Caution: Before 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 in order to eliminate over revving the engine. Once the learn procedure is completed, the control module will return engine control to the operator and the engine will respond to the throttle position.
Important: A Crankshaft Position System Variation Learning 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:
| • | PCM replacement |
| • | Engine replacement |
| • | Crankshaft replacement |
| • | Crankshaft position sensor replacement |
| • | Any engine repairs which disturb the crankshaft/harmonic balancer to the crankshaft position sensor relationship. |
Important: The battery must be fully charged and in good condition. The scan tool connection at the DLC is clean and tight before starting the Crankshaft Position System Variation Learning Procedure.
- Close the hood.
- Block the drive wheels and set the vehicle parking brake.
- Put vehicle in Park or Neutral.
- Turn all the accessories OFF.
- Install a scan tool.
- Run the engine until it is at normal operating temperature 85°C (185°F).
- With the engine still running, enable the Crankshaft Position System Variation Learning Procedure with the scan tool.
- Press and hold the brake pedal firmly and raise the engine speed to the specified value, RELEASING the throttle as soon as the engine cuts out.
- Verify with the scan tool that the Crankshaft Variation has been learned.
Perform this procedure up to 10 times. If the PCM will not learn the variation, a DTC P1336 should be set. Refer to DTC P1336 Crankshaft Position (CKP) System Variation Not Learned for diagnosis.
