Engine Speed Sensor
The engine speed sensor is actuated by the teeth of the flywheel. It produces 135 impulses for each crankshaft revolution (1 for each flywheel tooth). Signals are used to determine engine speed and ignition timing.
The fuel/timing control unit calculates engine speed by counting the number of flywheel teeth passing the sensor in a given unit of time. By counting the number of teeth passing the sensor after the reference mark pin, it determines crankshaft position.