Circuit/System Testing
WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
The high intensity discharge system produces high voltage and current. To reduce the risk of severe shocks and burns:
- Never open the high intensity discharge system ballast or the arc tube assembly starter.
- Never probe between the high intensity discharge system ballast output connector and the arc tube assembly.
- Ignition OFF, disconnect the (C2) harness connector at the underhood fuse block.
- Connect a test lamp between the control circuit terminal 19 and B+.
- Ignition ON, command the High Beams 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.
- If the circuit tests normal, test or replace the underhood fuse block.