Circuit/System Testing

2006 Chevrolet Chevy Express G2500, Van Cargo, 6.6 2SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector X2 at the BCM.
  2. Ignition ON, vehicle in park, verify the backup lamps are not on.
    • If the backup lamps are on, test the backup lamp relay control circuit terminal 22 for a short to voltage. If the circuit tests normal replace the underhood fuse block.
  3. Install a 10A fused jumper wire between the relay control circuit terminal 22 and battery voltage. Verify the backup lamps are on.
    • If the backup lamps are not on, test the backup lamp relay control circuit for an open/high resistance or short to ground. If the circuit tests normal replace the underhood fuse block.
  4. If all circuits test normal, replace the BCM.
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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.