i am having problem with my four wheel drive. the switch does not work and the light is on saying 4x4 service. i called gmc service department and they told me to go under the hood find fuse for the 4 wheel drive pull it out and put it back in. i did it and the vehicle was then in 4 wheel drive. does anyone know anything about this issue please let me know

I believe that there is a common problem with the selector switch itself. Mine has in the past switched from 2HI to 4HI, and then bind while turning, which is the only warning. The switch is still in the 2HI position, but the truck has changed itself. I would start with the selector switch, and then see what happens from there. Let us know how you make out.