Crankshaft position sensor is mainly used to detect engine crankshaft Angle, engine speed, throttle opening, speed detection, vehicle acceleration detection, vehicle deceleration detection and so on, to provide reference point signal for ignition time and fuel injection time, at the same time, provide engine speed signal. Automotive position and speed sensors are mainly alternator type, reluctance type, Hall effect type, reed switch type, optical type, semiconductor magnetic transistor type.