Tip of the Day… DC Circuits. RV have two DC circuits. One is for the towing or chassis and the other is for the house side of the RV. Both of them are 12 v DC and serviced by batteries with some kind of charging unit.
Lets start with the chassis circuit. All recreational vehicles have a chassis circuit. Some are simple and some are as complicated as a tractor trailer or transit bus. At the minimum this circuit will run the lights and break away switch. The break away switch is used to apply 12 Volts to the breaks in case of a disconnect from the tow vehicle if the RV is a towable. With the chassis circuit everything will start at the battery or batteries. From here it will go to the fuses. This is where things really get complicated. You may have multiple places for fuses. I suggest that you look for documentation. A towable will usually have fuses in a central location. Class vehicles (those with an engine) may have multiple locations. Our Class A has 7 different locations for 12 volt fuses, that I have found. These fuses will control the running lights, brake lights, turn signals, fuel pumps, wipers, horn etc. If the unit has air bags and air horns it will have fuses for them as well.
For an inspection, you just want to find out where the fuses are and make sure they are all OK and in place. It is not uncommon to remove a fuse to prevent a broken item from identifying itself.