I have a fontaine trailer, the service brakes work fine. I bought it off someone else and the abs wiring had been removed so that is not working, but when I pull the emergency/parking brake valve, the trailer brakes will set for 1 second and then release and i will not have any parking brakes. So when i disconnect, the trailer wants to roll. I cannot figure out why, i dont have a diagram for the lines or anything. Any help.