Wheel Speed Sensor

Location
The front axle VSS sensors (L6/1 and L6/2) are mounted on the front axle steering knuckle.

The rear axle VSS sensor (L-6) is mounted on the rear axle center assembly.

Task
To supply the current wheel speed to ABS, ETS, ASR or ESP control modules (N47-7, N47-2, N47-1 or N47-5).

Design
Inductive sensor: Coil with magnetic core at a defined distance to the rotor which is attached to the front wheel hub, rear axle shafts or rear axle drive pinion.

Function
The magnetic field of the speed sensor is cut by the teeth of a rotor. As a result the magnetic field changes and the coil induces an alternating voltage. The frequency of this alternating voltage changes corresponding to the wheel speed and the number of teeth, i.e. the frequency is proportional to wheel speed.