General Information

General Information

Automatic vertical headlight aim control keeps the tilt angle of the low beams constant, even when vehicle tilt is different due to a load shift or acceleration/deceleration.

There is one level sensor at the front axle and one at the rear axle that register the vehicle's spring deflection. A signal proportional to vehicle speed is also processed by the ABS control module.

The control module evaluates these signals and activates the automatic vertical headlight aim control actuators when the lights are switched on.

Automatic vertical headlight aim control is required by law for vehicles with gas-discharge (xenon) headlights.

Function:

Automatic vertical headlight aim control consists of:
- Automatic vertical aim control system control module -J431-
- Left rear level control system sensor -G76-
- Left front level control system sensor -G78-
- Left headlight beam adjusting motor -V48-
- Right headlight beam adjusting motor -V49-

When the vehicle is started, it's current tilt is determined according to a specified value and is sent to the automatic vertical headlight aim control actuator, which leads to a one time correction of the headlight tilt, regardless of whether or not low beams are switched on.

Thereafter, changes relative to the specified value are only sent to the automatic vertical headlight aim control actuator when low beams are switched on.

If malfunctions occur in the system, the driver is notified via a warning symbol in the instrument cluster's center display.


NOTE: The following description refers only to the VAG1551 Scan Tool (ST).