IF, and that's a big if, your system is set up the same as mine, that relay is bad, I would get no 12v power into the coach, because it is controlled by the salesman switch( battery disconnect).
Can you take a picture of you set up and post it, and I'll try and talk you through some tests.
Do you have a multi-meter? Doesn't have to be fancy, just volts and ohms. $12>15 bucks most every where.
All I know abut your coach is , Tiffin , could you take a minute and set up a " Signature Line" Left side of your " User CP" page click " Edit signature" type in your coaches info and click save at the bottom of the page , and the info will automatically appear below your posts; as mine does below.
Make, model, year and chassis manufacturer.