The crankshaft position (CKP) system variation learn feature is used to calculate reference period errors caused by slight build tolerance variations in the CKP sensor, crankshaft, and CKP sensor position. 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, 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, DTC P0315 sets.

The diagnostic runs continuously.

The ECM detects that the CKP system variation values are not stored in memory.

DTC P0315 is a Type A DTC.

DTC P0315 is a Type A DTC.

This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test.

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

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

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description.
2. Ignition ON, verify the scan tool hood position parameter displays Open.

⇒	If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.

3. Perform the CKP System Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn.
4. 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 still unable to complete the Learn Procedure, replace the ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.