn tool until bushing is flared. See Fig. 7 . To complete installation, reverse removal procedure.

Fig. 7: Flaring Lower Control Arm Front Bushing Courtesy of GENERAL MOTORS CORP. STEERING KNUCKLE Removal

1. If a frame hoist rather than twin post hoist is used to raise vehicle, support lower control arm so coil spring will remain compressed at its curb height position. 2. Raise vehicle and support lower control arm. Remove wheel assembly. Remove tie rod end from steering knuckle. Remove caliper, rotor and hub assembly. Support caliper out of way. 3. Remove splash shield and ball joint studs from steering knuckle. Remove steering knuckle.

Installation

1. Place steering knuckle in position and install upper and lower ball joint studs in bosses. Install stud nuts, splash shield, hub and rotor assembly. 2. Install outer bearing, spindle washer and nut. Adjust wheel bearings. See WHEEL BEARINGS under ADJUSTMENTS in this article. Install caliper and wheel assembly. Lower vehicle and check alignment. STABILIZER BAR Removal

1. Remove nuts, retainer and grommet from bottom of stabilizer links. Remove stabilizer bar mounting brackets from frame. 2. Remove rubber bushing from bar. Remove grommets, retainers, spacers, and links from stabilizer bar ends. Keep grommets and spacers in correct order for reassembly. Turn wheels to full stop and work stabilizer bar from vehicle. NOTE:

Stabilizer bar grommets and retainers are larger than those used on shock absorbers. Ensure replacement parts are correct size.

Installation

Position stabilizer bar under front frame side rails. Slide bushings into place with slit forward. Install mounting brackets over bushings and tighten bolts. To complete installation, reverse removal procedure. WHEEL BEARINGS Removal

Raise and support vehicle. Remove wheel assembly. Remove caliper and support out of way. Remove dust cap, cotter pin, spindle nut, washer and outboard bearing assembly. Remove hub and rotor from steering knuckle. Remove inner bearing and grease seal. Discard seal. Use a long punch and hammer to remove bearing outer races. Installation

1. Apply a small amount of grease to spindle at bearing seat and at inner seat, shoulder, and seal seat. Install both bearing outer races. Thoroughly grease both bearing inner races and roller assemblies. Place inboard bearing roller assembly into hub. 2. Install a new grease seal with flat plate. Seal should be flush with hub surface. Lubricate seal lip with thin coating of grease. Install hub and rotor assembly. Place outboard roller assembly in outer bearing race. 3. Install washer and nut and finger tighten. Install caliper and wheel assembly. Install lug nuts finger tight. Adjust wheel bearings. See WHEEL BEARINGS under ADJUSTMENTS in this article. Install dust cap. Tighten lug nuts and lower vehicle.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS Application Lower Ball Joint-to-Steering Knuckle Nut Lower Control Arm Bushing Bolt Nut Shock Absorber Lower Bolt Stabilizer Bracket-to-Frame Bolt Stabilizer Link Nut Tie Rod Pivot-to-Knuckle Nut Upper Ball Joint-to-Control Arm Nut Upper Ball Joint-to-Steering Knuckle Nut Upper Control Arm-to-Frame Nut Wheel Lug Nut

Ft. Lbs. (N.m) 83 (113) 114 (155) 92 (125) 20 (27) 24 (33) 13 (18) 35 (47) 20 (27) 61 (83) 72 (98) 100 (136)

SUSPENSION - REAR SUSPENSION General Motors Rear Suspension

DESCRIPTION The rear suspension is a 4-link type with coil springs, which are mounted between lower spring seats on the axle housing and upper spring seats in the frame. The axle housing is attached to the frame by 2 upper and 2 lower control arms. The control arms maintain a geometrical relationship between the axle housing and frame, to oppose torque reaction on acceleration and braking. Two shock absorbers are attached to the frame and axle housing.

ADJUSTMENTS CAMBER & TOE-IN See ALIGNMENT SPECIFICATIONS article in WHEEL ALIGNMENT. RIDING HEIGHT See RIDING HEIGHT SPECIFICATIONS in WHEEL ALIGNMENT section.

REMOVAL & INSTALLATION SHOCK ABSORBERS Removal

1. Raise and support vehicle. Support rear axle assembly. Disconnect air line from shock absorber (if equipped). See Fig. 1 .

Fig. 1: Removing Air Lines From Air Shock Fitting Courtesy of GENERAL MOTORS CORP. 2. Disconnect upper shock absorber mounting bolts. Use back-up wrench on upper shock absorber mounting nuts (if equipped). Disconnect lower mounting nut, using a back-up wrench to keep stud from turning. Installation

1. To install shock absorber, reverse removal procedure. If equipped with Electronic Level Control, left air shock has 2 line connections while right shock only has one connection. CAUTION: DO NOT allow vehicle weight to rest on air shock until it has been inflated to at least 10 psi. 2. Tighten mounting nuts to specification. Connect air line and add 10 psi (.7 kg/cm2 ) air pressure to prevent shock absorber damage (if equipped). 3. On models with Electronic Level Control, turn ignition on and ground compressor test lead to active system and inflate shocks. Test lead is Green connector with Yellow wire located to left of power brake booster. COIL SPRINGS & INSULATORS CAUTION: Manufacturers recommend removing and installing coil springs one side at a time. Removal

1. Raise vehicle and support frame and rear axle. Remove shock absorbers as previously described. Remove stabilizer bar-to-lower control arm bolts, and remove stabilizer bar. 2. Remove bolt securing junction block to top of rear axle. Disconnect brake lines from axle clips. Disconnect link from leveling sensor arm. Place jack stand under axle nose and remove lower control arm-to-axle bolts. 3. Disconnect drive shaft from pinion flange. Support drive shaft with wire. Remove jack stand from under axle nose. Remove upper arm pivot bolts at axle. Disconnect left side parking brake cable at equalizer. Disconnect cable at frame by removing clip and slide cable through hole. 4. Remove cable from clip at center of rear crossmember. Disconnect cable at connector located left of frame. Support rear frame rails. Lower axle enough to remove springs. WARNING: DO NOT let axle housing twist when lowering; springs may snap from their seats and cause personal injury. Installation

1. Tape upper rubber insulator to top of spring. Position upper end of left rear spring coil toward left side rail, and upper end of right rear spring coil toward right frame side rail. See Fig. 2 .

Fig. 2: Positioning Brougham Rear Coil Springs Courtesy of GENERAL MOTORS CORP. 2. Continue installation in reverse of removal procedure. Tighten all mounting nuts and bolts to specification. DO NOT tighten upper and lower control arms until vehicle is resting at normal standing

height position.

Fig. 3: Typical Rear Suspension Courtesy of GENERAL MOTORS CORP. UPPER CONTROL ARM NOTE:

Removal

Remove and replace one control arm at a time to prevent rear axle from rolling or slipping. Bushings are not serviceable on Cadillac Brougham.

1. Raise and support vehicle. If equipped with Electronic Level Control, remove height control sensor linkto-right upper control arm nut. 2. Remove stabilizer bar bolts and washers from upper control arm (if equipped). Place jack stands under rear axle. Unbolt control arm from upper and lower pivot bolt mounts. Remove control arm from vehicle. Installation

To install, reverse removal procedure. Tighten pivot bolts with vehicle on ground and at curb height. If equipped with Nylock or prevailing torque nuts, tighten nut, NOT bolt, to achieve accurate torque. LOWER CONTROL ARM NOTE:

Remove and replace one control arm at a time to prevent rear axle from rolling or slipping.

Removal

Raise and support rear of vehicle. Support axle housing to relieve tension on control arm bolts. If equipped with stabilizer bar, disconnect bar at lower control arm. Remove lower control arm pivot bolt. Disconnect control arm from frame crossmember and remove control arm. Installation

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Lower Control Arm-to-Axle Bolt Lower Control Arm-to-Axle Nut Lower Control Arm-to-Frame Bolt Lower Control Arm-to-Frame Nut Shock Absorber Nut (Lower Attachment) Shock Absorber Nut (Upper Attachment) Stabilizer Bar-to-Body Bracket Bolt Stabilizer Bar-to-Control Bracket Bolt Track Bar-to-Body Bracket Nut Track Bar-to-Axle Nut Track Bar Brace-to-Body Brace Bracket Torque Arm-to-Rear Axle Nut Torque Arm-to-Front Bracket Nut Upper Control Arm-to-Axle Bolt

Ft. Lbs. (N.m) 122 (165) 122 (165) 89 (121) 92 (125) 65 (88) 12 (16) 52 (70) 21 (29) 80 (108) 61 (83) 35 (47) 98 (133) 30 (41) 85 (115)

Upper Control Arm-to-Axle Nut Upper Control Arm-to-Frame Nut Wheel Lug Nuts

70 (95) 92 (125) 100 (136)

SUSPENSION - REAR ELECTRONIC LEVEL CONTROL SUSPENSION General Motors Rear Electronic Level Control

DESCRIPTION Rear level control automatically adjusts rear height of vehicle regardless of load. System is activated when ignition is on and weight is added or removed from vehicle. Electronic Level Control (ELC) consists of a compressor, air drier, exhaust solenoid, compressor relay, height sensor, air adjustable shock absorbers, pressure limiter and connecting air lines. Air drier contains a moisture absorbing chemical and pressure maintaining valves. Valves are used for maintaining minimum system pressure of approximately 7-14 psi (.5-.9 kg/cm2 ). A pressure limiter valve is used on some models to prevent pressure from exceeding 64-74 psi (4.5-5.2 kg/cm2 ) on "C" and "H" bodies or 65-80 psi (4.8-5.8 kg/cm2 ) on "E" and "K" bodies.

OPERATION RAISING VEHICLE When weight is added to vehicle, height sensor arm rotates upward. Rotating arm upward grounds compressor relay circuit. After a time delay of approximately 7-15 seconds on "A", "B" and "D" bodies, 7-10 seconds on "C" and "H" bodies or 13-27 seconds on "E" and "K" bodies, compressor relay turns air compressor on, causing vehicle to rise. As vehicle rises, height sensor rotates downward to curb height position. When vehicle is within 1" (25.4 mm) of curb height on "A", "D", "E" and "K" bodies or 3/4" (19.1 mm) on "B", "C" and "H" bodies, height sensor opens ground circuit to compressor relay, turning compressor off. LOWERING VEHICLE When weight is removed from vehicle, height sensor arm rotates downward. After a time delay of approximately 7-15 seconds on "A", "B" and "D" bodies, 7-10 seconds on "C" and "H" bodies or 13-27 seconds on "E" and "K" bodies, downward rotation of the arm grounds exhaust solenoid valve circuit. Energizing exhaust solenoid valve causes air to vent through air drier and out of exhaust solenoid valve. As vehicle lowers, height sensor arm rotates upward to curb height position. When vehicle is within 1" (25.4 mm) of curb height on "A", "D", "E" and "K" bodies or 3/4" (19.1) on "B", "C" and "H" bodies, height sensor opens exhaust solenoid valve circuit, causing exhaust solenoid valve to close. AIR REPLENISHMENT In order to ensure the system is operating with at least minimum air pressure, the height sensor commands an air replenishment cycle each time the ignition is cycled on. An internal timer circuit is activated when ignition switch is turned to ON position. After a delay of approximately 35-45 seconds, compressor turns on for 3-5

seconds to ensure residual system pressure. If weight is added or removed from vehicle during 35-45 second delay, air replenishment cycle will be overridden and vehicle will rise or lower after normal time delay.

ADJUSTMENTS HEIGHT SENSOR 1. Vehicle should be on level surface with gas tank full and NO load in car. Turn ignition switch to ON position. Bounce car 3 times to normalize suspension. To increase vehicle riding height, loosen lock bolt on sensor arm. Move plastic arm upward and tighten lock nut. 2. To lower riding height, loosen lock nut, move plastic arm down and tighten lock nut. There is a total of 5 degrees of adjustment on sensor. One degree of adjustment is equal to 1/4" change in height at bumper. If adjustment cannot be made, there is a problem with rear springs or suspension. See Fig. 1 .

Fig. 1: Adjusting Height Sensor Courtesy of GENERAL MOTORS CORP. RIDING HEIGHT See RIDING HEIGHT SPECIFICATIONS article in WHEEL ALIGNMENT.

SYSTEM TESTING SYSTEM OPERATIONAL TEST 1. Unload vehicle. With ignition off, check riding height. Turn ignition on. Add 300-350 lbs. (136-159 kg)

load to trunk. Compressor should start operating after a time delay of approximately 7-15 seconds on "A", "B" and "D" bodies, 7-10 seconds on "C" and "H" bodies or 13-27 seconds on "E" and "K" bodies. Vehicle should rise to 1" (25.4 mm) of curb height on "A", "D", "E" and "K" bodies or 3/4" (19.1) on "B", "C" and "H" bodies. 2. Remove load from trunk. Exhaust should start within approximately 7-15 seconds on "A", "B" and "D" bodies, 7-10 seconds on "C" and "H" bodies or 13-27 seconds on "E" and "K" bodies. Within 2 minutes, exhaust should stop and vehicle should be within 1" (25.4 mm) of curb height on "A", "D", "E" and "K" bodies or 3/4" (19.1) on "B", "C" and "H" bodies. SYSTEM LEAK TEST 1. Install Pressure Gauge (J-22124A ) in-line between drier assembly and existing line to shocks. See Fig. 2 . Install gauge so shut-off valve is on compressor side of gauge. With shut-off gauge open, apply shop air pressure through the service valve until valve reaches 100 psi (7.03 kg/cm2 ) on "A", "C" and "H" bodies, 110 psi (7.73 kg/cm2 ) on "D", "E" and "K" bodies or 80 psi (5.62 kg/cm2 ) on "B" body. 2. If a leak is indicated, close shut-off valve and continue to watch for a pressure drop. If pressure continues to drop, leak is external from the compressor. Leak test all connections. If pressure stops decreasing after shut-off valve is closed, leak is in the compressor assembly. 3. Check compressor for leaks. If pressure builds up rapidly but vehicle does not rise, check for pinched air line or stuck or binding shocks. COMPRESSOR PERFORMANCE TEST Eldorado, Seville, Toronado & Trofeo

1. Disconnect pressure line from dryer. Attach pressure gauge to dryer. Disconnect negative (Black) wire from compressor bracket. Install an ammeter between negative wire and compressor bracket. 2. If testing off vehicle, apply 12 volts to compressor connector pin "B" and ground pin "D". Pressure gauge reading should be 100 psi (7.03 kg/cm2 ) minimum, and ammeter reading should be 10 amps maximum. 3. Disconnect wiring and check compressor for leak-down. Replace compressor if readings are not as specified or internal leak-down is indicated. All Other Models

1. Disconnect pressure line from drier and attach Air Pressure Gauge (J-22124-A ) to drier fitting. Disconnect wiring from compressor motor and exhaust solenoid terminals. See Fig. 2 . 2. Connect 12-volt power supply to compressor through ammeter. Current draw must not exceed 14 amps. Allow pressure to reach 100 psi (7.03 kg/cm2 ) minimum and shut off compressor. Allow pressure to stabilize. Check for pressure leaks. NOTE:

If compressor is allowed to run to maximum output pressure of 170 psi (12.3 kg/cm2 ) on Brougham or 180 psi (12.7 kg/cm2 ) on all other models, the solenoid exhaust valve will act as a relief valve. This gives a false indication of system leakage.

3. On all models, if compressor operates correctly, reconnect wiring and air lines. If compressor does not operate correctly, refer to TROUBLE SHOOTING in this article.

Fig. 2: Testing Electronic Level Control (ELC) Compressor Courtesy of GENERAL MOTORS CORP. HEIGHT SENSOR OPERATIONAL TEST Eldorado, Seville, Toronado & Trofeo

1. Raise vehicle on hoist. Ensure all electrical connectors are properly mated. Cycle ignition off and on to reset sensor timing circuits. After a 35-45 second delay, compressor should run for 4 seconds. Disconnect height sensor link from control arm. 2. Move control arm upward. There should be a 13-27 second delay before compressor starts to run. As soon as struts start to fill, move control arm downward. After a 13-27 second delay, struts should start to deflate. Replace height sensor if it fails any of these tests. All Other Models

1. Cycle ignition switch to the ON position. Raise vehicle on hoist. Ensure axle housing is supported as close to ride height specification as possible. Check all wiring for good connections. Disconnect link from height sensor arm. 2. Move sensor arm upward. After a 7-15 second delay on "A", "B" and "D" bodies or 7-10 second on "C" and "H" models, the compressor should run and shock absorbers should start to inflate. As soon as shock absorber air boots fill, stop compressor by moving sensor arm down.

3. Move sensor arm below position where compressor stopped running. There should be a delay, as in step 2), before shock absorbers start to deflate and vehicle lowers. Replace height sensor if it does not function correctly.

CIRCUIT TESTING ELECTRONIC LEVEL CONTROL TESTS ("B" BODY) 1. Perform this test if:  Compressor runs  Vehicle will not raise  Vehicle lowers after compressor shut-off NOTE:

If test exceeds 7 minutes, cycle ignition off then on to reset compressor run time.

2. Disconnect pressure line from drier and attach Air Pressure Gauge (J-22124-A ) to drier fitting with shutoff valve lever in OFF position. See Fig. 2 . Disconnect wiring from compressor motor and exhaust solenoid terminals. 3. Inflate system to 80 psi (5.6 kg/cm2 ) through pressure gauge fill valve. Allow pressure to stabilize. Observe that vehicle rises and pressure holds steadily for approximately 10 minutes. NOTE:

If system won't inflate to 80 psi (5.6 kg/cm2 ), a severe leak is indicated.

4. If vehicle doesn't rise and pressure holds at 80 psi (5.6 kg/cm2 ), check for pinched pressure line between compressor and shocks. Check for plugged limiter valve. If vehicle rises but pressure leaks down, locate and repair pressure leak in shocks, fittings or lines. 5. Open pressure gauge shut-off valve (lever in upward position). If pressure leaks down, refill system to 100 psi (7.0 kg/cm2 ). Use soapy water solution around compressor cover, solenoid valve housing, drier cover and air intake and exhaust openings. See Fig. 3 . Repair or replace as necessary. 6. If pressure holds steadily, deflate system through pressure gauge fill valve. Turn ignition switch to ON position. Connect jumper wire from Yellow wire terminal at ELC relay to ground. If pressure does not build up over 90 psi (6.3 kg/cm2 ), repair or replace compressor.

Fig. 3: Checking Compressor Leak Courtesy of GENERAL MOTORS CORP. ELECTRICAL TESTING ("A" BODY) "A" BODY SYMPTOM DIRECTORY Symptom Compressor Does Not Run

System Does Not Exhaust System Does Not Vent

Perform ELC & COMPRESSOR MOTOR TESTS, ACTUATOR ARM TEST, ELC HEIGHT SENSOR TESTS EXHAUST SOLENOID TESTS, ACTUATOR ARM TEST, ELC HEIGHT SENSOR TESTS VENT SOLENOID TESTS, ACTUATOR ARM

TEST, ELC HEIGHT SENSOR TESTS Compressor Runs Continuously, Vehicle Rises & Does Not Leak Down Compressor Runs For Maximum Time & Turns Off. Vehicle Does Not Rise, Or Rises & Leaks Down System Vents Continuously

(1) ACTUATOR ARM TEST

ACTUATOR ARM TEST, VENT SOLENOID SHORT TEST ACTUATOR ARM TEST, VENT SOLENOID SHORT TEST (1) Unplug ELC height sensor connector. If compressor does not run, replace ELC height sensor. If compressor runs, check Yellow wire for short to ground. If wire is okay, replace ELC relay.

ELC RELAY & COMPRESSOR MOTOR TESTS Test No. 1

With ELC Relay connector connected, ground Yellow wire with a fused jumper wire. See Fig. 3 . If compressor runs, go to ACTUATOR ARM TEST . If compressor does not run, go to TEST NO. 2 of ELC RELAY & COMPRESSOR MOTOR TESTS. Test No. 2

Disconnect ELC relay connector and measure voltage from terminal No. 1 and 4 (Orange wires) to ground. If voltage reads zero, check CTSY fuse or Orange wires for an open. If voltage reads 12 volts, go to TEST NO. 3 of ELC RELAY & COMPRESSOR MOTOR TESTS. Test No. 3

With ELC relay connected, connect a fused jumper wire between terminals No. 1 (Orange wire) and No. 2 (Dark Green wire) of ELC relay connector. If compressor runs, replace ELC relay. If not, go to TEST NO. 4 of ELC RELAY & COMPRESSOR MOTOR TESTS. Test No. 4

With fused jumper still connected to ELC relay (from previous test), unplug ELC compressor connector. Measure voltage between terminal "B" (Dark Green wire) at compressor connector and ground. If voltage reads zero, check Dark Green wire for an open. If voltage is correct, check ground connection. If ground connection is good, replace compressor assembly. EXHAUST SOLENOID TESTS Test No. 1

Unplug ELC height sensor connector. Ground terminal No. "E" (White wire) with a fused jumper wire. If exhaust solenoid clicks and air vents, go to ACTUATOR ARM TEST . If exhaust solenoid does not click and air does not vent, go to TEST NO. 2 of EXHAUST SOLENOID TESTS. Test No. 2

1. With fused jumper wire still connected at height sensor (from previous test), unplug ELC compressor connector. Measure voltage between terminal "C" (Orange wire) at compressor connector and ground. If voltage reads zero, check Orange wire for an open. If voltage reads 12 volts, go to step 2). 2. Measure voltage between terminals "C" (Orange wire) and "E" (White wire) at ELC compressor connector. If voltage is zero volt, check White wire for an open. If both voltage readings are 12 volts, replace exhaust solenoid. ACTUATOR ARM TEST Raise vehicle and ensure link is attached to actuator arm correctly, and actuator arm is properly aligned. See Fig. 1 . ELC HEIGHT SENSOR TESTS Test No. 1

1. Unplug ELC connector. With ignition switch in RUN position, measure voltage between terminal "C" (Orange wire) and ground. If voltage does not read 12 volts, check and/or repair open in Orange wire. If voltage reading is 12 volts, go to step 2). 2. Measure voltage between terminals "C" (Orange wire) and "A" (Black wire). If voltage does not read 12 volts, check and/or repair open to ground in Black wire. If voltage reads 12 volts, go to step 3). 3. Measure voltage between terminal "D" (Brown/White wire) and ground. If voltage does not read 12 volts, check and/or repair Brown/White wire to terminal "D" for an open. If voltage reading is 12 volts, go to step 4). 4. Measure voltage between terminal "B" (Yellow wire) and ground. If voltage does not read 12 volts, check and/or repair open in Yellow wire. If all voltages read 12 volts, go to TEST NO. 2 of ELC HEIGHT SENSOR TESTS. Test No. 2

1. Cycle ignition switch and place in RUN position. Raise vehicle and support rear axle housing at ride height. Disconnect link from actuator arm. Move actuator arm upward. 2. If compressor begins to run but shocks do not inflate after a 7-15 second delay, perform SYSTEM LEAK TEST and COMPRESSOR PERFORMANCE TEST under SYSTEM TESTING. If compressor does not begin to run after a 7-15 second delay, replace ELC height sensor. 3. If compressor begins to run and shocks begin to inflate after a 7-15 second delay, slowly move actuator arm downward until compressor stops. If compressor does not stop, replace height sensor. If compressor does stop, continue to move actuator arm downward. 4. If the shocks do not start to deflate and vehicle does not begin to lower after a 7-15 second delay, replace the height sensor. If the shocks begin to deflate and the vehicle starts to lower after a 7-15 second delay, the ELC height sensor is okay. VENT SOLENOID SHORT TEST 1. Add 300 lbs. (136 kg) to luggage compartment. Disconnect ELC height sensor connector. Ground connector terminal "B" with a fused jumper. Allow compressor to run for 2 minutes.

2. If vehicle rises and maintains its height, replace ELC height sensor. If vehicle does not rise or rises and leaks down, check White wire for a short to ground. 3. If wire is found to have a short, repair it. If wire is okay, perform SYSTEM LEAK TEST and COMPRESSOR PERFORMANCE TEST under SYSTEM TESTING. ELECTRICAL TESTING ("B" BODY) NOTE:

Electrical testing procedures are not available from manufacturer. Follow procedures in TROUBLE SHOOTING and SYSTEM TESTING or CIRCUIT TESTING in this article

ELECTRICAL TESTING ("C" & "H" BODIES) "C" & "H" BODIES SYMPTOM DIRECTORY Symptom Compressor Does Not Run

System Does Not Exhaust System Does Not Vent

Perform ELC & COMPRESSOR MOTOR TESTS, ACTUATOR ARM TEST, ELC HEIGHT SENSOR TESTS EXHAUST SOLENOID TESTS, ACTUATOR ARM TEST, ELC HEIGHT SENSOR TESTS VENT SOLENOID TESTS, ACTUATOR ARM TEST, ELC HEIGHT SENSOR TESTS

Compressor Runs Continuously, Vehicle Rises & Does Not Leak Down Compressor Runs For Maximum Time & Turns Off. Vehicle Does Not Rise, Or Rises & Leaks Down System Vents Continuously

(1) ACTUATOR ARM TEST

ELC RELAY & COMPRESSOR MOTOR TESTS Test No. 1

Ground ELC test lead connector, located on Yellow wire near ELC relay, with a fused jumper wire. If compressor runs, go to ACTUATOR ARM TEST . If it does not run, go to TEST NO. 2 of ELC RELAY & COMPRESSOR MOTOR TESTS. Test No. 2

Disconnect ELC relay connector and measure voltage from terminals No. 1 and 5 (Orange wire) to ground. If voltage reads zero, check Orange wire and fuse No. 12 for an open. If voltage reads 12 volts, go to TEST NO. 3 of ELC RELAY & COMPRESSOR MOTOR TESTS.

Test No. 3

Connect a fused jumper wire between terminals No. 1 (Orange wire) and 4 (Dark Green wire) of ELC relay connector. If compressor runs, check Yellow wire for an open. If wire is okay, replace ELC relay. If compressor does not run go to TEST NO. 4 of ELC RELAY & COMPRESSOR MOTOR TESTS. Test No. 4

1. With fused jumper still connected to ELC relay (from previous test), unplug ELC compressor connector. Measure voltage between terminal "B" (Dark Green wire) at compressor connector and ground. 2. If voltage reads zero, check Dark Green wire for an open. If voltage reads 12 volts, measure voltage between terminals "B" (Dark Green wire) and "D" (Black wire) at ELC compressor connector. If voltage reads zero, check Black wire for an open. If voltage reads 12 volts, repair and/or replace ELC compressor assembly. EXHAUST SOLENOID TEST 1. Unplug ELC height sensor connector. Ground terminal "E" (White wire) with a fused jumper wire. If exhaust solenoid clicks and air vents, go to ACTUATOR ARM TEST . 2. If exhaust solenoid does not click and air does not vent with fused jumper wire still connected at height sensor (from previous test), unplug ELC compressor connector. Measure voltage between terminal "A" (Orange wire) at compressor connector and ground. 3. If voltage reads zero, check Orange wire for an open. If voltage reads 12 volts, measure voltage between terminals "A" (Orange wire) and "C" (White wire) at ELC compressor connector. If voltage is now zero volts, check White wire for an open. If voltage reads 12 volts, replace exhaust solenoid. ACTUATOR ARM TEST Raise vehicle and ensure link is attached to actuator arm correctly, and actuator arm is properly aligned. See Fig. 1 . ELC HEIGHT SENSOR TESTS Test No. 1

1. Unplug ELC height sensor connector. With ignition switch in RUN position, measure voltage between terminal "C" (Orange wire, Light Blue on Bonneville) and ground. If voltage reading is 12 volts, go to step 2). If voltage does not read 12 volts, check and/or repair open in Orange wire (Light Blue on Bonneville). 2. With ignition switch in RUN position, measure voltage between terminals "C" (Orange wire, Light Blue on Bonneville) and "A" (Black wire). If voltage is 12 volts, go to step 3). If voltage does not read 12 volts, check and/or repair open to ground in Black wire. 3. Measure voltage between terminal "D" (Brown wire) and ground. If voltage reads 12 volts, go to step 4). If voltage does not read 12 volts, check and/or repair Brown wire to terminal No. 5 for an open. 4. Measure voltage between terminal "B" (Yellow wire) and ground. If voltage does not read 12 volts, check and/or repair open in Yellow wire. If all test voltages read 12 volts, go to TEST NO. 2 of ELC HEIGHT

SENSOR TESTS. Test No. 2

1. Cycle ignition switch and place in RUN position. Raise vehicle and support rear axle housing at ride height. Disconnect link from actuator arm. Move actuator arm upward. 2. If compressor begins to run but shocks do not inflate after a 7-27 second delay, perform SYSTEM LEAK TEST and COMPRESSOR PERFORMANCE TEST under SYSTEM TESTING. If compressor does not begin to run after a 7-27 second delay, replace ELC height sensor. 3. If compressor begins to run and shocks begin to inflate after a 7-27 second delay, slowly move actuator arm downward until compressor stops. If compressor does not stop, replace height sensor. If compressor does stop, continue to move actuator arm downward. 4. If the shocks do not start to deflate and vehicle does not begin to lower after a 7-27 second delay, replace the height sensor. If the shocks begin to deflate and the vehicle starts to lower after a 7-27 second delay, the ELC is okay. VENT SOLENOID SHORT TEST 1. Add 300 lbs. (136 kg) to luggage compartment. Disconnect ELC height sensor connector. Ground ELC test connector (terminal "B" Yellow wire) with a fused jumper. Allow compressor to run for 2 minutes. 2. If vehicle rises and maintains its height, replace ELC height sensor. If vehicle does not rise or rises and leaks down, check White wire for a short to ground. 3. If wire is found to have a short, repair it. If wire is okay, perform SYSTEM LEAK TEST and COMPRESSOR PERFORMANCE TEST under SYSTEM TESTING. INFLATOR TIMER RELAY TESTS (BONNEVILLE) Test No. 1

Connect a fused jumper wire between terminal "F" (White wire) of inflator timer relay and ground with connector connected. If compressor runs and high pressure air is vented from air hose as valve operates, go to INFLATOR SWITCH TEST . If compressor doesn't run, remove jumper and go to TEST NO. 2 of INFLATOR TIMER RELAY TESTS. If compressor runs and no air is vented, leave jumper connected and go to TEST NO. 3 of INFLATOR TIMER RELAY TESTS. Test No. 2

1. Ensure inflator switch is in OFF position and compressor is not running. At inflator timer relay connector, measure voltage between terminal "D" (Orange wire) and ground. If voltage does not read 12 volts, check and/or repair open in Orange wire. If voltage reading is 12 volts, go to step 2). 2. Measure voltage between terminals "E" (Yellow wire) and ground. If voltage is 12 volts, go to step 3). If voltage does not read 12 volts, check and/or repair open to ground in Yellow wire. 3. Measure voltage between terminal "B" (Light Blue wire) and ground. If voltage reads 12 volts, go to step 4). If voltage does not read 12 volts, replace inflator timer relay. 4. Measure voltage between terminal "D" (Orange wire) and "H" (Black wire). If voltage does not read 12 volts, check and/or repair open in Black wire. If all test voltages read 12 volts, replace inflator timer relay.

Test No. 3

Connect jumper wire as in INFLATOR TIMER RELAY TEST NO. 1 . Measure voltage between connector terminal "C" (Dark Blue wire) and ground. If voltage reads 12 volts, go to INFLATOR SOLENOID VALVE TEST . If voltage does not read 12 volts, replace inflator timer relay. INFLATOR SWITCH TEST (BONNEVILLE) 1. Disconnect inflator timer relay connector. With inflator switch connected and held in ON position, use ohmmeter to measure resistance between terminal "A" (White wire) and "B" (Black wire). If reading is not zero ohm, replace inflator switch. If reading is zero ohm, go to step 2). 2. Hold inflator switch in OFF position. Measure resistance between terminal "C" (Purple wire) and "B" (Black wire). If reading is not zero ohm, replace inflator switch. INFLATOR SOLENOID VALVE TEST (BONNEVILLE) 1. Disconnect inflator solenoid valve connector. Connect a fused jumper wire between terminals "D" (Orange) and "C" (Dark Blue wire) of the inflator timer relay connector. Measure voltage between solenoid valve positive terminal (Dark Blue wire) and ground. If voltage does not read 12 volts, check and/or repair open in Dark Blue wire. If voltage reading is 12 volts, go to step 2). 2. Measure voltage between solenoid valve positive terminal (Dark Blue wire) and negative terminal (Black wire). If voltage does not read 12 volts, check and/or repair open in Black wire. If voltage is 12 volts in steps 1) and 2), check air lines and fittings. If air lines and fittings are okay, replace inflator solenoid valve. ELECTRICAL TESTING ("D", "E" & "K" BODIES) "D" BODY SYMPTOM DIRECTORY Symptom Compressor Does Not Run

System Does Not Exhaust System Does Not Vent Compressor Runs Continuously, Vehicle Rises & Does Not Leak Down Compressor Runs For Maximum Time & Turns Off. Vehicle Does Not Rise, Or Rises & Leaks Down System Vents Continuously

"E" & "K" BODIES SYMPTOM DIRECTORY - COMPRESSOR ONLY

Symptom Compressor Runs But Current Draw Exceeds 10 Amps Compressor Inoperative Pressure Build Up Okay, But Leaks Down Before Holding Pressure Leaks Down To Zero Or Will Not Build Up (1) If okay, replace motor/cylinder assembly.

Diagnosis Replace Motor/Cylinder Assembly (1) Inspect Compressor Motor

Replace Head Assembly Check Compressor & Drier For Leaks

ELC SYSTEM TEST 1. Open hood and trunk. Turn ignition switch to OFF position. Check vehicle height at rear wheel openings. Reset ELC system by cycling ignition on and off. Turn ignition switch to ON position but leave engine off. Add 300 lbs. load to trunk. 2. If compressor starts within 28 seconds, go to step 3). If compressor does not start within 28 seconds, but vehicle is within 1" of unloaded height, go to NO EXHAUST TEST . If vehicle is not within 1" of unloaded height, adjust height sensor and retest system. If system is still not okay, go to COMPRESSOR DOES NOT OPERATE TEST . 3. If compressor stops within 7 minutes, go to next step. If compressor runs continuously, check for a stuck relay, short to ground in circuit No. 321 or short to voltage in circuit No. 322. If okay, replace height sensor. 4. If vehicle returns to within 1" of unloaded height, go to next step. If system leaks down, go to IMPROPER OR CONTINUOUS EXHAUST TEST . If vehicle is not within 1" of original height, adjust height sensor and retest. If still not okay, go to IMPROPER OR CONTINUOUS EXHAUST TEST . 5. Remove load from trunk. If no exhaust is present after 28 seconds, go to NO EXHAUST TEST . If system exhausts within 28 seconds but vehicle does not return to within 1" of original height after 2 minutes, adjust height sensor and retest. If system exhausts within 28 seconds and vehicle returns to within 1" of original height after 2 minutes, system is okay. COMPRESSOR DOES NOT OPERATE TEST 1. Turn ignition to ON position. On Brougham, ground ELC test connector located on Yellow wire near ELC relay. On other models, apply 12 volts to compressor pin "B" and ground to pin "D". On all models, if compressor does not run, go to step 3). If compressor runs, go to step 2). 2. Disconnect height sensor harness connector. Using a jumper wire, jump pins No. 3 and 4 (Brougham) or "A" and "B" (all other models) of height sensor body wiring harness connector. If compressor does not run, check for an open in circuit 321 (Yellow wire). On Brougham, check compressor motor ground circuit (Black wire). On all others, check height sensor ground circuit (Black/White wire). If compressor runs, go to RESET CIRCUIT OPERATIONAL TEST . 3. Remove ELC relay. Check for battery voltage at pin No. 3 and 4 (Brougham) or No. 2 (all other models) of relay cavity. If battery voltage is present, go to next step. If not, check "GA-TRANS" fuse on Brougham or ELC compressor fuse on all other models. If okay, repair open in relay connector circuit

(Pink/Black wires on Brougham, or Brown/White wires on all other models). 4. Using a jumper wire, jump pins No. 1 and 4 (Brougham) or pins No. 2 and 3 (all other models) of ELC relay cavity. If compressor does not run, go to next step. If compressor runs, check for an open in circuit No. 321 (Yellow wire). If okay, replace ELC relay. 5. Disconnect compressor harness connector. Apply 12 volts to pin "B" and ground pin "D". If compressor runs, check compressor motor ground circuit (Black wire) and No. 322 (Dark Green wire). If compressor does not run, repair compressor motor. IMPROPER OR CONTINUOUS EXHAUST TEST Check for a short to ground in circuit from compressor to height sensor (White wire). If a short is present, repair short. If a short is not present, do a compressor performance test. See COMPRESSOR PERFORMANCE TEST under SYSTEM TESTING in this article. If not okay, replace compressor. If okay, perform SYSTEM LEAK TEST under SYSTEM TESTING. If okay, replace height sensor. If not okay, repair leak. NO EXHAUST TEST 1. Cycle ignition on and off to reset system. Disconnect compressor harness connector. On Brougham, check for voltage at harness connector pin "A". On all other models, check for voltage at harness connector pin "C". If battery voltage is present, go to step 2). If no voltage is present, check "BODY" fuse on Brougham or fuse No. 1 (all other models) and replace as necessary. If fuse is okay, repair open in circuit from fuse box to compressor to height sensor (Orange wires). 2. Disconnect compressor harness. Disconnect height sensor harness connector. Using a jumper wire, jump terminals "A" and "E". If system does not exhaust, go to next step. If system exhausts, check for voltage at pin "C". If no voltage is present, repair open in circuit from fuse box to compressor and compressor to height sensor (Orange wires). If voltage is present, replace height sensor. 3. On Brougham, apply 12 volts to pin "A" and ground pin "C". On all other models, apply 12 volts to pin "C" and ground pin "A" of compressor harness connector. If system does not exhaust, replace exhaust solenoid. If system does exhaust, repair open in White wire between compressor to height sensor or compressor motor ground circuit (Brougham, Black wire) or ELC height sensor ground circuit (all other models, Black wire). RESET CIRCUIT OPERATIONAL TEST 1. Turn ignition off. Disconnect height sensor harness. On Brougham, check for voltage at pins "B" and "C". On all other models, check for voltage at pins "C" and "D". If no voltage is present at pin "B" (Brougham) or "D" (all other models) and battery voltage is present at pin "C", go to next step. If voltage is present at pin "B" (Brougham) or "D" (all other models), repair short to voltage in fuse to height sensor circuit (Pink/Black wire on Brougham, Brown/White wire on all other models). If zero voltage is present at pin "C", check fuse. If fuse is okay, repair open in circuit from fuse box to compressor to height sensor (Orange wires). 2. Turn key to ON position. On Brougham, check voltage at pin "B". On all others, check voltage at pin "D". If battery voltage is present, go to next step. If zero volt is present, check fuse and replace as necessary. If okay, repair open in fuse to height sensor circuit (Pink/Black wire on Brougham, Brown/White wire on all other models). 3. Check voltage from pin "C" to pin "A". If battery voltage is present, replace height sensor. If not, repair

open in compressor motor to ground circuit (Brougham, Black wire) or height sensor to ground (all other models, Black/White wire).

TROUBLE SHOOTING CAR LOADED, WILL NOT RISE Leaks in air lines, fittings or shock absorbers. Pinched lines between compressor and shock absorbers. Defective height sensor. Compressor inoperative. Loose or damaged electrical connections to sensor or compressor. CAR LOADED, RISES, THEN LEAKS DOWN Severe leak in lines, fittings or shock absorbers. Internal leak in motor. CAR LOADED, RISES PARTIALLY Height sensor out of adjustment. Compressor or wiring defective. CAR RISES WHEN LOADED, LEAKS DOWN WHEN DRIVING Defective drier or compressor. Pinched air lines or leaks in fittings or air lines. CAR RIDES HIGH Height sensor out of adjustment. Drier plugged or air lines pinched. Poor electrical connections. COMPRESSOR RUNS BUT CURRENT DRAW EXCEEDS 10 AMPS ("E" BODY) Replace the motor/cylinder assembly.

REMOVAL & INSTALLATION ELC HEIGHT SENSOR Removal & Installation

Disconnect negative battery cable. Disconnect height sensor harness. Raise and support vehicle. Disconnect height sensor link from height sensor actuating arm. Remove 2 height sensor mounting screws. To install, reverse removal procedure. Tighten sensor mounting bolts to specification. Adjust height sensor. ELC COMPRESSOR Removal ("A" & "B" Bodies)

1. Disconnect negative battery cable. Raise and support vehicle. Deflate system. Disconnect high pressure line at drier by rotating spring clip 90 degrees while holding connector end. Remove tube assembly. See Fig. 4 .

2. Disconnect solenoid and motor connectors. Remove support bracket screws. Remove compressor and bracket as an assembly. Remove compressor-to-bracket screws. Remove compressor. Installation ("A" & "B" Bodies)

To install, reverse removal procedure. Turn ignition on and allow system to cycle. Check for leaks using soap and water solution. Removal ("C" & "H" Bodies)

Disconnect negative battery cable. Disconnect compressor electrical connectors. Remove pressure limiter retaining clip from compressor bracket. Remove rear strut feed line from pressure limiter valve. Remove mounting screws. Remove compressor-to-bracket screws. Remove compressor. Installation ("C" & "H" Bodies)

To install, reverse removal procedure. Turn ignition on and allow system to cycle. Check for leaks using soap and water solution. Removal ("D" Body)

Disconnect negative battery cable. Disconnect compressor electrical connectors. Remove air line from drier. Remove bracket-to-inner fender panel screws. Remove compressor-to-bracket screws. Remove compressor. Installation ("D" Body)

To install, reverse removal procedure. Turn ignition on and allow system to cycle. Check for leaks using soap and water solution. Removal ("E" & "K" Bodies)

1. Raise vehicle on frame contact type hoist. Loosen exhaust pipes at both sides of muffler. Remove muffler heat shield. Disconnect compressor electrical connectors and air line from drier. 2. Remove air inlet filter from underbody mount. Remove compressor bracket-to-suspension mounting screws. Remove compressor and bracket as an assembly by moving toward rear of vehicle next to exhaust pipe. Remove compressor-to-bracket screws. Remove compressor. Installation ("E" & "K" Bodies)

To install, reverse removal procedure. Turn ignition on and allow system to cycle. Check for leaks using soap and water solution. AIR DRIER Removal

Disconnect high pressure line by turning spring clip 90 degrees and removing tube assembly. Disconnect drier from compressor by turning spring clip and sliding dryer and "O" ring from compressor head assembly.

Installation

Lubricate "O" ring and install in port of compressor head. Return retainer spring to its original position. Install drier on compressor head assembly. If difficulty arises when installing drier in compressor head assembly, rotate slightly while applying pressure. Check system for leaks. AIR LINE REPAIR The air line used in system can be repaired by splicing in a coupling at leak area. Inflate system to 100 psi (7.03 kg/cm2 ). Use a soap and water solution to locate leak. Deflate system through service valve and cut out leaking area. Install coupling and tighten tube nuts to 72 INCH lbs. (8 N.m). See Fig. 4 . Inflate system and check for leaks using a soap and water solution.

Fig. 4: Air Line Repair Coupling Courtesy of GENERAL MOTORS CORP.

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Compressor Bracket Mounting Screws "A" Body "B" Body "C" & "H" Bodies "D" Body "E" & "K" Bodies

INCH Lbs. (N.m) 36 (4.0) 60 (6.8) 45 (5.0) 62 (7.0) 133 (15.0)

Compressor Head Bolts Compressor Mounting Screws "A", "C" & "H" Bodies "B" Body "D", "E" & "K" Bodies Height Sensor Mounting Screws "A" Body "B" Body "C" & "H" Bodies "D" Body "E" & "K" Bodies

WIRING DIAGRAMS

36 (4.0) 45 (5.0) 24 (2.7) 36 (4.0) 36 (4.0) 124 (14.0) 62 (7.0) 133 (15.0) 45 (5.0)

Fig. 5: Bonneville ELC Wiring Diagram

Fig. 6: Brougham ELC Wiring Diagram

Fig. 7: Custom Cruiser & Estate Wagon ELC Wiring Diagram

Fig. 8: ELC Wire Diagram Delta 88, Electra, LeSabre, Ninety-Eight, Park Avenue & Touring Sedan

Fig. 9: DeVille & Fleetwood ELC Wiring Diagram

Fig. 10: Eldorado & Seville ELC Wiring Diagram

Fig. 11: Riviera ELC Wiring Diagram

Fig. 12: Toronado & Trofeo ELC Wiring Diagram

Fig. 13: 6000 ELC Wiring Diagram

TAILGATE & TRUNK RELEASE ACCESSORIES & SAFETY EQUIPMENT General Motors Tailgate & Trunk Release

DESCRIPTION & OPERATION The electric trunk release system consists primarily of a release button in the glove box and a release solenoid in the trunk. On some models, additional components are included in the system. On some models, ignition switch must be in RUN position before system will operate. On some models, parking brake must be applied (manual transmission) or transmission must be in Park (automatic transmission). Pressing release button energizes the release solenoid, unlatching the trunk lid. Station wagon models have an electric tailgate release similar to trunk release. Some models have an additional power trunk pull-down unit that closes trunk lid when it is lowered. A permanent magnet reversible motor pulls the striker down, locking trunk lid in a fully closed position. When release solenoid is activated, the motor reverses and allows trunk lid to rise.

ADJUSTMENT LOCK ASSEMBLY ADJUSTMENT Ensure trunk lid is properly aligned. Loosen lock assembly bolts on trunk lid, move lock to desired position and tighten bolts.

TROUBLE SHOOTING NOTE:

Not all models are equipped with power trunk pull-down.

TRUNK WON'T OPEN WITH PANEL SWITCH, BUT OPENS WITH KEY SWITCH Open or short between switch and fuse block. Open or short in wire between switch and solenoid. Defective switch or lock solenoid. TRUNK CLOSING UNIT INOPERATIVE Open circuit in closing unit to fuse block feed wire. Defective switch or motor. Open circuit in switch wiring. CLOSING UNIT DOES NOT CYCLE TRUNK UP Switch tap plunger binding or out of position. CLOSING UNIT DOES NOT CYCLE TRUNK DOWN Switch contact not touching shaft of striker assembly. Foreign matter on lock striker, lock hook surface or

between contact blade and striker shaft. TRUNK UNIT CYCLES UP & DOWN CONTINUOUSLY Defective switch assembly. Internal contacts binding. Switch tap button binding. CLOSING UNIT DOES NOT FULLY CLOSE TRUNK Defective switch. Intermittent ground through striker and lock hook. Incorrectly positioned striker or lock hook. TRUNK CLOSING UNIT RAISES STRIKER TOO HIGH Arm of cycle cutout switch incorrectly positioned; broken or missing tab on striker shaft.

TESTING TRUNK RELEASE SOLENOID If solenoid will not release, check power at solenoid with release button pressed. If power is not present, check for power at switch in glove compartment. If power is present at solenoid, ensure ground connection is good. If still inoperative, replace solenoid.

REMOVAL & INSTALLATION TRUNK SOLENOID Open trunk lid. Remove trunk lock attaching bolts. Disconnect electrical connector and remove bolts attaching solenoid to lock. Remove solenoid and lock. To install, reverse removal procedure. Check operation. PULL-DOWN UNIT Open trunk lid and remove pull-down unit trim cover. Disconnect wiring and remove pull-down unit. To install, reverse removal procedure. Check operation.

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

1989-90 AUTOMATIC TRANSMISSIONS General Motors Torque Converter Clutch

APPLICATIONS THM 200-4R APPLICATIONS (1989) Manufacturer Buick Cadillac Chevrolet Oldsmobile Pontiac THM 3T40 APPLICATION (1989) Manufacturer & Model Buick Century Skyhawk Skylark Chevrolet Beretta Cavalier Celebrity Corisca Oldsmobile Cutlass Calais Cutlass Ciera Pontiac Grand Am Sunbird 6000 THM 4L60 APPLICATION (1989) Manufacturer/Model Caprice THM 4T60 APPLICATION (1989) Manufacturer & Model Buick Century Electra

Model Estate Wagon Brougham Caprice Custom Cruiser Safari

Engine 5.0L 5.0L 5.0L 5.0L 5.0L

Engine 2.5L, 2.8L, 3.3L 2.0L 2.3L, 2.5L, 3.3L 2.0L, 2.8L 2.0L, 2.8L 2.5L, 2.8L 2.0L, 2.8L 2.3L, 2.5L, 3.3L 2.5L, 2.8L, 3.3L 2.0L, 2.3L, 2.5L 2.0L 2.5L, 2.8L, 3.1L

Engine 4.3L, 5.7L

Engine 2.8L, 3.3L 3.8L

LeSabre Regal Chevrolet Celebrity Lumina Oldsmobile Cutlass Ciera Cutlass Supreme Delta 88 98 Regency Pontiac Bonneville Grand Prix 6000 THM 200-R4 APPLICATION () Manufacturer Buick Cadillac Chevrolet Oldsmobile THM 3T40 APPLICATION (1990) Manufacturer & Model Buick Century Regal Skylark Chevrolet Beretta Cavalier Celebrity Corsica Lumina Lumina APV Oldsmobile Cutlass Calais Cutlass Ciera Cutlass Supreme Silhouette Pontiac

3.8L 2.8L, 3.1 2.8L 3.1L 2.8L, 3.1L 2.8L, 3.1L 3.8L 3.8L 3.8L 2.8L, 3.1L 2.8L

Model Estate Wagon Brougham Caprice Custom Cruiser

Engine 5.0L 5.0L 5.0L 5.0L

Engine 2.5L, 3.3L 3.1L 2.3L, 2.5L, 3.3L 2.2L, 3.1L 2.2L, 3.1L 2.5L 2.2L, 3.1L 2.5L, 3.1L 3.1L 2.3L, 2.5L, 3.3L 2.5L, 3.3L 2.3L, 3.1L 3.1L

Grand Am Grand Prix Sunbird Trans Sport 6000

2.3L, 2.5L 2.3L, 3.1L 2.0L 3.1L 2.5L

THM 3T40-A APPLICATION (1990) Manufacturer Pontiac

Model 6000 STE

Engine 3.1L

THM 4L60 APPLICATION (1990) Manufacturer Cadillac Chevrolet

Model Brougham Caprice

Engine 5.7L 4.3L, 5.7L

THM 4T60 APPLICATION (1990) Manufacturer & Model Buick Century Electra LeSabre Park Avenue Regal Chevrolet Lumina Oldsmobile Cutlass Ciera Cutlass Supreme Delta 88 98 Regency Pontiac Bonneville Grand Prix 6000 Sedan 6000 Wagon NOTE:

Engine 3.3L 3.8L 3.8L 3.8L 3.1L, 3.8L 3.1L 3.3L 3.1L 3.8L 3.8L 3.8L 3.1L 3.1L 3.1L

This article contains test charts that are part of General Motors Computerized Engine Controls. Only those charts required to test Torque Converter Clutch (TCC) system and related circuits are included. Other diagnostic codes may appear while performing TCC electrical diagnosis. For complete information on General Motors Computerized Engine Control systems see appropriate COMPUTERIZED ENGINE CONTROLS article in ENGINE PERFORMANCE

section.

DESCRIPTION OVERVIEW The Torque Converter Clutch (TCC) assembly consists of a 3-element torque converter with the addition of a converter clutch. The converter clutch is an internal mechanism with friction material attached to front face. It is splined to the turbine assembly in converter. The purpose of the torque converter clutch feature is to eliminate power loss due to slippage when vehicle is cruising. This allows the convenience of an automatic transmission and the fuel economy of a manual transmission. When the TCC solenoid ground circuit is completed by the Electronic Control Module (ECM), the torque converter clutch is applied, resulting in a direct mechanical coupling between engine and transmission. When TCC solenoid is deactivated, the torque converter clutch is released, allowing torque converter clutch to operate in a conventional manner. TCC CONTROL COMPONENTS The following components are used to engage/disengage torque converter clutch. Not all components will be present on all vehicles. Brake Switch

Power from ignition switch passes through brake switch to TCC solenoid. When brake pedal is depressed with TCC engaged, power to TCC solenoid is interrupted, releasing converter clutch and preventing engine from stalling.

Fig. 1: Torque Converter Assembly With TCC Courtesy of GENERAL MOTORS CORP. Coolant Temperature Sensor

This sensor provides ECM with engine coolant temperature information. ECM will not allow TCC operation until signal from this sensor indicates coolant temperature greater than 130-150Â°F (55-65Â°C). Electronic Control Module (ECM)

To determine application of torque converter clutch, ECM receives and processes information from various input devices. On the most sophisticated vehicles, these devices may include the vehicle speed sensor, coolant temperature sensor, throttle position sensor, 3rd or 4th gear switch and brake switch. The ECM controls application of torque converter clutch by providing a ground circuit for the TCC solenoid circuit. TCC Solenoid Assembly

Energized by ECM to redirect transaxle fluid to the converter clutch apply valve in the auxiliary control valve assembly. Throttle Position Sensor (TPS)

Provides ECM with throttle position information. TCC operation is prevented when throttle position signal is less than a specified value. Vacuum Sensor

Sends engine vacuum (load) information to ECM. Vehicle Speed Sensor (VSS)

This sensor sends vehicle speed information to ECM. Vehicle speed must be greater than a certain value before TCC can be applied. Two types of speed sensor are used. A light emitting diode type is used in the instrument cluster on some models. Other models use a Permanent Magnet (PM) generator mounted in the transmission. 3rd & 4th Gear Switch

When open, 3rd and 4th gear switches prevent TCC operation. Switch status may be monitored by ECM, or switch may be an integral portion (series circuit) of TCC solenoid power supply.

TROUBLE SHOOTING NOTE:

Every diagnosis of automatic transmission problems should begin with a check of the transmission fluid and linkage. Most of the following conditions can be caused by one or more of the following factors: (1) Incorrect fluid level, (2) Contaminated fluid, (3) Improperly adjusted linkage, or (4) Damaged or worn linkage. When diagnosing Converter Clutch problems, ensure engine and vacuum systems are in perfect operating order.

NO CONVERTER CLUTCH APPLY Problem in Electronic Control Module ď Ź

Verify Electronic Control Module (ECM) operation. See appropriate CHART C-8 in this article.

Electrical Problems ď Ź

Voltage not reaching transmission. Ensure 12 volts reach transmission to engage solenoid.

 



Ground inside transmission. Ensure solenoid is not grounded inside case. Defective connector, wiring harness, or solenoid. Check and repair or replace as required. Defective pressure switch (if equipped). Check and replace pressure switch as required. 3rd and 4th gear switch inoperative. Check and replace switch(es) as required.

Valve Body Assembly   

Sticking converter clutch shift and/or apply valve. Clean, service and/or replace valve body as required. Sticking throttle valve. Clean, service and/or replace valve body as required. Inspect valve body and service as required.

Oil Pump Assembly       

Orifice plugged for converter signal oil in pump. Clean and inspect orifice for blockage. Solenoid "O" ring damaged or missing. Check and replace "O" ring. Oil pump wear plate or gasket mispositioned or damaged. Check and replace wear plate or gasket. Improper torque on oil pump-to-converter housing bolts. Tighten bolts to specifications. Turbine shaft seals damaged. Check and replace seals. Orifice cup plug omitted form cooler in passage. Check and install plug. Check and replace converter clutch blow-off check ball if not seated or if damaged. Check and replace torque converter clutch accumulator piston or seal if damaged.

CONVERTER CLUTCH APPLY SLIPS, ROUGH OR SHUDDERS     

Converter clutch pressure plate faulty. Check plate for damage and service as required. Damaged or missing check ball in end of turbine shaft. Check and replace turbine shaft, if required. Converter clutch regulator valve stuck. Clean, service and/or replace valve body as required. Converter clutch accumulator piston or seal damaged. Check and service as required. Channel plate seals damaged or missing. Check and service as required.

CONVERTER CLUTCH DOES NOT RELEASE 

    

Solenoid does not exhaust. Verify Electronic Control Module operation. See appropriate CHART C-8 in this article. Converter clutch apply valve stuck. Clean, service and/or replace valve body as required. Check damaged converter. Replace torque converter. Cup plug missing from pump release passage. Check and replace plug or pump assembly. Turbine shaft end seal damaged or missing. Check and replace end seal or turbine shaft as required. Hole not drilled through turbine shaft. Replace turbine shaft.

TESTING & DIAGNOSIS

DIAGNOSTIC TOOLS Diagnosis of the TCC system may be performed by following the appropriate C-8 chart for the transmission/engine application in question. When utilizing these charts, specific tools which may be required are a tachometer, test light, ohmmeter, digital voltmeter with 10-megohm input impedance (minimum), and 6 jumper wires 6" long (1 wire with female connectors at both ends; 1 wire with male connector at both ends; 4 wires with male and female connectors at opposite ends). A test light, rather than a voltmeter, must be used when indicated by a diagnostic chart(s). NOTE:

In the diagnostic and trouble code charts, special "Scan" testers are referred to (and recommended) by the manufacturer to read data parameters and check voltages in the system.

RETRIEVING TROUBLE CODES The ECM stores component failure information under a related trouble code which can be recalled later for diagnosis and repair. When recalled, these codes can be displayed on a "Scan" tester, or by entering diagnostic mode and observing flashes of the "CHECK ENGINE" or "SERVICE ENGINE SOON" light. It is NOT necessary to enter diagnostic mode to use TCC test chart(s); however, it will be necessary to enter ECM diagnostic mode to verify the presence of any codes. NOTE:

Even when using a "Scan" tester, it is recommended that the diagnostic mode be accessed in advance to verify the computer's ability to self-diagnose.

Entering ECM Diagnostic Mode

1. To enter diagnostic mode, turn ignition on but do not start engine. "CHECK ENGINE" or "SERVICE ENGINE SOON" light should glow. Locate Assembly Line Diagnostic Link (ALDL) connector attached to ECM wiring harness under instrument panel. Insert jumper wire across diagnostic mode "test" terminal "B" and ground terminal "A". See Fig. 2 . CAUTION: Inserting spade lug in terminals of ALDL connector grounds "test" terminal lead. Do not ground ALDL connector until after ignition is on.

Fig. 2: ALDL Diagnostic Terminal Locations Courtesy of GENERAL MOTORS CORP. 2. "CHECK ENGINE" or "SERVICE ENGINE SOON" light should flash Code 12 ("FLASH", pause, "FLASH", "FLASH") followed by a longer pause. Trouble Code 12 will be repeated 3 more times, then if any trouble codes are stored in the ECM memory, they will be displayed in the same manner. 3. Trouble codes will be displayed from lowest to highest numbered codes (3 times each) and be repeated as long as the "test" terminal of the ALDL connector is grounded. 4. To exit diagnostic mode, remove jumper wire from ALDL connector and turn ignition off. NOTE:

If Code 12 is not flashed when the ALDL diagnostic "test" terminal is grounded, information received by a "Scan" tester on the serial data line may not be accurate. For complete testing of the ECM's diagnostic circuit, see appropriate COMPUTERIZED ENGINE CONTROLS article in ENGINE PERFORMANCE section.

CLEARING TROUBLE CODES Trouble codes are cleared by removing battery voltage form ECM for at least 10 seconds. Ensure that "test" terminal is not grounded. Turn ignition off and remove ECM fuse from fuse block for 10 seconds and then reinsert it. Another way of removing battery voltage is to disconnect the battery positive cable (or pigtail) from the battery for 10 seconds and then reconnect it. In either case, ensure the ignition switch is in the "OFF" position before removing battery voltage. Otherwise, a voltage spike could occur and damage the ECM. OUTPUT DISPLAYS When trouble shooting a malfunction, the ECM and BCM output cycling can be used to determine if output tests can be actuated regardless of the inputs and normal program instructions. Once a test in outputs is selected,

except for ECM IAC, the test will display "HI" or "LO" for 3 seconds in each state to indicate the command and output terminal voltage. When ECM output "EO01" is entered, the torque converter clutch display will be "LO" when TCC is on (energized.)

DIAGNOSTIC CHARTS NOTE:

Codes not listed are not transmission related. See appropriate article in ENGINE PERFORMANCE.

PFI CHART C-1 - ECM CHECK Prior to replacing an ECM, vehicle must be tested for: 1. Check connector terminals. Ensure they are properly seated and locked in the connector and terminal retainers are properly positioned and locked. 2. Check ECM ground at generator and battery ground at engine and chassis. 3. Check IGN 1-ISO fuse in fuse block. Notes On Fault Tree

1. The ECM supplies power through a high side driver to Cruise Control Vent and Vacuum Solenoids. An internal short in servo causing a low resistance or short to ground in wiring harness may damage ECM or cause servo-to-solenoids to fail. 2. The ECM supplies power to fuel pump relay through a high side driver. An internal short in relay winding causing a low resistance or short to ground in wiring harness may cause damage to ECM or relay to fail. 3. The ECM supplies power to ISC through an internal switching IC that will change polarity of circuit. An internal short in ISC motor armature windings or short to ground in wiring harness may cause damage to ECM or ISC motor to fail. 4. The ECM provides ground for EGR solenoid, Electric Switching Valve (ESV). Canister Purge solenoid, and Electric Divert Valve (EDV) through a quad driver IC. An internal short in windings or resistor of devices or a short to ground in wiring harness may cause damage to ECM or Emission Control System (ECS) device. 5. The ECM provides ground for the VCC solenoid in transmission through a quad driver IC. An internal short in winding or diode of solenoid or a short to ground in wiring harness may cause damage to ECM or solenoid to fail. PFI Chart C-1 - ECM Check Flowchart

NOTE:

Always check "MEM-CAL" for the correct application and installation before replacing an "ECM".

Fig. 3: ECM Check Flowchart (1 Of 2)

Fig. 4: ECM Check Flowchart (2 Of 2) CHART C-7C, EGR CHECK - 5.0L FULL FUNCTION

Fig. 5: Chart C-7C - EGR Circuit Schematic (5.0L Full Function) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart. Steps 1-3 represent an EGR functional check.

1. This test checks to see if the EGR passages are restricted or if valve is stuck open. Engine should run roughly or stall as valve is opened manually. 2. EGR valve diaphragm should begin to move as engine speed approaches 2000 RPM. 3. This test should result in EGR solenoid being energized, shutting off vacuum to EGR valve. This indicates system is functioning properly. 4. If vacuum is less than 7in. Hg at 2000 RPM, a leak or restriction between the EGR diaphragm and vacuum source is indicated. 5. With ignition on and engine stopped, ECM normally grounds terminal "T" to energize the EGR solenoid. This test checks EGR solenoid and solenoid electrical control circuit. 6. The EGR is normally de-energized with the engine idling at normal operating temperature. This test checks EGR solenoid and solenoid electrical control circuit. 7. This determines whether ECM is providing ground to terminal "T" or circuit No. 435 is shorted to ground. Diagnostic Aids

Vacuum hoses should be checked for internal restrictions.

Fig. 6: Chart C-7C, EGR Check - 5.0L Full Function Flowchart (1 Of 2)

Fig. 7: Chart C-7C, EGR Check - 5.0L Full Function Flowchart (2 Of 2) CHART C-8, TORQUE CONVERTER CLUTCH ELECTRICAL DIAGNOSIS - 5.0L FULL FUNCTION

Fig. 8: Chart C-8 - TCC Circuit Schematic (5.0L Full Function) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

Fig. 9: Chart C-8, Torque Converter Clutch Electrical Diagnosis - 5.0L Full Function Flowchart CODE 24, VEHICLE SPEED SENSOR - 5.0L FULL FUNCTION

Fig. 10: Code 24 - VSS Circuit Schematic (5.0L Full Function) Courtesy of GENERAL MOTORS CORP. The ECM applies and monitors 12 volts on circuit No. 437 to Vehicle Speed Sensor (VSS). VSS alternately opens and grounds circuit No. 437 when drive wheels are turning. This pulsing action takes place about 2000 times per mile and ECM calculates vehicle speed based on time between pulses. "Scan" tester reading should closely match speedometer reading. CAUTION: To avoid damaging drive axle CV joints, control arms must be supported when wheels are turning off of ground. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test monitors ECM voltage on circuit No. 437. With drive wheels turning, pulsing action varies voltage. This variation is greater at low speeds to an average of 4-6 volts at about 20 MPH. Cruise control must be off for accurate test results. 2. A voltage of less than one volt indicates that circuit No. 437 is shorted to ground. Disconnect circuit No. 437 at VSS. The VSS is faulty if voltage now reads more than 10 volts. IF voltage remains less than one volt, circuit No. 437 is grounded. If circuit is not grounded, check for a faulty ECM connector or ECM. 3. A steady 8-12 volts at ECM connector indicates circuit No. 437 is open, or a faulty VSS. 4. This is a normal voltage condition and indicates a possible intermittent condition. See INTERMITTENTS in THEORY & OPERATION section. 5. This step will isolate whether problem is in circuit No. 437 or ECM.

Fig. 11: Code 24, Vehicle Speed Sensor - 5.0L Full Function Flowchart

CHART 24B, PARK/NEUTRAL CIRCUIT - 5.0L FULL FUNCTION

Fig. 12: Chart 24B - P/N Circuit Schematic (5.0L Full Function) Courtesy of GENERAL MOTORS CORP. The Park/Neutral (P/N) switch is closed when gear selector is in Park or Neutral and open in all other ranges. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This step separates a faulty switch or switch adjustment from a faulty electrical circuit or ECM. Normal voltage across terminals of connector, when removed from P/N switch, should be approximately battery voltage.

Fig. 13: Chart 24B, Park/Neutral Circuit - 5.0L Full Function Flowchart CHART C-8A, TORQUE CONVERTER CLUTCH - 5.0L & 5.7L TBI

Fig. 14: Chart C-8A - TCC Circuit Schematic (5.0L & 5.7L TBI) Courtesy of GENERAL MOTORS CORP. The purpose of Torque Converter Clutch (TCC) feature is to eliminate power loss of torque converter stage when vehicle is in cruise condition. This allows convenience of an automatic transmission and fuel economy of a manual transmission. Fused battery ignition is supplied to TCC solenoid through brake switch. The ECM will engage TCC by grounding circuit No. 422 to energize the solenoid. TCC will engage solenoid when vehicle speed is greater than 24 MPH, engine is at normal operating temperature, throttle position sensor output is not changing (indicating a steady road speed), and brake switch is close. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Confirms 12-volt supply as well as continuity of TCC circuit. 2. Grounding the ALDL "test" terminal with ignition on and engine off should energize the capability of the ECM to control the solenoid. 3. Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause early failure to the ECM "quad-drive". Using an ohmmeter, check the solenoid coil resistance of all ECM controlled solenoids and relays before installing a replacement ECM. Replace any solenoid or relay that measures less than 20 ohms. Diagnostic Aids

An engine coolant thermostat that is stuck open, or opens at too low a temperature, may result in an inoperative TCC.

Fig. 15: Chart C-8A, TCC - 5.0L & 5.7L TBI Flowchart (1 Of 3)

Fig. 16: Chart C-8A, TCC - 5.0L & 5.7L TBI Flowchart (2 Of 3) A 4th gear switch, mounted in the transmission, opens when the transmission shifts into 4th gear. This switch is used by the ECM to modify TCC lock and unlock points when in a 4-3 downshift maneuver. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Unless switch or circuit No. 446 is open, "Scan" tester should display "NO" or "OFF", indicating transmission is not in 4th gear. The 4th gear switch should only be open while in 4th gear. 2. This test determines if the ECM and wiring are okay. Grounding circuit No. 446 should cause "Scan" tester to display "NO" or "OFF", indicating the transmission is not in 4th gear. 3. Checks operation of the 4th gear switch. When the transmission shifts into 4th gear the switch should open and "Scan" tester should display "YES" or "ON". 4. Disconnecting the TCC connector simulates an open switch to determine if circuit No. 446 is shorted to ground or the problem is in the transmission. Diagnostic Aids

A road test may be necessary to verify the customer complaint. If the "Scan" tester indicates TCC is turning on and off erratically, check the state of the 4th gear switch to be sure it is not changing state under a steady throttle position. If the switch is changing state, check connections and wire routing carefully. Also, if 4th gear switch is always open, the TCC may engage as soon as sufficient oil pressure is reached.

Fig. 17: Chart C-8A, TCC - 5.0L & 5.7L TBI Flowchart (3 Of 3) CODE 23, MANIFOLD AIR TEMPERATURE SENSOR SIGNAL VOLTAGE HIGH - 5.0L & 5.7L TBI

Fig. 18: Code 23 - MAT Circuit Schematic (5.0L & 5.7L TBI) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 23 will set if signal voltage indicates manifold air temperature less than -22째F (-30째C) for 12 seconds and elapsed time since engine start is more than 1 minute. 2. Code 23 will set due to an open sensor, wire or connection. This test determines if wiring and ECM are okay. 3. This test determines if signal circuit No. 472 or sensor ground circuit No. 452 is open. Diagnostic Aids

"Scan" tester displays temperature of air entering engine and should read close to ambient temperature when engine is cold. Temperature reading should rise as underhood temperature increases. If vehicle is allowed to sit overnight, MAT temperature and CTS temperature should read close to the same. Carefully check harness and connections for possible open is circuits No. 472 or 452. MAT SENSOR TEMP VS. RESISTANCE VALUE (1) Temperature 째F (째C) 210 (100) 160 (70) 100 (38) 70 (20) 40 (4) 20 (-7) 0 (-18) -40 (-40) (1) Values are approximate.

Resistance Ohms 185 450 1,800 3,400 7,500 13,500 25,000 100,700

Fig. 19: Code 23, MAT Sensor Signal Voltage High - 5.0L & 5.7L TBI Flowchart CODE 24, VEHICLE SPEED SENSOR - 5.0L & 5.7L TBI (B BODY)

Fig. 20: Code 24 - VSS Circuit Schematic (5.0L & 5.7L TBI B Body) Courtesy of GENERAL MOTORS CORP. The ECM applies and monitors 12 volts on circuit No. 437. Vehicle Speed Sensor (VSS) alternately grounds and opens circuit No. 437 when vehicle is in motion. This pulsing action takes place about 2000 times per mile. ECM will calculate vehicle speed based on the time between "pluses". With vehicle in motion, "Scan" tester reading should closely match speedometer reading. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed equals zero MPH when the engine speed is between 1200-4400 RPM, TPS is less than 2 percent (closed throttle), a low load condition (high vacuum) exists and all conditions met for 5 seconds. These conditions are met during a road load deceleration. Disregard Code 24 that sets when vehicle is not in motion. 2. If 8-12 volts is indicated at IP connector, circuit No. 437 is open between IP connector and the VSS, or there is a faulty vehicle speed sensor. A voltage of less than one volt at the IP connector indicates that circuit NO. 437 is shorted to ground. If, after disconnecting circuit No. 437 at the vehicle speed sensor, voltage reads greater than 10 volts, vehicle speed sensor is faulty. If circuit No. 437 is not grounded, there is a faulty connection at ECM, or ECM is faulty. Diagnostic Aids

A "Scan" tester should indicate vehicle speed whenever vehicle is in motion. A faulty or misadjusted Park/Neutral switch can result in a false Code 24. Use "Scan" tester and check for proper signal while in Drive.

Fig. 21: Code 24, VSS - 5.0L & 5.7L TBI (B Body) Flowchart CODE 25, MANIFOLD AIR TEMPERATURE SENSOR SIGNAL VOLTAGE LOW - 5.0L & 5.7L TBI

Fig. 22: Code 25 - MAT Circuit Schematic (5.0L & 5.7L TBI) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 25 will set if signal voltage indicates manifold air temperature greater than 302째F (150째C) for 2 seconds, vehicle speed is greater than 5 MPH and elapsed time since engine start is more than 2 minutes. Diagnostic Aids

A "Scan" tester displays temperature of air entering engine. Temperature should read close to ambient temperature when engine is cold and rise as underhood temperature increases. Check harness and connections for possible short to ground on circuit No. 472. MAT will rarely exceed 176째F (80째C). If temperature is greater than this, check for proper THERMAC operation. See MAT SENSOR TEMP VS. RESISTANCE VALUE table.

Fig. 23: Code 25, MAT Sensor Signal Voltage Low - 5.0L & 5.7L TBI Flowchart CHART C-8A, TORQUE CONVERTER CLUTCH - THM 3T40 TRANSMISSION 2.8L A, J & L BODIES

Fig. 24: Chart C-8A - TCC Circuit Schematic (2.8L A, J & L Bodies - THM 3T40) Courtesy of GENERAL MOTORS CORP.

The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the transmission converter stage when the vehicle is in a cruise condition. Electrical power from the ignition circuit is supplied to the TCC solenoid through the brake switch and transmission 3rd gear switch. The ECM will engage TCC by grounding circuit No. 422 to energize the solenoid. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. If test light is off, this confirms 3rd gear switch in open. 2. At 25 MPH, the 3rd gear switch should close. Test light will come on and confirm battery supply and closed brake switch. 3. Grounding the ALDL "test" terminal with ignition on and engine off should energize the TCC solenoid when ECM grounds circuit No. 422. This test checks the ability of the ECM to supply a ground to the TCC solenoid. The test light connected from 12 volts to ALDL terminal "F" will turn on as circuit No. 422 is grounded. Diagnostic Aids

The "Scan" tester only indicates when the ECM has turned on the TCC driver. This does not confirm that the TCC has engaged. To determine if TCC is functioning properly, note engine RPM. RPM should decrease when "Scan" tester indicates TCC driver has turned on.

Fig. 25: Chart C-8A, TCC - THM 3T40 Trans. - 2.8L A, J & L Bodies Flowchart (1 Of 2)

Fig. 26: Chart C-8A, TCC - THM 3T40 Trans. - 2.8L A, J & L Bodies Flowchart (2 Of 2) CODE 24, VEHICLE SPEED SENSOR - 2.8L PFI A & J BODIES The ECM applies and monitors 12 volts on circuit No. 437. Circuit No. 437 is connected to the vehicle speed sensor buffer in the instrument cluster. The speed sensor buffer alternately grounds circuit No. 437 when drive wheels are turning. This pulsing action takes place about 2000 times per mile and the ECM will calculate vehicle speed based on the time between pulses. A, and J Bodies use a Hall Effect switch mounted in the speedometer head to signal the VSS buffer. The "Scan" tester reading should closely match the speedometer reading with drive wheels turning. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. To avoid possible damage to CV joints on FWD vehicles, always support control arms whenever drive wheels are turning off of ground. Code 24 will set if vehicle is stopped when the following conditions occur:  Reference signal indicates engine speed is between 1400 and 4400 RPM.  Throttle angle is less than 2 percent (closed throttle).  Low load condition (low airflow or high vacuum).

Transmission not in Park or Neutral. ď Ź All conditions met for 4-5 seconds. These conditions are met during a road load deceleration. Disregard Code 24 that sets when drive wheels are not turning. 2. A voltage of less than one volt at the IP connector indicates that circuit No. 437 is shorted to ground. If after disconnecting circuit No. 437 at the vehicle speed sensor, the voltage reads greater than 10 volts, the vehicle speed sensor is faulty. If voltage remains less than 10 volts, then it is possible that circuit No. 437 wire is grounded. If circuit No. 437 is not grounded, there is a faulty connection at the ECM, or a faulty ECM. ď Ź

Diagnostic Aids

A "Scan" tester should indicate a vehicle speed whenever the drive wheels are turning greater than 3 MPH. A faulty or misadjusted Park/Neutral switch can result in a false Code 24. Use "Scan" tester and check for proper signal while wiggling shifter in Drive.

Fig. 27: Code 24, VSS - 2.8L PFI - A & J Bodies Flowchart CODE 24, VEHICLE SPEED SENSOR - 2.8L J & L BODIES, & 2.8L & 3.1L A & W BODIES

Fig. 28: Code 24 - VSS Circuit Schematic (2.8L J Body & 2.8L & 3.1L A Body) Courtesy of GENERAL MOTORS CORP.

Fig. 29: Code 24 - VSS Circuit Schematic (2.8L L Body) Courtesy of GENERAL MOTORS CORP.

Fig. 30: Code 24 - VSS Circuit Schematic (2.8L & 3.1L W Body) Courtesy of GENERAL MOTORS CORP. The ECM monitors the output from the Permanent Magnet (PM) generator mounted in the transaxle on circuits No. 400 and 401. The PM generator produces a pulsating, alternating current whenever vehicle speed is greater than 3 MPH. The AC voltage level and the number of pulses increases with vehicle speed. The ECM will calculate vehicle speed based on the time between pulses. The VSS buffer used on other models is incorporated into the ECM on these models. If the vehicle is equipped with a digital speedometer and odometer and/or cruise control, the ECM provides pulses for operation of these components (2000 and 4000 pulses per mile respectively). The "Scan" tester reading should closely match speedometer reading when drive wheels are turning. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed equals zero MPH when engine speed is between 1400 and 3600 RPM, throttle opening is less than 2 percent, a low load condition exists and transmission is not in Park or Neutral. All conditions must be met for 5-10 seconds during a road load deceleration. Disregard Code 24 that sets when drive wheels are not turning. Diagnostic Aids

If "Scan" tester displays vehicle speed, check Park/Neutral switch operation using appropriate C-1 CHART. If switch is okay, check for intermittent connections. Also, check for proper application of PROM or MEM-CAL.

Fig. 31: Code 24, VSS - 2.8L J & L Bodies, & 2.8L & 3.1L A & W Bodies Flowchart CODE 25, MANIFOLD AIR TEMPERATURE SIGNAL VOLTAGE LOW 2.8L A & L BODIES

Fig. 32: Code 25 - MAT Circuit Schematic (2.8L A & L Bodies) Courtesy of GENERAL MOTORS CORP.

Fig. 33: Code 25 - MAT Circuit Schematic (2.8L J Body) Courtesy of GENERAL MOTORS CORP.

Fig. 34: Code 25 - MAT Circuit Schematic (2.8L & 3.1L W Body) Courtesy of GENERAL MOTORS CORP.

Fig. 35: Code 25 - MAT Circuit Schematic (3.1L A Body) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 25 will set if monitored voltage indicates manifold air temperature is high for 3 seconds and time since engine start is at least 3-8 minutes, depending upon engine application. Due to the conditions necessary to set a Code 25, the "SERVICE ENGINE SOON" light will remain on only while the signal is low and vehicle speed is present. Diagnostic Aids

The "Scan" tester reads temperature of the air entering the engine. Parameter should read close to ambient air temperature when engine is cold, and rise as underhood temperature increases. A short to ground in the MAT signal line will result in a Code 25. Use the MAT SENSOR TEMPERATURE-TO-RESISTANCE VALUES table to help determine if sensor calibration has shifted. MAT SENSOR TEMPERATURE-TO-RESISTANCE VALUES (1) Temperature °F (°C) 210 (100) 160 (70) 100 (38) 70 (20) 40 (4) 20 (-7) 0 (-18) -40 (-40) (1) Approximate

Fig. 36: Code 25, MAT Signal Voltage Low - 2.8L A & L Bodies - Flowchart CHART C-1A, PARK/NEUTRAL SWITCH - 2.8L PFI A, J, L & W BODIES

Resistance Ohms 185 450 1,800 3,400 7,500 13,500 35,800 100,700

Fig. 37: Chart C-1A - P/N Circuit Schematic (A, J & L Bodies) Courtesy of GENERAL MOTORS CORP.

Fig. 38: Chart C-1A - P/N Circuit Schematic (W Body) Courtesy of GENERAL MOTORS CORP. The Park/Neutral switch contacts are a part of the neutral start switch. Contacts are closed to ground in Park or Neutral. The ECM applies and monitors a 12-volt signal on circuit No. 434 and senses a closed switch when voltage drops to less than one volt. If circuit No. 434 indicates Park/Neutral (grounded) while in Drive, the EGR system would be inoperative, resulting in possible detonation. If circuit No. 434 indicates Drive (open), a dip in idle may exist when gear selector is moved to Drive. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Checks for a switch closed to ground in Park. 2. Checks for an open switch in Drive. 3. To test for an intermittent or misadjusted switch in Drive, be sure "Scan" tester indicates Drive, even while wiggling shifter.

Fig. 39: Chart C-1A, P/N Switch - 2.8L PFI A, J, L & W Bodies Flowchart

CHART C-8, TORQUE CONVERTER CLUTCH - 4.3L TBI B BODY

Fig. 40: Chart C-8 - TCC Circuit Schematic (4.3L TBI B Body) Courtesy of GENERAL MOTORS CORP. The purpose of automatic transmission torque converter clutch feature is to eliminate power loss of torque converter when vehicle is in cruise condition. This allows convenience of an automatic transmission and fuel economy of a manual transmission. Fused battery ignition is supplied to TCC solenoid through brake switch. The ECM will engage TCC by grounding circuit No. 422 to energize the solenoid. TCC will engage solenoid when vehicle speed is greater than 24 MPH, engine is at normal operating temperature, throttle position sensor output is not changing (indicating a steady road speed), and brake switch is closed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Confirms 12-volt supply as well as continuity of TCC circuit. 2. Grounding the diagnostic test terminal with ignition on and engine off should energize the capability of the ECM to control the solenoid. 3. Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause early failure to the ECM "driver". Using an ohmmeter, check the solenoid coil resistance of all ECM controlled solenoids and relays before installing a replacement ECM. Replace any solenoid or relay that measures less than 20 ohms. Diagnostic Aids

An engine coolant thermostat that is stuck open, or opens at too low a temperature, may result in an inoperative TCC. If TCC engages before "Scan" indicates, solenoid or sump overtemperature switch may be faulty.

Fig. 41: Chart C-8, TCC - 4.3L TBI B Body Flowchart (1 Of 2) NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Unless switch or circuit No. 446 is open, "Scan" tester should display "NO", indicating transmission is not in 4th gear. The 4th gear switch should only be open while in 4th gear. 2. This test determines if the ECM and wiring are okay. Grounding circuit No. 446 should cause "Scan" tester to display "NO", indicating the transmission is not in 4th gear. 3. Checks operation of the 4th gear switch. When the transmission shifts into 4th gear the switch should open and "Scan" tester should display "YES". 4. Disconnecting the TCC connector simulates an open switch to determine if circuit No. 446 is shorted to ground or the problem is in the transmission. Diagnostic Aids

A road test may be necessary to verify the customer complaint. If the "Scan" tester indicates TCC is turning "ON" and "OFF" erratically, check the state of the 4th gear switch to be sure it is not changing state under a steady throttle position. If the switch is changing state, check connections and wire routing carefully. Also if 4th gear switch is always open, the TCC may engage as soon as sufficient oil pressure is reached.

Fig. 42: Chart C-8, TCC - 4.3L TBI B Body Flowchart (2 Of 2) CODE 24, VEHICLE SPEED SENSOR - 4.3L TBI - B BODY

Fig. 43: Code 24 - VSS Circuit Schematic (4.3L TBI B Body) Courtesy of GENERAL MOTORS CORP. The ECM applies and monitors 12 volts on circuit No. 437. Vehicle Speed Sensor (VSS) alternately grounds and opens circuit No. 437 when vehicle is in motion. This pulsing action takes place about 2000 times per mile. ECM will calculate vehicle speed based on the time between "pulses". With vehicle in motion, "Scan" tester reading should closely match speedometer reading. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed equals zero MPH when the following conditions occur:  Engine speed is between 1200-4400 RPM.  TPS is less than 2 percent (closed throttle).  Low load condition (high vacuum).  All conditions met for 5 seconds. These conditions are met during a road load deceleration. Disregard Code 24 that sets when vehicle is not in motion. 2. If 8-12 volts is indicated at IP connector, circuit No. 437 is open between IP connector and the VSS, or there is a faulty vehicle speed sensor. A voltage of less than one volt at the IP connector indicates that circuit No. 437 is shorted to ground. If, after disconnecting circuit No. 437 at the vehicle speed sensor, voltage reads greater than 10 volts, vehicle speed sensor is faulty. If voltage remains less than 8 volts, check circuit No. 437 for short to ground. If circuit No. 437 is not grounded, there is a faulty connection at ECM, or ECM is faulty. Diagnostic Aids

Fig. 44: Code 24, VSS - 4.3L TBI - B Body Flowchart CHART C-1A, PARK/NEUTRAL SWITCH - 4.3L TBI - B BODY

Fig. 45: Chart C-1A - P/N Circuit Schematic (4.3L TBI B Body) Courtesy of GENERAL MOTORS CORP. The Park/Neutral switch is closed to ground in Park or Neutral, and open in Drive. The ECM supplies and monitors 12 volts through an internal resistor to circuit No. 434, ECM senses that switch is closed when voltage on circuit No. 434 drops to less than one volt. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Checks for a closed switch to ground in Park position. Different makes of "Scan" tester will read P/N differently. Refer to "Scan" tester operation manual for type of display used. 2. Checks for an open switch in Drive. 3. Be sure "Scan" tester indicates Drive, even while wiggling shifter to test for an intermittent or misadjusted switch in Drive.

Fig. 46: Chart C-1A, P/N Switch - 4.3L TBI - B Body - Flowchart CODE 24, VEHICLE SPEED SENSOR - 3.8L PFI - C & H BODIES The Vehicle Speed Sensor (VSS) consists of a PM generator, buffer, speedometer and ECM. The PM generator is a permanent magnet assembly attached to the transmission or transaxle (in speedometer cluster on "A" body).

As the vehicle moves, the generator creates a "sine wave" electrical pulse, which is routed to the buffer. In the buffer, the signal is changed form a "sine wave" to a "square wave" and amplified. The "square wave" is an on/off signal. The length of time between pulses determines vehicle speed. The ECM sends a 12-volt signal out on circuit No. 437. The frequency of the signal, which is pulsed low, is used by the ECM to determine vehicle speed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed equals zero MPH when the following conditions occur:  Engine speed is between 1500 and 4000 RPM.  TPS voltage reading shows closed throttle.  Low load condition (low airflow).  Not in Park or Neutral.  All conditions met for 20 seconds. 2. Probe terminal "G" on "A" body. This test checks to see if the fault is circuit No. 437, including the ECM or the VSS/Buffer circuit. The ECM is the source of 12 volts via circuit No. 437 to the buffer in a normal working system. NOTE:

Disregard Code 24 that sets when the drive wheels are not turning.

Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect ECM harness connector terminal "A10" for improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harness. If connections and harness check out okay, raise drive wheels (support drive axles to prevent damage to CV joints). Block other wheels and idle engine more than 3 MPH, in low gear. Use "Scan" tester to check the vehicle speed while moving related connectors and wiring harness. If the failure is induced, the vehicle speed display will change. This may help to isolate the location of the malfunction. A shorted cruise control module or a faulty or misadjusted Park/Neutral switch can result in a false Code 24. NOTE:

Disregard CODE 24, if set while drive wheels are not turning.

Fig. 47: Code 24, VSS - 3.8L PFI - C & H Bodies - Flowchart CHART C-1A, PARK/NEUTRAL SWITCH - 3.8L PFI - C & H BODIES The Park/Neutral (P/N) switch contacts are a part of the neutral start switch and are closed to ground in Park or Neutral, and open in Drive. The ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when the voltage on circuit No. 434 drops to less than one volt. The ECM uses the P/N signal as one of the inputs to idle air control and VSS diagnostics. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks for a closed switch to ground in Park position. Different makes of "Scan" tester will display P/N status differently. Refer to owners manual for display used. 2. This test checks for an open switch in Drive.

3. Be sure "Scan" tester indicates Drive, even while wiggling shifter. This will test for an intermittent condition due to an faulty or misadjusted P/N switch.

Fig. 48: Chart C-1A, P/N Switch - 3.8L PFI - C & H Bodies - Flowchart CHART C-8A, TORQUE CONVERTER CLUTCH - THM 3T40 TRANSMISSION 3.1L A BODY

Fig. 49: Chart C-8A - TCC Circuit Schematic (3.1L A Body - THM 3T40) Courtesy of GENERAL MOTORS CORP. The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the transmission converter stage when the vehicle is in a cruise condition. Electrical power from the ignition circuit is supplied to the TCC solenoid through the brake switch and transmission 2nd or 3rd gear switch. The ECM will engage TCC by grounding circuit No. 422 to energize the solenoid. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks the continuity of the TCC circuit from the fuse to the ALDL connector. 2. When the brake pedal is released, light should come on and then go off when the ALDL "test" terminal is grounded. This tests circuit No. 422 and the ECM driver. Diagnostic Aids

Fig. 50: Chart C-8A, TCC - THM 3T40 - 3.1L A Body Flowchart (1 Of 3) NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Some "Scan" tester display the gear switch status in different manners. Refer to manufacturer's operating manual for additional information. Since both switches should be in the closed state during this test, scan should read the same for either 2nd or 3rd gear switch. 2. Determines whether the switch or signal circuit is open. The circuit can be checked for an open by measuring voltage at the TCC connector. Reading should be about 12 volts. 3. Because switch should be grounded in this step, disconnecting TCC connector should cause "Scan" tester display to change state. 4. Switch state should change when vehicle shifts into 2nd gear. Diagnostic Aids

If vehicle is road tested for a TCC related problem, ensure the switch state does not change while in 3rd gear because the TCC will disengage. If switch changes state, carefully inspect wire harness/routing and connections.

Fig. 51: Chart C-8A, TCC - THM 3T40 - 3.1L A Body Flowchart (2 Of 3)

Fig. 52: Chart C-8A, TCC - THM 3T40 - 3.1L A Body Flowchart (3 Of 3) CHART C-8A, TORQUE CONVERTER CLUTCH - THM 3T40 TRANSMISSION 3.3L A & N BODIES

Fig. 53: Chart C-8A - TCC Circuit Schematic (3.3L A Body - THM 3T40) Courtesy of GENERAL MOTORS CORP.

Fig. 54: Chart C-8A - TCC Circuit Schematic (3.3L N Body - THM 3T40) Courtesy of GENERAL MOTORS CORP. The TCC will engage when the engine is warmed up, vehicle speed is greater than about 32 MPH, throttle sensor output is not changing (indicating a steady road speed), 3rd gear switch is closed and brake switch is closed. An engine coolant thermostat that is stuck open, or opens at too low a temperature, may result in an inoperative TCC. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. When test light is off, this confirms 3rd gear switch is open. 2. At 25 MPH the 2nd gear switch should close. Test light will come on and confirm battery supply and closed brake switch. 3. Grounding the ALDL "test" terminal with ignition on and engine off, should energize the TCC solenoid

by grounding circuit No. 422. This test checks the capability of the ECM to supply a ground for the TCC solenoid. Test light should turn on as circuit No. 422 is grounded. Diagnostic Aids

The "Scan" tester only indicates when the ECM has commanded the TCC driver to engage. This does not confirm that the TCC has engaged. To determine if the TCC has engaged, RPM should drop when the "Scan" tester indicates the TCC driver has turned on.

Fig. 55: Chart C-8A, TCC - THM 3T40 - 3.3L A & N Bodies - Flowchart (1 Of 2)

Fig. 56: Chart C-8A, TCC - THM 3T40 - 3.3L A & N Bodies - Flowchart (2 Of 2) CHART C-8, TORQUE CONVERTER CLUTCH - 3.8L PFI (TURBO) G BODY The purpose of the converter clutch feature is to eliminate the power loss of the torque converter when the

vehicle is in a cruise condition. This allows the convenience of an automatic and the fuel economy of a manual transmission. The heart of the system is an ECM-controlled solenoid which is located inside the transmission. When the solenoid coil is energized, the torque converter clutch is applied, which results in straight through mechanical coupling from the engine to the wheels. When the transmission solenoid is deactivated. the torque converter clutch is released which allow the torque converter to operate in the conventional manner (fluid coupling between engine and transmission). The TCC will engage on a warm engine under road load, in 4th gear only. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. A test light on indicates battery voltage and continuity through TCC solenoid is okay. 2. Vacuum hose on throttle shaft pin increases TPS signal so TCC will engage without excessive wheel speed. Without the hose, it would require vehicle speed in excess of 65 MPH to engage TCC. 3. Checks for vehicle speed signal to ECM. Voltage should vary from 2-9 volts. 4. Checks 3rd and 4th gear signal to ECM. Signals will not prevent TCC engagement, speed points. 5. Solenoids and relays are turned on or off by ECM internal electronic switches called "drives". Each driver is part of a group of 4 called "quad-drivers". Failure of one can damage any other driver within the set. NOTE:

Before replacing ECM, be sure to check the coil resistance of all solenoids and relays controlled by the ECM.

Fig. 57: Chart C-8, TCC - 3.8L PFI (Turbo) - G Body - Flowchart (1 Of 2)

Fig. 58: Chart C-8, TCC - 3.8L PFI (Turbo) - G Body - Flowchart (2 Of 2) CODE 24, VEHICLE SPEED SENSOR - 3.3L & 3.8L PFI

Fig. 59: Code 24 - VSS Circuit Schematic (3.3L & 3.8L PFI) Courtesy of GENERAL MOTORS CORP. The Vehicle Speed Sensor (VSS) is a PM generator type located in the transmission or transaxle. As the vehicle moves, the generator creates AC voltage signal which is routed to the buffer inside the ECM. In the buffer, the AC signal is changed from a "sine wave" to a "square wave" and amplified. The "square wave" is an on/off

signal. The length of time between pulses determines vehicle speed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed equals less than 3 MPH when the following conditions occur:  Engine is running.  Vehicle is in high gear.  No Code 29 or 31 is present.  All conditions met for 40 seconds. 2. Before replacing ECM, check MEM-CAL for proper application. Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect ECM harness connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection and damaged harness. If connections and harness check out okay, raise drive wheels (support drive axles to prevent damage to CV joints). Block other wheels and idle engine at greater than 3 MPH, in low gear. Use "Scan" tester to check the vehicle speed while moving related connectors and wiring harness. If the failure is induced, the vehicle speed display will change. This may help to isolate the location of the malfunction.

Fig. 60: Code 24, VSS - 3.3L & 3.8L PFI - Flowchart

CODE 25, MANIFOLD AIR TEMPERATURE SENSOR SIGNAL VOLTAGE HIGH - 3.8L PFI

Fig. 61: Code 25 - MAT Circuit Schematic (3.8L PFI) Courtesy of GENERAL MOTORS CORP. Code 25 will set if the following conditions occur:   

Signal voltage indicates manifold air temperature is greater than 275°F (135°C). Vehicle speed is greater than 35 MPH. Both of the above requirements are met for at least 16 seconds. Due to conditions necessary to set a Code 23, the SERVICE ENGINE SOON light will stay on only while the fault is present.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. The "Scan" tester may not be used to diagnose this fault, due to the ECM transmitting "default" values. ECM and wiring are good if voltage is greater than 4 volts. 2. If resistance is less than 185 ohms, replace sensor. INTERMITTENTS is located in THEORY & OPERATION section. NOTE:

A Scan Tool may not be used to diagnose this fault, due to the ECM transmitting "DEFAULT" (substitute) values when the fault is present.

Fig. 62: Code 25, MAT Sensor Signal Voltage High - 3.8L PFI - Flowchart CHART C-7, EXHAUST GAS RECIRCULATION - 3.8L PFI

Fig. 63: Chart C-7 - EGR Circuit Schematic (3.8L PFI) Courtesy of GENERAL MOTORS CORP. The digital EGR valve is designed to accurately supply EGR to the engine independent of intake manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through 3 orifices which increment in size to produce 7 combinations. When solenoid is energized, the armature with attached shaft and swivel pintle is lifted, opening the orifice. Flow accuracy is dependent on metering orifice size only, which results in improved control. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Disconnect 4-wire EGR connector. Install a fused jumper from battery to terminal "D" of the EGR valve. Start engine and allow to idle. Grounding terminal "A" should result in a small change in RPM, while terminal "C" should result in a large change in RPM. Engine may stall when terminal "C" is grounded. If the EGR valve shows signs of extreme heat (melting), check the exhaust system for blockage. See CHART B-1. If the exhaust system is plugged due to a restricted converter, this may be due to a defective injector or injector circuit which is causing injector to open constantly.

Fig. 64: Chart C-7, EGR - 3.8L PFI - Flowchart CHART C-5, ELECTRONIC SPARK CONTROL (ESC) SYSTEM CHECK 2.3L PFI

Fig. 65: Chart C-5 - ESC Circuit Schematic (2.3L PFI) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. With engine idling, a knock signal should not be present at ECM, as detonation is not likely under noload condition. 2. Tapping on the engine lift hook bracket should simulate a knock condition. This will determine if knock sensor is capable of detecting detonation. If knock is not detected, try tapping on engine block near sensor. If knock is still not detected, replace sensor. 3. If engine has an internal problem that is simulating a knock, the knock sensor may be responding to that condition. Internal problem should be diagnosed and repaired. 4. This test determines if the knock sensor is faulty, or the ESC portion of the MEM-CAL is faulty. If MEM-CAL is at fault, ensure that it is properly installed and latched in place. If not properly installed, repair and retest. Diagnostic Aids

While observing "Scan" tester, a knock should be indicated whenever detonation is present (heard). Detonation is most likely to take place under high engine load condition.

Fig. 66: Chart C-5, ESC System Check - 2.3L PFI - Flowchart CHART C-8A, TRANSMISSION CONVERTER CLUTCH (TCC) (ELECTRICAL DIAGNOSIS) 2.3L

PFI

Fig. 67: Chart C-8A - TCC Circuit Schematic (2.3L PFI) Courtesy of GENERAL MOTORS CORP. The TCC will engage under the following conditions:    

Vehicle road speed exceeds calibrated value of about 34 MPH (55km/h). TPS not varying signal, indicating a steady road speed. Transmission 2nd gear switch closed. Brake switch closed.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. If light is not illuminated, this confirms transmission 2nd gear apply switch is open. 2. Transmission 2nd gear apply switch should close at 25 MPH. Test light should illuminate and confirm battery voltage, and closed brake switch. 3. Grounding diagnostic terminal with ignition on and engine off, should energize TCC solenoid. When terminal is grounded, circuit No. 422 is simultaneously grounded. This test ECM's ability to supply a ground to the TCC solenoid. Test light should illuminate when connected to battery voltage and ALDL terminal "F". This illumination occurs as circuit No. 422 is grounded. Diagnostic Aids

"Scan" tester will only indicate whether ECM has turned on TCC driver, and does not confirm that TCC has engaged. Check for RPM drop as "Scan" tester indicates TCC driver has been turned on. If RPM drops occurs, TCC has engaged.

Fig. 68: Chart C-8A, TCC (Electrical Diagnosis) 2.3L PFI - Flowchart (1 Of 2)

Fig. 69: Chart C-8A, TCC (Electrical Diagnosis) 2.3L PFI - Flowchart (2 Of 2) CHART C-8D, TRANSMISSION GEAR SWITCHES CIRCUIT CHECK 2.3L PFI

Fig. 70: Chart C-8D - Trans. Gear Switches Circuit Schematic (2.3L PFI) Courtesy of GENERAL MOTORS CORP. This chart will check 2nd and 3rd gear switch inputs to ECM. Transmission gear input signals to ECM are determined as follows: GEAR INPUT SIGNALS Gear Position Park/Neutral & Reverse 1st Gear 2nd Gear 3rd Gear 3rd Gear 3rd Gear NOTE:

Switch Condition 3rd Gear Switch Open 2nd Gear Switch Closed 2nd Gear Switch Open Switch Open 2nd Gear Switch Open Switch Closed

Test numbers refer to test numbers on diagnostic chart.

1. This checks for an open or grounded circuit between transmission connector and ECM. Since ECM terminals are normally high, battery voltage should be indicated at both terminals with connector removed. A DVOM must be used for this step. 2. A test light to battery voltage is used in this step to check transmission switches for normal state. This is 1st gear (of Park/Neutral) state. The test light should be "ON" for normally closed (N.C.) 2nd gear switch. Use of Wiring Probe Kit (J-35616) will assist here and step 3). 3. This checks if transmission switches function normally. In 3rd gear both switches should have changed from their original 1st gear state.

Diagnostic Aids

A sticky or improperly functioning 2nd or 3rd gear switch may cause Code 26 to set intermittently.

Fig. 71: Chart C-8D, Trans. Gear Switches Circuit Check - 2.3L PFI - Flowchart

CHART C-8, TORQUE CONVERTER CLUTCH 2.3L PFI - N BODY

Fig. 72: Chart C-8 - TCC Circuit Schematic (2.3L N Body) Courtesy of GENERAL MOTORS CORP. The purpose of the TCC is to prevent converter slippage during cruise conditions. Once the TCC is engaged, all slippage is eliminated, thus improving fuel economy. Fused battery voltage is supplied to the TCC solenoid through the brake switch, and transmission 3rd gear apply switch. ECM will engage TCC by grounding circuit No. 422 to energize solenoid. The TCC will engage under the following conditions:    

Vehicle road speed exceeds calibrated value of about 34 MPH (55m/h). TPS not varying signal, indicating a steady road speed. Transmission 2nd gear switch closed. Brake switch closed.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

Diagnostic Aids

Scan tester will only indicate whether ECM has turned on TCC driver, and does not confirm that TCC has engaged. Check for RPM drop as "Scan" tester indicates TCC driver has been turned on. If RPM drops occurs, TCC has engaged.

Fig. 73: Chart C-8, Torque Converter Clutch 2.3L PFI - N Body Flowchart (1 Of 2)

Fig. 74: Chart C-8, Torque Converter Clutch 2.3L PFI - N Body Flowchart (2 Of 2) CODE 23, MANIFOLD AIR TEMPERATURE SENSOR SIGNAL VOLTAGE HIGH 2.3L PFI

Fig. 75: Code 23 - MAT Circuit Schematic (2.3L PFI) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. The following conditions must exist for a Code 23 to set:  Signal voltage indicates manifold air temperature is less than -29°F (-34°C).  Engine had been running for at least 320 seconds.  Vehicle speed is less than 15 MPH. 2. Code 23 is set due to an open sensor, wire or connection. This test determines if wiring and ECM are okay. 3. This test indicates if signal circuit No. 472 or 5-volt return circuit No. 469 is open. Diagnostic Aids

Scan tester should display temperature of air entering engine close to ambient air temperature when engine is cold, and rise as underhood temperature increases. Improper connections or open circuits No. 472 or 469, can set Code 23. Code 23 and 24 stored simultaneously, could be result of an open circuit No. 469. See MAT SENSOR TEMPERATURE-TO-RESISTANCE VALUES table.

Fig. 76: Code 23, Manifold Air Temperature Sensor Signal Voltage High 2.3L PFI Flowchart CODE 24, VEHICLE SPEED SENSOR CIRCUIT - 2.3L PFI

Fig. 77: Code 24 - VSS Circuit Schematic (2.3L PFI) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set (with vehicle speed less than 2 MPH) only if the following conditions are met:  Engine RPM is between 1600 and 3600.  TPS is greater than 7 percent.  Gear selector not in Park or Neutral.  All conditions met for 20 seconds.  No Codes 21 or 22. Above conditions are met during road load deceleration. Ignore Code 24 that sets when drive wheels are turning faster than 3 MPH. PM generator only produces a signal if drive wheels are turning greater than 3 MPH. 2. Ensure that correct PROM is used before replacing ECM. Diagnostic Aids

A problem in circuit No. 434 will not affect VSS input or readings displayed by "Scan" tester. Ensure that circuits No. 400 and 401 have proper connections. Also check for correct harness routing. NOTE:

On vehicles with automatic transmission, a faulty or improperly adjusted Park/Neutral switch can result in a false Code 24. Use a Scan tester and check for proper signal while in Drive. Refer to CHART C-1A for P/N switch diagnosis.

NOTE:

Disregard CODE 24 if set while drive wheels are not turning.

Fig. 78: Code 24, Vehicle Speed Sensor Circuit - 2.3L PFI Flowchart CODE 24, VEHICLE SPEED SENSOR - 2.3L PFI - N BODY

Fig. 79: Code 24 - VSS Circuit Schematic (2.3L N Body) Courtesy of GENERAL MOTORS CORP. The speed sensor, which is a Permanent Magnet (PM) generator, provides ECM with vehicle speed information. The PM generator, mounted in the transmission, produces a pulsing voltage signal whenever vehicle speed is greater than 3 MPH. The AC voltage level and the number of pulses increase with vehicle speed. ECM converts pulsing voltage to MPH, which is used for calculations. MPH can be displayed with a "Scan" tool. Output of generator can be monitored with a digital voltmeter on the AC scale while rotating generator. The function of the VSS buffer used in past models years has been incorporated into the ECM. ECM supplies the necessary signal for the instrument panel (4000 pulses per mile) for operating the speedometer, and for the odometer and cruise control (2000 pulses per mile). NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set only if the following conditions are met:  Engine RPM is between 1600 and 3600.  TPS is less than 7 percent.  Gear selector not in Park or Neutral.  All conditions met for 20 seconds.  No Codes 21 or 22. Above conditions are met during road load deceleration. Ignore Code 24 that sets when drive wheels are turning faster than 3 MPH. 2. Ensure that correct PROM is used before replacing ECM. Diagnostic Aids

Vehicle speed should be indicated whenever drive wheels are rotating greater than 3 MPH. Ensure that circuits No. 400 and 401 have proper connections. Also check for correct harness routing. NOTE:

On vehicles with automatic transmission, a faulty or improperly adjusted Park/Neutral switch can result in a false Code 24. Use a Scan tool and check for proper signal while in drive. Refer to CHART C-1A for P/N switch diagnosis check.

Fig. 80: Code 24, Vehicle Speed Sensor - 2.3L PFI - N Body Flowchart CHART C-1A, PARK/NEUTRAL SWITCH - 2.3L PFI - N BODY

Fig. 81: Chart C-1A - P/N Switch Circuit Schematic (2.3L PFI - N Body) Courtesy of GENERAL MOTORS CORP. The Park/Neutral switch contacts are a part of the neutral start switch and are closed to ground in Park of Neutral and open in Drive ranges. The ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when voltage on circuit No. 434 drops to less than one volt. The ECM uses the P/N signal as one of the inputs to control Idle Air Control (IAC) and VSS diagnostics. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks for a closed switch to ground in Park position. If using an ohmmeter, instead of a test light or Scan tester, the resistance will be low, indicating continuity to ground. 2. This test checks for an open switch in Drive range. 3. Ensure that Scan tester indicates Drive while wiggling shifter to test for a faulty or misadjusted switch.

Fig. 82: Chart C-1A, Park/Neutral Switch - 2.3L PFI - N Body Flowchart CHART C-8, TORQUE CONVERTER CLUTCH - 2.0L & 2.5L TBI - A, J, & N BODIES

Fig. 83: Chart C-8 - TCC Circuit Schematic (2.0L & 2.5L TBI - A, J & N Bodies) Courtesy of GENERAL MOTORS CORP. The purpose of automatic transmission/transaxle Torque Converter Clutch (TCC) feature is to eliminate power loss of torque converter stage when vehicle is in cruise condition. This allows convenience of automatic transmission/transaxle and fuel economy of a manual transmission. Fused battery ignition is supplied to TCC solenoid through brake switch, and transmission 3rd gear apply switch. The ECM will engage TCC by grounding circuit No. 422 to energize solenoid. TCC will engage when vehicle speed is above 30 MPH, engine at normal operating temperatures above 158Â°F (70Â°C), throttle position sensor output not changing (indicating a steady road speed), transmission 3rd gear switch closed, and brake switch closed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Light off confirms transmission 3rd gear apply switch is open. 2. At 30 MPH transmission/transaxle 3rd gear switch should close. Test light will come on and confirm battery supply and closed brake switch. 3. Grounding diagnostic terminal with engine off should energize TCC solenoid. This test checks capability of ECM to control solenoid. Solenoids are turned on or off by ECM internal electronic switches called "drivers". Failure of one can damage another driver within a set. Solenoid coil resistance must measure more than 20 ohms. Less resistance will cause early failure of ECM driver. Using an ohmmeter, check solenoid coil resistance before installing a replacement ECM. Check TCC solenoid resistance. Disconnect TCC at transmission. Connect ohmmeter between transmission connector opposite harness connector terminals "A" and "D". Raise drive wheels. Run vehicle in Drive at about 30 MPH to close 3rd gear apply switch. Replace TCC solenoid and ECM if resistance measures less than 20 ohms when switch is close.

Fig. 84: Chart C-8, TCC - 2.0L & 2.5L TBI - A, J, & N Bodies Flowchart (1 Of 2)

Fig. 85: Chart C-8, TCC - 2.0L & 2.5L TBI - A, J, & N Bodies Flowchart (2 Of 2) CODE 24, VEHICLE SPEED SENSOR - 2.0L & 2.5L TBI - A, J, & N BODIES (WITH PM GENERATOR)

Fig. 86: Code 24 - VSS Circuit Schematic (2.0L & 2.5L TBI - A, J & N Bodies) Courtesy of GENERAL MOTORS CORP. The speed sensor, which is a Permanent Magnet (PM) generator, provides the ECM with vehicle speed

information. The PM generator, mounted in the transmission, produces a pulsing voltage signal whenever the vehicle speed is over 3 MPH. The voltage level and the number of pulses increase with vehicle speed. The ECM converts the pulsing voltage to MPH, which is used by the ECM in calculations to determine vehicle adjustments. A Code 24 will set when MPH reads zero, transmission is not in Park or Neutral, engine speed is between 14004400 RPM, TPS is at 2 percent (closed throttle), and a high manifold vacuum is sensed by the MAP sensor. All of these conditions must be met for 3-5 seconds. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test monitors the ECM voltage on circuit No. 993. With wheels turning, the pulsating action created in circuits No. 400 and 401 will result in a voltage signal to the ECM and be displayed as MPH. The PM generator only produces a voltage signal if drive wheels are turning greater than 3 MPH. 2. Before replacing the ECM, PROM should be checked for correct application. Diagnostic Aids

A faulty or misadjusted Park/Neutral switch may set a false Code 24. Use "Scan" tester and check for proper signal in drive, while wiggling shifter.

Fig. 87: Code 24, VSS - 2.0L & 2.5L TBI - A, J, & N Bodies (With PM Generator) Flowchart CODE 24, VEHICLE SPEED SENSOR 2.5L TBI - A BODY (WITH IN-DASH SPEED SENSOR) The ECM applies and monitors a 12-volt signal on circuit No. 437. Circuit No. 437 connects to the vehicle speed sensor and is alternately grounded when the wheels are turning. The pulsing action takes place approximately 2000 times per mile and the ECM will calculate vehicle speed based on the time between pulses. Code 24 will set if vehicle speed reads zero MPH, transmission is not in Park or Neutral, engine speed is between 1400-4400 RPM, TPS is less than 2 percent, a high manifold vacuum is sensed by the MAP sensor,

and these conditions have existed for more than 5 seconds. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. ECM monitors circuit No. 437, counting voltage pulses created by the grounding of the speed sensor. "Scan" reading should closely match speedometer reading with drive wheels turning. 2. 8-12 volts at the I.P. connector indicates circuit No. 437 is open or there is a faulty speed sensor. A voltage of less than one volt at I.P. connector indicates that circuit No. 437 wire is shorted to ground or open between the connector and the ECM. The I.P. connector is located in the center console near the ECM. Diagnostic Aids

A faulty or misadjusted Park/Neutral switch may set a false Code 24. Use "Scan" tester and check for proper signal in Drive, while wiggling shifter.

Fig. 88: Code 24, VSS 2.5L TBI - A Body (With In-Dash Speed Sensor) Flowchart CHART C-1A, PARK/NEUTRAL SWITCH - 2.0L & 2.5L TBI - A, J, & N BODIES

Fig. 89: Chart C-1A - P/N Switch Circuit Schematic (2.0L & 2.5L TBI - A, J & N Bodies) Courtesy of GENERAL MOTORS CORP. The Park/Neutral switch contacts are part of neutral start switch, are closed to ground in Park or Neutral, and open in Drive ranges. The ECM uses this signal as one of the inputs to control IAC and VSS diagnostics. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Checks for closed switch to ground in Park position. Use an ohmmeter, instead of a test light to 12 volts. Resistance will be low, indicating continuity to ground. 2. Checks for an open switch in Drive range. Use an ohmmeter, instead of a test light to 12 volts. Resistance will be high or infinity, indicating an open switch. 3. Be sure "Scan" tester indicates Drive. Wiggle shifter to test for an intermittent or misadjusted switch.

Fig. 90: Chart C-1A, P/N Switch - 2.0L & 2.5L TBI - A, J, & N Bodies Flowchart CHART C-4D-2, DIS MISFIRE UNDER LOAD - 2.0L (VIN 1) TBI

Fig. 91: Chart C-4D-2 - DIS Circuit Schematic (2.0L (VIN 1) TBI) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. If the "misfire" compliant exists at idle only, use CHART C-4D-1. Spark Tester (ST-125) must be used because it is essential to verify adequate available secondary voltage at the spark plug (25,000 volts). Spark should jump tester gap on all 4 plug wires. 2. If spark jumps the tester gap after grounding the opposite plug wire, it indicates excessive resistance in the plug which was by-passed. A faulty or poor connection at that plug could also result in the misfire condition. Also check for carbon deposits inside the spark plug boot. 3. If carbon tracking is evident, replace coil and be sure spark plug wire to that coil is clean and tight. Excessive wire resistance or faulty connections could have caused the coil to be damaged. 4. If the no spark condition follows the suspected coil, that coil is faulty. Otherwise, the ignition module is the cause of no spark. This test could also be performed by substituting a known good coil for the one causing the no spark condition.

Fig. 92: Chart C-4D-2, DIS Misfire Under Load - 2.0L (VIN 1) TBI Flowchart CHART C-8A, TRANSMISSION CONVERTER CLUTCH - 2.0L (VIN 1) TBI - J & L BODIES

Fig. 93: Chart C-8A - TCC Circuit Schematic (2.0L (VIN 1) TBI - J & L Bodies) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

A thermostat that is stuck in the open position, or opens at too low a temperature, may result in an inoperative TCC.

Fig. 94: Chart C-8A, TCC - 2.0L (VIN 1) TBI - J & L Bodies Flowchart (1 Of 2)

Fig. 95: Chart C-8A, TCC - 2.0L (VIN 1) TBI - J & L Bodies Flowchart (2 Of 2) CHART C-10, A/C CLUTCH CONTROL - 2.0L (VIN 1) TBI J BODY

Fig. 96: Chart C-10 - A/C Clutch Circuit Schematic (2.0L (VIN 1) TBI - J Body) Courtesy of GENERAL MOTORS CORP. A/C clutch operation is delayed by ECM for approximately .43 second after A/C is turned on. This allows the IAC to adjust RPM before the A/C clutch engages. The ECM will also disengage the A/C relay during Wide Open Throttle (WOT) operation, during power steering operation greater than 40 psi (2.8 kg/cm2 ), ECM will engage clutch relay by grounding circuit No. 459. At about 430 psi (30 kg/cm2 ), the high pressure switch will open to disengage the A/C clutch and prevent system damage. Diagnostic Aids

If complaint was insufficient cooling, the problem may be caused by an inoperative cooling fan or A/C pressure fan switch. Engine cooling fan should turn on when A/C pressure exceeds value to open switch. See CHART C12 to diagnose cooling fan.

Fig. 97: Chart C-10, A/C Clutch Control - 2.0L (VIN 1) TBI J Body Flowchart (1 Of 2)

Fig. 98: Chart C-10, A/C Clutch Control - 2.0L (VIN 1) TBI J Body Flowchart (2 Of 2) CODE 23, MANIFOLD AIR TEMPERATURE SENSOR - TEMP. TOO LOW - 2.0L (VIN 1) TBI

Fig. 99: Code 23 - MAT Circuit Schematic (2.0L (VIN 1) TBI) Courtesy of GENERAL MOTORS CORP. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks to see if Code 23 is the result of a hard failure or an intermittent condition. Code 23 will be displayed if the engine is running for longer than 2 minutes (J Body) or 8.5 minutes (L Body), signal voltage indicates a MAT temperature less than -22Â°F 30Â°C) or there is no VSS signal. 2. This test simulates conditions for a Code 25. If the "Scan" tester displays a high temperature, the ECM and wiring are okay. 3. This test checks continuity of sensor wiring. If wiring is open there may also be a Code 21. Diagnostic Aids

If the engine has been allowed to cool to an ambient temperature (overnight), coolant and MAT temperature may be checked with the "Scan" tester and should read close to each other. A code 23 will result if either sensor wire becomes open. See MAT SENSOR TEMPERATURE-TO-RESISTANCE VALUES table.

Fig. 100: Code 23, MAT Sensor - Temp. Too Low - 2.0L (VIN 1) TBI Flowchart CODE 24, VEHICLE SPEED SENSOR (VSS) - 2.0L (VIN 1) TBI

Fig. 101: Code 24 - VSS Circuit Schematic (2.0L (VIN 1) TBI) Courtesy of GENERAL MOTORS CORP. Vehicle speed information is provided to the ECM by the vehicle speed sensor Permanent Magnet (PM) generator mounted in the transaxle. The PM generator produces a pulsing voltage whenever vehicle speed is greater than 3 MPH. The A/C voltage level and the number of pulses increases with vehicle speed. The ECM then converts the pulsing voltage to MPH, which is used for calculations. MPH can be displayed with the "Scan" tester and should match speedometer reading. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed equals zero MPH when the following conditions occur:  Engine speed is between 1400 and 3600 RPM.  Throttle angle is less than 2 percent.  Low load condition, low MAP voltage, high manifold vacuum.  Not in Park or Neutral.  All conditions met for 5 seconds. These conditions are met during a road load deceleration. Disregard Code 24 that sets when drive wheels are not turning. 2. Circuits No. 400, 401 and 993 are okay if the speedometer works properly. Code 24 is being caused by a faulty ECM, faulty PROM or an incorrect PROM. Diagnostic Aids

The Scan tester should indicate a vehicle speed whenever the drive wheels are turning more than 3 MPH. Check circuits No. 400 and 401 for proper connections. Make sure connections are clean and tight and the harness is routed correctly. ON vehicles with automatic transmissions, a faulty or misadjusted Park or Neutral safety switch can result in a false Code 24. Use the Scan tester and check for proper signal while in Drive. Scan reading should match speedometer.

Fig. 102: Code 24, Vss - 2.0L (VIN 1) TBI Flowchart CHART C-1A, PARK/NEUTRAL SWITCH - 2.0L (VIN 1) TBI - J & L BODIES

Fig. 103: Chart C-1A - P/N Switch Circuit Schematic (2.0L (VIN 1) TBI J & L Bodies) Courtesy of GENERAL MOTORS CORP. The Park/Neutral switch contacts are part of neutral start switch. They are closed to ground in Park or Neutral, and open in Drive ranges. The ECM supplies Ignition voltage through a current limiting resistor to circuit No. 434, and senses a closed switch when voltage on circuit No. 434 drops to less than one volt. The ECM uses this signal as one of the inputs to control IAC and VSS diagnostics. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Checks for a closed switch to ground with transmission in Park position. Different makes of "Scan" testers will display P/N status differently. Refer to manufacturer's tester operation manual for type of display used. 2. Checks for an open switch circuit in Drive. 3. Be sure "Scan" indicates Drive, even while wiggling shifter to test for an intermittent or misadjusted switch in Drive.

Fig. 104: Chart C-1A, P/N Switch - 2.0L (Vin 1) TBI - J & L Bodies Flowchart CHART C-8, TORQUE CONVERTER CLUTCH - 2.0L PFI - J & N BODIES Fused battery ignition is supplied to the Torque Converter Clutch (TCC) solenoid through the brake switch and transmission/ transaxle third gear apply switch. The ECM will engage TCC by grounding circuit No. 422 to energize the solenoid. TCC will engage when engine is warmed up, vehicle speed is greater than a calibrated

value, throttle position sensor output is not changing (indicating a steady road speed), transaxle third gear apply switch is closed and brake switch is closed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Light off confirms transmission/transaxle third gear supply switch is open. 2. At 30 MPH the transmission/transaxle third gear switch should close. Test light will come on and confirm battery supply and closed brake switch. 3. Grounding the diagnostic terminal with engine off should energize the TCC solenoid. This test checks the capability of the ECM to control the solenoid. 4. Solenoids and relays are turned on and off by the ECM internal electronic switches called "Drivers". Each Driver is part of a group of 4 called "Quad-Drivers". Failure of one can damage any other Driver within the set. Diagnostic Aids

Check TCC solenoid resistance. Disconnect the TCC at transmission. Connect ohmmeter between transmission connector, opposite harness connector terminal "A" and "D". Raise drive wheels (support drive axles) and run vehicle in Drive to about 30 MPH to close third gear apply switch. Replace TCC solenoid and ECM if resistance measures less than 20 ohms when switch is closed. An engine coolant thermostat that is stuck open, or opens at too low a temperature, may result in an inoperative TCC.

Fig. 105: Chart C-8, TCC - 2.0L PFI - J & N Bodies Flowchart (1 Of 2)

Fig. 106: Chart C-8, TCC - 2.0L PFI - J & N Bodies Flowchart (2 Of 2) CODE 24, VEHICLE SPEED SENSOR 2.0L PFI - J & N BODIES The Vehicle Speed Sensor (VSS), which is a Permanent Magnet (PM) generator mounted in the transmission, provides the ECM with vehicle speed information. The PM generator produces a pulsing voltage signal whenever the vehicle speed is greater than 3 MPH. The voltage level and the number of pulses increase with vehicle speed. The ECM converts the pulsing voltage to MPH, which is used by the ECM in calculations to determine vehicle adjustments. A Code 24 will set when MPH reads zero, transmission is not in Park or Neutral, engine speed is between 14004400 RPM, TPS is at 2 percent (closed throttle), and a low airflow condition is sensed. All of these conditions must be met for at least 3 seconds. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test monitors the ECM voltage on circuit No. 389. With wheels turning, the pulsing action created in circuits No. 400 and 401 will result in a voltage signal to the ECM, and be displayed as MPH. The PM generator only produces a voltage signal if drive wheels are turning at speeds greater than 3 MPH. 2. Before replacing the ECM, PROM should be checked for correct application.

Diagnostic Aids

A faulty or misadjusted Park/Neutral switch may set a false Code 24. Use "Scan" tester and check for proper signal in Drive, while wiggling shifter. NOTE:

Disregard CODE 24 if set while drive wheels are not turning.

Fig. 107: Code 24, Vehicle Speed Sensor 2.0L PFI - J & N Bodies Flowchart

CHART C-1A, PARK/NEUTRAL SWITCH - 2.0L PFI - J & N BODIES The Park/Neutral (P/N) switch contacts are a part of the Neutral/Start switch and are close to ground in Park or Neutral and open in Drive. The ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when the voltage on circuit No. 434 drops to less than one volt. The ECM uses the P/N signal as one of the inputs to control Idle Air Control (IAC) and Vehicle Speed Sensor (VSS) diagnostics. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks for a closed switch to ground in Park position. If using an ohmmeter instead of a test light or "Scan" tester, the resistance will be low, indicating continuity to ground. 2. This test checks for an open switch in Drive. 3. Be sure "Scan" tester indicates Drive while wiggling shifter to test for a faulty or misadjusted switch.

Fig. 108: Chart C-1A, Park/Neutral Switch - 2.0L PFI - J & N Bodies Flowchart CHART C-7, EGR VALVE CHECK - 2.5L A & N BODIES

Fig. 109: Chart C-7, EGR Valve Check - 2.5L A & N Bodies Flowchart CHART C-8, TORQUE CONVERTER CLUTCH - 2.0L (VIN K) & 2.5L TBI

Fig. 110: Chart C-8 - TCC Circuit Schematic (2.0L (VIN K) & 2.5L TBI) Courtesy of GENERAL MOTORS CORP. The purpose of automatic transmission/transaxle Torque Converter Clutch (TCC) feature is to eliminate power loss of torque converter stage when vehicle is in cruise condition. Fused battery ignition is supplied to TCC solenoid through brake switch, and transmission 3rd gear apply switch. The ECM will engage TCC by grounding circuit No. 422 to energize solenoid. TCC will engage when vehicle speed is greater than 30 MPH, engine at normal operating temperatures greater than 158Â°F (70Â°C), throttle position sensor output not changing (indicating a steady road speed), transmission 3rd gear switch closed, and brake switch closed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

An engine coolant thermostat that is stuck open or opens at too low a temperature may result in an inoperative TCC.

Fig. 111: Chart C-8, TCC - 2.0L (VIN K) & 2.5L TBI Flowchart (1 Of 2)

Fig. 112: Chart C-8, TCC - 2.0L (VIN K) & 2.5L TBI Flowchart (2 Of 2) CODE 23, MAT SENSOR TEMPERATURE LOW - 2.0L (VIN K) & 2.5L TBI

Fig. 113: Code 23 - MAT Circuit Schematic (2.0L (VIN K) & 2.5L TBI) Courtesy of GENERAL MOTORS CORP. The ECM supplies and monitors a voltage signal (4-6 volts) to the sensor through circuit No. 472. When temperatures are low, sensor resistance is high and the ECM will see a high monitored voltage signal. As temperatures increase, sensor resistance decreases and the voltage sensed by the ECM drops. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This step checks to see if Code 23 is the result of a hard failure or an intermittent condition. Code 23 will set if the engine has been running for more than 58 seconds and the signal voltage indicates a MAT temperature less than -22Â°F (-30Â°C). 2. This step simulates conditions for a Code 25. If the Scan tester displays a high temperature, the ECM and wiring are not at fault. 3. This step checks for continuity of circuits No. 472 and 469. If circuit No. 469 is open there may also be a Code 33 stored. Diagnostic Aids

If the engine is allowed to cool overnight, the coolant and MAT sensors, when measured with a Scan tester, should read close to each other. See MAT SENSOR TEMP VS. RESISTANCE VALUE table. When Code 15 is set, the ECM will turn on the cooling fan. A Code 23 will also result if circuits No. 472 or 469 become open.

Fig. 114: Code 23, MAT Sensor Temp. Low - 2.0L (VIN K) & 2.5L TBI Flowchart CODE 24, VEHICLE SPEED SENSOR (VSS) - 2.0L (VIN K) & 2.5L TBI - A, J & N BODIES (WITH PM GENERATOR)

Fig. 115: Code 24 - VSS Circuit Schematic (2.5L TBI - N Body) Courtesy of GENERAL MOTORS CORP.

Fig. 116: Code 24 - VSS Circuit Schematic (2.0L (VIN K)) Courtesy of GENERAL MOTORS CORP. The speed sensor, which is a Permanent Magnet (PM) generator, provides the ECM with vehicle speed information. The PM generator, mounted in the transmission, produces a pulsing voltage signal whenever the vehicle speed is over 3 MPH. The voltage level and the number of pulses increase with vehicle speed. The ECM converts the pulsing voltage to MPH, which is used by the ECM in calculations to determine vehicle adjustments. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. A Code 24 will set when MPH reads zero, transmission is not in Park or Neutral, engine speed is between 1800-4400 RPM, TPS is at zero percent (closed throttle), and a high manifold vacuum is sensed by the MAP sensor. All of these conditions must be met for 3-5 seconds. The PM generator only produces a voltage signal if drive wheels are turning greater than 3 MPH.

2. Before replacing the ECM, PROM should be checked for correct application. Diagnostic Aids

A faulty or misadjusted Park/Neutral switch may set a false Code 24. Use "Scan" tester and check for proper signal in Drive, while wiggling shifter. NOTE:

Disregard CODE 24 if set while drive wheels are not turning.

Fig. 117: Code 24, VSS - 2.0L (VIN K) & 2.5L TBI - A, J & N Bodies (With PM Generator) Flowchart CHART C-8, TORQUE CONVERTER CLUTCH - 2.0L (VIN M) PFI

Fig. 118: Chart C-8 - TCC Circuit Schematic (2.0L (VIN M) PFI) Courtesy of GENERAL MOTORS CORP. Fused battery ignition is supplied to the Torque Converter Clutch (TCC) solenoid through the brake switch and transmission/ transaxle 3rd gear apply switch. The ECM will engage TCC by grounding circuit No. 422 to energize the solenoid. TCC will engage when engine is warmed up, vehicle speed is greater than a calibrated value, throttle position sensor output is not changing (indicating a steady road speed), transaxle 3rd gear apply switch is closed and brake switch is closed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Light off confirms transmission/transaxle 3rd gear supply switch is open. 2. At 30 MPH the transmission/transaxle 3rd gear switch should close. Test light will come on and confirm battery supply and closed brake switch. 3. Grounding the diagnostic terminal with engine off should energize the TCC solenoid. This test checks the capability of the ECM to control the solenoid. Diagnostic Aids

An engine coolant thermostat that is stuck open, or opens at too low a temperature, may result in an inoperative TCC.

Fig. 119: Chart C-8, TCC - 2.0L (VIN M) PFI - Flowchart (1 Of 2)

Fig. 120: Chart C-8, TCC - 2.0L (VIN M) PFI - Flowchart (2 Of 2) CODE 24, VEHICLE SPEED SENSOR (PM GENERATOR) - 2.0L (VIN M) PFI

Fig. 121: Code 24 - VSS Circuit Schematic (2.0L (VIN M) PFI) Courtesy of GENERAL MOTORS CORP. The Permanent Magnet (PM) generator mounted in the transmission, produces a pulsing voltage signal whenever the vehicle speed is greater than 3 MPH. The voltage level and the number of pulses increase with vehicle speed. The ECM converts the pulsing voltage to MPH, which is used by the ECM in calculations to determine vehicle adjustments. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed equals zero MPH when transmission is not in Park or Neutral, engine speed is between 1600-4400 RPM, TPS indicates closed throttle, and a low airflow condition is sensed. All of these conditions must be met for at least 5 seconds. 2. Before replacing the ECM, MEM-CAL should be checked for correct application. Diagnostic Aids

A faulty or misadjusted Park/Neutral switch may set a false Code 24. Use Scan tester and check for proper signal in Drive, while wiggling shifter.

Fig. 122: Code 24, VSS (PM Generator) - 2.0L (VIN M) PFI Flowchart CODE 25, MANIFOLD AIR TEMPERATURE SENSOR SIGNAL VOLTAGE LOW - 2.0L (VIN M) PFI

Fig. 123: Code 25 - MAT Circuit Schematic (2.0L (VIN M) PFI) Courtesy of GENERAL MOTORS CORP. Code 25 will set if signal voltage indicates a manifold air temperature greater than 275°F (135°C) for at least 30 seconds. Due to the conditions necessary to set Code 25, the "SERVICE ENGINE SOON" light will only stay on while the fault is present. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. A Scan tester may not be used to diagnose this fault due to the "default values" substituted by the ECM. If voltage is greater than 4 volts, the ECM and wiring are not at fault. 2. If the resistance is less than 100 ohms, replace the sensor. See MAT SENSOR TEMP VS. RESISTANCE VALUE table. NOTE:

INTERMITTENTS is located in THEORY & OPERATION section of this article.

Fig. 124: Code 25, MAT Sensor Signal Voltage Low - 2.0L (VIN M) PFI Flowchart CHART C-8, TORQUE CONVERTER CLUTCH - 3.8L "3800" PFI BONNEVILLE, ELECTRA & NINETY-EIGHT The purpose of the converter clutch is to eliminate the power loss of the torque converter when vehicle is in cruise condition. This allows the convenience of automatic transmission and fuel economy of a manual transaxle. The heart of the system is a solenoid located inside the transaxle which is controlled by the ECM. When solenoid coil is activated (on), the torque converter clutch is applied which results in straight through mechanical coupling from engine to drive wheels. When the transaxle (TCC) solenoid is deactivated, the torque converter clutch is released which allows the torque converter to operate in the conventional manner (fluid coupling between engine and transaxle). TCC will engage under the following conditions: ď Ź

Engine warmed to operating temperature.

  

Vehicle speed greater than a calibrated value (about 28 MPH). TPS output not changing, indicating a steady road speed. Brake switched closed.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks the continuity of TCC circuit from the fuse to ALDL connector. 2. When brake pedal is released, light should come back on, and then go off when diagnostic terminal is grounded. This test circuit No. 422 and TCC driver in ECM. Diagnostic Aids

The Scan tester only indicates when ECM has turned on TCC driver, and this does not confirm that TCC has engaged. To determine if TCC is functioning properly, road test vehicle. Engine RPM should decrease when "Scan" tester indicates TCC driver has turned on.

Fig. 125: Chart C-8, TCC - 3.8L PFI Bonneville, Electra & Ninety-Eight Flowchart (1 Of 2) Each gear switch opens when the appropriate clutch is applied. All gear switches are open in 4th gear. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Some Scan testers display the state of these switches in different ways. Read instructions on Scan tester usage before proceeding with test procedures. Since both switches should be in closed state during this test, "Scan" tester should indicate same readings for 2nd, 3rd or 4th gear switches. 2. Determines whether switch or signal circuit is open. The circuit can be checked for an open be measuring voltage at TCC connector. Reading should be about battery voltage. Because switch or switches should be grounded at some point in this procedure, unplugging TCC connector should cause "Scan" tester switch state to change. The switch state should change when vehicle shifts into 3rd gear. Diagnostic Aids

If vehicle is road tested because of a TCC related problem, ensure switch states do not change while in 4th gear, because TCC will disengage. If switches change state, carefully check wire routing and connections.

Fig. 126: Chart C-8, TCC - 3.8L PFI - Bonneville, Electra & Ninety-Eight Flowchart (2 Of 2) CODE 24, VEHICLE SPEED SENSOR - 3.8L "3800" PFI - BONNEVILLE, ELECTRA & NINETYEIGHT Vehicle speed information is provided to the ECM by the vehicle speed sensor, a permanent magnet (PM) generator mounted in the transmission. The PM generator produces a pulsing voltage whenever vehicle speed is

greater than about 3 MPH. The AC voltage level and the number of pulses increases with vehicle speed. The ECM converts the pulsing voltage to MPH, and the MPH can be displayed with a Scan tester. The function of the VSS buffer, used in the past model years, has been incorporated into the ECM. The ECM supplies the necessary signal for the instrument panel (4004 pulses per mile) for operating the speedometer and the odometer. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Code 24 will set if vehicle speed signal equals zero MPH when:  Engine speed is between 1500 and 4000 RPM.  TPS reading shows closed throttle.  Low load condition (low air flow).  Not in Park or Neutral.  No Code 29 or 31.  When vehicle is in 4th gear.  All conditions met for 20 seconds. Disregard Code 24 that sets when drive wheels are not rotating. The PM generator only produces a signal if drive wheels are rotating faster than 3 MPH. 2. Before replacing the ECM, check MEM-CAL for correct application. Diagnostic Aids

Scan tester should indicate a vehicle speed whenever drive wheels are rotating faster than 3 MPH. Check circuit No. 400 and 401 for proper connections. Ensure they are clean and tight, and harness is routed correctly. See INTERMITTENTS in TROUBLE SHOOTING section.

Fig. 127: Code 24, VSS - 3.8L PFI - Bonneville, Electra & Ninety-Eight Flowchart CODE 31, PARK/NEUTRAL SWITCH - 3.8L "3800" PFI - BONNEVILLE, ELECTRA & NINETY-

EIGHT

Fig. 128: Code 31 - P/N Switch Circuit Schematic (3.8L PFI) Courtesy of GENERAL MOTORS CORP. The Park/Neutral (P/N) switch contacts are part of the neutral start switch and are closed to ground in Park or Neutral, and open in Drive. The ECM supplies ignition voltage through a current limiting resistor to circuit No. 434 and senses a closed switch when the voltage on circuit No. 434 drops to less than one volt. The ECM uses the P/N signal as one of the inputs to idle air control, EGR and VSS diagnostics. Code 31 will set under the following conditions: 



If circuit No. 434 indicates P/N(grounded) while in drive range and 4th gear TCC engaged, EGR would be inoperative, resulting in possible detonation. If circuit No. 434 indicates drive (open) at start-up, a drop in idle may exist when gear selector is moved into drive range. If transaxle 4th gear switch has an intermittent open, ECM thinks vehicle is in 4th gear and will set Code 31.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Checks for a closed switch to ground in "PARK" position. Different types of SCAN testers will read P/N differently. Refer to Scan tester operators manual for type of display used for specific tester. 2. Checks for an open switch in drive range. 3. Ensure Scan tester indicates Drive, even while wiggling shifter. This will test for an intermittent or misadjusted switch in Drive or Overdrive range.

Fig. 129: Code 31, P/N Switch - 3.8L PFI - Bonneville, Electra & Ninety-Eight Flowchart CHART C-8A, TORQUE CONVERTER CLUTCH - THM 4T60 TRANSMISSION - 3.8L

Fig. 130: Chart C-8A - TCC Circuit Schematic (3.8L W/THM 4T60) Courtesy of GENERAL MOTORS CORP. The TCC will engage when the engine is warmed up, vehicle speed is greater than 28 MPH, throttle position sensor output is not changing (indicating a steady road speed) and the brake switch is closed. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks the continuity of the TCC circuit from the fuse to the ALDL connector. 2. When the brake pedal is released and the diagnostic terminal is ground, the light should come back on and then go off. This tests circuit No. 422 and the TCC driver in the ECM. 3. TCC electrical circuits have checked out properly. Fault may be an internal hydraulic problem. Diagnostic Aids

The Scan tester only indicates when the ECM has turned on the TCC driver. This does not confirm that the TCC has engaged. to determine if TCC is functioning properly, monitor engine RPM. Engine RPM should decrease when the Scan tester indicates the TCC driver has turned on. NOTE:

Mechanical checks such as linkage, oil level, etc. should be performed prior to using this chart.

Fig. 131: Chart C-8A, TCC - THM 4T60 - 3.8L Flowchart (1 Of 2) NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Some SCAN testers display the state of these switches in different ways. Be familiar with the type of tester being used. All switches should be in the closed state during this test, the tester should read the same for 2nd, 3rd and 4th gear switches. 2. Determines whether the switch or signal circuit is open. The circuit can be checked for an open be measuring the voltage (with a voltmeter) at the TCC connector. Voltage should be about 12 volts. 3. Because the switch should be grounded in this test, disconnecting the TCC connector should cause the SCAN tester switch state to change. 4. The switch state should change when the vehicle shifts into 2nd, 3rd and 4th gear. Diagnostic Aids

If vehicle is road tested because of a TCC related problem, be sure the switch states do not change while in 4th gear, because the TCC will disengage. If switches change state, carefully check wire routing and connections.

Fig. 132: Chart C-8A, TCC - THM 4T60 - 3.8L Flowchart (2 Of 2) CHART C-8B, TORQUE CONVERTER CLUTCH - 3.3L "A" BODY W/THM 4T60 TRANSMISSION (1 OF 2)

Fig. 133: Chart C-8B - TCC Circuit Schematic (3.3L A Body W/THM 4T60) Courtesy of GENERAL MOTORS CORP. Each gear switch opens as the appropriate clutch is applied. All switches are open in 4th gear. NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Some Scan testers display the state of these switches in different ways. Be familiar with the type of tester being used. All switches should be in the closed state during this test, the tester should read the same for 2nd, 3rd and 4th gear switches. 2. Determines whether the switch or signal circuit is open. The circuit can be checked for an open be measuring the voltage (with a voltmeter) at the TCC connector. Voltage should be about 12 volts. Diagnostic Aids

Fig. 134: Chart C-8B, TCC - 3.3L "A" Body W/THM 4T60 - Flowchart (1 Of 2) NOTE:

Test numbers refer to test numbers on diagnostic chart.

Fig. 135: Chart C-8B, TCC - 3.3L "A" Body W/THM 4T60 - Flowchart (2 Of 2) CHART C-8B, TORQUE CONVERTER CLUTCH - THM 4T60 TRANSMISSION - 2.8L "A" BODIES

Fig. 136: Chart C-8B - TCC Circuit Schematic (2.8L A Body W/THM 4T60) Courtesy of GENERAL MOTORS CORP. The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter when the vehicle is in a cruise condition. When the solenoid coil is activated by the ECM, the torque converter clutch is applied, resulting in a straight through mechanical coupling from engine to the wheels. When the transmission solenoid is deactivated, the TCC is released, which allows the torque converter to operate in the conventional manner (fluidic coupling between engine and transmission). NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. This test checks the continuity of the TCC circuit from the fuse to the ALDL connector. 2. When the brake pedal is released, the light should come back on and then go off when the ALDL "test" terminal is grounded. This will test circuit No. 422 and the TCC driver in the ECM. Diagnostic Aids

A Scan tester only indicates when the ECM has turned on the TCC driver. This does not confirm that the TCC has engaged. To determine if TCC is functioning properly, observe engine RPM. RPM should decrease when the Scan tester indicates the TCC driver has turned on.

Fig. 137: Chart C-8B, TCC - THM 4T60 - 2.8L A Bodies Flowchart (1 Of 3) The 3rd gear switch is open both in 3rd and 4th gear. The 4th gear switch is open only in 4th gear, which allows for TCC when in 4th gear. The TCC will disengage during a 4-3 downshift.

NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Some Scan testers display the state of these switches in different ways. Be familiar with the type of tester being used. Since both switches should be in the closed state during this test, the tester should read the same for either the 3rd and 4th gear switch. 2. Determines whether the switch or signal circuit is open. The circuit can be checked for an open by measuring the voltage (with a voltmeter) at the TCC connector. Reading should be about 12 volts. 3. Because the switch should be grounded in this step, disconnecting the TCC connector should cause the SCAN tester statue to change. 4. Switch status should change when vehicle shifts into 3rd gear. Diagnostic Aids

If vehicle is road tested because of a TCC related problem, be sure the switch status does not change while in 4th gear because the TCC will disengage. If switches change state, carefully check wire routing and connections.

Fig. 138: Chart C-8B, TCC - THM 4T60 - 2.8L A Bodies Flowchart (2 Of 3)

Fig. 139: Chart C-8B, TCC - THM 4T60 - 2.8L A Bodies Flowchart (3 Of 3) CHART C-8B, TORQUE CONVERTER CLUTCH - THM 4T60 TRANSMISSION - 2.8L "W" BODIES

Fig. 140: Chart C-8B - TCC Circuit Schematic (2.8L W Body W/THM 4T60) Courtesy of GENERAL MOTORS CORP. The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter when the vehicle is in a cruise condition. When the solenoid coil is activated by the ECM, the torque converter clutch is applied, resulting in a straight through mechanical coupling from engine to the wheels. When the transmission solenoid is deactivated, the TCC is released, which allows the torque converter to operate in the conventional manner (fluidic coupling between engine and transmission). NOTE: 1. 2. 3. 4.

Test numbers refer to test numbers on diagnostic chart.

This test checks the functional operation of the TCC circuit. This test checks the TCC control driver in the ECM. This test will confirm there is battery voltage to terminal "A". This test will confirm that ECM has the ability to turn on TCC.

Diagnostic Aids

Fig. 141: Chart C-8B, TCC - THM 4T60 Transmission 2.8L W Bodies Flowchart (1 Of 3) NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Some Scan testers display the gear switch status in different manners. Refer to manufacturer's operating manual for additional information. Since both switches should be in the closed state during this test, Scan should read the same for either 3rd or 4th gear switch. 2. Determines whether the switch or signal circuit is open. The circuit can be checked for an open be measuring voltage at the TCC connector. Reading should be about 12 volts. 3. Because switch should be grounded in this step, disconnecting TCC connector should cause SCAN tester display to change state. 4. Switch status should change when vehicle shifts into 3rd gear. Diagnostic Aids

If vehicle is road tested for a TCC related problem, ensure the switch state does not change while in 4th gear because the TCC will disengage. If switch changes state, carefully inspect wire harness/routing and connections.

Fig. 142: Chart C-8B, TCC - THM 4T60 Transmission 2.8L W Bodies Flowchart (2 Of 3)

Fig. 143: Chart C-8B, TCC - THM 4T60 Transmission 2.8L W Bodies Flowchart (3 Of 3) CHART C-8B, TORQUE CONVERTER CLUTCH - THM 4T60 TRANSMISSION - 3.1L "W" BODIES

Fig. 144: Chart C-8B - TCC Circuit Schematic (3.1L W Body W/THM 4T60) Courtesy of GENERAL MOTORS CORP. The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter when the vehicle is in a cruise condition. When the solenoid coil is activated by the ECM, the torque converter clutch is applied, resulting in a straight through mechanical coupling from engine to the wheels. When the transmission solenoid is deactivated, the TCC is released, which allows the torque converter to operate in the conventional manner (fluidic coupling between engine and transmission). NOTE: 1. 2. 3. 4.

Test numbers refer to test numbers on diagnostic chart.

Diagnostic Aids

Fig. 145: Chart C-8B, TCC - THM 4T60 Transmission 3.1L W Bodies Flowchart (1 Of 3) NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Some Scan testers display the gear switch status in different manner. Refer to manufacturer's operating manual for additional information. Since both switches should be in the closed state during this test, Scan should read the same for either 3rd or 4th gear switch. 2. Determines whether the switch or signal circuit is open. The circuit can be checked for an open by measuring voltage at the TCC connector. Reading should be about 12 volts. 3. Because switch should be grounded in this step, disconnecting TCC connector should cause SCAN tester display to change state. NOTE:

Checks made in this chart will not prevent the TCC from working, but will affect engagement or disengagement points.

Fig. 146: Chart C-8B, TCC - THM 4T60 Transmission 3.1L W Bodies Flowchart (2 Of 3) NOTE:

Test numbers refer to test numbers on diagnostic chart.

1. Switch state should change when vehicle shifts into 3rd gear. Diagnostic Aids

Fig. 147: Chart C-8B, TCC - THM 4T60 Transmission 3.1L W Bodies Flowchart (3 Of 3)

M - VACUUM DIAGRAMS ENGINE PERFORMANCE General Motors Vacuum Diagrams

VACUUM HOSE DIAGRAM(S) NOTE:

Vacuum diagrams for applications not shown were not available from manufacturer.

2.0L ENGINES

Fig. 1: 2.0L TBI (VIN K) Pontiac (J Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 2: 2.0L PFI (VIN M) Pontiac (J Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP. 2.2L ENGINES

Fig. 3: 2.2L TBI (VIN G) Chevrolet (J Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP. 2.3L ENGINES

Fig. 4: 2.3L PFI (VINs A & D) Buick, Oldsmobile & Pontiac (N & W Bodies) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 5: 2.3L PFI (VIN A) Chevrolet (L Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

2.5L ENGINES

Fig. 6: 2.5L TBI (VIN U) Buick, Oldsmobile & Pontiac (N Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

VACUUM HOSE DIAGRAM(S) NOTE:

3.1L ENGINES

Vacuum diagrams for applications not shown were not available from manufacturer.

Fig. 7: 3.1L PFI (VIN T) Chevrolet & Pontiac (F Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 8: 3.1L PFI (VIN T) Chevrolet (J Body) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 9: 3.1L PFI (VIN T) Chevrolet (L Body) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 10: 3.1L PFI (VIN T) Buick, Chevrolet, Oldsmobile & Pontiac (W Body) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 11: 3.1L PFI (VIN T) Buick, Chevrolet, Oldsmobile & Pontiac (W Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 12: 3.1L PFI (VIN T) Buick, Chevrolet, Oldsmobile & Pontiac (W Body) Calif. Man. Trans. Courtesy of GENERAL MOTORS CORP. 3.3L ENGINES

Fig. 13: 3.3L PFI (VIN N) Buick & Oldsmobile (A Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP. 3.8L ENGINES

Fig. 14: 3.8L PFI (VIN C) Buick & Oldsmobile (C Body) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 15: 3.8L PFI (VIN C) Buick, Oldsmobile & Pontiac (E & H Bodies) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 16: 3.8L PFI (VIN L) Buick Regal (W Body) Calif. Courtesy of GENERAL MOTORS CORP. 4.3L ENGINES

Fig. 17: 4.3L TBI (VIN Z) Caprice (B Body), Fed. Courtesy of GENERAL MOTORS CORP.

VACUUM HOSE DIAGRAM(S) NOTE:

4.5L ENGINES

Vacuum diagrams for applications not shown were not available from manufacturer.

Fig. 18: 4.5L PFI (VIN 3) Cadillac (C Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 19: 4.5L PFI (VIN 3) Cadillac (E & K Bodies) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

5.0L & 5.7L ENGINES

Fig. 20: 5.0L 4-Bbl. (VIN Y) Cadillac, Chevrolet & Pontiac (B & D Bodies) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 21: 5.0L TBI (VIN E) Chevrolet & Pontiac (B & F Bodies) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 22: 5.0L PFI (VIN F) Pontiac (F Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 23: 5.0L PFI (VIN F) Chevrolet (F Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 24: 5.0L TBI (VIN E) Chevrolet (B Body) Calif. Courtesy of GENERAL MOTORS CORP.

Fig. 25: 5.0L PFI (VIN F) Chevrolet (F Body) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

Fig. 26: 5.0L & 5.7L TBI (VINs E & 7) Cadillac, Chevrolet & Pontiac (B & D Bodies) Calif. & Fed. Courtesy of GENERAL MOTORS CORP.

VACUUM HOSE DIAGRAM(S) A/CL - Air Cleaner AIR CLR - Air Cleaner ACT - Actuator ASM - Assembly

BP - Back Pressure BRK - Break CCV - Canister Control Valve CC - Canister Control DIST - Distributor EAC - Electronic Air Control EAS - Electronic Air Switching EFE - Early Fuel Evaporation EGR - Exhaust Gas Recirculation EPR - Exhaust Pressure Regulator HVAC - Heating Ventilation A/C ILC - Idle Load Compensator MAP - Manifold Pressure Sensor MTR VAC - Vacuum Motor PCV - Positive Crankcase Ventilation RESTR - Restrictor SEC ACT - Secondary Actuator SOL - Solenoid SSC - Stepped Speed Control SW - Switch TBI - Throttle Body Injection TVS - Thermal Vacuum Switch VDV - Vacuum Delay Valve VRV - Vacuum Regulator Valve

VLV - Valve

WHEEL ALIGNMENT SPECIFICATIONS & PROCEDURES (RWD) 1986-92 WHEEL ALIGNMENT General Motors Corp. - Specifications & Procedures

ADJUSTMENTS NOTE:

Prior to performing wheel alignment, perform visual and mechanical inspection of wheels, tires and suspension components. See PRE-ALIGNMENT CHECKS article. For basic wheel alignment theory, refer to WHEEL ALIGNMENT THEORY/OPERATION article.

NOTE:

While performing following procedures, perform rear wheel alignment first to ensure proper front alignment angles. Corvette requires 4-wheel alignment.

CAMBER ADJUSTMENT Adjust front camber by adding or subtracting equal number of shims between both ends of upper control arm shaft and frame. See Fig. 1 . To adjust rear camber on Corvette, loosen lower spindle rod adjusting cam lock nut and bolt. Turn cam to obtain correct camber. See Fig. 1 . Tighten adjusting cam lock nut and bolt.

Fig. 1: Adjusting Front Camber & Caster Courtesy of GENERAL MOTORS CORP. CASTER ADJUSTMENT Caster is adjusted by transferring shims, from front to rear or rear to front, of the upper control arm shaft mounts and frame. See Fig. 2 . The difference between left and right caster should NOT be more than 1/2 degree. TOE-IN ADJUSTMENT (FRONT)

Loosen tie rod end adjusting sleeve clamp bolts. Turn center adjuster sleeve to adjust toe-in. See Fig. 2 . Ensure bolts are at bottom of tie rod and bolt head is facing forward. Tighten tie rod end adjuster sleeve clamp bolts.

Fig. 2: Adjusting Front Toe-In Courtesy of GENERAL MOTORS. CORP.

ALIGNMENT SPECIFICATIONS WHEEL ALIGNMENT SPECIFICATIONS Application Camber (Degrees) Front Camber (Degrees) Rear Caster (Degrees) Front Caster (Degrees) Rear Toe-In (Inches) Front Toe-In (Inches) Rear Toe-In (Millimeters) Front Toe-In (Millimeters) Rear Toe-In (Degrees) Front Toe-In (Degrees) Rear ° Toe-Out On Turns Steering Axis Inclination (SAI)

Preferred 0 ... 3 ... 0 ... 0 ... 0 ... N/A 12 1/2°

Range .5 to .5 ... 2 to 4 N/A -.1 to .1 ... -2.5 5o 2.5 ... -.2 to .2 ... *** ***

Wheelbase Inches Wheelbase Millimeters

121.5 3086

*** ***

TORQUE SPECIFICATIONS TORQUE SPECIFICATIONS Application Ball Joint-to-Control Arm Bolt & Nut Ball Joint-to-Knuckle Nut Brake Caliper Mount Bolts Brake Vibration Damper Bolt Control Arm Ball Joint (Rear) Control Arm Pivot Bolts (Rear) Control Arm Pivot Nuts (Rear) Front Crossmember Moutnting Bolt Hub and Bearing Retainer Bolt Hub-to-Drive Axle Nut Inner Rear Control Arm Bolt Insulator Mounting Bolts & Nuts Knuckle Pinch Bolt Knuckle Pivot Bolt Lower Control Arm-to-Crossmember Pivot Bolt Front Rear Lower Rear Strut Mounting Nuts Rear Spring Retainer Bolts Rear Stabilizer Bar Mounting Bolt Rear Stabilizer Bushing Clip Rear Stabilizer-to-Control Arm Bracket Rear Suspension Adjustment Link Inner Rear Suspension Adjustment Link Outer Tie Rod End-to-Knuckle Mount Nut Upper Rear Crossmember Mounting Bolt Upper Rear Strut Mounting Nuts Wheel Hub-to-Rear Knuckle

Ft. Lbs. (N.m) 50 (68) 81 (110) 38 (52) 21 (28) 7 (9) 125 (169) 85 (115) 66 (89) 70 (95) 180 (245) 66 (89) 21 (28) 40 (54) 59 (80) 140 (190) 90 (123) 144 (195) 21 (28) 43 (58) 37 (50) 13 (18) 63 (85) 37 (50) 41 (56) 66 (89) 65 (88) 52 (70)

POWER WINDOWS ACCESSORIES & SAFETY EQUIPMENT General Motors Power Windows

DESCRIPTION & OPERATION DESCRIPTION Reversible electric motors are located in each door. Each motor contains a circuit breaker and a self-locking gear drive. Individual switches are used for all passenger windows. The driver's door has a single, 4-button switch or 2 double-button switches. All models are grounded through the master or console switch. A junction block, located on left shroud, connects body power accessories to chassis wiring. Power window wiring harness plugs into the accessory block. A 30-amp circuit breaker mounted on fuse panel protects wiring for all power window systems. ALL MODELS Power windows are driven by reversible permanent magnet motors. Each motor is controlled by a switch with 2 sets of contacts that are normally closed to ground. With the power switch in the UP position, one set of contacts is closed, applying battery voltage to the power window motor. The remaining set of contacts remains closed, providing the ground to complete the circuit. With the power window switch in the DOWN position, the functions of the switches are revered and the motor runs in the opposite direction.

TROUBLE SHOOTING WINDOWS WILL NOT OPERATE No power at circuit breaker or master switch. Ignition off. Bad ground connection at master switch. Switch defective. INDIVIDUAL WINDOW DOES NOT OPERATE, ALL OTHERS OPERATE Defective motor. Open circuit in door. Defective window switch or master switch. INDIVIDUAL WINDOW DOES NOT OPERATE FROM WINDOWSWITCH, BUT OPERATES FROM MASTER SWITCH Open circuit in power feed wire. Window switch defective.

TESTING CIRCUIT BREAKER Check power feed to circuit breaker. Test power feed after circuit breaker. Repair as necessary.

MASTER CONTROL SWITCH Check for power at Pink wire. All other wires should have continuity to ground when switch is in rest position. Check for clean and tight ground connection. WINDOW CONTROL SWITCH 1. Connect test light between Pink wire in switch connector and ground. If light does come on, check power feed wire. Locate wires to motor. 2. Using jumper wire, connect Pink wire in switch connector between one motor wire and ground. Motor should operate. Reverse wires and retest. If motor operates properly, replace window control switch. If not, test motor. WINDOW MOTOR Connect power to one motor lead and ground other lead. Reverse connections and retest. If motor does not operate correctly in both directions, replace window motor.

REMOVAL & INSTALLATION CAUTION: On some models, motor can be removed separately from regulator only if window is intact and attached to regulator. If not, regulator MUST be removed first. Weight of door glass is needed to neutralize tension of counterbalance spring during motor removal. WINDOW MOTOR 1. Remove door trim pad and water deflector. On "B" and "D" bodies, place glass in full up position and tape in place. 2. On "K" bodies, lower the glass until regulator sash attaching bolts are in line with inner panel access hole. 3. Remove attaching bolts. On "K" bodies, remove front up stop through inner panel offset. Remove glass. Drill out motor attaching rivets and remove motor. 4. To install, reverse removal procedure. Use 3/16" rivets or bolts to attach regulator to motor. FRONT WINDOW MOTOR & REGULATOR WARNING: To prevent personal injury, before removing regulator and motor assembly, lock sector gear to back plate. Drill a 1/8" hole through sector gear and back plate, no closer than 1/2" from edge of sector gear. Install a metal screw (3/4" long) to lock gear, then remove motor. See Fig. 1 .

Fig. 1: Installing Lock Bolt to Window Regulator (Typical) Courtesy of GENERAL MOTORS CORP. Remove door trim and water deflector. Raise window and tape in raised position. Remove lower sash channel bolts. Punch out rivet center pins and drill out regulator rivets. Disconnect wiring, then remove regulator and motor. To install, reverse removal procedure. Secure regulator with "U" bolts and nuts. REAR DOOR WINDOW REGULATOR & MOTOR Tape glass in raised position. Remove lower sash bolts. Punch out rivet center pins and drill out rivets. Disconnect wiring and remove regulator and motor. To install, reverse removal procedure. Secure regulator with "U" bolts and nuts.

WIRING DIAGRAMS See appropriate chassis wiring diagram in WIRING DIAGRAMS.

WIPER/WASHER SYSTEM ACCESSORIES & SAFETY EQUIPMENT General Motors Wiper/Washer System

DESCRIPTION & OPERATION DESCRIPTION Models may be equipped with either the standard type system or the multiplex pulse wiper system. The standard system has 2 speeds for wiper operation. A single or steady wiping action can be obtained. On this system the electrical wiring for the motor and gearbox are internally routed through motor casting. On the multiplex pulse wiper system, the speed of the wiping action can be controlled. With wiper switch in DELAY mode, knob can be turned from MIN (minimum) to MAX (maximum) position to vary the amount of delay between the wiping operation. Delay ranges from zero to 12 seconds depending on position of knob. MIN delay or zero seconds between wipes provides equivalent of LO (low) speed continuous operation. This system can be identified by a single exposed Black/Pink wire to the timing circuit. See Fig. 1 .

Fig. 1: Multiplex Pulse Wiper Motor & Pump Assembly Courtesy of GENERAL MOTORS CORP. STANDARD SYSTEM

Standard systems consists of 2 speeds, either high or low. When washer button is depressed, wiper motor operates and drives the washer pump to deliver washer fluid to windshield as long as switch is depressed. MULTIPLEX PULSE SYSTEM The motor operation is controlled by the Wiper/Washer switch. The wiper/washer switch is a combination of switches and a variable resistor. The parking and pulse relays are used for motor operation. A timing circuit consisting of a capacitor, variable resistor and integrated circuit board are used to control the time that the pulse wiper operation exists. The washer system requires the use of 3 relays and a integrated circuit board containing resistors and capacitors for the operation of the piston type water pump.

ADJUSTMENTS WIPER ARM ADJUSTMENT - BROUGHAM 1. For left wiper arm adjustment, open hood and remove wiper arms. Loosen and raise left side of cowl vent screen. Loosen wiper transmission link-to-crank arm bolts. DO NOT remove bolts. See Fig. 13 . 2. Rotate right wiper arm so it is positioned 3/4" below ramp stops. Tighten wiper transmission link-to-crank arm bolts to 36-48 INCH lbs. (4-5 N.m). 3. Install left wiper arm on transmission spindle splines. Raise wiper arm slightly and slide lock to retain wiper arm. Position wiper blade on ramp stop on vent screen. 4. Place right wiper arm against ramp stop. Force wiper arm downward on transmission spindle splines. Raise wiper arm slightly and slide lock to retain wiper arm. Operate wipers and note cleaning pattern. The pattern at top of wiper blade should be 1.37" (34.7 mm) from the edge of windshield at the paint line and upper wiper blade overlap should be 1" (25 mm). NOTE:

Wiper patterns should be checked with a wet windshield and operating on low speed.

5. For right wiper arm adjustment, disengage wiper arm from transmission spindle splines. Reposition wiper arm on transmission spindle splines to obtain correct pattern. Install cowl vent screen. WIPER ARM ADJUSTMENT - ALL OTHERS Caprice, Custom Cruiser, Estate Wagon

1. Remove right wiper arm. Loosen wiper transmission link-to-crank arm nuts. DO NOT remove nuts. See Fig. 13 . Position left wiper arm slightly below stops. 2. Tighten wiper transmission link-to-crank arm nuts 66 INCH lbs. (7 N.m). Place right wiper arm slightly below stop and install wiper arm on transmission spindle splines. Lift wiper blades above stops. 3. Operate wipers and note cleaning pattern. The pattern at top of driver's wiper blade should be approximately .687" (17.44 mm) from edge of pattern to outer edge of the windshield. In the parked position, there should be .234" (5.94 mm) from edge of wiper blade to edge of windshield.

NOTE:

Wiper patterns should be checked with a wet windshield and operating on low speed.

ARMATURE END PLAY ADJUSTMENT Loosen adjusting screw lock nut. See Fig. 2 . Adjusting screw should be rotated until adjusting screw just contacts the armature. Back off adjusting screw 1/4 turn and tighten lock nut.

Fig. 2: Adjusting Armature End Play Courtesy of GENERAL MOTORS CORP. DRIVE GEAR ASSEMBLY END PLAY ADJUSTMENT End play should not exceed .005" (.13 mm) on Brougham models or be .004" +/- .002" (.10 +/- .05 mm) on all other models. Install proper shim washers to obtain correct end play. See Fig. 13 .

TROUBLE SHOOTING ON-VEHICLE NOTE:

Ignition must be on while performing all electrical tests. Determine wiper motor terminal identification. See Fig. 3 and Fig. 4 .

Wiper Inoperative Or Intermittent

Check for open in wire from wiper terminal No. 1 to wiper switch and wiper switch operation. See WIPER SWITCH & HARNESS under TESTING in this article. Check for loose wiper switch mounting. Ensure spray nozzle is not contacting wiper blade.

Fig. 3: Standard System Wiper Motor Terminal Identification Courtesy of GENERAL MOTORS CORP. Will Not Shut Off (Blades Make Full Wiper Stroke)

Check for defective wiper switch. See WIPER SWITCH & HARNESS under TESTING in this article. Check for grounded lead wire from wiper terminal No. 1 to wiper switch. Ensure wiper terminals are not corroded. Wipers Will Not Shut Off (Blades Move Up & Down Approximately 15 Degrees From Park Position)

Check for open in wire from wiper terminal No. 3 to wiper switch and wiper switch operation. See WIPER SWITCH & HARNESS under TESTING in this article. Check switch for loose mounting. Wiper Operates At High Speed Only

Check for open in wire from wiper terminal No. 3 to wiper switch and wiper switch operation. See WIPER SWITCH & HARNESS under TESTING in this article. Wiper Operates At Low Speed Only

Check for grounded wire from wiper terminal No. 3 to wiper switch and wiper switch operation. See WIPER SWITCH & HARNESS under TESTING in this article. Wiper Shuts Off With Blades Stopping In Wipe Area

Check for improper crank arm, crank arm rotated 180 degrees or defective crank arm-to-linkage adjustment. See WIPER ARMS under ADJUSTMENTS in this article. OFF-VEHICLE NOTE:

Check that wiper has low and high speeds and shuts off correctly.

Wiper Inoperative (Motor Does Not Run)

1. Check for open in relay switch coil, circuit breaker, armature, or the motor field. Ensure brushes are not binding. 2. Check for loose or defective solder joints at relay switch. Check for binding of relay switch latch arm or bent relay switch contact. Wiper Won't Shut Off (Crank Arm Rotates 360 Degrees)

Check for grounded relay switch coil. Check for faulty or disconnected relay switch latch arm spring. Ensure relay switch latch arm is not binding and proper gap exists. Wiper Will Not Shut Off (Accompanied By A Loud Knock)

Check for shorted switch contacts or disconnected drive pawl spring. Check for open shunt field, causing wiper to have high speed only. Wiper Has High Speed Only

Check for open shunt field, loose or defective solder joints at No. 3 terminal of relay switch and terminal board. Wiper Has Low Speed Only

Check for internally grounded shunt field, grounded terminal board or shorted armature. Ensure shunt field lead to the relay switch is not grounded. Wiper Has Excessive Speed In High (Low Speed Normal)

Check for open circuit in 20-ohm resistor or poor resistor ground connection. Wiper Stops At Random W/No Return To Park Position

Check for dirty or defective relay switch contacts. Intermittent Operation

Check for defective or weak circuit breaker or sticking brushes. Check for circuit breaker tripping caused by shorted armature and/or shorted fields causing excessive motor draw. Check for sticking brushes. No Apparent Trouble On Bench Test But Fails Occasionally On Vehicle

Check for tight armature or drive gear assembly end play. Ensure no loose or defective solder joints exist. Ensure wiper switch mounting is tight. MULTIPLEX PULSE WIPER SYSTEM TESTS NOTE:

Ignition must be on while performing all electrical tests. Determine wiper motor terminal identification. See Fig. 4 .

Fig. 4: Multiplex Pulse System Wiper Motor Terminal Identification Courtesy of GENERAL MOTORS CORP. Wipers Inoperative

1. Ensure wiper switch is in OFF position. With ignition switch on, check for voltage at wiper motor terminal No. 2. Refer to Fig. 4 . If no voltage exists, check for blown fuse. If fuse is okay, check for open circuit between fuse block and wiper motor. If fuse was blown, replace fuse. 2. If fuse blows again, check wiper motor for high amperage draw or short in wire to terminals No. 2 and 5. See Fig. 4 . If voltage exists, touch test light probe to wiper terminal No. 1. See Fig. 4 . If wipers operate, check for open circuit in wire between terminal No. 1 and wiper switch or for defective wiper switch. 3. If wipers fail to operate, place wiper switch in the LOW position. Touch probe to terminal No. 6. See Fig.

4 . If wipers operate, check for open circuit in wire between terminal No. 6 and wiper switch or defective wiper switch. 4. If wiper fails to operate, disconnect wiring connector and remove washer pump cover. Reinstall wiring connector. Place wiper switch in the LOW position. Ground test light and check for voltage at the Red wire at pulse relay. See Fig. 5 . 5. If no voltage exists, check connection to wiper terminal No. 1 or for open in Red wire to pulse relay. Replace park relay if connections are okay and no open exists.

Fig. 5: Testing Wiper Motor Pulse Relay Courtesy of GENERAL MOTORS CORP. 6. If voltage exists, ground test light and touch probe to Orange wire terminal at pulse relay. If wiper operates, replace timing circuit board assembly. 7. If wiper does not operate, check for voltage at Pink/Black wire terminal of the pulse relay. Replace pulse relay if no voltage exists. If voltage exists, repair or replace wiper motor. Wipers Won't Shut Off (Blades Operate In Normal Pattern)

1. Try wipers in delay mode. If wipers do not delay between wipes, proceed to step 3). If wipers delay, turn ignition on. Place wiper switch in the OFF position. Remove wiper motor wiring connector.

2. Connect test light between terminals No. 1 and 2 of wiring connector. See Fig. 6 . If no voltage exists, remove washer pump assembly. Check park relay spring. If spring is okay, replace park relay. If voltage exists, check for grounded wire between wiper switch and terminal No. 1, or defective wiper switch. See, under TESTING in this article, WIPER SWITCH & HARNESS . 3. Place wiper switch in the OFF position. Turn ignition off and then on. If wipers do not shut off, check that override switch contacts are opened by projection on rim of ratchet gear. See Fig. 7 .

Fig. 6: Wiring Connector Terminal Identification Courtesy of GENERAL MOTORS CORP.

Fig. 7: Checking Override Switch Contacts Courtesy of GENERAL MOTORS CORP. 4. If contacts are open, check for grounded Blue wire. If contacts are closed, check for loose timing circuit attaching screw. If okay, adjust contacts or replace timing circuit assembly. 5. If wipers shut off with blades properly positioned, check holding switch contacts. See Fig. 8 . Adjust contacts as necessary. Replace timing circuit assembly if holding switch contacts are okay.

Fig. 8: Checking Holding Switch Contacts Courtesy of GENERAL MOTORS CORP. Low Speed Only (Operates In Delay Mode & Shuts Off Correctly)

1. Turn ignition on. Place wiper switch in the HIGH speed position. Remove wiper motor wiring connector. Note connector terminal identification. See Fig. 6 . Connect test light between terminals No. 2 and 3 and check for voltage. 2. If no voltage exists, wiper motor must be repaired. Check for ground in shunt field. If voltage exists, check for grounded wire of No. 3 terminal and wiper switch. If no ground exists, check for defective wiper switch. See WIPER SWITCH & HARNESS under TESTING in this article. Wiper Has High Speed Only (Will Not Delay Between Wipes)

1. Note wiper motor wiring connector terminal identification. See Fig. 6 . Check for proper contact at No. 3 terminal of wiper motor connector. If connection is okay, install a jumper wire from terminal No. 3 to ground with wiring wiper motor connector installed. If condition still exists, remove motor and check shunt field for an open circuit. 2. If low speed now exists and then shuts off, check wire between terminal No. 3 and switch for an open. If no open exists, check for defective wiper switch. See WIPER SWITCH & HARNESS under TESTING in this article. Blades Cycle In & Out Of Park (When Wiper Is Shut Off)

1. Note wiper motor wiring connector terminal identification. See Fig. 6 . If wiper has high speed only, check for proper contact at No. 3 terminal of wiper motor connector. If connection is okay, proceed to step 2). If wiper has high and low speeds, replace park relay. 2. If connection is okay, install a jumper wire from terminal No. 3 to ground with wiper motor wiring connector installed. If condition still exists, remove motor and check for open in shunt field. 3. If low speed now exists and then shuts off, check wire between terminal No. 3 and switch for an open. If no open exists, check for defective wiper switch. See WIPER SWITCH & HARNESS under TESTING in this article. Wipers Run Continuously (Delay Mode - No Delay Between Wipes)

1. Turn ignition on and operate wipers at low, medium and high speeds. Ensure wipers shut off correctly. If wipers operate in high speed only or will not shut off, proceed to appropriate test. 2. If wipers operate properly, but do not delay between wipes, operate wipers in the mid-delay position. Disconnect lead from the No. 6 terminal. See Fig. 4 . If wipers continue to operate, proceed to step 3). If wipers stop, proceed to step 4). 3. Disconnect wiring connector and remove washer pump cover. Reinstall wiring connector. Operate wipers continuously in the delay mode and disconnect lead to timing circuit from pulse relay. Replace timing circuit assembly if wipers stop. Replace pulse relay if wipers continue to operate. 4. If wipers stop, check for grounded circuit between terminal No. 6 and wiper switch. If okay, replace wiper switch. Wipers Inoperative In Delay Mode (Wipers Function Only In Low Or High Speed)

1. Disconnect washer pump relay wiring connector with wiper switch in mid-delay. See Fig. 4 . Using an ohmmeter, connect one ohmmeter lead to the No. 6 terminal wire of the connector and the other lead to ground. See Fig. 6 . 2. Adjust ohmmeter to the Megohm scale and check for resistance. Replace wiper switch if no resistance exists. Replace timing circuit assembly if resistance exists. Intermittent Wiper Operation (Blades Stop At Random Positions With Wiper Switch In Low Or High Positions)

1. Remove wiper fuse. Install a 0-30 ammeter across fuse block terminals. Operate wipers in low speed and note the lowest current draw (current draw will fluctuate). 2. If lowest current draw exceeds 6.5 amps, proceed to step 3). If lowest current draw is 5-6.5 amps, repair wiper motor by replacing brush plate and circuit breaker assembly.

3. Replace wiper blade elements and repeat test. If lowest current draw still exceeds 6.5 amps, disconnect wiper linkage for wiper motor and repeat test. If current draw is okay, repair or replace binding wiper transmission linkage. Replace wiper motor if current draw still exceeds 6.5 amps. STANDARD WIPER SYSTEM TESTS Wiper Inoperative

1. Remove washer pump to gain access to relay switch and terminal board assembly. Using jumper wire, connect 12-volt power source to No. 2 terminal of wiper motor. See Fig. 3 . Connect jumper wire from wiper motor housing to ground. DO NOT connect jumper to terminal No. 1 and terminal No. 3. 2. To determine if relay switch coil is open, connect test light to wiper terminal No. 1. See Fig. 3 . Voltage should exist. Also test relay switch. Relay Switch Test

1. If gear mechanism is in full-park position, install a small screwdriver into switch slot between drive pawl and latch arm. Push latch arm downward and toward relay switch coil in direction of arrow. See Fig. 3 . 2. Remove washer pump assembly. Using test light, check for voltage at Black/Pink wire. If voltage exists, but motor does not operate, proceed to step 3). If voltage does not exist, relay switch and terminal board are defective. 3. Disassemble motor section. Check for binding brushes, defective solder connections at brush holders, defective splice joints at field coil, open armature, defective circuit breaker ground connection on field lamination. Check for dirty or defective circuit breaker contacts or loose connections at circuit breaker terminals. Wiper Won't Shut Off (Crank Arm Rotates 360 Degrees)

1. Ensure latch arm spring is properly connected. Manually operate latch arm and check for binding. See Fig. 3 . 2. Using jumper wire, connect 12-volt power source to the No. 2 terminal of wiper motor. See Fig. 3 . Connect jumper wire from terminal No. 3 to wiper motor housing. DO NOT make any connections from terminal No. 1. 3. Wiper motor should start to operate when connections are made. If motor operates and continues to run, relay switch and terminal board assembly must be replaced as the coil is internally grounded. Wiper Will Not Shut Off (Recycles)

1. Crank arm oscillates in a horizontal plane and a loud knock is heard with each revolution of gear. Ensure drive pawl and latch arm springs are connected properly. 2. Check wiper for low speed operation. Using jumper wire, connect 12-volt power source to No. 2 terminal of wiper motor. See Fig. 3 . Connect jumper wire from terminal No. 1 to terminal No. 3 and to wiper motor housing. 3. If no low speed exists and only has high speed, check for defective connections at terminal No. 3, field coil crossover splice or Black lead to field coil. 4. To check relay switch and terminal board, remove washer pump assembly to gain access to Black/Pink

wire. Connect positive side of power source to terminal No. 2. See Fig. 3 . Connect ground wire to wiper motor housing. Install jumper wire from terminal No. 1 to wiper motor housing. 5. Using test light, check for voltage at the Black/Pink wire. Note if test light shows constant voltage or if light goes out once for each revolution of the gear. 6. If constant voltage exists, relay switch contacts are not opening and switch is defective. Relay switch is good if light went out each time drive pawl moves into relay switch slot. Wiper Has Only Low Speed

Check for grounded area in Black lead to No. 3 terminal. See Fig. 3 . Disassemble motor section of wiper and check for grounded shunt field coil. Excessive Speed In High (But Low Speed Is Normal)

Check for open circuit in 20-ohm resistor. Intermittent Operation

1. Check for loose connections at relay switch and terminal board. Check wiper for low speed operation. Using jumper wire, connect 12-volt power source to the No. 2 terminal of wiper motor. See Fig. 3 . Connect jumper wire from terminal No. 1 to terminal No. 3 and to wiper motor housing. 2. Connect a 0-30 amp ammeter in power wire to wiper motor. Operate motor and note current draw. Motor should operate until the motor is hot. If current draw is less than 4 amps on low speed and wiper cycles on and off, the circuit breaker is defective. Replace brush plate assembly. If current draw exceeds 4 amps, adjust armature end play and recheck current draw. See ARMATURE END PLAY under ADJUSTMENTS in this article. 3. Adjust drive gear assembly end play. See DRIVE GEAR ASSEMBLY END PLAY under ADJUSTMENTS in this article. Check current draw. If excessive current draw still exists, disassemble wiper motor and checked for grounded armature. MULTIPLEX PULSE WASHER SYSTEM TESTS Washer System Inoperative

1. With ignition on, remove washer pump relay wiring connector from washer pump terminals No. 4 and 5. See Fig. 4 . Using test light, check for voltage at terminals No. 4 and 5. See Fig. 6 . If no voltage exists at both terminals, check for open in feed circuit to washer relay from No. 2 terminal of wiper motor connector. 2. If voltage exists, connect test light between terminals No. 4 and 5 and push the wash button. If no voltage exists, check for open in wire to wiper switch or a defective switch. 3. If voltage exists, reconnect wiring to terminals No. 4 and 5. Using test light, check voltage at terminals No. 4 and 5. Replace washer relay if no voltage exists on one terminal. 4. If voltage exists on both terminals, disconnect wiring connector and remove washer pump cover. Reconnect wiring and operate wipers in low speed. Observe movement of ratchet pawl. See Fig. 9 . If ratchet pawl fails to move, check for binding of cam-follower pin. Replace washer pump if binding exists.

Fig. 9: Multiplex Pulse System Washer Pump Components Courtesy of GENERAL MOTORS CORP. 5. If ratchet pawl moves back and forth, depress washer button. Note if ratchet gear rotates. Replace valve assembly if ratchet gear rotates. If problem still exists, replace piston and pump housing assembly. If ratchet gear failed to rotate, check for missing or improperly connected ratchet pawl spring or ratchet dog spring not engaging ratchet gear teeth. See Fig. 9 . Windshield Washer Will Not Shut Off

1. With ignition on, remove washer pump relay wiring connector from washer pump. See Fig. 4 . Using test light, check for voltage at terminals No. 4 and 5. See Fig. 6 . If voltage exists, check for grounded wire between washer connector and wiper switch or a defective wiper switch. 2. If no voltage exists, disconnect wiring and remove washer pump cover. Reconnect wiring to wiper

terminals to re-establish condition. Note location of relay armature leg. If relay armature leg is on the ramp, check that ratchet dog spring engages with ratchet gear teeth. Check for excessive wear on ratchet gear teeth and ratchet pawl spring missing or not properly connected. See Fig. 10 . 3. If relay armature leg is on rim slot area, check for loose pole piece on washer relay or burr on relay armature leg. See Fig. 10 .

Fig. 10: Checking Relay Armature Leg Positioning Courtesy of GENERAL MOTORS CORP. Washer Squirts Twice & Wipers Shut Off

Check that override switch contacts are clean and properly closing when wash cycle is started. See Fig. 7 . Clean or adjust as necessary. Wipers Remain In Delay Mode (Washer Started From Delay Mode)

Check that override switch contacts are clean and properly closing when wash cycle is started. See Fig. 7 .

Clean or adjust as necessary. STANDARD WASHER SYSTEM TESTS Washers Inoperative

1. Check for following: Inadequate fluid supply, damaged or kinked hoses, restricted screen at reservoir hose, loose electrical connections to washer pump or wiper switch and open circuit in feed wire to ratchet relay coil. 2. Check for defective wiper switch or ratchet relay coil, plugged washer nozzle, missing ratchet gear teeth or ratchet pawl spring. Check for defective pump valve assembly or stuck cam-follower pin arm. Washer Pumps Continuously (With Wipers Operating)

Check for grounded wire from ratchet relay to wiper switch. Check for defective wiper switch, missing ratchet gear teeth, missing or weak spring tooth or broken ratchet wheel dog or no contact with ratchet gear teeth. Ensure lock-out tang is not broken or bent on piston actuator plate. WIPER SWITCH & HARNESS TEST 1. Check for proper wiring connections at relay switch, terminal board and wiper switch. Ensure wiper motor retaining bolts are tight and wiper switch is securely mounted. 2. Remove wiper motor connector. With ignition on, use test light and check for voltage at No. 2 terminal of switch harness. See Fig. 6 . If no voltage exists, check for defective power supply. 3. To check remaining terminals, connect test light to a 12-volt power supply and probe the 2 outside terminals. Place wiper switch in the LOW position. Check that voltage exists at either outside terminal. 4. Place wiper switch to the HIGH position. Voltage should exist at one outside terminal only. With wiper switch in the OFF position, voltage should exist at the opposite outside terminal only. Check relay wiper switch if wiper switch and harness are okay. RELAY WIPER SWITCH TEST Ensure wiper motor is well grounded. Connect jumper wire from battery source to Black/Pink wire of wiper motor. If wiper motor now operates, and not when wiper switch is used, the relay switch is defective. Wiper motor is defective if motor fails to operate.

REMOVAL & INSTALLATION WIPER TRANSMISSION Removal

1. Raise hood. Remove wiper blade arms. Remove lower windshield reveal molding and cowl vent screen. Place large screwdriver between drive link and crank arm. Twist to disengage link retainer. 2. Remove transmission-to-body bolts. Remove transmission and linkage assembly by guiding it through chamber opening.

Installation

To install, reverse removal procedure. Install wiper arm assemblies and adjust wiper arms. See WIPER ARMS under ADJUSTMENTS in this article. Check wiper operation, wiper pattern and park position. TIMING CIRCUIT 1. To remove, position wiper arms in vertical position and disconnect negative battery cable. Disconnect wiper motor and washer relay wires. 2. Remove washer pump cover. Remove pulse relay and timing circuit board retaining screw. Disconnect motor leads from relay terminals and remove timing circuit. To install, reverse removal procedure. RELAY WIPER SWITCH (TERMINAL BOARD) Removal

1. Remove washer pump from gearbox. See appropriate WASHER PUMP in this article. Note if drive pawl is in full-park position. See Fig. 12 . If drive pawl is in full-park position, wiper motor must be operated to move pawl out of relay slot. 2. Connect battery voltage to No. 2 terminal of wiper motor. See Fig. 3 and Fig. 4 . Connect jumper wire from terminal No. 1 to wiper motor housing. 3. This will operate motor on the low speed. Operate until wiper gear drive pawl is moved out of the relay slot. If motor will not operate, remove gear mechanism. 4. Remove relay screw and remove terminal board assembly from gearbox. Unsolder Black lead from relay terminal and remove terminal board.

Fig. 11: Removing & Installing Wiper Motor Drive Gear Courtesy of GENERAL MOTORS CORP. Installation

To install, reverse removal procedure. Operate wiper to park position and install washer pump. During relay installation in gearbox, ensure wiring leads are not pinched between relay and housing.

Fig. 12: Drive Pawl Positioning Courtesy of GENERAL MOTORS CORP. DRIVE GEAR Removal

1. With wiper motor gearbox removed, place crank arm in vise. Remove crank arm retaining nut, crank arm, rubber seal cap, retaining ring, shim washers, shield and spacer washer. See Fig. 13 . 2. Remove drive gear assembly from wiper motor housing. If relay switch terminal board assembly has not been removed, position relay latch arm out of the way. 3. Slide drive plate and shaft assembly out of gear and tube. See Fig. 11 . Remove drive pawl, lock pawl and coil spring. Retain inside spacer washer for reassembly.

Fig. 13: Crank Arm & Components Courtesy of GENERAL MOTORS CORP. NOTE:

Replacement drive plate and shaft assembly contain 2 retaining ring grooves. Service part instructions will indicate proper groove usage.

Installation

1. Position drive and lock pawls in drive plate. Install drive gear and tube over drive plate shaft. Move drive and lock pawls to pins to engage in the drive gear guide channel. 2. Hold drive gear and rotate drive plate in proper direction until drive and lock pawl pins engage into drive gear pockets. See Fig. 11 . Install pawl spring. 3. Install inner spacer washer over drive gear tube. Reassemble drive gear mechanism in gearbox. Ensure drive gear assembly does not come apart during installation. 4. Install spacer washer, shield, shim washers and retaining ring. Note drive gear assembly end play. End play should not exceed .005" (.13 mm) on Brougham models or be .004"+/-.002" (.10+/-.05 mm) on all other models. Install proper shim washers to obtain correct end play. See Fig. 13 . 5. Connect battery voltage to No. 2 terminal of wiper motor. See Fig. 3 and Fig. 4 . Connect jumper wire from terminal No. 3 to wiper motor housing. Operate motor to park position. Install crank arm on shaft in proper direction. See Fig. 13 . 6. Install crank arm retaining nut and tighten to 25 ft. lbs. (34 N.m). Install washer pump to gearbox. BRUSH PLATE & CIRCUIT BREAKER

Removal

1. Place mark on motor case for reassembly reference. Remove motor through bolts. Pull motor wiring through casting grommet. 2. Move motor end case with field assembly and armature backward until armature clears the bearing. It may be necessary to remove armature end play adjusting screw and insert a rod through opening to apply pressure against end of armature. See Fig. 2 . 3. Note all wire routing. Unsolder Black lead from circuit breaker. Straighten out brush plate-to-field coil bracket retaining tabs. Install "U" shaped brush retainer clip over brush holder containing the brush lead attached to circuit breaker. 4. Hold remaining brush outward and lift brush holder upward far enough to clear armature commutator. Allow brush to move outward and remove brush spring. Remove brush holder from armature. Installation

1. Position partially assembled brush plate over armature far enough for installation of remaining brush in brush holder. Install brush holder over mounting tabs. 2. Ensure brush holder is centered and bend tabs toward brush holder. DO NOT bend or distort metal brush holders. Remove brush retainer clips. Resolder circuit breaker ground lead to circuit breaker. WASHER PUMP MOTOR ARMATURE 1. To remove, remove brush plate and circuit breaker as previously described. Lift armature from motor case and field assembly. Remove thrust ball from end of armature. 2. To install, reverse removal procedure. Lubricate bearing end of armature with Multipurpose (EP-1) grease prior to installation. Install armature in motor case. Start armature shaft through case bearing until it begins to mesh with drive gear teeth. 3. Pull excess wire leads through the grommet. Rotate armature slightly to align armature with drive gear teeth and install. Install brush assembly. MOTOR CASE & FIELD ASSEMBLY Removal

1. Remove brush plate and armature as previously described. End case and field assembly is serviced as a unit. Cut the field wire in convenient area for splicing. 2. Remove felt lubricating washer, steel thrust plate and rubber disc from case bearing. Installation

To install, reverse removal procedure. Ensure wires are spliced back in correct location. WASHER PUMP (STANDARD SYSTEM) Removal

Disconnect hoses from washer pump and wiring from pump relay. Remove washer pump cover. Remove washer pump-to-gearbox retaining bolts and remove washer pump. NOTE:

Ensure sure gearbox is in park position prior to installing washer pump. See Fig. 12 .

Installation

1. Wiper motor must be in the park position prior to installing washer pump. See Fig. 12 . Rotate cam lobe until index hole in cam is aligned with mounting plate. Install locator pin through pump cover and into hole of cam. See Fig. 12 . 2. Install washer pump on wiper motor so drive pin slot of cam lobe aligns over drive pin. See Fig. 12 . Install washer pump bolts. Remove locator pin and install wiring connector. Check operation. If knocking noise is heard, this indicates cam is not properly engaged. Install pump cover. WASHER PUMP (MULTIPLEX PULSE SYSTEM) Removal

1. Remove washer cover. Disconnect Green wire. See Fig. 14 . Disconnect Yellow and Red wires from pulse relay terminals. Unsolder Black/Pink wire from remaining relay terminal. See Fig. 14 .

Fig. 14: Multiplex Pulse Relay Terminals Courtesy of GENERAL MOTORS CORP. 2. If only pump assembly is being removed with wiper motor on the vehicle, cut Black/Pink wire 4" (102 mm) from motor grommet. Depending on repair required, it may be necessary to splice this lead to replacement lead or to original relay lead after pump is installed. Remove pump-to-gearbox retaining screws and remove washer pump. NOTE:

Ensure gearbox is in park position prior to installing washer pump. See Fig. 12 .

Installation

Install locator pin in pump assembly while rotating cam counterclockwise. See Fig. 12 . Install pump on gearbox and install retaining screws. Remove locator pin. Reconnect electrical leads. Install washer cover. Reinstall wiper in vehicle (if removed).

WIRING DIAGRAMS See appropriate chassis wiring in WIRING DIAGRAMS.

WIRING DIAGRAMS Wiring Diagrams General Motors Corporation

IDENTIFICATION COMPONENT LOCATION MENU COMPONENT LOCATIONS Component A/C Cutout Relay A/C Electronic Climate Control (ECC) Head A/C ECC Power Module A/C ECC Programmer ABS Control Module Accessory Relay Panel ALDL Conn Alternator Anti-Diesel Solenoid Automatic Door Lock Controller Automatic Transmission Battery Brake Switch Chime Module Cigarette Lighter Coolant Temp Sensor Cruise Control Module Cruise Control Switch Defogger Grid Dir/Hazard Switch Door Handle Switches Door Latch Switches Door Lock Cylinder Switches Door Lock Relay Door Lock Switches Door Switches ELC Compressor Assembly ELC Height Sensor ELC Relay Electronic Control Module (5.0L VIN Y) Electronic Control Module (5.7L VIN 7) Electronic Spark Control Module

Figure No. (Location) 6 (B 22) 6 (A-B 20) 6 (B 23) 6 (A 23) 6 (D-E 20) 4 (C 12-15) 2, 3 (B 4, B 11) 1 (A 1) 2 (D 7) 9 (C 35) 2, 3 (B 7, C 11) 1 (A 2) 6 (C 21) 7 (B 24) 5, 10 (E 16-17, D 36) 6 (A 21) 6 (E 22-23) 6 (C 23) 4 (E 14) 7 (C-D 24-25) 7 (D-E 27) 8 (B 30) 9 (B-C 34) 9 (A 35) 9 (A 33) 9 (C-D 32-33) 1 (D 3) 1 (E 2-3) 4 (C 12) 2 (A 4-6) 3 (D 8) 2, 3 (A 4, E 10)

Engine Oil Pressure Switch EST Distributor Fuel Injectors Fuel Pump Relay (VIN 7) Fuel Pump/Oil Pressure Switch Fuel Tank Unit Fuse Block Fusible Links Gear Selector Switch High Level Stop Light Horn Relay Horns Ignition Key Warning Switch Ignition Switch Lock Enable Relay Opera Light Overvoltage Protection Relay Park/Neutral Relay Passive Restraint Module Power Antenna Relay Power Mirror Switches Power Seat Switch Power Window Switches Seat Recliner Switch Sentinel Amplifier Speed Sensor Buffer Start Interrupt Relay Starter Solenoid Stop Light Switch Sunroof Switch Sunshade Visor Support Theft Deterrent Controller Theft Deterrent Relay Trailer Conn Trunk Light Switch Trunk Pulldown Unit Trunk Release Switch Vanity Mirror Wiper/Washer Assembly Wiper/Washer Switch

8 (A 29) 2, 3 (E 4, E 9) 3 (D 11) 3, 4 (A 8, C 13) 3 (A 11) 8 (B 29) 5 (C-D 17-18) 1 (A-B 2-3) 4 (A 12-14) 10 (C 39) 4 (C 12) 1 (C 1) 7 (B 24) 7 (A-D 27) 9 (D 35) 10 (C 36) 6 (C-D 20) 4 (C 14) 8 (B 31) 4 (C 12, E 13) 9 (E 35) 8 (D 28) 10 (A-C 36-38) 8 (C 29-30) 7 (A 25) 4 (A 15) 4 (C 13) 1 (B 3) 7 (E 24) 10 (C 36) 8 (E 29-30) 9 (A 32-33) 9 (B-C 32) 10 (D 38) 10 (D 36) 10 (E 36-37) 10 (D 36) 8 (D 31) 1 (B 2) 8 (A 30-31)

WIRING DIAGRAMS

Fig. 1: Engine Compartment & Headlights (Grid 1-3)

Fig. 2: Electronic Control Module (5.0L VIN Y) (Grid 4-7)

Fig. 3: Electronic Control Module (5.7L VIN 7) (Grid 8-11)

Fig. 4: Accessory Relay Panel & Fuse Block (Grid 12-15)

Fig. 5: Fuse Block (Grid 16-19)

Fig. 6: A/C-Heating, Cruise Control & ABS Module (Grid 20-23)

Fig. 7: Sentinel Control & Illuminated Entry Timer (Grid 24-27)

Fig. 8: Instrument Cluster (Grid 28-31)

Fig. 9: Theft Deterrent Controller (Grid 32-35)

Fig. 10: Passenger Compartment & Taillights (Grid 36-39)

System Wiring Diagrams Cadillac - Brougham

DEFOGGERS

Fig. 1: Defogger Circuit

HORN

Fig. 2: Horn Circuit

POWER ANTENNA

Fig. 3: Power Antenna Circuit

POWER DOOR LOCKS

Fig. 4: Power Door Lock Circuit

POWER MIRRORS

Fig. 5: Automatic Day/Night Mirror Circuit

Fig. 6: Power Mirror Circuit

POWER SEATS

Fig. 7: Driver Power Seat Circuit

Fig. 8: Passenger Power Seat Circuit

Fig. 9: Recliner Circuit

POWER WINDOWS

Fig. 10: Power Window Circuit

RADIO

Fig. 11: Radio Circuits

STARTING/CHARGING

Fig. 12: Charging Circuit

Fig. 13: Starting Circuit

TRUNK, TAILGATE, FUEL DOOR

Fig. 14: Trunk Pull-Down Circuit

Fig. 15: Trunk Release Circuit

WIPER/WASHER

Fig. 16: Wiper/Washer Circuit