Headlamp Alignment Sensor: Description and Operation

The headlamp leveling system uses two headlamp level sensors to determine when the vehicle has had its ride height or angle changes, due to passenger/ cargo additions and road conditions.




There is one sensor (1) mounted on the spring link (3) on the right side of the rear suspension.




Each sensor has a link that is connected to the suspension and to the sensor, one electrical connector that connects the sensor to the vehicles electrical system wiring harness, and one bracket that mounts with one nut to the vehicle.

The system is designed to automatically level the headlamps, regardless of cargo/passenger loads or road conditions. When the vehicle is loaded with passengers and/or cargo, as the ignition is turned to RUN, the system will look at the front and rear sensors and make an adjustment to the headlamp stepper motors based upon feedback from the sensor to see if it has moved approximately 27.5 degrees from its zero or neutral position. The headlamp stepper motor then adjusts the headlamp up or down for proper headlamp aiming.

The headlamp level sensors act like a potentiometer to relay information via the data bus to the HID translator module when the vehicle has changed its angle or ride height in either the front or rear of the vehicle.

NOTE: If the headlamp leveling module (HID translator module) or sensors are replaced, the system needs to be calibrated using a Scan Tool.
When in calibration mode, the vehicle doors, trunk/liftgate, and hood must be closed. In addition, the vehicle may not be touched (bounced or bumped) until the calibration is complete. The headlamps must be ON to power the stepper motors. The approximate calibration time is 12 - 15 seconds. The scan tool will display a "status of calibration" message. These being either "still in progress", "passed", or "failed".
If a system fault occurs, the translator module will store the Diagnostic Trouble Code (DTC) and enable it to be read using the scan tool and assist in diagnosing the headlamp leveling system.