RAM 2500 Van V8-5.9L VIN Z (1997)
Wheel Speed Sensor: Description and Operation
Four Wheel Antilock Brakes
OPERATION
The ABS brake system uses 3 wheel speed sensors. A sensor is mounted to each front steering knuckles. The third sensor is mounted on top of the
rear axle differential housing. The sensor is a magnet coil that is mounted over a tone wheel front/exciter ring rear with an air gap between them.
The sensors measure the wheel speed by monitoring the rotation of the tone wheels front/exciter ring rear. As the teeth of the tone wheels
front/exciter ring rear move through the magnetic field of the sensor an AC voltage is generated. This signal frequency increases or decreases
proportionally to the speed of the wheel. The Controller Antilock Brake (CAB) monitors these signals for changes in wheel deceleration. If the
CAB detects a sudden wheel or wheels deceleration within a predetermined amount the CAB will activate the ABS system.
CIRCUIT OPERATION
The all wheel Anti-Lock Brake System (ABS) uses three wheel speed sensors; a single sensor for both rear wheels and individual sensors for the
front wheels. The single sensor used for the rear wheels mounts on the top of the rear axle differential housing. Each sensor converts wheel speed
into an electrical signal that is transmitted to the Controller Anti-Lock Brakes (CAB). A pair of twisted wires connect to each sensor and provide
signals to the CAB.
Circuits B6 and B7 provide signals to the CAB from the right front wheel speed sensor. Circuit B6, which provides the LOW signal, connects to
cavity 15 of the CAB. Circuit B7 connects to cavity 2 of the CAB and provides the HIGH signal.
Circuits B8 and B9 provide signals to the CAB from the left front wheel speed sensor. Circuit B8, which provides the LOW signal, connects to
cavity 16 of the CAB. Circuit B9 connects to cavity 3 and provides the HIGH signal.
Circuit B114 connects to cavity 14 of the CAB and to circuit B2 of the rear wheel speed sensor harness at the sensor connector. Circuit B113
connects to cavity 1 of the CAB and to circuit B1 at the rear wheel speed sensor harness connector. Circuit B114 provides the rear wheel speed
sensor LOW input while circuit B113 provides the HIGH input.
