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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P1133 Or P1153: Ho2S Circuit - Insufficient Switching (Bank 1 & 2, Sensor 1) >> Diagnostic Procedures

Diagnostic Procedures

  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. Start engine. Allow the engine to reach operating temperature. Operate engine at 1500 RPM for 30 seconds. Observe the affected HO2S voltage parameter with a scan tool. Is the HO2S voltage parameter varying at greater than and less than 200-600 mV? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the 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. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.
  4. Turn ignition off. Disconnect the affected HO2S. Connect a 3-amp fused jumper wire between the high signal circuit of the HO2S harness connector on the engine harness side and a good ground. Turn ignition on, with engine off. Observe the HO2S voltage parameter with a scan tool. Is the HO2S voltage parameter less than 100 mV? If yes, go to step  6. If no, go to next step.
  5. Test the HO2S high signal circuit for an open. Did you find and correct the condition? If yes, go to step  12. If no, go to step  9.
  6. Remove the jumper from the previous step. Connect a 3-amp fused jumper wire between the high signal circuit of the HO2S harness connector on the engine harness side and the low signal circuit of the HO2S harness connector on the engine harness side. Observe the HO2S voltage parameter with a scan tool. Is the HO2S voltage parameter less than 100 mV? If yes, go to step  8. If no, go to next step.
  7. Test the HO2S low signal circuit for an open. Did you find and correct the condition? If yes, go to step  12. If no, go to step  9.
  8. Test for an intermittent and for a poor connection at the HO2S. Did you find and correct the condition? If yes, go to step  12. If no, go to step  10.
  9. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  12. If no, go to step  11.
  10. Replace affected HO2S. See appropriate REMOVAL & INSTALLATION article. After repairs, go to next step.
  11. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  12. 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  10.
  13. 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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