['89Z71]

The 4 wheel drive in my girlfriends 94 chevy K1500 quit working 2 days ago. If I shift it into 4Hi and watch out the window at the front tires they do not spin, same thing in 4Low. The 4x4 indicator light on the floor also does not come on. Could the transfer case be shot or could this be as simple as a switch or sensor? Any help will be greatly appreciated.....TIA, DK