Alero L4-144 2.4L DOHC VIN T SFI (2000)
Crankshaft Position Sensor: Service and Repair
CKP System Variation Learn Procedure
IMPORTANT: A Crankshaft Position System Variation Learn Procedure must be performed any time a change is made to the crankshaft sensor to
crankshaft relationship. Changing the crank sensor to crankshaft relationship will not allow the PCM to detect misfire at all speeds and loads accurately.
Resulting in a possible false misfire DTC being set. Removing a part for inspection and then reinstalling the same part is considered a disturbance. A
false DTC P0300 could be set if this procedure is not performed.
The learn procedure is required after the following service procedures have been performed, regardless of whether or not DTC P1336 is set:
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A PCM replacement
^
An engine replacement
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A crankshaft replacement
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A crankshaft position (CKP) sensor replacement
^
Any engine repair which disturbs the crankshaft/harmonic balancer relationship to the crankshaft position sensor.
A fully warmed up engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed on that ignition cycle. If
the engine cuts out before the specified learn procedure engine speed or at normal fuel cut-off RPM, the PCM is not in the learn procedure mode.
Review the crankshaft position system variation learn procedure and re-enable the learn procedure. Verify that the scan tool displays Test in Progress.
CAUTION: When performing the Crankshaft Position System Variation Learning Procedure always set the vehicle parking brake and block
the drive wheels in order to prevent personal injury. Release the throttle immediately when the engine starts to decelerate. Once the learn
procedure is completed, engine control will be returned to the operator and the engine will respond to throttle position.
IMPORTANT: The battery must be fully charged and in good condition. Verify that the scan tool connection at the DLC is clean and tight before
starting the Crankshaft Position System Variation Learn procedure.
1. Close the hood.
2. Block the drive wheels and set the vehicle parking brake.
3. Put the vehicle in Park or Neutral.
4. Turn all the accessories off.
5. Connect a scan tool.
6. Start and run the engine until the engine is at normal operating temperature 85°C (185°F).
7. With the engine still running, use the scan tool in order to enable the Crankshaft Position System Variation Learning Procedure.
8. Press and hold the brake pedal firmly and raise the engine speed to the specified value of 3,920 RPM, RELEASING the throttle as soon as the
engine cuts out.
9. Verify with the scan tool that the crankshaft variation has been learned.
A fully warmed up engine is critical to learning the variation correctly. If a valid learn occurs, no other learns can be completed on that ignition cycle. If
the engine cuts out before the specified learn procedure engine speed or at normal fuel cut-off RPM, the PCM is not in the learn procedure mode.
Review the crankshaft position system variation learn procedure and re-enable the learn procedure. Verify that the scan tool displays Test in Progress.
If the variation will not learn, perform this procedure up to 10 times
