Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
Install a scan tool. Attempt to start the engine. With a scan tool, monitor the DTC information. Are DTCs P0335, P0340, and P0385 set? If yes, go to step 9. If no, go to next step.
Start the engine. With a scan tool, monitor the DTC information. Does the scan tool indicate that DTC P0340 passed? If yes, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
Turn the ignition OFF. Leave the scan tool installed. Disconnect the CMP sensor harness connector. Turn the ignition ON, with the engine OFF. Connect test lamp between the CMP sensor 12-volt reference and low reference circuits. Does the test lamp illuminate? If yes, go to step 6. If no, go to next step.
Test for the following circuit conditions:
- An open CMP sensor 12 volt reference circuit.
- An open CMP sensor low reference circuit.
- Poor connections at the PCM.
If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step 17. If no, go to step 16.
Turn the ignition ON, with the engine OFF. Connect test lamp to battery voltage. Observe the CMP sensor data display on the scan tool while repeatedly touching the test lamp to the CMP high resolution signal circuit, in the harness connector. Does the scan tool indicate an RPM? If yes, go to step 8. If no, go to next step.
Test the CMP sensor high resolution signal circuit for the following conditions:
- An open.
- Short to voltage.
- Short to CMP sensor 12-volt reference circuit.
- Short to ground.
- Short to CMP sensor low reference circuit.
- Poor connections at the PCM.
If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step 17. If no, go to step 16.
Inspect for poor connections at the CMP sensor. If the condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step 17. If no, go to step 13.
Disconnect the CMP sensor harness connector. With a scan tool, monitor the 12-Volt Reference parameter. Does the scan tool display OK? If yes, go to step 13. If no, go to next step.
Raise the vehicle. Disconnect the CKP "A" sensor harness connector. With a scan tool, monitor the 12-Volt Reference parameter. Does the scan tool display OK? If yes, go to step 14. If no, go to next step.
Disconnect the CKP "B" sensor harness connector. With a scan tool, monitor the 12-Volt Reference parameter. Does the scan tool display OK? If yes, go to step 15. If no, go to next step.
Turn OFF the ignition. Disconnect the PCM harness connectors. Test the 12-volt reference circuit of the CKP "A", CKP "B", and the CMP sensors for a grounded circuit. Repair as necessary. After repairs, go to step 17.
Replace the CMP sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 17.
Replace the CKP "A" sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 17.
Replace the CKP "B" sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step 17.
Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
Use the scan tool in order to clear the DTCs. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.