900 SE Hatchback L4-1985cc 2.0L DOHC Turbo EFI (1997)
Speedometer Head: Description and Operation
The car is equipped with an electronic speedometer. The ABS control module sends speed information continuously to pin 7 (14p).
This information is represented by a square wave which varies periodically between 8 V and 0 V, 29 times per wheel revolution.
When the wheels are stationary, the voltage may be either 8 V or 0 V.
This information controls the speedometer, odometer and trip odometer
