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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 15 (BODY CONTROL MODULES)DIAGNOSTIC TESTSDTC B2964: KEY IN IGNITION CIRCUIT HIGHTESTING FOR B2964
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Testing for B2964

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Testing for B2964
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.

Schematic Reference: AUDIBLE WARNINGS SYSTEM DIAGNOSTIC SYSTEM CHECK 

  1. Did you perform the Audible Warnings Diagnostic System Check? If yes, go to next step. If no, go to INSTRUMENT PANEL CLUSTER SYSTEM DIAGNOSTIC SYSTEM CHECK 
    1. Install a scan tool.
    2. Turn ON the ignition, with the engine OFF.
    3. With the scan tool, observe the Key In Ignition parameter in the Body Control Module input data list.
    Does the Key In Ignition parameter display Yes? If yes, go to TESTING FOR INTERMITTENT & POOR CONNECTIONS . If no, go to next step
    1. Turn OFF the ignition.
    2. Disconnect the BCM connector C2.
    3. Connect a test lamp between the key in ignition input circuit and battery positive voltage.
    4. Turn ON the ignition, with the engine OFF.
    Does the test lamp illuminate? If yes, Go to step  7. If no, go to next step.
  4. Test the key in ignition input circuit for an open or a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems. Did you find and correct the condition? If yes, go to step  10. If no, go to next step.
  5. Test the ground circuit of the ignition key alarm switch for for an open or a high resistance. Refer to CIRCUIT TESTING and WIRING REPAIRS in Wiring Systems. Did you find and correct the condition? If yes, go to step  10. If no, go to next step.
  6. Inspect for poor connections at the harness connector of the ignition switch. Refer to TESTING FOR INTERMITTENT & POOR CONNECTIONS in Wiring Systems. Did you find and correct the condition? If yes, go to step  10. If no, go to step  8.
  7. Inspect for poor connections at the harness connector of the BCM. Refer to TESTING FOR INTERMITTENT & POOR CONNECTIONS in Wiring Systems. Did you find and correct the condition? If yes, go to step  10. If no, go to step  9.
  8. Replace the ignition switch. Refer to IGNITION SWITCH in Steering Wheel and Column. Did you complete the replacement? If yes, go to step  10.
    9. IMPORTANT: Perform the set up procedure for the replacement BCM.
  9. Replace the BCM. Refer to BODY CONTROL MODULE . Did you complete the replacement? If yes, go to next step.
    1. Use the scan tool in order to clear the DTCs.
    2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
    Does the DTC reset? If yes, go to step  2. If no, system OK.
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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.