I have a 2011 GMC Sierra 4x4, 5.3 Automatic. I don't often put it in 4 wheel drive but I'm working in the back yard of my house and I have to go through a shallow grassy ditch. I put it in 4 Lo so I wouldn't spin the tires and tear up the yard. When I got back on the road, it wouldn't come out of Lo 4. It happened once while the truck was under warranty but it wouldn't repeat so I blew it off. Today it did it again and I had to drive about 2 miles before it would come out of Lo 4. Any information on this out there ?? Damned electronic junk. What was wrong with a transfer case shifter.