For 1990-2009 cars

### Circuit Description

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 the crankshaft position sensor hall effect switches. The calculated error allows the powertrain control module (PCM) to accurately compensate for reference period variations. The crankshaft position system variation learning feature enhances the ability of the PCM to detect misfire events over a wider range of engine speed and load.

The crankshaft position system variation values are stored in the PCM non volatile memory after the crankshaft position system variation learn procedure has been performed. DTC P1336 set indicates that the crankshaft position system variation values have not been stored in the PCM and the crankshaft position 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 DTC P1336 is set:

• | PCM replacement

• | Engine replacement

• | Crankshaft replacement

• | Crankshaft balancer replacement

• | Crankshaft position sensor replacement

• | Any engine repairs which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship

### Conditions for Running the DTC

• | DTCs P0336, P0341, or P1374 are not set.

• | The engine coolant temperature is more than 69°C (149°F).

### Conditions for Setting the DTC

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

### 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.

### Diagnostic Aids

The crankshaft position system variation compensating values are stored in the PCM non volatile memory 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. Refer to Diagnostic Aids for DTC P0300.

The crankshaft position system variation learn procedure must be performed when replacing the PCM to clear DTC P1336. The crankshaft position system variation learn procedure is also required when the following service procedures have been performed, regardless of whether or not DTC P1336 is set:

• | Engine replacement

• | Crankshaft replacement

• | Crankshaft balancer replacement

• | Crankshaft position sensor replacement

• | Any engine repairs which disturbs crankshaft/harmonic balancer to crankshaft position sensor relationship

If the crankshaft position system variation learn procedure cannot be performed successfully, check for the following conditions and correct as necessary:

• | Engine coolant temperature below 70°C (158°F)--Allow the engine to warm to above 70°C (158°F).

• | Powertrain DTCs set--Refer to Diagnostic System Check - Engine Controls . The scan tool crankshaft position system variation learn function will be disabled if any Powertrain DTCs other than DTC P1336 are stored.

• | 24X reference signal problem detected--Refer to DTC P0336 .

• | Camshaft position signal problem detected--Refer to DTC P0341 .

• | 3X reference signal problem detected-- Refer to DTC P1374 .

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | Go to Diagnostic System Check - Engine Controls
2 | Perform the crankshaft position system variation learn procedure. Refer to Crankshaft Position System Variation Learn . Did you complete the repair? | System OK | --