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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 >> Courtesy Lamps Malfunction >> Circuit/System Testing >> Courtesy/Reading Lamp Malfunction - Front or Rear

Courtesy/Reading Lamp Malfunction - Front or Rear

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 harness connector at the inoperative courtesy/reading lamp assembly.
  2. Ignition OFF, scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 1.0 ohm between the ground circuit terminal B and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition OFF, connect a test lamp between the courtesy lamp supply voltage circuit terminal C and the ground circuit terminal 3.
  4. Command the courtesy 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 OFF, test the courtesy lamp supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
    • If the test lamp is always ON, test the courtesy lamp supply voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM.
  5. If all circuits test normal, replace the inoperative courtesy/reading lamp assembly.
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