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
PCM to accurately compensate for reference period varations. 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. 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:
| • | Crankshaft replacement. |
| • | Crankshaft balancer replacement. |
| • | Crankshaft position sensor replacement. |
| • | Any engine repair(s) which disturbs crankshaft/harmonic balancer
to crankshaft position sensor relationship. |
Conditions for Running the DTC
| • | No CMP or CKP sensor DTC(s) set. |
| • | Engine Coolant Temperature is greater 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 runs and fails. |
| • | If equipped with traction control, the PCM will command the EBTCM
via the serial data circuit to turn OFF traction control and illuminate
the TRACTION OFF lamp. |
| • | The PCM will store conditions which were present when the DTC
set as Freeze Frame/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 does not match 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. The crankshaft position
system variation learn procedure is also required when the following service
procedures have been performed, regardless of whether or not DTC P1336
is set:
| • | Crankshaft replacement. |
| • | Crankshaft balancer replacement. |
| • | Crankshaft position sensor replacement. |
| • | Any engine repair(s) which disturbs crankshaft/harmonic balancer
to crankshaft position sensor relationship. |
If the crankshaft position system variation learn procedure cannot be
performed sucessfully, check 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). |
| | 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 detected. |
| • | A 3X reference signal problem detected. |
| • | An 18X reference signal problem detected. |
