Crankshaft Position Sensor: Description and Operation

DESCRIPTION
The system uses a magnetic Crankshaft Position (CKP) sensor which protrudes into the block, within approximately 0.050" of the crankshaft reluctor. The reluctor is a special wheel cast on the crankshaft that has seven machined slots, six of which are equally spaced 60 degrees apart). The seventh slot is spaced 10 degrees from one of the other slots.

OPERATION
As the reluctor rotates with the crankshaft, the slots change the magnetic field of the sensor, causing an induced voltage pulse.
By counting the time between pulses, the Ignition Control Module (ICM) can recognize the pulse of the seventh slot (sync pulse). Based on this sync pulse, the module sends the reference signal to the ECM to calculate CKP (used to fire coils in correct sequence) and engine speed.