Circuit/System Testing
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, remove the OVRHD LAMPS Relay from the rear fuse block.
- Connect a test lamp between the control circuit terminal 4 and ground.
- Ignition ON, 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 control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
- If the circuit tests normal, test or replace the overhead lamp relay.