Wheel Speed Sensor: Description and Operation

OPERATION
There is one wheel speed sensor located at each wheel. Each sensor consists of a stationary signal sending unit and a tone wheel which rotates with the vehicle's wheels. As the tone wheel rotates past the stationary unit, a magnetic induction field is created momentarily, causing a signal to be sent to the Controller Anti-Lock Brake (CAB). This signal is used by the CAB to determine if one or more wheels are locking. Based upon wheel speed sensor information, the CAB can then modulate hydraulic pressure to each wheel as necessary to prevent further lock-up.

CIRCUIT OPERATION
Input to the ABS controller is done on the following circuits, each of which is a twisted pair: B8 and B9 for the left front wheel (cavity 21 and cavity 2) B6 and B7 for the right front wheel (cavity 22 and cavity 22 B3 and B4 for the left rear wheel (cavity 94 and cavity 5), B1 and B2 for the right rear wheel (cavity 23 and cavity 4).