Circuit Description

PCM receives signals from the Crankshaft Position (CKP) sensor to determine position of crankshaft at various degrees of rotation. PCM can then base misfire diagnostics on the principle that crankshaft velocity will increase as each cylinder contributes its power input. PCM must know precisely the degree of variability in crankshaft notches to perform misfire functions. Replacement of either the PCM or crankshaft requires "crankshaft learn" procedure. DTC will set if learn procedure has not been performed due to replacement or reprogramming.

DO NOT transfer PCMs from one vehicle to another without resetting crankshaft adaptives and performing crankshaft learn procedure. Failure to perform this procedure may result in false misfire detection. Procedure must also be performed anytime CKP sensor is replaced.