The crankshaft position system variation learning feature is used to calculate reference period errors caused by slight tolerance variations in the crankshaft, the crankshaft balancer interupter rings, and the crankshaft sensor hall effect switches. The calculated error allows the PCM to accurately compensate for reference period variations. The crankshaft position system variation learning feature enhances the ability of the PCM to detect misfire events over a wide range of engine speed and load.

The crankshaft position system variation values are stored in the PCM non-volatile memory after the crankshaft position system variationlearn procedure has been performed. DTC 1336 set indicates that the crankshaft position system variation values have not been stored in the PCM and the crankshaft position system variationlearn procedure must be 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 balancer replacement
- Crankshaft position sensor replacement
- Any engine repair(s) which disturbs the crankshaft/harmonic balancer to crankshaft position sensor relationship.

The Steps for a Variable Crankcase Learn Procedure:

NOTE: When you go to have your "learn" done, it'll go quicker if the engine is at normal operating temperature. The procedure isn't run on a cold engine. This should take NO MORE than 5 minutes and you need access to a TECH-II to complete this procedure:

1.) Turn key to on position
2.) Turn Tech II on
3.) Select the Diagnostics Menu
4.) Select Car Information (Year, Make, Engine, Etc.)
5.) Select Special Functions
6.) Select Variable Crankcase Learn Procedure
7.) Follow On Screen Directions.

The Crankcase Learn Procedure is going to ask the Technician to do the following :

1.) Put E-brake On
2.) Make sure car is in neutral or park
3.) Turn engine on.
4.) Rev Car to Rev Limiter (car will hit limiter at 3,000 RPM.)
5.) Wait about 5 seconds
6.) Rev Car to Rev Limiter (The car will this time his about 5,500 to 6,000
RPM)
7.) Wait about 5 seconds.
8.) Car is done.