Crankshaft Position Sensor: Description and Operation

Crankshaft Position Sensor:

Crankshaft Position (CKP) Sensor:

DESCRIPTION
This system uses a magnetic Crankshaft Position Sensor (CKP) sensor (2), mounted remotely from the Ignition Control Module (ICM) (3), which protrudes into the block within approximately 0.050 inches from the crankshaft reluctor. The graphic illustrates a typical sensor in relationship to the crankshaft reluctor. The reluctor is a special wheel which is cast into the crankshaft with 7 slots machined into the wheel, 6 of which are equally spaced (60 apart). A seventh slot is spaced 10 from one of the other slots and serves to generate sync-pules. As the reluctor rotates as part of the crankshaft, the slots change the magnetic field of the sensor, creating an induced voltage pules. Based on the CKP sensor pules, the CKP sensor sends a 7x reference signal to the PCM which is used to indicate the crankshaft position and the engine speed. The CKP sensor continues to send these reference pulses to the PCM at a rate of seven times per 360° of crankshaft revolution. This signal is called the 7x reference because the signal occurs 7 times per crankshaft revolution. The 7x reference signal is necessary in order for the PCM to determine when to energize the fuel injectors.

OPERATION
The CKP provides the PCM with crankshaft speed and crankshaft position. The PCM utilizes this information to determine if an engine Misfire is present. The PCM monitors the CKP sensor for momentarily drop in crankshaft speed to determine if a misfire is occurring.