Camshaft Position Sensor: Description and Operation

Top Dead Center/Crankshaft Position/Cylinder Position Sensors:

PURPOSE
The Top Dead Center (TDC) sensor determines ignition timing at start-up (cranking) and when crank angle is abnormal and inputs this information to the Engine Control Module (ECM). The Crankshaft Position (CKP) sensor detects engine RPM and is also a primary input signal to the ECM for determining fuel injection timing and ignition of each cylinder. The Cylinder Position (CYP) sensor detects the position of cylinder number 1 and sends its input signal to the ECM for determining sequential fuel injection of each cylinder. The three sensors are grouped together into the TDC/CKP/CYP sensor.

CONSTRUCTION
Installed inside the distributor housing, the TDC/CKP/CYP sensor is an assembly consisting of the TDC sensor rotor, CKP sensor rotor and CYP sensor rotor, their associated pick-up coils, and a common shaft that is directly coupled to the camshaft.

OPERATION
The shaft coupled to the camshaft turns all three sensors in time with the engine camshaft. 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 ECM.