How It Works

WARNING: This page does not describe the selected car, but rather 46 other vehicles, including the 2008 BMW M5, 2008 BMW 650i, 2007 BMW Z4, 2007 BMW M6, and 2007 BMW M5. However, it is still accessible from the selected car via links, so may be relevant.

The ride-height sensors for automatic headlight-range adjustment send voltage signals to the control unit for adaptive headlights as follows: As the springs are compressed, the output voltage of the ride-height sensors changes linearly.

Example: Voltage change on E60 up to 03/2005:

Front axle: As the springs are compressed, the output voltage of the ride-height sensor drops. As the springs extend, the output voltage of the ride-height sensor increases.
Rear axle: As the springs are compressed, the output voltage of the ride-height sensor increases. As the springs extend, the output voltage of the ride-height sensor drops.

On vehicles with electronic height control (EHC), the signal of the double sensor at the rear right is evaluated for the automatic headlight-range adjustment.

NOTE: Analogue sensors cannot be evaluated by several control units.

For this reason, a double sensor has to be installed at the rear right on vehicles with EHC.

Reason: Hall sensors transmit an analogue voltage signal. This voltage signal is measured against a resistance in the control unit.

If 2 control units were to receive the voltage signal, the resistance would form a parallel circuit (voltage divider). This would change the measured values. The earth offset between the front and rear ends (the front and rear have different earths) will also affect the measured value if the control units are installed far apart from one another. An unambiguous evaluation of the signal would then no longer be possible.

For this reason, sensors whose signals are important for several control units (e.g. the steering angle sensor) are digital sensors with CAN connection.