The headlamp switch indicators are supplied by the LED dimming control circuit from the BCM. The indicators are controlled on and off by the BCM through low side drive control circuits. When a headlamp switch function is activated that requires an indicator to be illuminated, the BCM will ground the control circuit and the indicator will be illuminated at the level of brightness determined by the LED dimming control.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, with the IP dimmer switch at the full bright position, operate the headlamp switch to the headlamps ON position, and back to the automatic headlamps OFF position. The headlamp switch indicators should turn ON and OFF when changing between the commanded states.

1. Ignition OFF, disconnect the harness connectors at the headlamp switch.
2. Ignition ON, headlamps ON, verify that a test lamp illuminates between the LED dimming control circuit terminal K X1 and ground.
3. Connect a test lamp between the LED dimming control circuit terminal K X1and the headlamp on indicator control circuit terminal L X1.

⇒	If the test lamp does not illuminate, test the LED dimming control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between headlamp on switch signal circuit terminal D X1 and the ground circuit terminal C X1. The test lamp should illuminate.

⇒	If the test lamp is always OFF, test the headlamp ON indicator control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.