Crankshaft Position (CKP) Sensor

IMPORTANT: Perform a Crankshaft Position (CKP) system variation learn procedure any time you make a change to the crankshaft sensor to crankshaft relationship. Changing the crank sensor to crankshaft relationship will not allow the PCM to detect a misfire at all speeds and loads accurately. Resulting in possibly setting a false misfire DTC. Removing a part for inspection and then reinstalling the same part is considered a disturbance. A false DTC P0300 could set if you do not perform this procedure. Refer to Crankshaft Position System Variation Learn Procedure. Programming and Relearning

This system uses a magnetic CKP sensor that is mounted remotely from the ICM. The CKP sensor protrudes into the block within approximately .050 in. of the crankshaft reluctor. The reluctor is a special wheel cast into the crankshaft with seven slots machined into it, six of which are equally spaced 60 degrees apart. A seventh slot, spaced 10 degrees from one of the other slots, generates a sync-pulse. As the reluctor rotates with the crankshaft, the slots change the magnetic field of the sensor, creating an induced voltage pulse.

Based on the CKP sensor pulses, the ICM sends 7X reference signals to the PCM which is used to indicate crankshaft position and engine speed. The ICM continues to send these reference pulse to the PCM at a rate of seven per 360 degrees of crankshaft rotation. This signal is called the 7X reference because it occurs 7 times per crankshaft revolution. The 7X reference signal is necessary for the PCM to determine when to activate the fuel injectors.

By comparing the time between pulses, the PCM can recognize the pulse representing the seventh slot, sync pulse, which starts the calculation of ignition coil sequencing. The second crank pulse following the sync pulse signals the PCM to fire the #2-3 ignition coil and the fifth crank pulse signals the PCM to fire the #1-4 ignition coil.