I know a million threads are on here about 4x4. I've searched all around and I can't find my exact answer or how to diagnose it. I have a 98 blazer ls with the 3 button selector. I've been having this problem for awhile and I am going to fix it now since yesterday I decided to go off roading but I kept on getting stuck in sand. Well everytime I hit the 4 hi it blinks and will not go in. It goes into 4lo sometimes but yesterday I got stuck in 4lo and I looked at the tccm and pin 1 2 and 6 are corroded but I cleaned it with salt and vinegar. Then I noticed that my atc fuse kept blowing. Well I cleaned the connections and replaced the fuse and reconnected everything, and it worked.....for about 6 times then it stopped again. Do you think my problem is the corrosion, I just don't want to start rplacing things that I don't have to. Thank you