Camshaft Position Sensor: Description
This is a Hall effect sensor producing four pulses for every two engine revolutions. The sensing element is positioned between 0.0-2.0 mm (0.0-0.079") from the side of the cam gear wheel. The sensor is, in effect, a magnetically operated electrical switch, switching a battery supply level voltage on or off dependent on the position of the cam gear wheel with respect to the sensor. See Fig 1 .
The cam gear wheel has four slots machined in it enabling cylinder identification every 90°. The signal is used for cylinder recognition; enabling sequential fuel injection, knock control and cylinder identification for diagnostic purposes.
The system checks the camshaft position sensor signal at every software reference mark i.e., 54° before top dead center (2 teeth after the reluctor 2nd missing tooth). A fault condition is recognized if the signal does not change state (high to low or low to high voltage) every crankshaft revolution. See Fig 2 .