I drive a seirra truck with 117,000 miles & at times it will lock itself in 4 wheel low when I first start the vehicle. I have to shift into neutral and press 2 wheel high to get it back to normal. Dealer couldn’t recreate the situation thus said they could not solve the problem. Any ideas?
Do you use 4wd very much? I would start by unplugging the 4wd selector switch and see if that solves it. If it does, I think that you can blame the switch. If not, we have to dig deeper.
What year was this truck made?
If you have the dash mounted 4x4 push buttons, pull the switches out (I believe they pop out together) and check for loose wiring connections.
I read a post where one fellow said to do this and he said he re-soldered the connection.
You can read quite a few references to this problem on http://www.chevytalk.org/fusionbb
This site covers all years and models GM.