Don't know if you found it yet but Bruno's picture is the same as mine in my 2015 Vegas. I'm thinking it's the same in your Four Winds. And it is one PITA to find.
I found mine by having my wife cycle the USE/STORE switch on & off while I tracked down where the relay click was coming from. Eventually found it behind the grill in my "hallway" next to the converter box. Opened the grill (that's also where my water heater bypass valves are located. Moved the heater ducting aside and found the relay mounted to the backside of a wooden bulkhead under the refrigerator.
I wasn't having a problem with it -- I just wanted to knw where it was in the event that I had a problem sometime in the future. Had the contacts of the relay not been clicking when activating the USE/STORE switch, I never would have found it.
Here's a picture of mine in situ:
Ed & Bev Felker
Retired USAF Col and retired Nurse
Traveling with Lily & Bella ('Teddy Bear' breed)
2015 Vegas 24.1 (E-350)