Crankshaft Position Sensor: Description and Operation

Figure 6B-1 - Sensor to Crankshaft Reluctor Relationship, Ignition Coil Assembly,:

CRANKSHAFT POSITION (CKP) SENSOR
This system uses a magnetic CKP sensor, mounted remotely from the 1CM, which protrudes into the block within approximately .050" from the crankshaft reluctor. Figure 6B-1 illustrates a typical sensor in relationship to the crankshaft reluctor. The reluctor is a special wheel cast into the crankshaft with seven slots machined into the wheel, six of which are equally spaced (600 apart). A seventh slot is spaced 100 from one of the other slots and serves to generate a "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 crankshaft position and engine speed. The CKP sensor continues to send these reference pules 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 for the PCM to determine when to energize the fuel injectors.