there was one post (within the past week) that showed the circuit board breaking loose from the plate. usually the last thing i check is in the wall. it that is the case and the living room is the one with the switch plate, that could be it.
other thought would be digital or analogue.
if u have a sat connection, it is probably next to it.
unfortunately, i don't know ur trailer. on mine it is located on the outside wall just a couple feet away form the plate that u supply power to ur ant with.
switch has to be off for it to switch to cable (little light on face plate off).