Circuit Description

WARNING: This page is about a different car, the 2002 GMC Sonoma and 2002 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

The Crankshaft Position (CKP) system variation learning feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, the crankshaft balancer interrupter rings, and crankshaft position sensor hall effect switches. The calculated error allows PCM to accurately compensate for reference period variations. The crankshaft position system variation learning feature enhances the ability of PCM to detect misfire events over a wider range of engine speed and load.

The crankshaft position system variation learning procedure must be performed anytime a change is made to CKP sensor to crankshaft relationship, or if PCM is replaced or reprogrammed.

DTC indicates that crankshaft position system variation values have not been stored in PCM and CKP system variation learn procedure must be performed. The learn procedure is required after the following service procedures have been performed, regardless of whether or not this DTC is set:

PCM replacement or reprogramming.
Engine replacement.
Crankshaft balancer replacement.
Crankshaft position sensor replacement.
Any engine repair(s) which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship.

DTC will set when crankshaft position system variation values are not stored in the PCM memory.