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 (CMP) 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 CKP system variation values are stored in the PCM non-volatile
memory after a learn procedure is performed. A DTC P1336 set indicates
that the CKP system variation values are not stored in the PCM and the CKP
system variation learn procedure must be performed. The learn procedure is
required after the following service procedures are performed, regardless
of whether or not DTC P1336 is set:
| • | A crankshaft replacement. |
| • | A crankshaft balancer replacement. |
| • | A CKP sensor replacement. |
| • | Any engine repairs which disturb the crankshaft/harmonic balancer
to CKP sensor relationship. |
Conditions for Running the DTC
| • | No camshaft position (CMP) sensor or CKP sensor DTCs are set. |
| • | The ECT is more than 70°C (158°F). |
Conditions for Setting the DTC
The CKP system variation values are not stored in the PCM memory.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during
the first trip in which the diagnostic test has run and failed. |
| • | The PCM stores the conditions which were present when the DTC
set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns the MIL off during the third consecutive trip in
which the diagnostic has run and passed. |
| • | The history DTC clears after 40 consecutive warm-up cycles have
occurred without a malfunction. |
| • | The DTC may be cleared by using the scan tool Clear Info function
or by disconnecting the PCM battery feed. |
Diagnostic Aids
The CKP system variation compensating values are stored in the PCM non-volatile
memory after a learn procedure is performed. If the actual CKP variation
is not within the CKP system variation compensating values stored in the PCM,
DTC P0300 may set. Refer to
DTC P0300 Engine Misfire Detected
.
The CKP system variation learn procedure must be performed when replacing
the PCM in order to clear DTC P1336. The CKP system variation learn procedure
is also required when the following service procedures are performed, regardless
of whether or not DTC P1336 is set:
| • | A crankshaft replacement. |
| • | A crankshaft balancer replacement. |
| • | A CKP sensor replacement. |
| • | Any engine repairs which disturb the crankshaft/harmonic balancer
to CKP sensor relationship. |
If the CKP system variation learn procedure cannot be performed successfully,
inspect for the following conditions and correct the conditions as necessary:
| • | An ECT below 70°C (158°F). Allow the engine to
warm to above 70°C (158°F). |
| • | Any powertrain DTC(s) set. The scan tool CKP system variation
learn function is disabled if any powertrain DTCs other than DTC P1336 are
stored. |
