Crankshaft Position Sensor: Testing and Inspection

DESCRIPTION
The Powertrain Control Module (PCM) receives the 7X reference signal from the Crankshaft Position (CKP) sensor to enable alternating synchronous double fire fuel control. This signal is called a "7X" reference signal because it is a pulse which occurs 7 times per revolution. The PCM uses this signal from the CKP sensor to calculate engine RPM.

DIAGNOSIS
A Tech 1 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.