Daytime Running Lamps Malfunction
Daytime Running Lamps Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* 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 HVAC control module provides a low reference ground and 5-volt reference signals to the ambient light sensor. 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 (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. With the turn signal/multifunction switch in the OFF position, the DRLs which consists of the front turn signal lamps will either be turned ON or OFF after a 30-second delay, depending on whether daylight or low light conditions are sensed by the ambient light sensor. For more detailed information concerning exterior lamp operation refer to Exterior Lighting Systems Description and Operation.
Diagnostic Aids
Important: This diagnostic procedure assumes that the turn signal lamps are operating within specifications. If the turns signal lamps are inoperative, diagnose the turn signal malfunction before proceeding with the following diagnostic. Refer to Turn Signal Lamps and/or Indicators Malfunction. Turn Signal Lamps and/or Indicators Malfunction
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the sunload sensor assembly.
2. Ignition OFF, scan tool OFF, doors CLOSED, test for less than 20.0 ohms of resistance between the low reference circuit terminal C 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 status parameter is INVALID/UNKNOWN.
• If not the specified value, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal D and the low reference circuit terminal C. Verify the scan tool Ambient Light status parameter is DAY.
• If the scan tool displays NIGHT, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the sunload sensor assembly.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Sun Load Sensor Replacement
* Control Module References for BCM or HVAC control module replacement, setup, and programming. Programming and Relearning