Wheel Speed Sensor: Description and Operation

GF42.45-D-5134H Wheel Rpm Sensor, Component Description






Location shown on left front wheel

L6/1 Left front rpm sensor
L6/2 Right front rpm sensor

The left front rpm sensor and right front rpm sensor are mounted on the front axle steering knuckle in each case.





Location shown on left rear wheel

L6/3 Left rear rpm sensor
L6/4 Right rear rpm sensor

The left rear rpm sensor and right rear rpm sensor are mounted on the rear axle wheel carrier in each case.

Task

The rpm sensor records the rpm of the wheel and in each case makes available an alternating voltage signal at a frequency proportional to the wheel speed.

Body

The sensor consists of a housing and a sensor element which is based on the Hall principle.

Function

Inside the sensor a change in the internal resistance is caused by the strength and direction of an external magnetic field. Via evaluation electronics accommodated in the sensor a square wave signal is produced, the frequency of which depends on the rpm and the amplitude of which is constant. The direction of travel Body is detected by a different signal representation when the wheel is running to the left or right. This signal is read in by the ESP control unit (N30/4) and placed on the Controller Area Network bus Class C (interior) (CAN C).