Cavalier L4-2.2L VIN 4 (1998)
Crankshaft Position Sensor: Description and Operation
The Crankshaft Position (CKP) sensor provides a signal to the electronic Ignition Control Module (ICM), which the PCM uses as a reference to
calculate RPM and crankshaft position. A fault in the CKP sensor circuits will cause a DTC P0335.
This system uses a magnetic CKP sensor, mounted remotely from the ICM, which protrudes into the block within approximately 0.050 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, is spaced 10 degrees from one of the other slots and serves to generate a sync-pulse. As the reluctor rotates as part of 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.
IMPORTANT: A Crankshaft Position System Variation Learning Procedure must be performed any time a change is made to the crankshaft sensor to
crankshaft relationship. Changing the crankshaft sensor to crankshaft relationship will not allow the PCM to detect misfire at all speeds and loads
accurately. Resulting in a possible false misfire DTC being set. Removing a part for inspection and then reinstalling the same part is considered a
disturbance. A false DTC P0300 could be set if this procedure is not performed. Refer to the CKP System Variation Learn Procedure for the Crankshaft
Position System Variation Learning Procedure.
See Electronic Ignition System Diagnosis for further information.
