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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1293 (Lighting Systems) >> Diagnostic Information and Procedures >> Headlamps Malfunction >> Circuit/System Testing >> Headlamp Dimmer Switch Malfunction

Headlamp Dimmer Switch Malfunction

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
  2. Verify that a test lamp illuminates between B+ and the ground circuit terminal D.
    • If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Verify the scan tool High Beam Select switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the BCM.
  4. Verify the scan tool Flash to Pass Switch parameter is Inactive.
    • If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
  5. Install a 3A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool High Beam Select Switch parameter is Active.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  6. Install a 3A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Flash to Pass Switch parameter is Active.
    • If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. If all circuits test normal, test or replace the signal/multifunction switch.
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