Neutral Blocked Shift Strategy (Phase 2 Shifts)

When a shift is commanded out of neutral, the shift motor will be driven towards its destination position, except in the case of shifting out of NEUTRAL if 4LO was selected (the transfer case will shift to the 4LOCK position first, before proceeding to 4LO). If the shift is blocked on the way to the destination, the FCM may attempt to drive the motor back to the original position. This process will be allowed to occur 5 times. If the transfer case has reached a non-NEUTRAL position during the shift re-attempts, the message icon for the achieved gear position is illuminated and the shift attempts are stopped. To re-attempt the desired shift, the selector switch will need to be rotated to the current position until the switch debounce timer expires then a shift will need to be requested again. 

At the end of the 5th blocked attempt, the shift motor is driven towards the last known mode sensor position. If this motor drive allows the transfer case to reach the 2WD or AWD position, the shift is considered complete and the shift attempts are ended. 

If the mode sensor is in the NEUTRAL region at the expiration of the shift timer, the FCM will continue to make the shift attempts according to the blocked shift strategy independent of whether or not the driver controlled conditions are met. 

For shifts from NEUTRAL, if all 5 attempts fail to reach the desired position (which by default is 4LOCK), the motor will be driven to stall in the direction of 4LOCK or 4LO, depending on the achieved position. Otherwise, the transfer case will be driven in the direction opposite the last attempt with the desired target being 4LOCK or 4LO. 

If the transfer case reaches the 2WD or AWD position when being driven in the 4LOCK direction, then one final 1.0 second drive toward 4LOCK is attempted. If the transfer case then reaches the 4LOCK position, the shift is considered complete and the 4LOCK message icon is illuminated. If the transfer case is still the 2WD or AWD position, the shift is considered complete and all message icons are extinguished.