DTC P1336 Crankshaft Position (CKP)
System Variation Not Learned
The Crankshaft Position
(CKP) sensor sends pulses to the PCM as the reluctor
wheel teeth rotate past the CKP sensor. The PCM uses the CKP pulses to
synchronize the ignition and fuel injector operation, and to time the interval
between each CKP pulse. The PCM determines when an excessive change in
crankshaft speed occurs by comparing each new time interval with the previous
interval. A misfire causes an unexpected change in the crankshaft speed. A
certain amount of acceleration/deceleration is expected between each firing
stroke, but if the crankshaft speed changes more than an expected amount, the
PCM interprets this as a misfire. The interval between CKP sensor pulses is
extremely small. At high engine speeds, slight variations in the following
components make misfire detection difficult:
- Crankshaft
- Reluctor wheel
- CKP sensor
The PCM learns
variations during the Crankshaft Position System Variation Learning Procedure.
The PCM compensates for these variations when performing detect
misfire calculations. Only a scan tool can command the PCM to perform the
Crankshaft Position System Variation Learning Procedure again.
Perform the learning
procedure after the following actions:
- A PCM replacement
- Any operation or repair involving
the crankshaft, the CKP sensor, or the CKP sensor to reluctor
wheel gap relationship.
- An engine replacement.
- The ignition switch is in the ON
position until the battery is drained.
Important
A PCM power
disconnect with the ignition ON may erase the stored pulse value and set
the DTC P1336.
Disconnecting the PCM
will not erase the learned Crankshaft Position System Variation as long as the
ignition switch is in the OFF position.
Important
Reprogramming the PCM does
not require running the Crankshaft Position System Variation Learn Procedure
unless the PCM is new or from another vehicle.
A DTC P1336 sets if the
Crankshaft Position System Variation is not within an acceptable range, or can
not be learned.
Conditions
for Running the DTC
There are no crankshaft
position (CKP) or camshaft position (CMP) sensor DTCs
Conditions
for Setting the DTC
The PCM has not learned
the Crankshaft Position System Variation
Action
Taken When the DTC Sets
- The PCM illuminates the malfunction
indicator lamp (MIL) when the diagnostic runs and fails.
- The PCM records the operating
conditions at the time the diagnostic fails. The PCM stores this
information in the Freeze Frame and/or Failure Records.
Conditions
for Clearing the MIL/DTC
- The PCM turns OFF the malfunction
indicator lamp (MIL) after 3 consecutive ignition cycles that the
diagnostic runs and does not fail.
- A last test failed, or current DTC,
clears when the diagnostic runs and does not fail.
- A history DTC clears after
40 consecutive warm-up cycles, if no failures are reported by this or
any other emission related diagnostic.
- Use a scan tool in order to clear
the MIL and the DTC.
If the Crankshaft
Position System Variation Learn Procedure cannot be learned, inspect for the
following conditions:
- A chipped or damaged reluctor wheel
- Incorrect alignment of the CKP
sensor to the reluctor wheel
- Excessive crankshaft run-out
- Interference in the signal circuit
to the CKP sensor
- Incorrect ratio of crankshaft to
camshaft pulses
Important
If
the PCM receives an incorrect crankshaft to camshaft ratio the PCM will not
allow the scan tool to enable the learn procedure.
Engine diagnostic
misfire is not operable when the engine is above 1000 RPM and DTC P1336 is
set.
When the learn procedure
is in progress and the engine speed is at 4000 RPM, a decrease in engine
speed will occur. During the engine coast down, the PCM monitors the CKP sensor
signal and stores the pattern. This pattern is used to determine if the
crankshaft speed variations are due to misfire.
The number(s) below
refer to the step number(s) on the diagnostic table.
|
Step |
Action |
Value(s) |
Yes |
No |
|
Did
you perform the Powertrain On-Board Diagnostic
(OBD) System Check? |
-- |
|||
|
Perform
the Crankshaft Position System Variation Learning Procedure as follows.
Important While
the learn procedure is in progress, release the throttle immediately when the
engine starts to decelerate. The engine control is returned to the operator
and the engine will respond to throttle position after the learn procedure is
complete.
Does
the scan tool indicate the Learn Status: Learned This Ignition? |
65°C (150°F)
4000 RPM |
|||
|
Attempt
the Crankshaft Position System Variation Learn Procedure as many times as the
specified value. Does the scan tool indicate the Learn Status: Learned This
Ignition? |
3 |
|||
|
Inspect
the Crankshaft Position (CKP) sensor and the crankshaft reluctor
wheel for damage. Refer to Diagnostic Aids. Did you find a condition? |
-- |
Go to Diagnostic Aids |
||
|
Turn
OFF the ignition for 15 seconds. Is the action complete? |
-- |
-- |
||
|
Replace
the Crankshaft Position (CKP) sensor and/or reluctor
wheel. Refer to Crankshaft
Position (CKP) Sensor Replacement or Crankshaft and Bearings Removal
in Engine Mechanical 5.7L. Is the action complete? |
-- |
-- |
||
Does
the scan tool indicate that this diagnostic ran and passed? |
-- |
|||
|
Select
the Capture Info option and the Review Info option using the scan tool. Does
the scan tool display any DTCs that you have not diagnosed? |
-- |
Go to the applicable
DTC table |
System OK |