At 10k miles my new Silverado 1500 started to change drive modes without any input from the driver. Like it would change into tow haul mode, then sport mode, back to normal. annoying but not a big deal. It then started shifting into 4x4 without input and would do it going down the highway. That was a big problem. Dealership replaced the switch gear, that did not fix the problem. The problem continued until 13k miles when the truck was inoperable due to a different warranty issue.