U Hauls are not considered to be commercial vehicles so that means that U Haul trucks do not have to stop at weigh stations.
I've always just passed by weigh stations when in a U Haul and nothing has happened.
I asked the U Haul place where I rented the U Haul whether or not I had to stop at a weigh station in the larger U Haul truck.
They said that the U Haul trucks were exempt from stopping at weigh stations since they are not considered to be commercial vehicles.
Only commercial vehicles are required to stop at weigh stations and those driving commercially such as a hired moving truck and company.
So if you hired a moving company with their own truck for moving your stuff then yes they would be required to stop at the weigh station.
However if you're driving a U Haul truck and moving your own stuff with the U Haul truck then you can pass right by the weigh station.