I have the push button 4 wheel drive unit. I tried to put it in 4HI but there are no indicator lights and it feels as if it is still in 2HI. Any idea what could be wrong and how to fix it inexpensively (I'm strapped for cash)? I have instrument lights but no lights indicating which mode it is in. If it is a fuse which one is it? Thanks for any help. I'm no mechanic so please keep it simple.