Circuit Description
The crankshaft position system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft and the crankshaft position sensors. 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 PCM stores the crankshaft position system variation values after a learn procedure has been performed. If the PCM detects the crankshaft position (CKP) system variation values are not stored in the PCM memory, DTC P1336 sets.
Conditions for Running the DTC
| • | DTCs P0335, P0336, P0340, P0341, P0385, P0386, P1372 are not set. |
| • | The engine coolant temperature (ECT) 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 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 PCM 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.
The crankshaft position system variation learn procedure is also required when the following service procedures have been performed, regardless of whether DTC P1336 is set:
| • | Engine replacement |
| • | PCM replacement |
| • | A harmonic balancer replacement |
| • | Crankshaft replacement |
| • | Crankshaft position sensor replacement |
| • | Any engine repairs which disturb the crankshaft to crankshaft position sensor relationship. |
If the crankshaft position system variation learn procedure cannot be performed successfully, inspect for the following conditions:
| • | A damaged reluctor wheel |
| • | Excessive crankshaft runout |
| • | A damaged crankshaft |
| • | Interference in the signal circuit of the CKP sensor |
| • | A coolant temperature that is not within the Condition For Running the DTC |
| • | The ignition switch is in the ON position until the battery is drained |
| • | A PCM power disconnect with the ignition ON may erase the stored value and set DTC P1336 |
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |
2 | Perform the crankshaft position (CKP) system variation learn procedure. Refer to Crankshaft Position System Variation Learn . Does the scan tool display Learned This Ignition? | Go to Step 3 | Go to Diagnostic Aids |
3 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 4 |
4 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK |
