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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 89 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 3.1L ENGINE)DIAGNOSTIC TESTSDTC P1134: HO2S TRANSITION TIME RATIO (BANK 1; SENSOR 1)DIAGNOSTIC PROCEDURES
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Diagnostic Procedures

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Pontiac Grand Prix, 2002 Chevrolet Malibu, and 2002 Buick Century. 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. Observe the HO2S 1 voltage parameter with a scan tool. Clear the DTC and record the Freeze/Frame Failure Records data if the HO2S 1 voltage is fixed at bias voltage. Does the HO2S 1 voltage fluctuate rapidly at greater than and less than the specified value of 350-550 millivolts? 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 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, go to INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn ignition off. Disconnect HO2S 1 harness connector. Turn ignition on, with engine off. Using a Digital Multimeter (DMM), measure voltage from HO2S 1 harness connector high signal circuit to a good ground. Is HO2S voltage within 0.425-0.500 volt? If yes, go to next step. If no, go to step  6.
  5. Turn ignition off. Connect a 3-amp fused jumper wire between HO2S 1 harness connector high signal circuit and low reference circuit. Turn ignition on, with engine off. Observe HO2S 1 voltage on scan tool. Does scan tool display less than 25 millivolts? If yes, go to step  8. If no, go to next step.
  6. Turn ignition off. Disconnect both PCM harness connectors. Measure resistance of each of the following circuits with a DMM: HO2S 1 high signal circuit between HO2S connector and PCM connector, HO2S 1 low reference circuit between HO2S connector and PCM connector low reference loop between terminal C1-29 and terminal C2-80 of PCM connectors. Is the resistance of each circuit less than 5 ohms? If yes, go to step  11. If no, go to next step.
  7. Repair the circuit that measured a high resistance or an open. After repairs, go to step  14.
  8. Remove the jumpers from HO2S 1 terminals. Connect a test light between the HO2S harness connector heater ignition voltage circuit and heater low control circuit. Start engine. Does test light illuminate? If yes, go to next step. If no, go to DTC P0135: HO2S HEATER PERFORMANCE .
  9. Inspect for the following conditions that may affect the HO2S operation: HO2S for contamination, chafed, burnt, cut, pinched, or otherwise damaged HO2S wiring, exhaust system leaks or restrictions, EVAP canister purge, and for proper fuel pressure. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  10. Inspect for poor connections at the HO2S 1 connector. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Inspect for poor connections at the PCM harness connectors. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace HO2S 1. After repairs, go to step 14.
  13. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  14. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start 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.
  15. Using scan tool, observe stored information and Capture Info. 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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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.