Daytime Running Lamps Malfunction

Daytime Running Lamps Malfunction

Diagnostic Instructions

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

Diagnostic Fault Information






Circuit/System Description

When the headlight switch is in the Auto position and the ambient light sensor detects sunlight, the body control module (BCM) will command the daytime running lamps to illuminate by providing 12 volts to the daytime running lamp control circuit.

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 End Views By Name
Description and Operation

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

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, command the Left Dedicated Daytime Running Lamp ON and OFF with a scan tool. The E4C daytime running lamp - left should turn ON and OFF while changing between the commanded states.
2. Command the Right Dedicated Daytime Running Lamp ON and OFF with a scan tool. The E4D daytime running lamp - right should turn ON and OFF while changing between the commanded states.

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector K9 BCM.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal listed below ground:

* B+ circuit terminal 2
* B+ circuit terminal 3

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect the X1 harness connector K9 BCM
4. Ignition OFF, disconnect the harness connector at the appropriate E4 daytime running lamp.
5. Test for less than 30 ohm between the ground circuit terminal G and ground.

• If greater than the specified value, test the ground circuit for an open/high resistance.

6. Connect a test lamp between the control circuit terminal A and ground.
7. Command the Dedicated Daytime Running Lamp 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 voltage. If the circuit tests normal, replace the K9 BCM.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 BCM.

8. If all circuits test normal, replace the daytime running lamp bulb.

Repair Instructions

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

* Daytime Running Lamp Bulb Replacement (TT2) Service and Repair
* Control Module References Control Module References for BCM replacement, setup and programming