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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1087 (Lighting Systems) >> Diagnostic Information and Procedures >> Daytime Running Lamps Malfunction >> Circuit/System Testing >> Daytime Running Lamps with HID

Daytime Running Lamps with HID

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. Ignition OFF, disconnect the appropriate DRL relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
    • If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the appropriate DRL relay.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Ignition OFF, disconnect the harness connector at the inoperative DRL.
  6. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms between the inoperative DRL ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the inoperative DRL.
  8. Connect a 15A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the appropriate DRL is activated.
    • If the DRL does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the inoperative DRL.
  9. Connect a test lamp between the B+ circuit terminal 85 and the relay control circuit terminal 86.
  10. Ignition ON, vehicle in DRIVE, place a bright incandescent lamp over the ambient light sensor and verify the appropriate DRL is illuminated.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
  11. If all circuits test normal, test or replace the inoperative DRL relay.
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