Active wheel speed sensor
What is an active wheel speed sensor
An active wheel speed sensor detects the presence of a magnetic field and reports that presence as a square wave DC digital on/off signal, as opposed to an analog AC signal generated by a passive wheel speed sensor . When used in an anti-lock brake system, the sensor detects the alternating the north/south poles of a rotating multipole magnetic ring, usually inserted into the wheel bearing.
As the wheel bearing rotates, the active wheel speed sensor detects the pole switching and sends a digital on/off signal to the ABS control module.
Here’s the description from a 2018 Buick LaCrosse: “The active sensor receives a 12v power supply from the electronic brake control module and provides an output signal to the EBCM. As the wheel spins the wheel speed sensor sends a DC square wave signal. The EBCM uses the frequency of the square wave signal to calculate the wheel speed.”
How does an active wheel speed sensor differ from a passive wheel speed sensor?
An active wheel speed sensor requires power to operate a Hall Effect sensor that detects the presence of a magnetic field. A passive sensor, on the other hand, requires no power. A passive sensor includes a wire wrapped magnet that generates a low AC voltage as a steel toothed ring passes by the sensor.
©, 2021 Rick MuscoplatPosted on by Rick Muscoplat