Crankshaft Position Sensor: Description and Operation

Fig. 4 Crankshaft Position Sensor:

The crankshaft position sensor is mounted to the transmission bellhousing at the left/rear side of the engine block (Fig. 4).

Engine speed and crankshaft position are provided through the crankshaft position sensor The sensor generates pulses that are the input sent to the powertrain control module (PCM). The PCM interprets the sensor input to determine the crankshaft position. The PCM then uses this position, along with other inputs, to determine injector sequence and ignition timing.

The sensor is a hall effect device combined with an internal magnet. It is also sensitive to steel within a certain distance from it.

Fig. 6 Sensor Operation:

OPERATION
The flywheel/drive plate has groups of four notches at its outer edge. There are three sets of notches (Fig. 6).

The notches cause a pulse to be generated when they pass under the sensor. The pulses are the input to the PCM. For each engine revolution there are 3 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 PCM does not receive a crankshaft position sensor input.

CIRCUIT OPERATION
The Powertrain Control Module (PCM) supplies 5 Volts to the camshaft position sensor (in distributor) on circuit K7. Circuit K7 connects to cavity A17 of the PCM.

The PCM receives the camshaft position sensor signal on circuit K44. Circuit K44 connects to cavity A18 of the PCM.

The PCM provides a ground for the camshaft position sensor signal (circuit K44) through circuit K167. Circuit K167 connects to cavity A4 of the PCM.