Crankshaft Position Sensor: Testing and Inspection
SCAN TOOL TESTINGThe Crankshhaft Position Sensor (CKP) signal is a "7X" reference signal. It is because a pulse occurs every 7 times per crankshaft revolution.
The PCM uses this signal from the electronic Ignition Control Module (ICM) to calculate engine RPM. A scan tool has two displays based on this input. One indicates crank RPM or simply that the PCM is receiving the 7X reference pulses while cranking. The other indicates engine RPM while the engine is running. More information about this signal may be found in Ignition System. Ignition System