Circuit/System Testing

2008 Pontiac Grand Prix BaseSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the affected component.
  2. Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and battery voltage.
    • Left steering wheel switch terminal 8
    • Right steering wheel switch terminal 1
    • Windshield wiper/washer switch terminal 1
    • Analog clock terminal 2
    • DIC switch terminal 5
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the listed LED dimming control circuit terminal and ground.
    • Left steering wheel switch terminal 6
    • Right steering wheel switch terminal 2
    • Windshield wiper/washer switch terminal 4
    • Analog clock terminal 3
    • DIC switch terminal 4
    • Radio terminal 8 X1
  4. Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
    • If the test lamp is always off, test the control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
    • If the test lamp is always bright, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, test or replace the affected component.
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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.