Circuit Description
The crankshaft position 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 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 crankshaft position system variation values are stored in the PCM non-volatile memory after a 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 repair that disturbs the crankshaft/harmonic balancer to crankshaft position sensor relationship. |
Conditions for Running the DTC
| • | No camshaft position (CMP) or crankshaft position (CKP) sensor DTCs are set. |
| • | The engine coolant temperature is more than 70°C (158°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 PCM illuminates the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test runs and fails. |
| • | The PCM stores conditions that were present when the DTC set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic runs and passes. |
| • | The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear Information function or by disconnecting the PCM battery feed. |
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 DTC P0300 Engine Misfire Detected .
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--The scan tool crankshaft position system variation learn function will be disabled if any powertrain DTCs other than DTC P1336 are stored. |
| • | A camshaft position signal problem has been detected--Refer to DTC P0341 Camshaft Position (CMP) Sensor Performance |
| • | A 3X reference signal problem has been detected--Refer to DTC P1374 Crankshaft Position (CKP) High to Low Resolution Frequency Correlation . |
| • | A 18X reference signal problem has been detected--Refer to DTC P0336 Crankshaft Position (CKP) Sensor Circuit . |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
2 | Perform the crankshaft position system variation learn procedure. Refer to Crankshaft Position System Variation Learn . Is the action complete? | -- | System OK | -- |
