900 SE Convertible V6-2489cc 2.5L DOHC EFI (1997)
The electronic control module receives wheel speed information from the forward left wheel sensor at pin 7. The sensor is grounded at pin 6.
The electronic control module receives wheel speed information from the front right wheel sensor at pin 5. The sensor is grounded at pin 3.
The sensor module consists partly of a 29-point toothed wheel and partly of an inductive sensor.
The inductive sensor operates similar to a small a.c. generator that's sinusoidal potential increases with increasing wheel speed. The sinusoidal potential
changes between negative and positive polarity, that is caused by alternating teeth and gaps on the gear wheel. The electronic control module uses this
alternation of polarity like a pulsating transmitter. The pulse frequency increases with the wheel speed.
Using a multimeter adjusted to a.c. attached to the two conductors at the sensor it is possible to register a voltage of 100 mV when the wheel is rotated at
1 turn a second.
A wheel speed of 20 km/h gives approx. 5 V. If the sensor fails or an open-circuit occurs in the circuit the ABS function ceases and the ABS indicator
lamp comes on.
The distance between the sensor and the toothed wheel should be 0.6+0.3 mm. The measurement is not adjustable.
