For 1990-2009 cars

### Diagnostic Instructions

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

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC P0315: Crankshaft Position (CKP) System Variation Not Learned

### Circuit/System Description

The crankshaft position (CKP) system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, and the CKP sensor. 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 wider range of engine speed and load. The ECM stores the CKP system variation values after a learn procedure has been performed. If the actual CKP variation is not within the CKP system variation compensating values stored in the ECM, DTC P0300 may set.

### Conditions for Running the DTC

• | The engine is running.

• | This DTC runs continuously when the above condition is met.

### Conditions for Setting the DTC

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

### Action Taken When the DTC Sets

DTC P0315 is a Type A DTC.

### Conditions for Clearing the MIL/DTC

DTC P0315 is a Type A DTC.

### Reference Information

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

Note: The CKP system variation learn procedure may have to be repeated up to 5 times before the procedure is learned.

Perform the CKP system variation learn procedure. Refer to Crankshaft Position System Variation Learn. The scan tool should display Learned this Ignition.

⇒ | 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 in the ON position until there is insufficient system voltage.

• | An ECM power disconnect with the ignition ON that may have erased the stored value and set DTC P0315

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