Wheel Speed Sensor: Description and Operation

Wheel Sensors
The wheel sensors are the magnetic contactless type. The wheel sensors detect changing of magnetic polarity on the magnetic encoder contained inside the wheel bearings. The ABS control unit calculates the wheel speed based on signals received from the wheel sensor.

NOTE: The wheel bearings are directional.

Wheel speed and modulator control





When the wheel speed drops sharply below the vehicle speed, the outlet valve opens momentarily to reduce the caliper fluid pressure. The pump motor starts at this time. As the wheel speed is restored, the inlet valve opens momentarily to increase the caliper fluid pressure.