How to Troubleshoot the PCM for a 1997 Chevy Lumina

A bad PCM is one of many reasons the check engine light may become active.

For the Chevrolet vehicles, not all control modules are the same. After the EPA standardized the second generation of On-Board Diagnostics in 1996, the function and programming of powertrain control modules became similar in all makes and models. The PCM works as a central computer, and it monitors functions within the engine. As soon as problems present themselves, the PCM assigns an OBD-II code. A non-working PCM means your Lumina will not give you advance warning of serious engine problems, so it should be replaced immediately.

Things You'll Need

• OBD-II scanner

Instructions

1. Connect your OBD-II scanner to the Lumina's diagnostic computer outlet. This port is called a "Data Link Connector," and you will find it under the dash and directly over the gas pedal.

2. Insert the Lumina's key into the ignition, and switch to the "On" designation. This will bring up the Lumina's electronic system. You may own an OBD-II scanner that requires the engine to be running.

3. Glance at your OBD-II scanner's display. If you do not find trouble codes waiting for you, then you will need to key in a "read" or "scan" command. Button orientation differs by brand of OBD-II scanner. For the correct instructions, you will need to consult your device's handbook.

4. Copy the retrieved OBD-II trouble codes onto a separate sheet of paper. Then, turn the scanner, the Lumina's electronic's and/or engine off. Disconnect the scanner from the Lumina's computer port and exit the vehicle.

5. Sit behind a computer and locate both generic and General Motor's supplemental OBD-II coding definitions online. You can use the scanner's print manual, but online references may be quicker. Your web browser has a "find" command. Once you pull up a page of OBD-II definitions, use this "find" command. Type in the code exactly as you had copied it from the scanner. For example, if you type in "P0606" you will end up with "PCM Processor Fault."

6. Cross off codes that do not mention the PCM. Everything left will indicate all the problems currently facing your Lumina's PCM. You may need to either reprogram the module, or have it replaced.

Tips & Warnings

• While your Lumina's owner's manual is a great source of information, you will not find any information regarding vehicle diagnostics there.

References

• Innova: Digital OBD II Code Reader Owner's Manual
• CarMD: How Do I Find My Vehicle's Connector?
• US EPA: On-Board Diagnostics
• Engine Light Help: OBD II Generic Check Engine Light Codes

Resources

• Chevrolet: 1997 Lumina Owner's Manual
• Engine Light Help: Chevy Check Engine Light Codes
• OBD Codes: OBD-II (Check Engine Light) Trouble Codes