Circuit/System Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Chevrolet Malibu Classic. However, it is still accessible from the selected car via links, so may be relevant.

Turn Signals Always On

  1. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
  2. Ignition ON, the turn signals should not be flashing.
    • If the turn signals are flashing, test the appropriate signal circuit for a short to ground:
      • Left turn signal - terminal G. If the circuit tests normal, replace the BCM.
      • Right turn signal - terminal H. If the circuit tests normal, replace the BCM.
  3. If all circuits test normal, replace the turn signal/multifunction switch.

Turn Signals Inoperative From BCM

  1. Ignition OFF, disconnect the harness connector at the inoperative turn signal.
  2. Connect a test lamp between the ground circuit terminal G and B+. The test lamp should illuminate.
    • If the test lamp does not illuminate, test the ground circuit terminal G for a short to voltage or an open/high resistance.
  3. Test the supply voltage circuit terminal A for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

Turn Signal Indicators Inoperative

  1. Command the instrument panel Display Test ON with a scan tool. The turn signal indicators should illuminate.
    • If the turn signal indicators do not illuminate, replace the instrument panel cluster.
  2. If all circuits test normal, replace the BCM.

Turn Signals Inoperative From Switch

  1. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
  2. Verify that a test lamp illuminates between the ground circuit terminal B and B+.
    • If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance.
  3. Install a 3A fused jumper wire between the signal circuit of the inoperative turn signal and ground.
    • Left turn signal - terminal G.
    • Right turn signal - terminal H.
  4. Ignition ON, the turn signal should illuminate and flash.
    • If the turn signal does not illuminate and flash, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the turn signal/multifunction switch.

Hazard Lamps Inoperative

  1. Ignition OFF, disconnect the harness connector at the hazard switch.
  2. Verify that a test lamp illuminates between the ground circuit terminal B and B+.
    • If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance.
  3. Install a 3A fused jumper wire between the signal circuit terminal C and ground. The turn signals should illuminate and flash.
    • If the turn signals do not illuminate and flash, test the signal circuit terminal C for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  4. If all circuits test normal, replace the hazard switch.
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When to See a Mechanic

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

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