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
Conditions for Running the DTC
The body control module (BCM) receives a signal from the ambient light sensor indicating a low or high outside ambient light level. Under daylight conditions the BCM grounds the DRL relay control circuit energizing the DRL relay. The closed relay supplies voltage to the DRLs. Any time the headlamps are illuminated, the DRL will not illuminate.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views A/C Compressor Clutch
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
Supply sufficient light to simulate daylight conditions to the ambient light sensor. Ignition ON, engine running, and the gear selector in drive. The DRLs should illuminate.
Circuit/System Testing
1. Ignition OFF, disconnect the appropriate DRL relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the DRL relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.
• If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
6. Command the DRL 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.
7. Connect a 10 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87.
8. Disconnect the harness connector at the appropriate daytime running light.
9. Verify that a test lamp illuminates between the DRL control circuit listed below and ground:
* RPO W49/Z88 - terminal 1
* RPO WDA - terminal 2
* RPO WDA/X88 - terminal B
* RPO Z88 - terminal A
• If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance.
10. Verify that a test lamp illuminates between the DRL ground circuit listed below and B+:
* RPO WDA - terminal 1
* RPO W49/Z88 - terminal 3
* RPO WDA/X88 - terminal A
* RPO Z88 - terminal B
• If the test lamp does not illuminate, test the ground circuit for a open/high resistance.
11. If all circuits test normal, test or replace the DRL relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Headlamp Replacement (Traverse) Headlamp ReplacementHeadlamp Replacement (Acadia) Headlamp ReplacementHeadlamp Replacement (Enclave) Headlamp Replacement
* Headlamp Bulb Replacement (Traverse Low Beam) Headlamp Bulb Replacement (Traverse High Beam) Headlamp Bulb Replacement (Enclave/Acadia) Service and Repair
* Control Module References Control Module References for BCM replacement, programming and setup