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 ambient light sensor provides a voltage signal that will vary between 0.2 and 4.9 volts depending on outside lighting conditions. The body control module (BCM) provides a 5-volt reference signal to the ambient light sensor and the HVAC control module provides a low reference ground. 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. During low light conditions the BCM will command the low beam headlamps ON. Any function or condition that turns on the headlamps 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 Fuel Pump and Level Sensor Assembly
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, with a scan tool command the Low Beams ON and OFF. The low beam headlamps should turn ON and OFF when changing between the commanded states.
• If the low beam headlamps do not turn ON and OFF when commanded, refer to Headlamps Malfunction Headlamps Malfunction.
2. Ignition ON, park brake released, verify with a scan tool the Park Brake Switch parameter displays Released.
• If not the specified value, refer to Symptoms - Hydraulic Brakes Symptoms - Hydraulic Brakes.
3. Ignition ON, with a scan tool command the DRL ON and OFF. The low beam headlamps should turn ON and OFF when changing between the commanded states.
• If the low beam headlamps do not turn ON and OFF when commanded, refer to Daytime Running Lamps Malfunction.
• If the low beam headlamps turn ON and OFF when commanded, refer to Ambient Light Sensor Malfunction.
Circuit/System Testing
Daytime Running Lamps Malfunction
1. Ignition OFF, disconnect the KR42 daytime running lamps 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 30 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 F21DA fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, replace the KR42 daytime running lamps relay.
4. 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 an open/high resistance.
5. Connect a 15A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the low beam headlamps illuminate.
• If the low beam headlamps do not illuminate, test the control circuit for an open/high resistance.
6. Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
7. 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 K9 body control module.
• 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 K9 body control module.
8. If all circuits test normal, replace the KR42 daytime running lamps relay.
Ambient Light Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the B10B ambient light/sunload sensor.
2. Ignition ON, verify that a test lamp illuminates between the low reference circuit terminal C and B+.
• If the test lamp does not illuminate, 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. If all circuits test normal, replace the B10B ambient light/sunload sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Sunload and Twilight Sentinel Sensor Replacement Service and Repair
* Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)
* Control Module References Control Module References for BCM or HVAC control module replacement, setup, and programming