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 is wired to each headlamp leveling actuator with 4 directional actuator control circuits.
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, headlamps ON.
2. Verify the left headlamp operates Up and Down while commanding the Left Headlamp Vertical Motor Up and Down with a scan tool.
• If the left headlamp does not operate Up and Down
Refer to Headlamp Leveling Actuator Malfunction.
• If the left headlamp operates Up and Down
3. Verify the right headlamp operates Up and Down while commanding the Right Headlamp Vertical Motor Up and Down with a scan tool.
• If the right headlamp does not operate Up and Down
Refer to Headlamp Leveling Actuator Malfunction.
• If the right headlamp operates Up and Down
4. Verify the Front Leveling Position Sensor Signal voltage parameter is between 0.3 and 4.9 V with a scan tool.
• If not between 0.3 and 4.9 V
Refer to Headlamp Leveling Sensor Malfunction.
• If between 0.3 and 4.9 V
5. Verify the Rear Leveling Position Sensor Signal voltage parameter is between 0.3 and 4.9 V with a scan tool.
• If not between 0.3 and 4.9 V
Refer to Headlamp Leveling Sensor Malfunction.
• If between 0.3 and 4.9 V
6. 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. It may take up to 2 minutes for all vehicle systems to power down.
2. Remove the F39UA 5 A fuse from the X50A fuse block - underhood.
3. Test for 10 ohms -25k ohms between each control circuit terminal listed below and ground.
* M29 headlamp leveling actuator control terminal 1
* M29 headlamp leveling actuator control terminal 2
* M29 headlamp leveling actuator control terminal 3
* M29 headlamp leveling actuator control terminal 4
• If less than 10 ohms
1. Ignition OFF, disconnect the harness connector at the K28 headlamp leveling control module.
2. Test for infinite resistance between the appropriate control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K28 headlamp leveling control module.
• If greater than 25k ohms
1. Ignition OFF, disconnect the harness connector at the K28 headlamp leveling control module.
2. Test for less than 2 ohms in the appropriate control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms
3. Ignition ON.
4. Test for less than 1 V between the appropriate control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K28 headlamp leveling control module.
• If between 10 ohms -25k ohms
4. Ignition OFF, install the F39UA 5 A fuse at the X50A fuse block - underhood, ignition ON, headlamps ON.
5. Verify a test lamp does not illuminate between each control circuit terminal listed below and ground.
* M29 headlamp leveling actuator control terminal 1
* M29 headlamp leveling actuator control terminal 2
* M29 headlamp leveling actuator control terminal 3
* M29 headlamp leveling actuator control terminal 4
• If the test lamp illuminates
1. Ignition OFF, disconnect the harness connector at the K28 headlamp leveling control module, ignition ON.
2. Test for less than 1 V between the appropriate control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K28 headlamp leveling control module.
• If the test lamp does not illuminate
6. Test or replace the appropriate M29 headlamp leveling actuator.
Headlamp Leveling Sensor Malfunction
1. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate B152 suspension position sensor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 ohms between the low reference circuit terminal 3 and ground.
• If 10 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K28 headlamp leveling 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 K28 headlamp leveling control module.
• If less than 10 ohms
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 K28 headlamp leveling 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 K28 headlamp leveling control module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K28 headlamp leveling 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 K28 headlamp leveling control module.
• If between 4.8-5.2 V
5. Verify the appropriate scan tool Leveling Position Sensor Signal parameter is less than 0.5 V.
• If 0.5 V or greater
1. Ignition OFF, disconnect the harness connector at the K28 headlamp leveling control module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 2 and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K28 headlamp leveling control module.
• If less than 0.5 V
6. Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the signal circuit terminal 2.
7. Verify the appropriate scan tool Leveling Position Sensor Signal parameter is greater than 4.8 V.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K28 headlamp leveling 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 K28 headlamp leveling control module.
• If 4.8 V or greater
8. Test or replace the appropriate B152 suspension position sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Headlamp Replacement Headlamp Replacement
* Headlamp Leveling Front Suspension Height Sensor Replacement (Coupe) Headlamp Leveling Front Suspension Height Sensor Replacement (Coupe)
* Headlamp Leveling Rear Suspension Height Sensor Replacement (Coupe) Headlamp Leveling Rear Suspension Height Sensor Replacement (Coupe)
* Control Module References Control Module References for headlamp control module replacement, programming, and setup