Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Do you want to test it before you replace it?
Here is one method, but it requires a scan tool:
1. Check communication to Powertrain Control Module (PCM) with a scan tool.2. If no communication, check if the scanner will communicate with the Antilock Brake System (ABS) or air bag modules.3. If the scanner has communication with other modules but not the PCM, check powers and grounds to the PCM and ohm the data line wire from the DLC pin 2 to the PCM pin 58.4. If the powers and grounds are OK and the Data line has continuity, replace and reprogram the PCM.
Here is the accompanying wiring diagram to the test procedure.
Sorry I stepped away for a second.
Some parts stores will lend out scanners with a deposit. Diagnosing and replacing a PCM without one is nearly impossible.
You might check the wiring under the fuse box first though. It's very problematic on this truck.