Crankshaft Position Sensor: Description and Operation

PURPOSE
The Crankshaft Position (CKP) sensor provides crankshaft position and rotation speed input to the Powertrain Control Module (PCM). The PCM uses this signal to modify air/fuel ratio, idle speed, injector timing, ignition timing, purge flow, A/C cutoff and air inlet control.

OPERATION
A disc with 4 equally spaced slots rotates with the distributor shaft passing through a fixed photo sensor. This signals the PCM crankshaft position at 90° intervals.