I know that I have a different MH (2002 Winnebago Ultimate Advantage) but, my switch was under the coach where the air hoses come together under where the brake petal is on the MH. You might look under there for the right wire. When I wired my controller, I tapped in there and ran the wire through the firewall to to the controller.
Hope this might help ?
Dave and Karen -- '02 Ultimate Advantage 36 C, 350 HP Cummins, Allison 3060 Tranny
'07 Ford Escort, Brake Master 4160, '13 Ford Edge, InvisiBrake