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 sensor is used to monitor outside lighting conditions. The body control module (BCM) provides a low reference ground and 5-volt reference signal to the ambient light sensor. Depending on outside lighting conditions, the ambient light sensor provides a voltage signal to the BCM that will vary between 0.2 and 4.9 volts. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights (DRL) or automatic lamp control (ALC) when the headlamp switch is in the AUTO position. In daylight conditions, the BCM will command the DRLs ON by applying voltage to the left and right DRL control circuits illuminating the DRLs. Any function or condition that turns on the headlamps will cancel DRL operation.
Diagnostic Aids
The daytime running lamps will only operate in daylight conditions with the vehicle ON and in any transmission gear except PARK.
Reference Information
Schematic Reference
Exterior Lights Schematics Exterior Lights Schematics
Connector End View Reference
Component Connector End Views Hybrid/EV Battery Pack X1
Description and Operation
Exterior Lights Schematics Exterior Lights Schematics
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
Vehicle ON, command both left and right Dedicated Daytime Running Lamp ON and OFF with a scan tool. Both left and right daytime running lamps should turn ON and OFF when changing between the commanded states.
If both daytime running lamps turn ON and OFF when commanded, refer to Ambient Light Sensor Malfunction.
If one or both of the daytime running lamps do not turn ON and OFF when commanded, refer to Daytime Running Lamp Malfunction.
Circuit/System Testing
Ambient Light Sensor Malfunction
1. Vehicle OFF, disconnect the harness connector at the B10B ambient light/sunload sensor.
2. Vehicle OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 10 ohm between the low reference circuit terminal 6 and ground.
• If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K33 HVAC control module.
3. Vehicle in Service Mode, 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 5 for a short to ground. If the circuit tests normal, replace the K9 BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the low reference circuit terminal 6. 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 K9 BCM.
5. If all circuits test normal, replace the B10B ambient light/sunload sensor.
Daytime Running Lamp Malfunction
1. Vehicle OFF, disconnect the harness connector at the inoperative E13 headlamp.
2. Vehicle OFF, exterior lamps OFF, test for less than 5 ohm between the ground circuit terminal 4 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal 2 and ground.
4. Vehicle ON, command the appropriate 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 circuit tests normal, replace the K9 BCM.
5. If all circuits test normal, replace the inoperative E4 daytime running lamp.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Headlamp Replacement Removal and Replacement
* Sun Load Temperature and Headlamp Automatic Control Ambient Light Sensor Replacement Service and Repair
* Control Module References Programming and Relearning for BCM or HVAC control module replacement, setup, and programming