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Home >> Chevrolet >> 2006 >> Silverado 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1089 (Lighting Systems) >> Diagnostic Information and Procedures >> Park, License, and/or Tail Lamps Malfunction (European) >> Circuit/System Testing >> Park, License, and/or Tail Lamps Malfunction

Park, License, and/or Tail Lamps Malfunction

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, remove the fuse of the inoperative park/marker lamps and inspect.
    • If the fuse is OPEN, test the voltage supply circuit of the blown fuse for a short to ground.
  2. Ignition OFF, disconnect the appropriate position lamp relay.
  3. 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.
  4. 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 position lamp relay.
  5. 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.
  6. Disconnect the harness connector at the inoperative park/license/marker lamp.
  7. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms between the inoperative park/license/marker lamp ground circuit and ground
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  8. Connect the harness connector at the inoperative park/license/marker lamp.
  9. Connect a 10A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the appropriate park/marker lamps are activated.
    • If the park/marker lamps do not activate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the inoperative park/marker lamp.
  10. Connect a test lamp between the B+ circuit terminal and the relay control circuit terminal.
  11. Command the park lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM.
    • 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.
  12. If all circuits test normal, test or replace the appropriate position lamp relay.
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