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Daytime Running Lamps Malfunction

Daytime Running Lamps Malfunction

Diagnostic Instructions


Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions has overviews of all diagnostic categories.


Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Ambient Light/Sunload Sensor Signal

B2645 03

B2645 07

B2645 07

-

Left/Right Daytime Running Lamp (DRL) and Rear Park Lamp Control

B2585 02, B3867 02

1

2

-

Ambient Light/Sunload Sensor Ground

-

B2645 07

-

-

1. Daytime Running Lamps (DRL) and Park Lamps Inoperative

2. Daytime Running Lamps (DRL) and Park Lamps Always ON



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 1.4-4.5 V depending on outside lighting conditions. The body control module (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 when the headlamp switch is in the AUTO position. In daylight conditions the BCM will command the DRL and rear park lamps ON.

The BCM receives a signal from the ambient light/sunload sensor indicating a low or high ambient outside light level. Under daylight conditions the BCM will enable the daytime running lamps and rear park lamps. The daytime running lamps and rear park lamps share the same BCM control circuit. With the headlamp switch in the AUTO position, the DRL and rear park lamps will be illuminated at all times with the ignition on and engine running.

Reference Information

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference


Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs


Scan Tool Reference

Control Module References for information on diagnostic tools

Circuit/System Verification


1. Verify that no other DTC is set.

2. If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

3. Ignition ON, observe the scan tool Ambient Light Sensor parameter. The reading should be between 1.4-4.5 V and change with ambient light changes.


Circuit/System Testing


1. Ignition OFF, disconnect the harness connector at the B10B Ambient Light/Sunload Sensor.

2. Test for less than 5 Ω between the ground circuit harness connector terminal 6 and ground.

3. If greater than the specified range, test the low reference circuit for an open/high resistance.

4. Ignition ON, test for 4.8-5.2 V between the signal circuit harness connector terminal 5 and ground.

5. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.

6. If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

7. If all circuits test normal, test or replace the B10B Ambient Light/Sunload Sensor.


Component Testing


Dynamic Test

1. Ignition ON, observe the scan tool Ambient Light Sensor parameter. The reading should be between 1.4-4.5 V and change with ambient light changes.

2. Test the B10B Ambient Light/Sunload Sensor by varying the ambient light while monitoring the sensors voltage output.

3. Verify that the voltage output is within the range of the specification.

4. If not within the specified range, replace the B10B Ambient Light/Sunload Sensor.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


Sun Load Temperature and Headlamp Automatic Control Ambient Light Sensor Replacement

Control Module References for information on BCM replacement, setup, and programming