Cable connections weird

The logical places are by the microwave you described, and at the rear of the TV.

I'd also pull the cover plate at the "rear" sat connection and see if it's really connected.

Other than that, I'm just guessin' here.

The rear connectors are under the bottom bunk in the same area as the electrical and the water heater. The two cables connected to the connectors go up toward the ceiling behind the wall. That would have been a great place to put it. Lots of wasted space.

Where does the wiring diagram show the splitter? That should get you in the general vicinity. I've seen them behind the plate with the switch for the amplifier. You did turn that off? Your outlet that worked could really be for an outside TV and is on the output side of your splitter and it back fed your other TV's.

I asked Highland Ridge about this. Here is the response:

"Ray, how are you? We don’t usually use a splitter on the Ultralights. The booster has 2 outputs. Did you check the connections on the booster itself? If we installed a splitter for a third output, it would be in the wall directly behind the booster. I hope this helps,"

I replied letting her know my question is about the input connections. Haven't heard back yet. But she did let me know about the connections to the booster. The one component I didn't remove and look at. There does have to be a splitter somewhere, though. Outputs in the bedroom, living room and outside by the front door. And, three inputs. Cable and Sat in the back, and the antenna. Unless the Sat jack goes directly to the connection by the TV. Hopefully I can get the trailer into the back yard tomorrow so I can put the slide out, and get to the booster.

I'm guessing you also have an antenna, and an inside cable outlet with a button you press to turn the booster on. There are antenna and cable inputs to the booster, which are also selected with the switch.

To use the cable input, you have to turn the antenna amplifier off - that switch also switches between the cable and antenna inputs, so if it's on - no cable.

I'd guess the jack in back is the cable input to the booster, and the one by the door is for an outside TV. The booster has a splitter in it which would allow a cable signal to pass through to the other outlet (although not real well).

Where does the rear Sat connector go to? Might that go to the 3rd of the 3 outlets you mention?

Got it all figured out. Pulled the signal amplifier down. It had two coax inputs and one coax output. Shorting the input connection on the back of the trailer with tin foil, and using my meter on audible, I was able to track the cable to the cubby above the refrigerator, where the two connections are looped together. That connects to one of the inputs on the amplifier. The other input is from the antenna. Antenna is white coax, the cable input is grey. The output does go to a two way splitter whose output is orange. One goes to the main TV, and the other goes to the outside connector. I checked the satellite connector while I was at it. It goes directly from the rear connector to the main tv plate. To switch to it, I need to move the coax from cable to satellite. I hadn't checked it since I complained to the dealer about it. I mentioned it to the mechanic who actually works on my trailer. I guess he straightened it out. Could have been a bad amplifier, or the connections were gomered up. Who knows now. But it should all work. Whew. I got a stiff neck from looking at stuff on the ceiling all afternoon. Did that, changed the TV mount to one that swivels, and installed a small TV for the bedroom. The wife likes noise to fall to sleep to. That's why I use earplugs, and always have a black sock to cover my eyes handy. Thanks for all of the suggestions and comments.