Ed - we have a 2004 Designer Medallion 29RLTS that we purchased from the original owner, and it also has a small button in a wall plate, along with a small digital screen. The Winegard rooftop dish was apparently installed at the factory, but the original owner never used it. According to the Winegard literature that came with the trailer, that button is an dish elevation sensor. Pushing it is supposed to tell you what elevation your dish is currently at, but pushing mine gives me nothing in the digital screen. I have tried to use the dish, but never could get it to work.
I think in your case, you should contact Jayco via their website email contact, with your trailer's serial number, and they probably can email you a schematic of the wiring in your trailer. They just did that a week ago for my 12V converter wiring, so I'm sure they will do this for you.
If you get it working, how about another post with details ?
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.