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 switches. The calculated error
allows the powertrain control module (PCM) to accurately compensate
for reference period variations. The CKP system variation learning feature
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 the crankshaft position system variation learn procedure
has been performed. DTC P1336 set indicates that the CKP 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
| • | CMP or CKP sensor DTCs are not set. |
| • | Engine coolant temperature (ECT) is more 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 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 CKP 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 not within
the CKP system variation compensating values stored in the
PCM, DTC P0300 may set. Refer to Diagnostic Aids for
DTC P0300.
The CKP system variation learn procedure must be performed when replacing
the PCM to clear DTC P1336. The CKP 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 CKP System Variation Learn Procedure cannot be performed successfully,
inspect 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) |
