When backing up and turning the steering wheel my truck comes to a stop

While I’m backing up, and turning the steering wheel, my truck comes to a stop, without putting my brakes on. When I straighten the steering wheel it seems to free up. If I’m turning, it seems to lock up. What in the world is it? Checked the brake pads, they are good, with it jacked up and wheels turned straight I can move the wheel hub assembly. Thanks for any help.