Circuit Description
The crankshaft position system variation learning feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft reluctor wheel or the crankshaft position sensor. 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 |
| • | PCM reprogramming |
| • | Engine replacement |
| • | Crankshaft replacement |
| • | Crankshaft position sensor replacement |
| • | Any internal engine repairs which disturb the crankshaft to CKP sensor relationship |
Conditions for Running the DTC
| • | No CMP or CKP sensor DTC(s) set |
| • | Engine Coolant Temperature is greater than 70°C (158°F) |
Conditions for Setting the DTC
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) when the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns the MIL Off after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A last test failed (current DTC) clears when the diagnostic runs and does not fail. |
| • | A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures. |
| • | Use a scan tool in order to clear the MIL/DTC. |
| • | Interrupting the PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Powertrain Control Module (PCM) Description , Clearing Diagnostic Trouble Codes. |
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.
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 DTC(s) are set. |
| The scan tool crankshaft position system variation learn function will be disabled if any powertrain DTCs other than DTC P1336 are stored. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
2 | Perform the crankshaft position system variation learn procedure. Refer to Crankshaft Position System Variation Learn . Is action complete? | -- | System OK | -- |
