ISSUE 1 | JULY/AUGUST 2024
CASE STUDY
EN GARDE I am challenging the status quo to look at getting certified from a different perspective.
AND MORE! 1
Table of Contents 3 Editors Notes 4 8 12 14 16 19 21
Case Study: Voltage Drop Mechanic vs Technician
Head to Head tool review
Tech Tip of the Month
Smart Charge Generators En Garde
Four keys to Effective Diagnostic strategy
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EDITOR’S NOTE Greetings to all, I want to extend my deepest gratitude to everyone who takes the time to read the content on these pages. As an Automotive technician with over 8 years of professional experience, this publication will feature case studies, anecdotal stories, informative articles, and the occasional interview. I hope it will entertain, inform, and provide value to automotive industry professionals.
Author L.E.G.A.C.Y DRIVE
Marcus Johnson
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First off what is it? It is a diagnostic technique every automotive technician should have in their arsenal. In my early years, I considered it a hip catchphrase that only YouTube mechanics said to get views. Even the concept of fully grasping why it should be something an automotive technician studies eluded me. Eventually, I did a little digging and attended quite a few different OEM classes at various dealerships. That changed my perspective and I became determined to take my diagnostic skills to another level. To understand voltage drop, it is essential to clearly define Open Circuit Voltage. This refers to the voltage available at the point being tested with no current flowing through the circuit. Testing with current flowing through a circuit allows us to measure voltage drops due to connection, wiring, and load resistance issues. The voltage drop is the amount of voltage used to propel current through a resistance. Alternatively, it can be defined as the difference between the voltage on one side of the resistance and the voltage on the other side of the resistance. To simplify this even more resistance can be a wire, switch, connector, or the load /component itself. Anything that current must travel through to complete a path to ground.
Practical Application As my scan tool conducted an initial once over of all the ECUs in the vehicle, my analytical mind roared to life, taking in any physical cues that could help me create a decent diagnostic approach. The anticipation of finding out what was at fault for causing these issues made my skin prickle up with goosebumps. So I hurried back to my scan tool picking it up out of the driver's seat. There, I found an extensive list of over 40 diagnostic trouble codes, both historical and current. After saving this scan and clearing everything out of the Rav 4 to get a fresh start only three trouble codes returned. C146D ABS Motor relay circuit short stored in the ABS unit as active, B1507 Turn signal circuit open stored as active in the instrument cluster. I put the tablet back down and then I thought, "Man, this thing has a ton of DTCs for that ABS module. I wonder if anyone's messed around in that area before." Leaning over the driver-side fender with my pocket flashlight clenched between my teeth after manipulating a part of the engine harness. I could now see some wires going to the ABS unit soaked in brake fluid.
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Hmm, what do we have here? Two brake fluid-soaked splices on the same wire and a new ABS unit. "This is becoming more and more interesting by the minute." It's time to pull up a schematic. I need to know the function of the wires soaked in brake fluid. Minutes later it becomes clear as to what is going on here the left headlamp assembly and the abs module share a chassis ground.
The circuits soaked in brake fluid, especially the one with two splices, is a ground wire.
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I grabbed my DMM and placed it across all the ground wires going to the left headlamp assembly. Why is there a 0-11v pulse on three of the ground wires going to the left headlamp? I muttered to myself.
A quick voltage drop test on the left fog lamp reported the same results. A dim and flickering left headlamp assembly, fog lamp, and a ground wire where brake fluid has penetrated splices on the ABS Unit. Creating excessively high resistance on a ground circuit shared by over 10 modules that all had history codes for no communication to the ABS Unit.
I encountered a challenge putting all the pieces together internally, but addressing this issue was another hurdle. I cut the 3 wires with the pulsing 8v and installed new ground leads to the chassis. After that, I ran a new lead from the ABS Unit to its intended ground location in the driver fender area. When the moment of truth arrived, I put the vehicle back in a key-on engine off state and the operation was a success. The left headlamp and fog lamp assemblies both had the same intensity as the right. Another voltage drop test showed less than .200mv on all ground circuits that previously had an 8v pulse. A final scan reported no DTCs in any modules on the vehicle.
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LEGACY DRIVE
THE FUTURE STARTS NOW
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MECHANIC VS TECHICIAN These terms are as interchangeable to the average consumer as tomayto tomato but they are indeed quite different describing two different positions in the same industry. In fact, in some cases, they can even complement each other too. ECUs
The average vehicle from 1978 to 1996 had anywhere from 1 electronic control unit up to 12. Today if you pull up any schematic a vehicle can have 100 to over 150 electronic control units. They all receive information from various sensors reporting the current status or physical state of components. Communicating with each other over numerous data networks throughout the vehicle. Depending on the manufacturer and era the vehicle was developed the physical network could be PCI, LIN, K LINE, CAN BUS, CAN FD, EITHERNET, MOST, FIBRE OPTIC, etc. Using thousands to possibly millions of lines of coding to instruct these modules to perform a great many tasks in an automobile.
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To take this a step further, these ECUs, along with actuators, are responsible for controlling or monitoring the data in various systems. In previous years, there was a focus on the engine control unit but in most vehicles today there is the Powertrain, Antilock Brake, Drivetrain, Suspension, and HVAC Systems. Now within those 5 systems can be numerous modules with various tasks they are responsible for accomplishing. During this natural progression from mechanical control systems to electronic controlled systems. A new title was birth to define a more progressive role in the automotive industry. Which entails a different level of disciplined study. Certifications and employment along with high-caliber tools to diagnose more complex customer concerns The Difference, Let's Examine it Consider this as a question, what is the difference between a nurse practitioner and a doctor? Both are in the medical field and both require training. The obvious is one requires more extensive training than the other and a different level of certifications combine with clinicals of course. Now let us take this and frame it with the difference between an Automotive mechanic and an Automotive technician. Both are in the automotive field and both require training.
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The automotive technician in the United States typically has some form of original equipment manufactured (OEM) certification, trade school, or college degree. Hours upon hours of classroom and hands-on training that is continuous with their chosen field/ OEM and some choose to become specialists. Who focus on Powertrain, Electrical, and Chassis to name a few with some overlap between these areas. As mentioned earlier with the evolution from mechanical to electronic controlled systems a birth in diagnostic technology took place too. This means people had to be trained on how to properly interpret and apply the data being gathered from different diagnostic software and tools. The OG (original) An Automotive Mechanic has years of training too but typically speaking their training did not begin in a classroom or lab environment. These guys were getting hands-on experience and training from day 1 with their mentor. Their hands-on experience and how they choose to pursue more training or not is all on them. In often cases an Automotive Mechanic will steer clear of anything that is electronic/software related. Their work is more hands-on and involved in the repair of mechanical components on vehicles. This is not to say someone who considers themselves a mechanic is incapable of performing complex diagnostics. It's just more so a rule of thumb and observation from my many years as an Automotive Technician. Even the types of customer concerns that an automotive mechanic and technician deal with are quite different. “Customer concern is vehicle pulls to the right while driving constantly and upon applying brakes there is a pulsation felt in the steering wheel and the vehicle pulls left”. Automotive Technicians may see something along these lines. “Vehicle pulls to the right while driving constantly and upon applying brakes abs and reduce engine performance light flashes on the instrument cluster as the vehicle becomes hard to steer.” Which would require using a scan tool/diagnostic equipment at some point to solve these electrical issues by extracting live or stored data. Along with viewing and interpreting electrical waveforms possibly to gain insight into circuit and electrical components performance status that is not physically visible. Even checking software and firmware status on different control modules is a part of the diagnostic procedures that can lead to reprogramming ECUs before any mechanical repairs are needed. 10
The Wrap-up To some people, the terms are interchangeable like potato/patahto and it could be that way because the user of these words is from an older different generation or region in the world. Others may disagree and say hey Automotive Technicians have a higher skill set and they are expected to do and know more than their mechanic counterparts. As the automobile has changed and become more driven by sensors, Ecu’s data bus networks automated driver assist systems, etc. The role of the mechanic and the expectations they must meet was an inevitable evolution. This trend flows into the tools and specialized training employed by mechanics and Automotive Technicians alike. Generally speaking Automotive Technicians today require more in-depth handson and degree-oriented training on new emerging technologies. So they can analyze the data they have gathered to fix a customer’s concern. Others may simply not care and their attitude is just to make sure they are compensated accordingly. So which one are you? A potato or potato, mechanic or technician?
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v Multimeter
• CAT III 600V AC/DC .5%
accuracy (Up to 1V on Second Ch) • Current: 1uA to 10A AC/DC
max, ±1% • Resistance up to 10M Ohm • Diode Drop • Capacitance • Continuity • Guided test and Data
Interpretation • Internal temperature
thermistor • On Board Storage SD Card 32
GB max • OTA updates for firmware • ability to turn off TRMS • Battery 2xAA
Graphing mode • 4kHz analog bandwidth • 8hz dual channel bandwidth • Current: 1uA to 10A
(higher with an amp clamp)
USE DISCOUNT CODE "legacy" TO RECEIVE 25% OFF www.curienllc.com
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s The Contender - Pokit Pro - was designed for use by DIY enthusiasts, technicians, and engineers. I selected both of these tools because their primary function is to be a multimeter that happens to be wireless via Bluetooth.
Multimeter
• Voltage: 1mV to 600V DC, 600V AC (True RMS), CAT III, ±1%
• Current: 1uA to 10A AC (True RMS)/DC max, ±1% • True RMS Frequency: 40 to 100Hz • Resistance: 100m to 1M Ohm, ±1%, 3M Ohm ±5%
• Temperature: 0°C to 60°C ±1%°C (32°F to 140°F ±1.8°F)
• External Temperature: -40 to 120°C ±1% @25°C + 0.05%/°C (-40 to 248°F ±1% @77°F + 0.05%/1.8°F)
• Diode Check: 0V to 1V • Capacitance: 1nF to 1000μF, ±2% • Continuity Check: Yes • Continuity Check Delay (max): 100ms • Continuity Buzzer: Internal Buzzer • True RMS: Yes
Although this tool was designed to be a catch all product it it is no slouch either packing quite a punch with its specifications too. There are no guided tests but the user interface is clean and very modern. It only has one channel for gathering data. In the UI there is the ability to store and record data measurements to allow for them to be shared later in a report. While there are quite a few accessories that Pokit sells only two of their kits are worth buying. This would be the automotive or electronic engineer's kit. Looking at the design of the Pokit Pro at least one of these kits would be unnecessary if the tool had a more universal female BNC port eliminating the weak common ground cable. The other more useful accessory is the NTC Temperature Probe. While there is no official amp clamp support there are several Pokit Pro users who have experimented with them. The company itself does have a page on their site devoted to information of a wireless amp clamp they are working on. Despite that it this tool was built to be a jack of all trades but a master of none. It can still be quite useful in automotive diagnostics and one of its coolest features is the smartwatch App. This allows a user to view measurement data without the use of a cell phone or tablet.
Oscilloscope
• Voltage: 1mV to 850Vpk, 600V AC (RMS), CAT III • Current: 1uA to 10A max • DC Accuracy: ±1% • Analog Bandwidth: -3dB @ 200kHz • Sampling: 12bit, 1M sample/sec • Input Impedance (DC): 10M Ohm 13
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FUEL INJECTOR
CAMSHAFT POSITION SENSOR
GUIDED TESTS
CRANKSHAFT POSITION SENSOR
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Smart Charge Technology What is it and why should you care?
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Smart charge generators are one of many modifications made to internal combustion engine vehicles that allow original equipment manufacturers to increase fuel economy efficiency. This is important because since 1975, Corporate Average Fuel Economy (CAFE) regulations have indirectly driven innovation in the automotive industry. CAFE achieves this by penalizing automakers for producing inefficient vehicles. These standards were initially implemented after the Arab Oil Embargo to promote innovation in the automotive industry and reduce fuel consumption. In the past decade, these standards have become more stringent in an effort to create more domestic jobs and reduce global warming. Variable voltage output generators are controlled by an ECU instead of a regulator internal to the generator. The main goal of these systems is to reduce the electrical and mechanical load, thus increasing fuel efficiency. This is done through the ECU (PCM/BCM) having various operating modes for the vehicle charging system based on the input data it receives. An obvious sign that a vehicle has a smart charging system is a current sensing component attached to the battery cable or battery terminal sensor, typically found on the ground battery post.
Smart charging systems have become the industry standard in modern vehicles. These systems consist of different components, such as a battery sensor that measures voltage and amperage, and the PCM/BCM, which interprets various data PIDs including ambient temperature, coolant temperature, engine RPM, and battery temperature to calculate the state of charge. Manufacturers may implement different modes to optimize fuel efficiency, with some using up to three or more charging system strategies, while others may have only two. It's common to find vehicles where the alternator voltage output is equal to or close to the typical battery voltage at idle. When heavy loads are turned on, such as the HVAC system, headlights, or stereo, the alternator will output 13V or more. This type of system was used by Honda/Acura from 1990 to 2012. 17
Let's look at the Honda/Acura dual-mode charging strategy, which includes high and low output modes. The high output (normal) mode has a voltage of 13.5-14.9V, while the low mode is 12.5-12.7 volts. This dual-charging strategy can reduce engine load by as much as 10%, and it is accomplished by all the information gathered from the Electric Load Detector and various other sensors. The parameters required for low output mode are electrical load below 15 Amps (varies with the vehicle), vehicle speed between 10-45 mph or at idle while in drive, engine speed below 3,000 rpm, coolant temperature above 167°F (75°C), A/C Switch Off, intake air temperature above 68°F (20°C). High output mode is meant for when the exterior lights, HVAC system, and entertainment system are on or when more than one data PID indicates a heavy electrical load requirement. The Electric Load Detector, located inside the under-hood fuse box, is the single component that makes the Honda and Acura charging system one of a kind. Its main job is to monitor the amount of electrical energy the vehicle is consuming and then relay this information back to the ECM by pulling a 5V reference to ground as the load increases. This tells the ECM to increase or decrease the field strength in the alternator. At the ELD terminal, it is normal to find 2-4 volts when in low mode and 1-2 volts on the reference circuit when in high output mode. The ELD has a typical range of .27V up to 4.56V; anything outside these parameters will cause the ECM to trigger a DTC.
Amperage
Battery Voltage
High Output Mode
Honda in 2012 began using a different charging strategy called EMS (Engine Management System). A quick rundown of this system's operation: • PCM commanded setpoint voltage • Regulator with bi-directional LIN Communications • Receives PCM setpoint, Soft Start (SS) and Load Response Control (LRC) commands • Transmits alternator load and diagnostic information • PCM monitored the current demand for vehicle through the ELD • PCM monitored battery SOC • PCM Commanded Battery Lamp Remember to not make the error of assuming that a charging system is faulty if you only see 12.5-12.8V coming from the alternator at idle. Look for a shunt on battery post terminals or a current sensor, take into account when the vehicle was built, and most important of all, find accurate service information to give you insight into how the charging system operates. Smart charging systems have become an industry standard that is even becoming equipped on base trim levels by automakers, which helps them get closer to achieving CAFE regulations. Remember to diagnose and never guess. 18
EN GARDE
In the automotive industry, I have heard both sides of the argument concerning ASE, OEM, and ICAR certifications. I have also been employed by dealers where guys were considered OEM Master Certified and they have no clue what voltage drop is or even how to properly perform a parasitic draw test. Oh and by the way a lab scope is completely alien to them and the concept of having a diagnostic process for finding faults is nonexistent. Sometimes this was honestly the fault of OEM certification procedures that allow multiple attempts for example. I even recall being around a co-worker who was diesel master certified but due to current management, they did not trust him with in-depth diagnostic work or engine teardown rebuild or replacement jobs. Ok, I am finished with my soapbox whining. No one needs that attitude. I am all for getting certified in all things, whether it is software development, electrical engineering, or the automotive industry as a technician.
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The Argument for becoming Experience is important, and the process of acquiring fresh, juicy, ripe knowledge leads to an obsession with applying and refining my skill set. Studying for my next certification is a priceless experience that keeps my synapses firing. ASE tests are something I encourage any technician to take or any industry-recognized certification. The majority of industry-accredited certifications are set up to test if you have experience and the ability to grasp new concepts to apply with new emerging technologies. Suppose you're on the fence about getting certified due to your current shop not giving any incentive for technicians to show initiative in personally improving their skills. Then honestly I’m sure you heard the saying that toolboxes have wheels for a reason. A certified automotive technician with the actual hands-on experience to back it up is an invaluable asset to any company. The companies that are aware of this pay the big bucks and I’m not referring to Bambi’s uncle. Don't be afraid to go for certifications. You might learn something and get paid in the process!
Certified Automotive Tech’s All Data Collected from Zip Recruiter state average for IL as of Jan 2023
Annual Salary
Monthly Pay
Weekly Pay
Hourly Wage
0
20,000
40,000
60,000
80,000
Elite -5 years or more experiencestrong background in diagnostics Emerging tech 3 years or more startingto find their niche and pursue becoming a specialist. Average 2 years experience with certifications
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4 KEYS TO AN EFFECTIVE DIAGNOSTIC STRATEGY
PRIMARY INSPECTION If the problem area is visible, look it over to check for damage due to corrosion, stretched or cut wire harnesses, fluid leaks, physical cracks, and worn-out parts. Depending on the concern you are diagnosing, whether mechanical or electrical related, using your senses can be a valuable asset in diagnostics. For instance, pulsating brake peddle front end shutter and steering wheel vibration point to a front end suspension area as a starting point. Central vents are blowing out cold air and the defrost mode output is warm air to name a few simple examples. DIAGNOSTIC TESTS If you have it available through a service information provider rather it is OEM or aftermarket. Check for technical service bulletins ,recalls software updates that apply to the concern. Also make sure to look at description and operation for systems. This can not be stressed enough especially when dealing with electrical based concerns that could be communication faults/ performance issues etc. I have seen customer concerns that were nothing more than a misunderstanding in a system and its functions/features. If you do not have a clear understanding of a system and its design purpose. How can you be diagnose it to find the source of a fault? Looking up the correct schematic is critical here too; OEM schematics should take precedence over aftermarket ones and at least have both available to do a comparison and get the best information possible if one schematic lacks information that the other possesses. A good schematic in a diagnostic strategy sets you up to know what your expected values should be doing testing. Which point you to any faults in a system if those expected values are not obtain during testing.
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DATA ANALYSIS After performing any diagnostic tests, record your findings and keep it organized! This trait alone separates the season vets form the rookie automotive technicians. Keeping good notes during a diagnostics process can make or break you getting paid. This is especially true if you work for an OEM manufacturer. Along with making it easier for customers to see how thorough you are this creates a level of trust. When you are transparent in how you came to the solution to their concern. At this point you are taking you gathered information and comparing it to OEM specifications. Plus relevant known good data and your experience/training on how a particular circuit should operate. According to established standards of continuity, voltage drop, ohms law etc.
RECOMMENDATION OF SERVICES Now based on your results from prior data and research gathering and verifying the faults if present found. You should be able to recommend the correct course of action now. Leading you to getting the vehicle back on the road. If all these stages are perform correctly. Selling diagnostic service to a customer and explaining to them how you came to your decision for recommended services should be a breeze.
EXTRA CREDIT Never assume based on the customer’s concern you know what the problem is, relying on past experience without proper testing . Simply put this is guessing (an educated guess at best) and if diagnostic testing is perform relying on a previous diagnose vehicles you can leave yourself susceptible to tunnel vision. Steering blindly while ignoring the more important symptoms and data that could lead to proper solution. Diagnose never Guess!
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