Crankshaft Position Sensor: Description and Operation

LOCATION

The CPS is attached to the flywheel/drive plate housing of the transmission.


OPERATION

Fuel injection synchronization and cylinder identification are provided through the CPS. The sensor generates pulses that are the input sent to the engine controller. The engine controller interprets the CPS input to determine the crankshaft position. The engine controller then uses this position (along with other inputs) to determine injector sequence and ignition timing.

The CPS is a Hall effect device combined with an internal magnet. It is also sensitive to steel within a certain distance from it. The flywheel/drive plate has groups of four notches at its edge. On 2.5L engines there are two sets of slots.

The notches cause a pulse to be generated when they pass under the sensor. The pulses are the input to the engine controller. For each engine revolution there are two groups of four pulses generated.

The trailing edge of the fourth notch, (which causes the pulse) is four degrees before top dead center (TDC) of the corresponding piston.

The engine will not operate if the engine controller does not receive a CPS input.