Circuit Description
The crankshaft position (CKP) system variation learn feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft and the crankshaft position sensor. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. This enhances the ability of the ECM to detect misfire events over a wider range of engine speed and load.
The ECM stores the CKP system variation values after a learn procedure has been performed. If the actual CKP variation is not within the CKP system variation compensating valves stored in the ECM, DTC P0300 may set. If the CKP system variation values are not stored in the ECM memory, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1336 Crankshaft Position (CKP) System Variation Not Learned
Conditions for Running the DTC
| • | DTCs P0106, P0107, P0108, P0117, P0118, P0122, P0123, P0132, P0201, P0202, P0203, P204, P0325, P0327, P0336, P0337, P0341, P0342, P0351, P0352, P0402, P0404, P0405, P0406, P0502, and P1404 are not set. |
| • | DTC P1336 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
| • | The CKP system variation values are not stored in the ECM memory. |
| • | The manufacturer enable counter is set to zero. |
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 4 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
Caution: Before performing the Crankshaft Position System Variation Learning Procedure always set the vehicle parking brake and block the drive wheels in order to prevent personal injury. Release the throttle immediately when the engine starts to decelerate in order to eliminate over revving the engine. Once the learn procedure is completed, the control module will return engine control to the operator and the engine will respond to the throttle position.
DTC P1336 will only set if the ECM has not learned the CKP system variation. The ECM only needs to learn this variation once per life cycle of the vehicle unless the crank sensor to crankshaft relationship is disturbed. Removing a part is considered a disturbance. A fully warned engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed that ignition cycle.
If the engine cuts out before the specified learn procedure engine speed or at normal fuel cutoff rpm, the ECM is not in the learn procedure mode.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Yes | No | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | |||||||||||||||||||
Perform the crankshaft position system variation learn procedure. Refer to Crankshaft Position System Variation Learn . Does the scan tool display Learned This Ignition? | Go to Step 4 | Go to Step 3 | |||||||||||||||||||
3 | Inspect for the following conditions:
Did you complete the inspection? | Go to Step 4 | -- | ||||||||||||||||||
4 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 5 | ||||||||||||||||||
5 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK |
