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:
| • | A PCM replacement |
| • | An engine replacement |
| • | A crankshaft replacement |
| • | A crankshaft balancer replacement |
| • | A crankshaft position sensor replacement |
| • | Any engine repairs which disturbs the crankshaft/harmonic balancer-to-crankshaft position sensor relationship. |
Conditions for Running the DTC
| • | No camshaft position (CMP) sensor or CKP sensor DTCs are 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 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 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:
| • | The engine coolant temperature is less than 70°C (158°F). |
| Allow the engine to warm to more than 70°C (158°F). |
| • | A powertrain DTC is set. Refer to Powertrain On Board Diagnostic (OBD) System Check . 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 is detected. |
| • | A 3X reference signal problem is detected. |
| • | A 24X reference signal problem is detected. |
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 . Did you complete the repair? | -- | System OK | -- |
