PCM module diagnostics How can I know if it’s really the module? By Alex Portillo Vehicle diagnosed by Kevin Quinlan.
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are expensive, they cannot be returned, and on the late model vehicles they cannot be swapped without being reprogrammed or sometimes not swapped at all! The stakes are very high when diagnosing a module, but there is a way you can diagnose a module with 100% confdence. There are not that many steps, because diagnosing a module employs simple logic. Here are the steps to diagnose any module when you have a DTC:
ow long do most diagnostics take you? Maybe an hour? A diagnostic procedure that can be completed that quickly is usually pretty cut and dried, such as a bad sensor or vacuum leak. When diagnostics start taking longer and the problem seems to continue after we change common failure components, we start suspecting a bad module. 1. Check TSBs to see if there are any When a module arouses suspicion, you software updates, extended warranties for start to doubt yourself. Is it really the defective modules, or other good diagnosmodule or did you miss something? Modules tic information that indicates you need to
Figure 1. Early Jeep Libertys can burn the PCM as a result of simply flling the gas tank due to possible static. A ground strap needs to be added to the fll neck to prevent static electricity.
24 | July/August 2013
