See Figures 1 and 2
The crank angle sensor detects engine rpm and the crank angle (piston position). It also sends a signal to the control unit to control various operations. This sensor is built into the distributor.
The signal rotor plate has 360 slits at 1° intervals on its outer periphery. It also has four slits at 90° intervals. These four slits are used to detect the crank angle, that is, the position of each piston. The teeth are used to provide the 1° signal that is necessary to control engine rpm and ignition timing.
The crank angle sensor has two diodes and a wave forming circuit. When a signal rotor plate passes the space between the light emitting diode (LED) and photo diode, the slit of the signal rotor plate alternately cuts the light which is sent to the photo diode from the LED. This causes an alternative voltage and it is then converted into an on-off pulse by the wave forming circuit, which is sent to the control unit.
Crank angle sensor testing, requires complete testing of the ignition system. For information, refer to ignition system testing in Engine Electrical .
REMOVAL & INSTALLATION
The crank angle sensor is an integral part of the distributor and must be replaced as an assembly. Refer to Engine Electrical for distributor removal and installation procedures.