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 Powertrain Control Module (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
| • | DTCs P0336, P0341, or P1374 are not set. |
| • | The engine coolant temperature is more than 69°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 control module illuminates the malfunction indicator lamp
(MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time
the diagnostic fails. The control module stores this information in the Freeze
Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL)
after 3 consecutive ignition cycles that the diagnostic runs and does
not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs
and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles,
if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with 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 not 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, 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). |
| • | Powertrain DTCs set--Refer to
Diagnostic System Check - Engine Controls
. The scan tool crankshaft
position system variation learn function will be disabled if any Powertrain
DTCs other than DTC P1336 are stored. |
| • | A 24X reference signal problem is detected-- |
| • | A camshaft position signal problem detected-- |
| • | A 3X reference signal problem detected-- |
