TDC (Top Dead Center) Sensors

Crank Angle (TDC/CYL) Sensor:

The TDC/CYL sensor, found inside the distributor (crank angle) housing, consists of the TDC sensor rotor, CYL sensor rotor, their associated pick-up coils, and a common shaft that is directly coupled to the camshaft. Because the shaft is coupled to the camshaft both sensors turn in time with the engine. As the teeth on the sensors break the flux lines of their respective pick-up coils a voltage pulse is generated. These pulses are the input signal to the engine control unit (ECU).
The TDC sensor references #1 cylinder at TDC for the sequential fuel injection. The TDC sensor also supplies the ECU with an engine RPM signal.
The CYL sensor supplies the ECU with information needed to determine fuel injection timing for each cylinder.