There could be a few things that happened. First of linkage for the shifter could've gotten loosened up. Or there is some internal damage to the transmission/transfer case.
I think your truck as a cable shifter, which could have stretched or come out of adjustment from going back and forth to drive from reverse. Even its if its mechanical linkage the same applies. It is not being shifted exactly into gear the detent is not allowing the transfer case to disengage as if it were being shifted or between gears.
So, I would first check the shifter and make sure it is going exactly in the gear. If you can get under the truck safely, have someone shift in and out of the gears to find the shift shaft. But the truck into reverse or drive and feel at the shift shaft if there's any play or you can feel it fall into gear. On the shift shaft there is a notch that a ball falls into when in gear. This is what you are feeling for. If the shifter has become loose because the cable is stretched and needs adjustment or if the mounts for the shifter or cable are loose, this will cause this problem. Some transmissions are more sensitive than others, but if they are not put near exactly in gear, or a, "positive Shift", there can be issues. The shift shaft moves between different notches or, "Detents" and a bearing a ball falls into each notch for each gear. So, try to imagine that as you are feeling for a, "Positive Shift".
Also inspect the transfer case linkage for play.
If you do not find anything there, it might be internal and need to be at least partially taken apart or inspected by a qualified technician.
I hope this helps. Let me know how it goes.
Saturday, February 19th, 2011 AT 11:04 AM