Continuity problem with coax

I have two connection places on the side of the trailer, one is labeled DSS, the other is unlabeled. I assume DSS is the one I should be addressing, though I don't know what DSS stands for. At one time, I was considering pulling a new coax cable through the trailer, using the existing route, but is it possible there's some kind of splitter box involved? That would make that impossible, at least for me. My first order of business is to verify that the connection inside the trailer is good, by pulling out the wire slightly, and confirming that the threaded connector is seated properly. If that doesn't solve the problem, I'll have to consider installing another connection though the wall, but that's a little intimidating. I'll keep you posted.