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.
- Allow the engine to idle at operating temperature. Monitor the HO2S 1 Heater Current parameter on a scan tool. Allow the current to stabilize. Is the HO2S 1 Heater Current 0.25-0.85 amp? If yes, go to next step. If no, go to step 4.
- Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L MONTANA, SILHOUETTE & VENTURE article.
- Disconnect the HO2S 1 electrical connector. Turn ignition on, with engine off. Probe the HO2S heater ignition voltage circuit at the HO2S 1 electrical connector, on the PCM harness side, with a test light connected to ground. Does the test light illuminate? If yes, go to step 6. If no, go to next step.
- Test the HO2S 1 heater ignition voltage fuse. Is the fuse open? If yes, go to step 11. If no, go to step 12.
- Turn ignition off. Connect a test light between the HO2S 1 ignition 1 voltage circuit and the HO2S 1 heater low control circuit. Start engine. Does the test light illuminate? If yes, go to next step. If no, go to step 8.
- Leave the test light connected between the HO2S 1 heater ignition voltage circuit and the HO2S 1 heater low control circuit. Turn ignition off. Turn ignition on, with engine off. Does the test light illuminate? If yes, go to step 9. If no, go to step 13.
- Turn ignition off. Disconnect the PCM connector containing the HO2S 1 heater low control circuit. Measure the resistance of the HO2S heater low control circuit between the PCM harness connector, and the HO2S harness connector using a Digital Volt-Ohmmeter (DVOM). Is the resistance 0-5 ohms? If yes, go to step 15. If no, go to step 10.
- Test the HO2S 1 heater low control circuit for a short to ground. Did you find and correct the condition? If yes, go to step 18. If no, go to step 15.
- Test the HO2S 1 heater low control circuit for an open or high resistance condition. Repair as necessary. After repairs, go to step 18.
- Test the HO2S 1 heater ignition voltage circuit for a short to ground and replace the fuse. Did you find and correct the condition? If yes, go to step 18. If no, go to step 13.
- Test the HO2S 1 heater ignition voltage circuit for an open or high resistance condition. Repair as necessary. After repairs, go to step 18.
- At the disconnected HO2S 1 pigtail connector, test the HO2S heater ignition voltage circuit for continuity between the following circuits of the HO2S:
- The HO2S 1 high signal.
- The HO2S 1 low signal.
- The HO2S 1 outer shell or a good ground.
Do any of the circuits measure other than infinite resistance? If yes, go to step 16. If no, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L MONTANA, SILHOUETTE & VENTURE article.
- Check for poor connections at the harness connector of the HO2S 1. Did you find and correct the condition? If yes, go to step 18. If no, go to step 16.
- Check for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step 18. If no, go to step 17.
- Replace HO2S 1. See REMOVAL & INSTALLATION - MONTANA, SILHOUETTE & VENTURE article. After repairs, go to step 18.
- 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.
NOTE:
Use a known-good ground. Do not use the HO2S 1 heater low control circuit or the HO2S 1 low reference circuit.