Mirrors work through a fuse in the battery control center under the hood driver's side.
This portion of the "chassis" electrical works through the ignition relay. The ignition relay energizes after the chassis battery receive a quick charge after start up. Usually 10-20 seconds.
I would have to get drawing from my rig, but there is a few other items that work through the ignition relay. Items added by Fleetwood and wired to the battery control center. My ignition relay failed several times until I sealed the metal can with silicone before installing the last one.
Make sure that this relay is energizing and is putting power through it. The coil connections corrode.
Bud
USAF Retired
Pace Arrow
2003 Chev Ice Road Tracker