Volkswagen Passat '97, User Manual

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ABS speed sensor
Features of speed sensor:
- It is inserted into the wheel bearing and is
thus protected against external
influences.
- It generates signals contactlessly.
Signal utilisation
The signal supplied by the ABS speed sensor
is used to control the anti-lock braking system.
The navigation system calculates the distance
travelled from this signal.
Effect of signal failure
- The ABS system is switched off and the
ABS warning lamp comes on.
- The navigation system is de-energised.
- The brake warning lamp comes on.
This is how it works:
The rotor is integrated and the speed sensor
inserted in the wheel bearing.
The speed sensor comprises a permanent
magnet with two pole plates. A coil is wound
around the pole platesand the permanent
magnet.
When the wheel moves, the rotor rotates
about the speed sensor. In the process, it cuts
the field lines of the pole plates, thus inducing
a voltage in the coil. This voltage serves as the
signal for the ABS control unit and the
navigation system.
Rotor
Permanent
magnet
Coil
SSP 192/057
SSP 192/132
Speed sensor rotor
Speed sensor
Pole plate
Pole plate