Courtesy Lamp Circuit Test
WARNING: This page is about a different car, the 2006 Buick Lucerne. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the (C3, C4) harness connectors at the BCM.
- Verify that a test lamp illuminates between B+ circuits listed below and ground.
- Terminal 2 C3
- Terminal 2 C4
- 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 related courtesy lamp supply voltage circuits for a short to ground.
- Ignition OFF, connect the BCM harness connectors.
- Disconnect the harness connector at the inoperative courtesy lamp lamp.
- Test for less than 5.0 ohms of resistance between the appropriate ground circuit terminal listed below and ground.
- Left or Right Roof Rail Reading Lamp terminal B
- Overhead Console Lamp terminal A
- Left or Right Footwell Courtesy Lamp terminal B
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the appropriate supply voltage circuit terminal listed below and ground.
- Left or Right Roof Rail Reading Lamp terminal A
- Overhead Console Lamp terminal B
- Left or Right Footwell Courtesy Lamp terminal A
- Command the Courtesy Lamp 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 supply voltage circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- If all circuits test normal, test or replace the courtesy lamp bulb.