Daytime Running Lamps Malfunction

Daytime Running Lamps Malfunction

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

Circuit/System Description

The daytime running lamps (DRL) operate based on an input from the ambient light sensor. When the sensor indicates daylight conditions and the exterior lamps are not required to be on, the BCM will activate only the low beam headlamps as the DRLs. The DRLs will operate with the ignition ON, the parking brake released, and the headlamp switch in the OFF or AUTO position.

Reference Information
Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics (Headlights/Daytime Running Lights (DRL) Diagrams)
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

1. Verify the headlamp switch is in the AUTO position and the park brake is released.
2. Ignition ON, verify DTC B2645 is not set.

• If DTC B2645 is set, refer to DTC B2645 (B2645).

3. Verify the scan tool BCM Park Lamp Switch parameter is Off.

• If not the specified value, refer to Park, License, and/or Tail Lamps Malfunction (Park, License, and/or Tail Lamps Malfunction).

4. Verify the following scan tool BCM parameters are Off.

* Low Beam Switch
* High Beam Switch
* Flash to Pass Switch

• If any of the parameters are not the specified value, refer to Headlamps Malfunction (Headlamps Malfunction).

5. Verify the scan tool BCM Headlamp Off Switch parameter is Inactive.

• If not the specified value, refer to Headlamps Malfunction (Headlamps Malfunction).

6. Verify the scan tool BCM Park Brake Switch parameter is Released.

• If not the specified value, refer to Brake Warning Indicator Malfunction (Brake Warning Indicator Malfunction).

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the ambient light sensor (RPO C67) or sunload sensor assembly (RPO CJ2).
2. Ignition OFF, test for less than 5 ohms of resistance between the ground circuit terminal B (C67) or C (CJ2) and ground.

• If greater than the specified range, test the low reference circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 volts.

• If less than the specified range, test the signal circuit terminal A (C67) or D (CJ2) for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the signal circuit terminal A (C67) or D (CJ2) and the low reference circuit terminal ground. Verify the scan tool Ambient Light Sensor parameter is less than 0.2 volts.

• If greater than the specified range, test the signal 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 ambient light sensor (C67) or sunload sensor assembly (CJ2).

Repair Instructions

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

* Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (Service and Repair)
* Sun Load Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming