2005 Chev Trailblazer. Question : how do you know if the 4 wheel drive is gone. We only hear a noise when we drive. took it to a garage and they said there was nothing wrong. It sounds like something is dragging on something. I cant seem to find anything wrong.

Answer: A noise? Well that does not give me much to go by. Put it in 4 wheel high or low, then drive truck at a slow speed and you should feel the front end binding up. More so in 4 low. That means it is working. If the noise is only there in four wheel drive, then it must be related to that. If it is there anytime driving, in 2-wheel mode, you could have a front hub bearing that is noisy. Drive at 20 MPH and turn the steering right and left. This will usually cause a hub to change pitch or even get less or go away with the body roll shifting the weight of the truck.