Circuit Description
The crankshaft position (CKP) system variation learn feature is used
to calculate reference period errors caused by slight tolerance variations
in the crankshaft, and the CKP sensors. 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 PCM stores the CKP system variation values after a learn
procedure has been performed. This DTC set indicates that
the CKP system variation values have not been stored
in the PCM, and the CKP system variation learn
procedure must be performed.
Conditions for Running the DTC
| • | DTCs P0335, P0340, P0385, or P1372 are not set. |
| • | The engine coolant temperature (ECT) is more than 70°C (158°F). |
Conditions for Setting the DTC
The CKP 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) on the second consecutive ignition cycle that the diagnostic runs and
fails. |
| • | The control module records the operating conditions at the time
the diagnostic fails. The first time the diagnostic fails, the control module
stores this information in the Failure Records. If the diagnostic reports
a failure on the second consecutive ignition cycle, the control module
records the operating conditions at the time of the failure. The control
module writes the operating conditions to the Freeze Frame and updates
the 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 CKP system variation compensating values are stored
in PCM memory after a learn procedure has been performed. If the actual
CKP variation is not within the CKP system variation
compensating values stored in the PCM, DTC P0300 may
set. |
| • | The CKP system variation learn procedure is also required when
the following service procedures have been performed, regardless of whether
DTC P1336 is set: |
| - | A harmonic balancer replacement |
| - | A crankshaft replacement |
| - | A crankshaft position sensor replacement |
| - | Any engine repairs which disturb the crankshaft-to-crankshaft
position sensor relationship |
| • | If the CKP system variation learn procedure cannot be performed
successfully, inspect for the following conditions and correct as necessary: |
| - | A damaged reluctor wheel |
| - | Excess crankshaft runout |
| - | Interference in the signal circuit of the CKP sensor |
| - | A coolant temperature that is not within the Conditions For Running
the DTC |
| - | The ignition switch is in the ON position until the battery is
drained |
| • | A PCM power disconnect, with the ignition ON, may erase the stored
value, and may set DTC P1336. |
Step
| Action
| Yes
| No
|
1
| Did you perform the Diagnostic
System Check-Engine Controls?
| Go to
Step 2
| Go to
Diagnostic System Check - Engine Controls
|
2
| Perform the CKP system variation learn procedure. Refer
to
Crankshaft Position System Variation Learn
.
Is the action complete?
| Go to
Step 3
| Go to Diagnostic Aids
|
3
|
- Use the scan tool in order to clear the DTCs.
- Turn OFF the ignition.
- Start the engine.
- Operate the vehicle within the Conditions for Running the DTC
as specified in the supporting text.
Does the DTC run and pass?
| Go to
Step 4
| Go to
Step 2
|
4
| With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?
| Go to
Diagnostic Trouble Code (DTC) List
| System OK
|
