Activation of automatic headlight-range adjustment by the AHL control unit

WARNING: This page does not describe the selected car, but rather 37 other vehicles, including the 2006 BMW 330Ci, 2006 BMW 325Ci, 2005 BMW M3, 2005 BMW 330xi, and 2005 BMW 330i. However, it is still accessible from the selected car via links, so may be relevant.

If the vehicle is equipped with the "adaptive headlights" option, the AHL control unit also controls the automatic headlight-range adjustment.

The automatic headlight-range adjustment adjusts the vertical aim of the headlights to compensate for variations in the vehicle tilt angle. Variations in the vehicle tilt angle are produced by vehicle loads and braking or acceleration in extreme driving situations. The automatic headlight-range adjustment tilts the headlights up and down as required.

The AHL control unit controls the automatic headlight-range adjustment as follows:

The ride-height sensor and the brake light switch send the input signals for the headlight-range adjustment to the AHL control unit.
From the input signals received, the AHL control unit calculates the vehicle tilt angle (along the longitudinal axis, relative to the road surface).
The vertical aim of the headlights is controlled automatically and dynamically by the stepper motors for swivelling the headlights along the vertical axis.
The actual headlight range is adjusted to the legally specified headlight range as follows:
- If vehicle is lower at the rear than at the front:
  The actual headlight range will be longer than the legally specified range. The vertical aim is lowered to reduce the headlight range to meet the legal requirement.
- If the vehicle is perfectly horizontal:
  The actual headlight range will be the same as the legally specified range.
- If the vehicle is lower at the front than the rear:
  The actual headlight range will be shorter than the legally specified range. The vertical aim is raised to increase the headlight range to meet the legal requirement.