Camshaft Position Sensor
On 2.4L, the camshaft position sensor is mounted on the end of the cylinder head. See Fig 1 . On the 3.3L and the 3.8L, the camshaft position sensor is mounted in the front of the timing case cover. See Fig 2 .
On all applications, the camshaft position sensor provides cylinder identification to the Powertrain Control Module (PCM). See Fig 3 . The sensor generates pulses as groups of notches on the camshaft sprocket pass underneath it. See Fig 4 . The PCM keeps track of crankshaft rotation and identifies each cylinder by the pulses generated by the, notches on the camshaft sprocket. Four crankshaft pulses follow each group of camshaft pulses.
When the PCM receives 2 cam pulses followed by the long flat spot on the camshaft sprocket, it knows that the crankshaft timing marks for cylinder No. 1 are next (on drive plate). When the PCM receives one camshaft pulse after the long flat spot on the sprocket, cylinder No. 2 crankshaft timing marks are next. After 3 camshaft pulses, the PCM knows cylinder No. 4 crankshaft timing marks follow. One camshaft pulse after the 3 pulses indicates cylinder No. 5. The 2 camshaft pulses after cylinder No. 5 signals cylinder No. 6. See Fig 4 . The PCM can synchronize on cylinders No. 1 or 4.
When metal aligns with the sensor, voltage goes low (less than 0.3 volt). When a notch aligns with the sensor, voltage switches high (5 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.
Top Dead Center (TDC) does not occur when notches on the camshaft sprocket pass below the sensor. TDC occurs after the camshaft pulse (or pulses) and after the 4 crankshaft pulses associated with the particular cylinder. The arrows and cylinder call outs in the illustration represent which cylinder the flat spot and notches identify, they do not indicate TDC position. See Fig 4 .