90 Quattro 20V (Canada) L5-2309cc 2.3L DOHC (7A) (1989)
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Crankshaft Position Sensor: Description and Operation
Crankshaft Position (Reference) And Engine Speed Sensors
The crankshaft position sensor (or reference sensor) is a magnetic induction type sensor located on the rear of the engine block.
Crankshaft Position Sensor And Engine Speed Sensor
The sensor contains a permanent magnet, and an iron core surrounded by an induction coil. The magnet sets up a magnetic field around the iron core.
As the engine turns, a reference pin, located on the flywheel, passes in close proximity to the end of the iron core, disturbing the magnetic field. This
change in the magnetic field induces a small current in the coil surrounding the iron core, creating a wave-like pulse that the ECU can detect. This pulse
indicates the exact position of the crankshaft (60~BTDC #1 cyl.) once each revolution.