Blocked Shift Strategy

WARNING: This page is about a different car, the 2004 Dodge Pickup and 2004 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

When a shift is commanded, the shift motor will be driven towards its destination position, except in the case of shifting out of Neutral if 4L was selected (the transfer case will shift to the 4H position first, before proceeding to 4L). If the shift is blocked on the way to the destination, the TCCM 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 'D' channel during the shift re-attempts, the LED 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 'D' channel position. If this motor drive allows the transfer case to reach the 2WD/AWD 'D' channel, or the 2WD/AWD between gear position on the 4H side of 2WD/AWD, 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 TCCM 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 4H), the motor will be driven to stall in the direction of 4H or 4L, depending on the achieved position. If the transfer case has reached the 2WD/AWD or 4L between gear position nearest the NEUTRAL positions and the shift conditions are no longer being met, the transfer case will be driven toward the corresponding 'D' channel. Otherwise, the transfer case will be driven in the direction opposite the last attempt with the desired target being 4H or 4L.

If the transfer case reaches the 2WD/AWD 'D' channel when being driven in the 4H direction, then one final 1.0 second drive toward 4H is attempted. If the transfer case then reaches any of the 4H positions, the shift is considered complete and the 4H LED is illuminated. If the transfer case is still the 2WD/AWD position, the shift is considered complete and the 2WD/AWD LED is illuminated.

NOTE: If after the 5th blocked shift and reversal attempt, if the transfer case position is in the NEUTRAL region, shift attempts will continue until a non-NEUTRAL 'D' channel is reached.