Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

The crankshaft position (CKP) system variation learn feature is used to calculate reference period errors caused by slight build tolerance variations during manufacture. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. This enhances the ability of the ECM to detect misfire events over a wide range of engine speeds and load conditions. The ECM stores the Crankshaft Position System Variation values after a learn procedure has been performed. If the actual crankshaft position variation is not stored within the CKP compensating value look up table then DTC P0300 may set. If the CKP system variation values are not stored in the ECM memory or a proper ECM power down does not occur after completing the CKP Learn Procedure then DTC P0315 sets.

The diagnostic runs continuously.

The ECM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission levels to exceed mandated standards.

DTC P0315 is a type B DTC

DTC P0315 is a type B DTC

This test procedure requires that the vehicle battery has passed a load test and is completely charged.

Scan Tool Reference

Control Module References

Important: The CKP System Variation Learn Procedure may have to be repeated up to 5 times before the procedure is learned.

1. Perform the CKP System Variation Learn Procedure. Refer to Service Programming System (SPS) .
2. If the CKP System Variation Learn Procedure cannot be performed successfully, inspect for the following conditions:

•	Any worn crankshaft main bearings.

•	A damaged or misaligned reluctor wheel.

•	Excessive crankshaft runout.

•	A damaged crankshaft--Refer to Crankshaft and Bearing Cleaning and Inspection .

•	Interference in the signal circuit of the CKP sensor.

•	The ignition switch is left in the ON position, until the battery is discharged

•	An ECM power disconnect, with the ignition ON, that may have erased the CKP system variation values and set DTC P0315.

•	Any debris between the CKP sensor and the reluctor wheel.

•	If the ECM is unable to complete the learn procedure, replace the ECM.