Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Pontiac Montana, 2003 Oldsmobile Silhouette, and 2003 Chevrolet Venture. 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, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM.
- Is DTC P1635 also set? If yes, go to DTC P1635: 5-VOLT REFERENCE "A" CIRCUIT . If no, go to next step.
- Start engine. Observe the EGR position sensor parameter with scan tool. Is EGR position sensor parameter less than one percent? If yes, go to next step. If no, go to step 6.
- Turn ignition on, with engine off. Command the EGR valve from zero percent to 100 percent with scan tool. Is the EGR Position Variance parameter less than 15 percent? If yes, go to next step. If no, go to step 7.
- Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Operate the vehicle within the Conditions for Running DTC or within the parameters observed in the Freeze Frame/Failure Records. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
- Turn ignition off. Disconnect the EGR valve. Turn ignition on, with engine off. With a scan tool, observe the EGR position sensor parameter. Is the EGR position sensor parameter less than one percent? If yes, go to next step. If no, go to step 10.
- Connect a test light between the 5-volt reference circuit and low reference circuit of the EGR valve. Does the test light illuminate? If yes, go to next step. If no, go to step 9.
- Connect a fused jumper between the 5-volt reference circuit of the EGR position sensor and the EGR valve position signal circuit of the EGR position sensor. Does the scan tool indicate that the EGR position sensor is more than 99 percent? If yes, go to step 15. If no, go to step 12.
- Connect test light between the 5-volt reference circuit of the EGR valve and a good ground. Does the test light illuminate? If yes, go to step 11. If no, go to step 13.
- Test the EGR valve position signal circuit for a short to voltage. Did you find and correct the condition? If yes, go to step 19. If no, go to step 16.
- Test the EGR position sensor low reference circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step 19. If no, go to step 16.
- Test the signal circuit for high resistance or for a high-resistance short to ground. Did you find and correct the condition? If yes, go to step 19. If no, go to step 16.
- Test the 5-volt reference circuit of the EGR valve for an open or for high resistance. Did you find and correct the condition? If yes, go to step 19. If no, go to step 15.
- Test for an intermittent and for a poor connection at the EGR valve. Did you find and correct the condition? If yes, go to step 19. If no, go to step 17.
- Test all 5-volt reference circuits for a short to voltage. Did you find and correct the condition? If yes, go to step 19. If no, go to next step.
- Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step 19. If no, go to step 18.
- Replace EGR valve. See REMOVAL & INSTALLATION - MONTANA, SILHOUETTE & VENTURE article. After repairs, go to step 19.
- Replace PCM. See REMOVAL & INSTALLATION - MONTANA, SILHOUETTE & VENTURE article. Reprogram PCM. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After repairs, go to next step.
- Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step 2.
- Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.