Mine had the same issue. I put the car into neutral and into drive a few times and tried moving the level and eventually it popped back into 2WD. Sometimes they are a finicky. Especially if you lock it in and the differential lights light up on the dash for the front and rear in 4WD and lock the rear diff. Took me a while to get everything back into 2WD when I did that, but it finally did.
Wednesday, April 3rd, 2013 AT 3:38 AM