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.
Diagnostic Fault Information
Circuit/System Description
The ambient light 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 sensor indicates daytime conditions with the transmission in gear, the body control module (BCM) grounds the DRL relay control circuit, energizing the DRL relay. With the DRL relay energized, voltage is applied through the relay switch contacts, the DRL 1 fuse, and the DRL 2 fuse to the left and right low beam headlamps. 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 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. Turn the headlamp switch to the headlamps ON position, the low beam headlamps should illuminate.
• If the low beam headlamps do not illuminate, refer to Headlamps Malfunction (Headlamps Malfunction).
2. Headlamps OFF, command the Low Beams ON and OFF with a scan tool. The headlamps should turn ON and OFF between the commanded states.
• If the low beam headlamps are always ON, refer to the Headlamps Malfunction (Headlamps Malfunction).
• If the low beam headlamps are always OFF, refer to the Headlamps Malfunction (Headlamps Malfunction).
3. Headlamps OFF, command the DRL ON and OFF with a scan tool. The headlamps should turn ON and OFF between the commanded states.
• If the low beam headlamps are always ON, refer to Daytime Running Lamp Malfunction.
• If the low beam headlamps are always OFF, refer to the Daytime Running Lamps Malfunction.
4. Ignition ON, carefully supply sufficient light to simulate daylight conditions to the ambient light sensor for more than 30 seconds. Observe the scan tool Ambient Light Status parameter. The reading should be Day.
• If not the specified value, refer to the Ambient Light Sensor Malfunction.
Circuit/System Testing
Ambient Light Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal B and ground.
• If greater than the specified 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 volts.
• If less than the specified range, test the signal circuit terminal A 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 and ground. Verify the scan tool Ambient Light Sensor parameter is less than 1.96 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, replace the ambient light sensor.
Daytime Running Lamps Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the underhood fuse block.
2. Connect a test lamp between the relay control circuit terminal 40 and B+.
3. Ignition ON, command the DRL lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF.
• 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.
4. Connect the X3 harness connector at the underhood fuse block.
5. Ignition OFF, disconnect the inoperative low beam headlamp.
6. Test for less than 5 ohms between the listed ground circuit terminal below and ground.
* Headlamp terminal A - w/o V22
* Low Beam Headlamp terminal B - with V22
• If greater than the specified range, test the ground circuit for an open/high resistance,
7. Connect a test lamp between the listed control circuit terminal below and ground.
* Headlamp terminal C - w/o V22
* Low Beam Headlamp terminal A - with V22
8. Command the DRL lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF.
• If the test lamp is always ON, test the control circuit for short to voltage. If the circuit tests normal, replace the underhood fuse block.
• If the test lamp is always OFF, test the control circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
9. If all circuits test normal, replace the inoperative low beam headlamp.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Accessory Wiring Junction Block Replacement (Accessory Wiring Junction Block Replacement)
* Daytime Running Lamp (DRL) Ambient Light Sensor Replacement (Service and Repair)
* Headlamp Replacement (V22) (Service and Repair)
* Headlamp Capsule Replacement (Minus V22) (Service and Repair)
* Headlamp Bulb Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming