Our 92 breakaway has two switches on the bathroom vanity. One white overhead light switch, and one red colored switch....
For the life of me I cannot figure out what that red one does.

Guess on your switch?

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The RED switch turns on the electric hot water tank when hooked up to shore power?

My '93 Breakaway has two switches on vanity: one controls overhead cabinet lighting and the other is on/off for water pump (a 3-way switch, the other water pump control being
above the front exterior door)

Opposite bathroom wall has single on/off switch for holding
tank heat pad during winter ops.

Mine is the same as Lee's. Water Pump

Well, I figured it all out. The red switch does nothing as there is no electric element in my hot water heater. There are wires to it but they run nothing else that I can see. The opposites bathroom wall switch is the shower stall light.

Your description of "no working wires" to the water heater would seem to indicate a standing pilot light heater - something that would seem unusual for that year and upscale character of coach.