Daytime Running Lamps Malfunction (with T4F)
Daytime Running Lamps Malfunction (with T4F)
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
With Manual HVAC
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 which is permanently grounded at G203. 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.
With Automatic HVAC
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 Sunshade - Left
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.
2. Verify the left park/daytime running lamp turns ON & OFF when commanding the Left Park Lamps ON and OFF with a scan tool.
• If the left park/daytime running lamp does not turn ON and OFF
Refer to Daytime Running Lamps Malfunction.
• If the left park/daytime running lamp turns ON and OFF
3. Verify the right park/daytime running lamp turns ON & OFF when commanding the Right Park Lamps ON and OFF with a scan tool.
• If the right park/daytime running lamp does not turn ON and OFF
Refer to Daytime Running Lamps Malfunction.
• If the right park/daytime running lamp turns ON and OFF
4. Ignition ON, park brake released.
5. Verify the scan tool BCM Park Brake Status parameter displays Released.
• If the park brake status parameter does not display Released
Refer to Brake Warning Indicator Malfunction Brake Warning Indicator Malfunction.
• If the parameter displays Released
6. Refer to Ambient Light Sensor Malfunction.
Circuit/System Testing
Daytime Running Lamps Malfunction
1. Ignition OFF, exterior lamps OFF, remove the appropriate E4A park/daytime running lamp bulb.
2. Test for less than 15 ohms between the appropriate ground circuit terminal listed below and ground.
* E4AC park/daytime running lamp - left terminal B
* E4AD park/daytime running lamp - right terminal B
• If 15 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 15 ohms
3. Connect a test lamp between the appropriate control circuit terminal listed below and ground, ignition ON.
* E4AC park/daytime running lamp - left terminal A
* E4AD park/daytime running lamp - right terminal A
4. Verify the test lamp turns ON and OFF when commanding the appropriate Park Lamps ON and OFF with a scan tool.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the X4 harness connector at the K9 body control module.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If the test lamp is always ON
1. Ignition OFF, disconnect the X4 harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the control circuit terminal and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K9 body control module.
• If the test lamp turns ON and OFF
5. Test or replace the E4A park/daytime running lamp bulb.
Ambient Light Sensor Malfunction - with C67
1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the B10B ambient light/sunload sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 ohms between the ground circuit terminal 6 and ground.
• If 5 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Ignition ON.
4. Verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V.
• If 4.65 V or less
1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal circuit terminal 5 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 body control module.
• If greater than 4.65 V
5. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the low reference circuit terminal 6.
6. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V.
• If 0.196 V or greater
1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 5 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If less than 0.196 V
7. Test or replace the B10B ambient light/sunload sensor.
Ambient Light Sensor Malfunction - with CJ2/C68
1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector at the B10B ambient light/sunload sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 25 ohms between the low reference circuit terminal 6 and ground.
• If 25 ohms or greater
1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC control module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC control module.
• If less than 25 ohms
3. Ignition ON.
4. Verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V.
• If 4.65 V or less
1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module.
2. Test for infinite resistance between the signal circuit terminal 5 and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K9 body control module.
• If greater than 4.65 V
5. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the low reference circuit terminal 6.
6. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V.
• If 0.196 V or greater
1. Ignition OFF, disconnect the X2 harness connector at the K9 body control module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 5 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K9 body control module.
• If less than 0.196 V
7. Test or replace the B10B ambient light/sunload sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Sun Load Temperature Sensor Replacement HVAC - Automatic
* Daytime Running Lamp Bulb Replacement (Base) Daytime Running Lamp Bulb Replacement (Base)Daytime Running Lamp Bulb Replacement (HID) Daytime Running Lamp Bulb Replacement (HID)
* Control Module References Control Module References for BCM or HVAC Control Module replacement, programming, and setup