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 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. With a scan tool clear the DTC.
  2. Ignition OFF, disconnect the harness connector at the I/P Dimmer switch.
  3. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 10.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  4. Verify the scan tool dimming control signal parameter is less than 0.2 volts.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. Install a 3A fused jumper wire between the signal circuit terminal 9 and the B+ voltage reference circuit terminal 5. Verify the scan tool dimming control signal parameter is greater than 2.5 volts.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. If all circuits test normal, test or replace the I/P dimmer switch.
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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.
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