Important: If the crankshaft position variation learn procedure has not learned, a false misfire could be detected and DTC P0300 may set. If sent here from DTC P0300, proceed with the crankshaft position variation learn procedure.

1. Monitor the engine control module (ECM) for DTCs with a scan tool. If other DTCs are set, except DTC P0300, or P1336, refer to Diagnostic Trouble Code (DTC) List for the applicable DTC.
2. Select the crankshaft position variation learn procedure with a scan tool.
3. The scan tool instructs you to perform the following:

3.1.	Accelerate to wide open throttle (WOT).

3.2.	Release throttle when fuel cut-off occurs.

3.3.	Observe fuel cut-off for applicable engine.

3.4.	Engine should not accelerate beyond calibrated RPM value.

3.5.	Release throttle immediately if value is exceeded.

3.6.	Block drive wheels.

3.7.	Set parking brake.

3.8.	DO NOT apply brake pedal.

3.9.	Cycle ignition from OFF to ON.

3.10.

Apply and hold brake pedal.

3.11.

Start and idle engine.

3.12.

Turn A/C OFF.

Vehicle must remain in Park or Neutral.

The scan tool monitors certain component signals to determine if all the conditions are met to continue with the procedure. The scan tool only displays the condition that inhibits the procedure. The scan tool monitors the following components:

•	Crankshaft position (CKP) sensors activity--If there is a CKP sensor condition, refer to the applicable DTC.

•	Camshaft position (CMP) signal activity--If there is a CMP signal condition, refer to the applicable DTC.

•	Engine coolant temperature (ECT)--If the engine coolant temperature is not warm enough, idle the engine until the engine coolant temperature reaches the correct temperature.

4. Enable the CKP system variation learn procedure with the scan tool and perform the following:

Important: While the CKP variation learn procedure is in progress, hold the throttle at WOT for 5 fuel-cutoffs. The learn procedure must determine there has been 5 fuel-cutoffs to properly perform the test.

•	Accelerate to WOT.

•	Hold throttle while fuel cut-off occurs.

5. The scan tool displays Learn Status: Learned this ignition. If the scan tool indicates that DTC P1336 ran and passed, the CKP variation learn procedure is complete. If the scan tool indicates DTC P1336 failed or did not run, refer to DTC P1336 . If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List for the applicable DTC.
6. Turn OFF the ignition for 30 seconds after the learn procedure is completed successfully.

The CKP system variation learn procedure is also required when the following service procedures have been performed, regardless of whether or not DTC P1336 is set: