I have one of these units too. No problems yet. I thin you should call them M-F at 800-815-2159 and talk to customer support.
I checked their online FAQ and this question doesn't seem to be answered. I think you may have a leak in the RVI pump system that keeps it from coming up to full pressure and therefore the pressure shutoff switch doesn't turn off. Or maybe the pressure shutoff switch has failed. Good luck!
2004 Tiffin Allegro 27.5 ft. P32 18,000 lb GVW. 8.1 liter. Workhorse chassis built May 2002. 21,000 miles. 2012 Jeep Liberty Toad. RVi2 brake unit.