Crankshaft Sensor

Crankshaft sensor contains a pick-up coil. A signal plate (rotor) is mounted on the crankshaft pulley. As the crankshaft rotates, protrusions on the signal plate pass near the pick-up coil. This induces AC voltage in the pick-up coil. The ECM senses the AC voltage, and uses it to determine engine speed and crankshaft position.