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Active wheel speed sensor

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.”

Active wheel speed hall effect sensor

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.

passive wheel speed sensor

digital wheel speed signal

digital wheel speed signal

Active wheel speed sensor with multipole magnetic ring

Active wheel speed sensor with multipole magnetic ring

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Posted on by Rick Muscoplat

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