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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 330 (Engine Controls - Self-Diagnostics - 3.0L) >> Diagnostic Tests >> DTC P0030, P0036, P0050 Or P0056: Ho2S Heater Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Saturn Vue. 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, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS .
  2. Clear DTCs with scan tool. Start engine. Observe the DTC info parameter with a scan tool for at least 30 seconds. Does the DTC fail this ignition? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, problem is intermittent. Refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L & 3.0L VUE article.
    4. NOTE: Use a known-good ground. Do not use the HO2S heater low control circuit or HO2S low signal circuit.
  4. Turn ignition off. Disconnect the affected HO2S connector. Turn ignition on, with engine off. Probe the HO2S heater ignition 1 voltage circuit, at the engine harness side of the HO2S connector with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  6.
  5. Turn ignition off. Test light may flash OFF-ON as the ECM commands the sensor heating operation. Connect a test light between the HO2S ignition 1 voltage circuit and the HO2S heater low control circuit on the engine harness side connector. Start engine. Does the test light illuminate? If yes, go to step  9. If no, go to step  7.
  6. Test the appropriate HO2S heater ignition 1 voltage circuit fuse for an open. Is the fuse open? If yes, go to step  8. If no, go to step  11.
  7. Test the affected HO2S heater low control circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  8. Test all circuits supplied by this ignition 1 fuse for excessive current draw and replace the fuse. Did you find and correct the condition? If yes, go to step  14. If no, problem is intermittent. Refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L & 3.0L VUE article.
  9. Test for an intermittent and for a poor connection at the HO2S harness connector. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  10. Test for an intermittent and for a poor connection at the ECM harness connector. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  11. Repair open or high resistance in the affected HO2S heater ignition 1 voltage circuits. After repairs, go to step  14.
  12. Replace affected HO2S. After replacing sensor, go to step  14.
  13. Replace ECM. Perform ECM relearn procedures. See ENGINE CONTROL MODULE  under PROGRAMMING. After replacing ECM, go to next step.
  14. Clear the DTCs with scan tool. Turn ignition off. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  15. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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