6000 V6-173 2.8L (1988)
Wheel Speed Sensor: Description and Operation
The LF, RF, LR, and RR wheel speed sensors are processed by the EBCM to determine if any of the wheels are decelerating too rapidly. Each vehicle
application has its own drive line, suspension, and brake system hardware. This means that the parts of each wheel speed sensor are physically and
electrically different. However, each sensor has parts that operate similarly. Each wheel speed sensor has
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A toothed ring (or drive axle or wheel hub/bearing assembly) made of ferrous metal, called a reluctor.
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A permanent magnet with a coil of wire wrapped close to it. The two ends of the wire connect to the EBCM.
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An air gap between the magnet/coil and the toothed wheel. As a wheel rotates, each tooth of the ring does three things:
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It goes closer to the magnet/coil.
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It aligns with the magnet/coil.
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It moves away from the magnet/coil. When each tooth of the ring gets closer to the magnet/coil, the lines of magnetic force around the magnet
move as they become stronger. This movement generates a small electrical signal traveling between the coil and the EBCM in a certain
direction. When each tooth of the ring aligns with the magnet/coil, the lines of magnetic force around the magnet stop moving. This is because
the magnet is as strong as possible. This stops the small electrical signal between the sensor coil and the EBCM. When each tooth of the ring
moves away from the magnet/coil, the lines of magnetic force around the magnet move as they become weaker. This movement generates a
small electrical signal traveling between the coil and the EBCM in a direction opposite to the previous signal. When the tooth moves a certain
distance away from the magnet/coil, the electrical signal stops. As the next tooth of the ring comes closer to the magnet/coil, the process of
generating an alternating current (AC) signal begins again. The EBCM compares the four separate AC signals and can detect braking
deceleration from other vehicle maneuvers that cause individual wheel speed changes. Applications may differ in wheel speed sensor features:
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The size of the toothed ring, as well as the number and spacing of teeth
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The strength of the permanent magnet
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The coil placement relative to the magnet
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The number of coil windings and wire size
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The air gap between the toothed ring and the sensor (magnet/coil).
