Crankshaft Position Sensor: Description and Operation
SYSTEM OPERATIONCrankshaft Position Sensor - Typical:
The crankshaft position sensor is mounted to the transmission bellhousing at the left/rear side of engine block.
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.
Sensor Operation
Sensor Operation:
Sensor Operation:
The flywheel/drive plate has groups of four notches at its outer edge. On 4.0L 6-cylinder engines there are three sets of notches. On 2.5L 4-cylinder engines there are two sets of notches.
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 two groups of four pulses generated on 2.5L 4-cylinder engines. There are 3 groups of four pulses generated on 4.0L 6-cylinder engines.
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.