All rpm sensors record the standstill and the wheel speed. The front rpm sensors also record the direction of rotation.
The signals from the rotational speed sensors are read in directly by the ESP® control unit.
The rpm sensors are located on the respective steering knuckle.
Function
An rpm speed sensor is a magnetoresistive sensor element (active rpm sensor). It changes its resistance depending on the externally applied magnetic field (multi-pole ring on wheel).
The ESP® control unit measures the current which flows through the sensor.
Depending on the position of the multi-pole ring (negative pole or positive pole), a current strength of I = 7 mA or I = 14 mA is measured, producing a square wave signal. The ESP® control unit uses this square wave signal to divert the wheel speed and direction of rotation.
