How Can I Test on the Powertrain Control Module?

by Richard Ristow

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Powertrain control modules (PCM) are used in vehicles compliant with the second generation of On-Board Diagnostics. This means the vehicle has to have been manufactured after 1996, and any troubleshooting must be done with a diagnostic hardware. The PCM is your vehicle's central computer, and it is part of the the OBD-II system. The module runs a series of tests, and once it finds a malfunction, it activates your service engine soon light. If the PCM has failed to work properly, it will need to be replaced or reprogrammed.

Step 1

Bookmark the pages in you OBD-II scanner's handbook the pages containing definitions for generic OBD-II codes.

Step 2

Look up online your vehicle manufacturer's codes and print them out. You can also find these codes in a Haynes Repair Manual for your make and model-year. Your vehicle's manual, however, will not provide your manufacturer's supplemental OBD-II codes.

Step 3

Open the passenger's side front door to your vehicle, and place both the scanner's manual and your printed out materials. These are research materials you will need towards the end of this process.

Step 4

Shut the passenger's side door, and walk around the vehicle. Open the driver's side door, and look under the dashboard, near the steering column. You are looking for a sixteen pin-receiving computer outlet. This diagnostic port is called a Data Link Connector, and the DLC is located in different spots. Where to look depends on your exact make and model year.

Step 5

Connect your OBD-II scanner to the DLC outlet. Look at the scanner's display read-out, and if it has not automatically turned itself on, find the power button and switch it on yourself. All brands of scanners function slightly different from each other. To find the exact operational procedures for your device, consult your device's handbook.

Step 6

Place your key into your vehicle's ignition and turn the electrical system on. Your scanner may also need the engine running as well. If your OBD-II scanner does not immediately retrieve the trouble codes recorded in the PCM, key in a "Scan" command as per your scanner's handbook.

Step 7

Scroll through the codes on your scanner's display. Pay attention only to codes that start with a "P" for powertrain. You are looking specifically for trouble codes that deal only with the PCM. Most of those trouble codes will be manufacturer specific, so you will have to consult the print outs or the Haynes Manual you left in the navigator's seat. There are a few generic PCM codes, one of which is P0606, which means "PCM Processor Fault."

References

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