I now see in small print on my wiring diagram that it says the controller is in the electrical bay, though I didn't spot it there. I assume that is what you mean by front run bay. On second look I did find the controller mounted low right on the melamine panel, as you indicate, albeit totally obscured behind several hard-bundled wire looms.
I show 5 wires from the controller, a black feed from the #5 breaker, a green ground on the left side with the incoming hot black feed, then 3 on the right, one unused black, and a battery green with a convex mirror select red that both enter the switch you checked. Apparently the upper mirror gets power automatically unless one selects for the convex mirror, then the red wire should be active too - but I would expect the red at 0 volts when switched for the upper mirror.
It is disconcerting to realize that the controller module is at floor level in the electrical bay, given water instrusion is a problem in mine, and the bay becomes a lake for me all winter, despite continual efforts to resolve the problem. I may have to see if there's enough slack, after cutting a slough of wire loom strapping, to remount the device a couple inches higher on the melamine panel. Thanks for alerting me to its precise location, Bob.
Joel