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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 15 (BODY CONTROL MODULES)SYSTEM TESTSTEST E: POWER MODE MISMATCHTEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Test Description

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, 2001 Chevrolet Monte Carlo, and 2001 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

For body control system wiring diagrams, see WIRING DIAGRAMS .

NOTE: Open the driver door and leave it open during this test. This will disable the RAP power mode and eliminate this power mode from the power mode parameter list.
    1. Install a scan tool.
    2. Turn OFF the ignition.
    3. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
    Does the displayed power mode parameter match the actual ignition switch position? If yes, go to next step. If no, go to step  6.
    1. Turn the ignition switch to the UNLOCK position.
    2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
    Does the displayed power mode parameter match the actual ignition switch position? If yes, go to next step. If no, go to step  6.
    1. Turn ON the ignition, with the engine OFF.
    2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
    Does the displayed power mode parameter match the actual ignition switch position? If yes, go to next step. If no, go to step  6.
    NOTE: The engine may start during this procedure. Turn the ignition OFF after verifying this power mode.
    1. Turn the ignition switch to the CRANK position.
    2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
    Does the displayed power mode parameter match the actual ignition switch position? If yes, go to next step. If no, go to step  6.
    1. Turn the ignition switch to the ACCY position.
    2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
    Does the displayed power mode parameter match the actual ignition switch position? If yes, go to TESTING FOR INTERMITTENT AND POOR CONNECTIONS . If no, go to next step.
    NOTE: The engine may start during this procedure. Turn the ignition OFF after verifying this power mode.
  6. This step tests for battery voltage on the signal circuits that are not required.
    1. Turn OFF the ignition.
    2. Disconnect the PMM.
    3. Hold the ignition switch in the position that indicated the incorrect power mode.
    4. With a test lamp attached to a good ground, test the PMM ignition switch inputs for voltage. Refer to DESCRIPTION & OPERATION .
    Is voltage present on only the inputs specified for the ignition switch position? If yes, go to next step. If no, go to step  8.
    NOTE: The engine may start during this procedure. Turn the ignition OFF after verifying this power mode.
  7. This step tests for no battery voltage on the required signal circuits.
    1. Hold the ignition switch in the position that indicated the incorrect power mode.
    2. With a test lamp attached to a good ground, test the PMM ignition switch inputs for voltage. Refer to DESCRIPTION & OPERATION .
    Is voltage not present on any inputs specified for the ignition switch position? If yes, go to step  9. If no, go to step  11.
  8. If any ignition switch parameters that should be inactive in the present ignition switch position are active, 2 ignition switch signal circuits may be shorted together.
    1. Disconnect the ignition switch.
    2. Test the PMM ignition switch input circuits for a short to voltage.
    3. Test the PMM ignition switch circuits for a short between circuits.
    Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  9. This step eliminates open circuits as the cause of the malfunction.
    1. Disconnect the ignition switch.
    2. Test the PMM ignition switch input circuits for an open.
    Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  10. Inspect for poor connections and terminal tension at the harness connector of the ignition switch. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS . Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Inspect for poor connections and terminal tension at the harness connector of the PMM. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS . Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace the ignition switch. Refer to IGNITION SWITCH . After replacement is complete, go to step  14.
    NOTE: After replacement of the PMM perform the set up procedure if required.
  13. Replace the PMM. Refer to Control Module References. After replacement is complete, go to next step.
    1. Reconnect all disconnected components.
    2. With a scan tool, under the Diagnostic Circuit Check menu observe the Class 2 Power Mode parameter.
    3. Cycle the ignition switch through all possible positions one at a time.
    Does the displayed power mode parameter match the actual ignition switch position? If yes, system is okay. If no, go to step  1.
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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.