Headlamp Switch On Indicator Inoperative

Headlamp Switch On Indicator Inoperative

Diagnostic Instructions

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

Reference Information
Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics (Headlights/Daytime Running Lights (DRL) Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

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, 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.

Repair Instructions

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

* Headlamp Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, programming, and setup