I have a 2006 Sierra 4WD with about 150,000 miles on it. It has buttons in the dashboard to switch from 2WD/4WD. At some point it had switched itself from 2WD to "AUTO 4WD". When I switched it back it worked fine until I got to about 50 mph. At that speed when I let up on the accelerator the truck started coasting like it was in neutral (it doesn't seen to do it at speeds below 50 mph). It works fine while in "AUTO 4WD".
Does anybody have any idea what this could be?
Does anybody have any idea what this could be?