03 chevy silverado with 200,000 miles on it. New transfer case 4 years ago. 4 wheel drive in 4 high works when it wants to work. New switch in cab Feb 2014 and another new one Dec 2014. New actuator on transfer case last year also. Push switch to 4high, sometimes it works other times nnce it works in 4high it can go out at any time. It works in 4low but I can't drive around with it 4low.