Circuit/System Testing
- Ignition OFF, disconnect the HDLP relay.
- Connect a test lamp between the control circuit terminal 86 and the B+ circuit terminal 85.
- Ignition ON, command the low beam headlamps 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 open/high resistance. If the circuit tests normal, replace the BCM.
- If all circuits test normal, test or replace the HDLP relay.