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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 991 (Door Lock Systems & Door Handles) >> Diagnostic Information and Procedures >> Power Door Locks Inoperative - Rear >> Circuit/System Testing

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.

Rear Door Lock Relay Control Circuit Test

  1. Verify that a test lamp connected to battery voltage illuminates when connected to each of the lock and unlock 1 and 2 fuses in the IP fuse block.
    • If the test lamp does not illuminate at all 4 fuses replace the IP fuse block.
  2. Disconnect the BCM connector X7.
  3. Verify that the rear door lock actuators unlock when a fused jumper wire is connected to the unlock relay control circuit terminal 9 and briefly applied to ground.
    • If the rear door lock actuators do not unlock test the unlock relay control circuit for an open/high resistance. If the circuit tests normal replace the IP fuse block.
  4. Verify that the rear door lock actuators lock when a fused jumper wire is connected to the lock relay control circuit terminal 7 and briefly applied to battery voltage.
    • If the rear door lock actuators do not lock test the lock relay control circuit for an open/high resistance. If the circuit tests normal replace the IP fuse block.
  5. If the circuits test normal replace the BCM.

Rear Door Lock Actuator Circuit Test

  1. Verify that a test lamp connected to battery voltage illuminates when connected to each of the lock and unlock 1 and 2 fuses in the IP fuse block.
    • If the test lamp does not illuminate at all 4 fuses replace the IP fuse block.
  2. Disconnect the affected rear door latch connector and connect a test lamp across the lock actuator control circuit terminals.
  3. Verify that the test lamp illuminates briefly when a lock and unlock switch is activated.
    • If the test lamp does not illuminate in both switch positions test the lock actuator control circuits for an open/high resistance or short to ground. If the circuits test normal replace the IP fuse block.
  4. If the circuits test normal replace the affected door latch.
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