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 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 crankshaft position system variation values are stored in the PCM non-volatile memory after a learn procedure has been performed. If the crankshaft position system variation values have not been stored in the PCM, DTC P1336 will set. The learn procedure is required after the following service procedures have been performed:
| • | 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
| • | No CMP or CKP Sensor DTCs set. |
| • | Engine coolant temperature is more 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 will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using 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 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, inspect 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. |
| • | Camshaft position signal problem detected -- Refer to DTC P0341 Camshaft Position (CMP) Sensor Performance . |
| • | 3X reference signal problem detected -- Refer to DTC P1374 Crankshaft Position (CKP) High to Low Resolution Frequency Correlation . |
| • | 18X reference signal problem detected -- Refer to DTC P0336 Crankshaft Position (CKP) Sensor Circuit . |
Step | Action | Values | 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 the action complete? | -- | System OK | -- |
