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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 101 (Engine Control System Self-Diagnostics - 3.4L) >> Diagnostic Tests >> DTC P0135: Ho2S Heater Performance >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, 2002 Chevrolet Monte Carlo, and 2002 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  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 within 0.25-0.85 A? 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 the engine. Operate the vehicle within the Conditions for Running the 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? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
    4. NOTE: Use a known-good ground. Do not use the HO2S 1 heater low control circuit or 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, 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  11. If no, go to step  12.
  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 the 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  13.
  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 DMM. Is the resistance within 0-5 ohms? If yes, go to step  15. If no, go to step  10.
  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  15.
  10. Test the HO2S 1 heater low control circuit for an open or high resistance condition. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  11. 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  15.
  12. Test the HO2S 1 heater ignition voltage circuit for an open or high resistance condition. Did you find and correct the condition? If yes, go to step  18. If no, go to step  15.
  13. At the disconnected HO2S 1 pigtail connector test the HO2S heater ignition voltage circuit for continuity between the HO2S 1 high signal, low signal, sensor 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 INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  14. Inspect 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 next step.
  15. Inspect 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.
  16. Replace the HO2S 1. After repairs, go to step  18
  17. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  18. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  19. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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