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 powertrain control module (PCM)
to accurately compensate for reference period variations. 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. If the
crankshaft position system variation values have not been
stored in the PCM, the diagnostic trouble code (DTC) P1336 will
set. The learn procedure is required after the following
service procedures have been performed:
| • | Crankshaft balancer replacement |
| • | Crankshaft position (CKP) sensor replacement |
| • | Any engine repair 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 greater than 70°C (158°F). |
Conditions for Setting the DTC
The 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 within the crankshaft position
system variation compensating values stored in the PCM, DTC P0300
may set refer to
DTC P0300
.
If the crankshaft position system variation learn procedure cannot be
performed successfully, inspect for the following conditions and correct any
conditions as necessary:
| • | The engine coolant temperature is less than 70°C (158°F). |
| | Allow the engine to warm to above 70°C (158°F). |
| • | Powertrain DTCs are set. |
| | 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 condition is detected. Refer to
DTC P0341
. |
| • | A 3X reference signal condition is detected. Refer to
DTC P1374
. |
| • | An 18X reference signal condition is detected. Refer to
DTC P0336
. |
