Engine Speed Sensor: Description and Operation

Speed Sensor/Reference Sensor

The speed sensor is a magnetic pick-up which produces 135 impulses per engine revolution, (i.e.: one impulse per flywheel tooth). These impulses are used by the control unit to determine engine speed and the ignition timing point. The sensor is located on the upper left side of the transmission bell housing.

By means of a pin inserted in the flywheel the reference sensor sends one impulse per crankshaft revolution at 60° BTDC. This signal is used by the control unit along with the Hall sensor in the distributor to identify TDC for #1 cylinder. The sensor is also located next to the speed sensor.