Where is this "salesman" switch. Guess how I charge my batteries is a secret but suffice to say My system seems to work because I have not had the converter/charger hooked up for many years. wa8 people in 3rd world countries are smarter than that. Anyway I can trace the 12V house power until it goes into the frame 35+feet from the front and thought someone might know a LOGICAL place to look for the trouble and the location of where it is. Switch, fuse, connection. It is grounded to the frame in the rear but couldn't it be a ground as well as a positive break in the circuit? All 120 circuits work as well as everything with the chassis batteries. But no house power period.