Information About ABS Wheel Sensors

Information About ABS Wheel Sensors

The ABS wheel sensor measures the speed of a vehicle's wheels. It consists of a gear-shaped sensor rotor and a sensor element. The wheel-speed sensors are used by ABS to monitor wheel speeds.

How Do They Work?

  • Inside the wheel sensor is a permanent magnet around which a coil is wound. This is a magnetic pickup that reads the teeth on the tone ring. As each tooth passes under the sensor, it changes the magnetic field. This movement, or change, creates a single-direction current in the coil windings inside the sensor. After the tooth passes, the field returns to normal. This also creates a current in the wire coil but in the opposite direction. This results in an alternating current pattern or voltage signal.

Where Does the Signal Go?

  • In some effect, the sensor acts a small generator. The faster the wheel goes, the greater the voltage and signal travel. The voltage signal travels to the ABS control module. The AC signal is converted to digital for processing. The control module monitors and compares wheel speeds. When the signal from one wheel changes abruptly from the others, the control module understands that the wheel is beginning to lose traction. It then takes the appropriate action by applying the brakes or traction control.

20th Jan 2015

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