Headlamp Leveling Malfunction

Headlamp Leveling 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 front suspension position sensor provides the headlamp leveling modules with front suspension position information. The sensor is permanently grounded and has voltage supplied with the ignition in the ON or CRANK position. The sensor arm is connected to the control arm of the front suspension. As the vehicle travels, the suspension compresses and rebounds moving the suspension position sensor arm. This causes the signal output of the sensor to change. The headlamp leveling modules compare this information with the rear suspension position sensor information and adjusts the headlamp leveling as needed. For more detailed information concerning headlamp leveling operation, refer to Exterior Lighting Systems Description and Operation.

Diagnostic Aids

Important: When one of the suspension position sensor voltage reference or sensor signal circuits are shorted to ground, it may not be possible to determine which suspension position sensor voltage reference or sensor signal circuits, front or rear, has failed. If this condition occurs, all suspension position sensor voltage reference and sensor signal circuits will have to be tested for a short to ground.

Circuit/System Verification

Ignition ON, with a scan tool perform the headlamp motor test for the left and right headlamp leveling modules. The headlamp should move UP and DOWN as the test is performed.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inoperative headlamp assembly.
2. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5.0 ohms of resistance between the ground circuit terminal M and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, test for B+ between the voltage circuit terminal H and ground.

• If less than the specified range, test the voltage circuit for a short to ground or an open/high resistance.

4. If all circuits test normal, replace the inoperative headlamp assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Headlamp Replacement
* Headlamp Aiming
* Relay Replacement (Within an Electrical Center)
* Underhood Electrical Center or Junction Block Replacement
* Control Module References for headlamp leveling module replacement, setup, and programming. Programming and Relearning