Headlamp Switch On Indicator Inoperative

Headlamp Switch On Indicator Inoperative

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

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.

Circuit/System Verification

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.

Circuit/System Testing

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

^ 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 and remove a 3A fused jumper wire between headlamp on switch signal circuit terminal X1 D and the low reference circuit terminal X1 C. The test lamp should turn on and off when changing between the commanded states.

^ If the test lamp is always ON, test the headlamp on indicator control circuit for a short to ground. If the circuit tests normal, replace the BCM.

^ 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.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Headlamp Switch Replacement