are you dealing with snow or mud/water? could have gotten something wet up on the linkage and it froze. get underneath and see what ya got. maybe part of the linkage popped out of the bushing or something of the sort. I had a similar issue with my XJ years ago and it was the linkage. it was very finicky, one time it would work flawless then the next it would jam up or it would come undone completely.
had one particular hairy situation where I had to cross a short section of dirt road COMPLETELY iced over after an ice storm. grabbed for 4hi and had NOTHING, it popped out while the t-case was in NEUTRAL. and with the icy road the parking brake wouldnt hold the rig still, if was off camber and was sliding SIDEWAYS, not forward or backwards. I was by myself and couldnt go forward or backwards because of the ice. I got fortunate and it caught a rut and stopped. I was able to get out climb under and pull the case linkage into 4hi enough to just get out of the sitaution. once I was out I got back out and "rigged the linkage to get me home.
had one particular hairy situation where I had to cross a short section of dirt road COMPLETELY iced over after an ice storm. grabbed for 4hi and had NOTHING, it popped out while the t-case was in NEUTRAL. and with the icy road the parking brake wouldnt hold the rig still, if was off camber and was sliding SIDEWAYS, not forward or backwards. I was by myself and couldnt go forward or backwards because of the ice. I got fortunate and it caught a rut and stopped. I was able to get out climb under and pull the case linkage into 4hi enough to just get out of the sitaution. once I was out I got back out and "rigged the linkage to get me home.
