these systems should not freeze up, my truck is outside all night in -35 and everything works all the time, i drive my truck through lots of mudd, lots of snow and lots of water, and my 4x4 holds up great.
i remember reading a thread on this forum about this same issues. but sadly i can't remember when and where. but the guys trucks message would come up all the time, all he did was change the fuse and he said the message never came back.
mine came on about 3 weeks ago and then went out 1 minute later and never came back on.
i would check the fuse. i can't remember what fuse but its a cheap fix if it is the problem.