Headlamp Range Adjustment, Function

Headlamp Range Adjustment, Function

The electric headlamp range control is prescribed by law to prevent xenon headlamps dazzling on-coming traffic. Exception: Vehicles with ABC (Active Body Control) - Chassis are not equipped with automatic headlamp range control.

The headlamp range control automatically maintains the inclination angle of the headlamps within the legally defined limits regardless of the vehicle load.

Requirement:
- Circuit 15 ON
- Exterior lamp switch in parking lamp, headlamp or AUTO position

A xenon control module (xenon headlamp control module E1n1, E2n1) is integrated into both headlamps. Two control modules operate in a master/slave combination for the automatic headlamp range control function. Values required for control are transmitted to the left headlamp (master) as analog signals.

The right headlamp control module is supplied with control functions as slave via a serial interface

The master control module of the left headlamp uses the signals of the level sensors at the front and rear axle for controlling the headlamps.

The master control module in the left headlamp compares the signals from the sensors with the headlamp adjustment and, when necessary, actuates the left and right headlamp range control motors (E1m1 and E2m1) in the headlamp to correct the inclination angle.

In addition to the signals from the level sensors the master control module in the left headlamp processes a wheel speed signal proportional to the vehicle speed output as an analog signal by the EPS, PML and BAS control module (N47-5).

Evaluation of the wheel speed signal indicate to the master control module whether the vehicle is moving at constant, accelerating or decelerating.

A constant vehicle speed the headlamp range control operates in the "static mode" with slow motor adjustment speed in the headlamps.

If the vehicle is accelerating or braking, it activates "dynamic mode" with a high adjustment rate.