Refer to Engine Controls Schematic
Cell 21: Ignition Controls
Circuit Description
The Crankshaft Position (CKP) 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 balancer replacement |
| • | Crankshaft position sensor replacement |
| • | Any engine repairs 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 65°C (149°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 test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC
set as Freeze Frame and 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 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 balancer replacement |
| • | Crankshaft position sensor replacement |
| • | Any engine repairs which disturbs crankshaft/harmonic balancer
to crankshaft position sensor relationship. |
If the crankshaft position system variation learn procedure cannot
be performed successfully, inspect 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. |
| • | 3X reference signal problem detected. |
| • | Camshaft position signal problem detected. |
| • | 24X reference signal problem detected. |
