Camshaft Position Sensor: Description and Operation

OPERATION




Crankshaft Sensor Operation The crankshaft position sensor contains a hall effect device that generates a square wave pulse for each notch that passes underneath it. There are 32 notches on the target wheel. Most are every 10 degrees. The PCM determines crankshaft angular position using these pulses and then uses camshaft position sensor pulses to determine engine phasing. The crankshaft target wheel has one long (30 degree) tooth and one long (30 degree) notch so that if the camshaft sensor signal is lost, the PCM can still run the engine, though with less accurate fueling and sparking. The notches also help the PCM more quickly determine engine position.

The camshaft position sensor contains a hall effect device that provides cylinder identification to the Powertrain Control Module (PCM). The sensor generates pulses as groups of notches on the camshaft sprocket pass underneath it. The PCM keeps track of crankshaft rotation and identifies each cylinder by the pulses generated by the notches on the camshaft sprocket.

When metal aligns with the sensor, voltage goes low (less than 0.3 volts). When a notch aligns with the sensor, voltage spikes high (5.0 volts). As a group of notches pass under the sensor, the voltage switches from low (metal) to high (notch) then back to low. The number of notches determine the amount of pulses. If available, an oscilloscope can display the square wave patterns of each timing event.