Important: A crankshaft position (CKP) 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 powertrain control module (PCM) to detect misfire at all speeds and loads accurately, resulting in a possible false misfire diagnostic trouble code (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 the CKP position variation learn 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 disturbs the crankshaft/harmonic balancer to the crankshaft position sensor relationship |
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.
Important:
• Before performing the crankshaft position system variation learn
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. • The battery must be fully charged and in good condition. The scan
tool connection at the data link connector (DLC) is clean and tight before
starting the crankshaft position system variation learn procedure.
- Close the hood.
- Block the drive wheels and set the vehicle parking brake.
- Put the vehicle in Park or Neutral.
- Turn all the accessories OFF.
- Install a scan tool.
- Start and run the engine until it is at the normal operating temperature of 74°C (165°F).
- With the engine still running, enable the crankshaft position system variation learn procedure with the scan tool.
- Press and hold the brake pedal firmly. Accelerate to wide-open throttle (WOT). Release the throttle when fuel cut-off is achieved.
- Verify with the scan tool that the crankshaft variation has been learned.
If the variation will not learn, perform this procedure up to 3 times.
