[universeman]

I'd grab a trouble light and start tracing backward from the switch & relay, looking for current, if it were me. It's going to be a pain, but somewhere you're going to find a t-tap or something that's not supposed to be there.

If you pull the fuse does it kill the power? If so, that means your trouble is that you're on a different circuit than the intended one (maybe the clock circuit or something.)