Refer to Engine Controls Schematics
Cell 21: Ignition Controls
.
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 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:
| • | 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 DTCs 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 and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip
in which the diagnostic has been 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 the 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 no 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. 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 successfully, 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. |
| • | Camshaft position signal problem detected. |
| • | 3X reference signal problem detected. |
| • | 24X reference signal problem detected. |
