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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
  1. 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.
  2. 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.
  3. 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 AZTEK & RENDEZVOUS article.
    4. NOTE: Use a known-good ground. Do not use the HO2S 1 heater low control circuit or the HO2S 1 low reference circuit.
  4. 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.
  5. Test the HO2S 1 heater ignition voltage fuse. Is the fuse open? If yes, go to step  10. If no, go to step  15.
  6. 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.
  7. 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  12.
  8. 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  13. If no, go to step  14.
  9. 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  13.
  10. Test the HO2S 1 heater ignition voltage circuit for a short to ground and replace fuse. Did you find and correct the condition? If yes, go to step  18. If no, go to next step.
  11. Measure the resistance from the HO2S ignition 1 voltage circuit, on the sensor side of the HO2S harness connector, to each of the following circuits: HO2S low reference circuit and ground circuit. Is resistance less than 5 ohms? If yes, go to step  16. If no, problem is intermittent. Refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article.
  12. Test for an intermittent and for a poor connection at the HO2S 1 harness connector. Did you find and correct the condition? If yes, go to step  18. If no, go to step  16.
  13. Test for an intermittent and for a poor connection at the PCM harness connector. Did you find and correct the condition? If yes, go to step  18. If no, go to step  17.
  14. Repair open or high resistance in the HO2S heater low control circuit. After repairs, go to step  18.
  15. Repair the open or high resistance in the HO2S ignition 1 voltage circuit. After repairs, go to step  18.
  16. Replace HO2S 1. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to step  18.
  17. Replace PCM. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  18. 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 . Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  19. 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.
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