[QUOTE=That 4x4, you say is push button. Does that mean you have a vacuum setup ? If so, probably water is frozen in the lines. Make sure you put a good drier in line with it. Other things, like un even tire sizes will cause trouble also.[/QUOTE]

I don't really know i know the older ones like my 91 were vaccume but this one has a electric motor on the transfer case to select 2hi 4hi 4low? its a 97 4dr S15 GMC jimmy SLE 4x4 4.3 vortec and either a 700R4 or a 4L60?

my 91 is a 4dr 4x4 with a 4.3 TBI & 700R4 and a new process (NP) transfer case NP 205 or 208 or something?
as far as tires they both have new tires the 91 has 29 x 9.5 x 15 aggressive tread and the 97 have new goodyears on them 235/75R15 all season