I have a 91 winnebago chieftain 25'. When i am plugged in everything works. Unplugged everything is gone, no step, radio, ac, headlights, etc. It will start and drive thats it. It is driving me crazy....
What chassis is your rig on? Could be a problem with a fuse link. Ford has one adjacent to start relay. GMs are located near the starter. Need more information as what exactly is working and what is not.