Where did you find the box, I have a 2014 Bounder and am always pissed off that they didn't put one more switch in the bay with the pump.
None of the Fleetwood engineers have ever had to winterize one of these things.
The schematics show the fuse for the water pump is on wire number 640 (if they labeled the wire) that runs to a thing labeled 'int fuse block' in the back bedroom.
Looks like the controller is near the fuse block.
Ron and Kitchy with
Scottie our tri-color Sheltie
2014 Fleetwood Bounder 35k, 2019 Jeep Cherokee Limited toad