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
The ambient light/sunload sensor is a light sensitive transistor that varies the voltage signal to the body control module (BCM) based on outside lighting conditions. When the ambient light/sunload sensor indicates daytime conditions with engine running, the BCM, will then apply battery voltage through the front turn signal lamp supply voltage circuits illuminating the left and right front turn lamps. Any function or condition that turns the headlamps ON will cancel DRL operation.
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 (Programming and Relearning)for scan tool information
Circuit/System Verification
Command the Left or Right Front Turn Signal ON and OFF with a scan tool. The appropriate front turn signal should turn ON and OFF when changing between the commanded states.
If the front turn signals turn ON and OFF when commanded, refer to Ambient Light/Sunload Sensor Malfunction.
If the front turn signals do not turn ON and OFF when commanded, refer to Daytime Running Lamps Malfunction.
Circuit/System Testing
Ambient Light/Sunload Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the ambient light/sunload sensor.
2. Ignition OFF, test for less than 5 ohm between the ground circuit terminal C and ground.
• If greater than the specific range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V.
• If less than the specified range, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal D and the ground circuit terminal C. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V.
• If greater than the specified range, test the signal circuit for a short to voltage an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the ambient light/sunload sensor.
Daytime Running Lamps Malfunction
1. Supply sufficient light to the ambient light sensor to simulate daylight conditions.
2. Ignition ON, headlamp switch in the AUTOMATIC LIGHT position, observe the headlamps. The headlamps should not be illuminated.
• If the headlamps are illuminated, replace the ambient light/sunload sensor.
3. Ignition OFF, disconnect the harness connector at the appropriate headlamp.
4. Connect a test lamp between the control circuit terminal A and the ground circuit terminal C.
5. Command the Turn Signal 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 ground. If the circuit tests normal, replace the BCM.
• If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the headlamp.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Ambient Light Sensor Replacement (Service and Repair)
* High Intensity Discharge Headlamp Replacement (High Intensity Discharge Headlamp Replacement)
* Control Module References (Programming and Relearning)for BCM replacement, setup, and programming