BMW 34523420330 Front Abs Wheel Speed Sensor

To begin, raise the car and support it safely before removing the rear wheels. For the front wheel speed sensor, work in the junction box located in the wheel housing to separate the electrical harness, noting that the left front junction box is illustrated while the right front contains a single harness connector. Unscrew the sensor mounting bolt at the steering knuckle, and during installation, apply a thin coat of Staburags ONBU 12/K or equivalent grease to both the speed sensor and housing, with installation being the reverse of removal. For the rear wheel speed sensor, if necessary, remove the small underbody plastic cover. In the junction box under the body near the trailing arm mount, separate the ABS sensor electrical connector and unclip the harness from the trailing arm, noting that the left rear contains a single harness connector. Unscrew the mounting bolt in the rear wheel bearing carrier, and similarly, during installation, apply a thin coat of Staburags ONBU 12/K or equivalent grease to the speed sensor and housing, with installation being the reverse of removal.

The active wheel speed sensors require a supply voltage for operation and output a constant non-speed dependent amplitude signal. Each wheel's speed sensor operates as a 2 wire Hall effect sensor that generates square wave pulses 48 times per wheel revolution. A stabilized power supply is provided to the Hall element through one wire, while the ground path for the sensor is connected through a second wire back to the control module. An impulse wheel is incorporated in the wheel bearing seal to protect against contamination, and the signal is generated by the impulse wheel affecting the voltage flow through the Hall element. The right rear wheel speed sensor is responsible for providing vehicle speed recognition.