Daytime Running Lamps Malfunction (w/ TT6)
Daytime Running Lamps Malfunction (w/ TT6)
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 a light sensitive transistor that varies its voltage signal to the body control module (BCM) in response to changes to the outside (ambient) light level. When the BCM receives this signal it will turn on the front turn signal lamps at full intensity. Any function or condition that turns on the headlights will cancel the DRL operation. With the headlight switch in the OFF position, the headlamps will either be turned ON or OFF, after an approximate 8 second delay depending on whether daylight or low light conditions are sensed. When the BCM signals the turn signals for DRL operation in daylight conditions, the turn signal/hazard flasher module illuminates the turn signal lamps. The DRL will operate when the ignition switch is in the RUN position, the gear selector is not in the PARK position and the parking brake is released. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will 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 (Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
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 (Programming and Relearning)for scan tool information
Circuit/System Verification
1. Ignition ON, observe the front turn signal lamps while the hazard switch is ON.
• If none of the lamps flash normally, refer to Hazard Lamps Malfunction (w/o TT6) (Hazard Lamps Malfunction (w/o TT6))Hazard Lamps Malfunction (w/TT6) (Hazard Lamps Malfunction (w/TT6))
• If one of the front lamps flash normal, refer to Turn Signal Lamps and/or Indicators Malfunction (w/o TT6) (Turn Signal Lamps and/or Indicators Malfunction (w/o TT6))Turn Signal Lamps and/or Indicators Malfunction (w/ TT6) (Turn Signal Lamps and/or Indicators Malfunction (w/ TT6))
2. Ignition ON, observe the scan tool Ambient Light Sensor parameter voltage while carefully supplying sufficient light to simulate daylight conditions to the ambient light sensor, then covering to simulate darkness. The voltage reading should change from approximately 1.75 to 4.9 volts.
• If the reading does not change between light and dark, refer to the Ambient Light Sensor Malfunction.
3. Ignition ON, command the Daytime Running Lamps ON and OFF with a scan tool. The low beam headlamps should turn ON and OFF.
• If the low beam headlamps do not turn ON and OFF, refer to the Daytime Running Lamps Malfunction.
Circuit/System Testing
Ambient Light Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
2. Ignition OFF, 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 an open/high resistance. If the circuit tests normal, replace the BCM.
3. Ignition ON, verify the scan tool Light Sensor parameter is greater than 4.5 volts.
• If less than the specified range, test the signal circuit 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 Light Sensor parameter is less than 1.0 volt.
• If greater than the specified range, 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 ambient light sensor.
Daytime Running Lamps Malfunction
1. Ignition OFF, disconnect the X2 harness connector at the BCM.
2. Ignition ON, connect a fused jumper wire from the DRL signal circuit terminal E10 to ground.
• If the front turn signal lamps are not illuminated, test the DRL signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the turn signal/hazard flasher module.
3. If all circuits test normal, replace the BCM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Ambient Light Sensor Replacement (Service and Repair)
* Hazard and Turn Signal Flasher Replacement (Service and Repair)
* Parking and Turn Signal Lamp Bulb Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for BCM replacement, programming, and setup