Wheel Speed (Pulse) Sensors
WARNING: This page does not describe the selected car, but rather 34 other vehicles, including the 2004 BMW M3, 2004 BMW 330xi, 2004 BMW 330i, 2004 BMW 330Ci, and 2004 BMW 325xi. However, it is still accessible from the selected car via links, so may be relevant.
Wheel speed sensors are installed at each wheel. Each wheel speed sensor generates a signal proportional to the speed of a rotating toothed wheel. Wheel speed sensors relays the signal to the ABS/ASC+T control module, which computes the actual wheel speed. The toothed wheels, which run past the permanently magnetized edge of the speed sensor, are attached to the hub.