Wheel Speed Sensor: Description and Operation

FRONT SENSOR
The front wheel speed sensors are of a variable reluctance type. Each sensor is attached to the knuckle assembly in close proximity to a toothed ring. An AC voltage is generated when the toothed ring passes by the sensor. The magnitude and frequency are proportional to the speed of the wheel and both will increase with increasing speed. The sensor is not repairable, nor is the air gap adjustable.

REAR SENSOR
A single rear wheel speed sensor is used for this ABS application and is located on the rear differential. It operates in the same manner as the front wheel speed sensors. However, the toothed ring is located within the rear differential. There are no provisions for air gap adjustments.

JUMPER HARNESS
Between each wheel speed sensor and the main wiring harness is a jumper harness made up of highly flexible twisted pair wiring. This wiring exists because the main harness must connect to the suspension of the vehicle, thus the wiring in this area is subjected to the same motion as a spring or shock absorber. Consequently, any repair to this section of the wiring harness will result in stiffening and eventual failure due to wire fatigue.

CAUTION: The wheel speed sensor jumper harnesses are not repairable and must be replaced. Do not attempt to solder, splice, or crimp these harnesses as eventual failure will result.