For 1990-2009 cars

### Circuit 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 crankshaft position sensors. The calculated error allows the powertrain control module (PCM) to accurately compensate for reference period variations. This enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load. The PCM stores the crankshaft position system variation values after a learn procedure has been performed. If the actual crankshaft position variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set. If the PCM detects the CKP system variation values are not stored in the PCM memory, DTC P0315 sets.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0315 Crankshaft Position (CKP) System Variation Not Learned

### Conditions for Running the DTC

• | The engine is running.

• | DTC P0315 runs continuously once the above condition is met.

### Conditions for Setting the DTC

• | The crankshaft position system variation values are not stored in the PCM memory.

• | The above condition is met for 0.5 second.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Important: The Crankshaft Position (CKP) System Variation Learn Procedure may have to be repeated up to 5 times before the procedure is learned for various reasons. Perform the CKP system variation learn procedure. Refer to Crankshaft Position System Variation Learn .

Does the scan tool display Learned This Ignition?

Go to Step 4

Go to Step 3

3 | If the CKP system variation learn procedure cannot be performed successfully, inspect for the following conditions:

• | A damaged 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 the battery is drained.

• | A PCM power disconnect with the ignition ON that may have erased the stored value and set DTC P0315.

Did you find and correct the condition?

Go to Step 4

--

4 |

1. Clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 5

5 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK