Headlamp Leveling Malfunction
Headlamp Leveling 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
Each headlamp assembly contains a headlamp leveling actuator that is controlled by the headlamp leveling control module. The front and rear suspension position sensors provide the headlamp leveling control with suspension position information. Each sensor receives a 5 V reference, signal, and low reference circuits from the headlamp leveling control module. The sensors are connected to the control arms of the front and rear suspension. As the vehicle travels, the suspension compresses and rebounds moving the suspension position sensor arms. This causes the signal output of the sensor to change. The headlamp leveling control module compares the information from both suspension position sensors and adjusts the headlamp leveling as needed. The headlamp leveling control module communicates with the left and right headlamp leveling actuators via the LIN serial data circuit.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
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 scan tool Front Leveling Position Sensor Voltage parameter is between 0.5 and 4.9 V.
• If the parameter is not between 0.5 and 4.9 V
Refer to Headlamp Leveling Sensor Malfunction.
• If the parameter is between 0.5 and 4.9 V
3. Verify the scan tool Rear Leveling Position Sensor Voltage parameter is between 0.5 and 4.9 V.
• If the parameter is not between 0.5 and 4.9 V
Refer to Headlamp Leveling Sensor Malfunction.
• If the parameter is between 0.5 and 4.9 V
4. Verify the left and right headlamps operate to the UP and DOWN positions when commanding the DHL Motor Control UP and DOWN with a scan tool.
• If the left and right headlamps do not operate UP and DOWN
Refer to Headlamp Leveling Actuator Malfunction
• If the left and right headlamps operate UP and DOWN
5. All OK.
Circuit/System Testing
Headlamp Leveling Actuator Malfunction
1. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate M29 headlamp leveling actuator.
2. Test for less than 5 ohms between the ground circuit terminal 2 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 a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate
1. Ignition OFF, disconnect the X2 harness connector at the X50A fuse block - underhood.
2. Test for infinite resistance between the B+ 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 X50A fuse block - underhood.
• If the test lamp illuminates
5. Test or replace the K26 headlamp control module.
6. Ignition ON.
7. Verify the appropriate headlamp operates to the UP and DOWN positions when commanding the DHL Motor Control UP and DOWN with a scan tool.
• If the appropriate headlamp does not operate UP and DOWN, test or replace the appropriate headlamp assembly.
Headlamp Leveling Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate B152L suspension position sensor, ignition ON.
2. Verify a test lamp illuminates between the low reference circuit terminal 2 and B+.
• If the test lamp does not illuminate
1. Ignition OFF, disconnect the harness connector at the K26 headlamp 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 K26 headlamp control module.
• If the test lamp illuminates
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K26 headlamp control module.
2. Test for infinite resistance between the 5 V reference 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 5 V 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 K26 headlamp control module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K26 headlamp control module, ignition ON.
2. Test for less than 1 V between the 5 V reference circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K26 headlamp control module.
• If between 4.8-5.2 V
5. Verify the appropriate scan tool Leveling Position Sensor parameter is less than 1 V.
• If 1 V or greater
1. Ignition OFF, disconnect the harness connector at the K26 headlamp control module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 3 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K26 headlamp control module.
• If less than 1 V
6. Install a 3 A fused jumper wire between the 5-volt reference circuit terminal 1 and the signal circuit terminal 3.
7. Engine RUNNING, verify the appropriate scan tool Leveling Position Sensor parameter is greater than 4.8 V.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K26 headlamp control module.
2. Test for infinite resistance between the signal 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 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 K26 headlamp control module.
• If 4.8 V or greater
8. Test or replace the appropriate B152L suspension position sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Electronic Suspension Front Position Sensor Replacement Electronic Suspension Front Position Sensor Replacement
* Electronic Suspension Rear Position Sensor Replacement Electronic Suspension Rear Position Sensor Replacement
* Headlamp Replacement Headlamp Replacement
* Control Module References Control Module References for headlamp control module replacement, programming, and setup