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 low beam headlamps (DRLs) ON by applying low voltage to the low beam headlamp control circuits illuminating the low beam headlamps at reduced intensity. 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 Sunshade - Left (D6I)
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, command both Low Beam Headlamps ON and OFF with a scan tool. 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 BCM Park Brake Status parameter displays Released.
• If not the specified value, refer to Brake Warning Indicator Malfunction Brake Warning Indicator Malfunction.
Circuit/System Testing
With C67
1. Ignition OFF, disconnect the harness connector at the B10B ambient light/sunload sensor.
2. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 5 ohm between the ground circuit terminal 6 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 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 ground 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.
With C68
1. Ignition OFF, disconnect the harness connector at the B10B ambient light/sunload sensor.
2. Ignition 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 an open/high resistance. If the circuit tests normal, replace the HVAC control module.
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 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 ground 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.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Sun Load Temperature and Headlamp Automatic Control Ambient Light Sensor Replacement Service and Repair
* Control Module References Control Module References for BCM or HVAC control module replacement, setup, and programming