I had this problem in my Prowler.
My dealer was too inept to figure out the problem and made it worse twice (ie.- two warranty visits, plus they destroyed one stereo unit and the cabinet - see photo below), so I then tore into it while camping (ie.- wasted a day of rest and relaxation) and figured it out!
Which involved emptying the basement and removing the wall to the underside . . .
First off, from the factory and straight out from the outside cable connection that was connected to the OUTPUT of the first coax splitter (signal only travels one way through a splitter) in the basement, the whole coax system was wired backwards.
Once I got that all figured out and connected correctly I now had cable to the TV, but a fuzzy picture.
I removed one of the TV's from the trailer and plugged it in directly to the cable connection at the power pedistal and got a perfect picture, which told me the issue was still inside of the trailer somewhere.
Anyway, to make a long story short, I removed the Furrion AM/FM/CD/DVD player from the cabinet and found one more splitter back there, and as it turned out, the antenna for the stereo unit was connected to that splitter with a diapole-to-coax adapter.
As a fluke, I needed to unplug this radio antenna from the splitter so that I could pull the stereo out so I could get my arms in that tiny hole to check the coax connections in there . . .
And when I unscrewed the coax connection from the stereo . . .
I HAD A PERFECT CABLE PICTURE ON THE TV!
In other words, it was this connection that was grounding out the cable signal!
Check this out . . . it could be your issue as well!
Second shot is the new replacement stereo - notice in both shots they used wood grain tape to cover up the cabinet damage.