Headlamp Range Adjustment

Electric headlamp range adjustment is required by law for vehicles with xenon headlamps to prevent dazzling oncoming traffic. The headlamp range adjustment automatically keeps the inclination angle of the low beams within the legally defined limit regardless of how the vehicle is loaded.

The headlamp range adjustment control module utilizes the signals from the level sensors on the front and rear axles for control and adjustment of the low beams. The pneumatic suspension control module processes the signals from the level sensors and transfers these to the headlamp range adjustment control module via the data bus (CAN).

The headlamp range adjustment control module compares the signals with the headlamp adjustment and, if necessary actuates the headlamp range adjustment motors in the head lamps to correct the angle of inclination.

In addition to the signals from the level sensors the headlamp range adjustment control module also processes a wheel speed signal proportional to the vehicle speed transferred on the data bus from the ASR/ESP control module.

Evaluation of this wheel speed signal indicates to the headlamp range adjustment control module whether the vehicle is driving at constant speed, accelerating or decelerating.

At constant vehicle speed the headlamp range adjustment operates in the "static mode" with minimum headlamp motor adjustment speed.

During acceleration or deceleration the "dynamic mode" with high adjustment speed is actuated.