Not enough information.. There are two different types of systems. One MUST have 12 volt or nothing works.
Now, I have the basic 120 volt system for a motor home
Power comes in from the INLET (a "hole" in the outside wall with contacts inside where the outlet end of a cord plugs on) to a box called an automatic transfer switch... IF this switch is not working no 120vac gets through to the RV,,, Generator also feeds the Automatic transfer switch by the way and if it does the switch is SUPPOSED to transfer over to generator power...
To test. First make sure you have power at the outlet you plug into. Find the switch, using a volt meter or 120 volt test lamp test for voltage from the HOT lead(s) to neutral on the SHORE input, (May be marked shore or mains) and on the LOAD output. NO power in = cord, wire, inlet, outlet or external to motor home issues.
Power in but not out, Bad ATS
On my coach the next stop is the MAIN circuit breaker(s) in the power distribution panel (My rig is 50 amps)
SOME coaches have Energy Monitors, Or Surge Guards Some have Energy Managers (mostly 30 amp on this last) and Other than testing for power in and out, on the first.. I can not much help you. SOME of these systems are operated by 12 volt battery power. Some are not.
If you have 120vac to the breakers.. Then you do not have a "no 120 volt" problem, you have a not tested (more than likely) problem or a problem IN the breaker box itself.
12 volts
120vac is supplied to a device called a converter, MAY BE ON THE BACK OF THE Breaker/Fuse box (if both are in the same box) may be elsewhere (As mine is) this CONVERTS 120vac to 12vdc. to both run lights and charge batteries.
Make sure it's getting 120vac and measure it's output.
There are fuses, usually a pair, usually 30 amp In/On the converter or the right hand fuses on the fuse panel. (Usually right hand)
Charge your batteries using an external charger, (SMART automotive type) and see if this gets 12 volts back. If it does, find that converter and it's fuises. if not, you are in for a "Where did it go" session.
I recommend a test lamp.. I have 4
One is a device I got at a Auto parts store, looks like an ice pick with a wire coming out of the transulent handle, you can see a light bulb inside the handle. LIGHT (Bright) is good, dim or dark not good.
I have one I made using a license plate lamp and a license plate lamp socket socket.
One I made with a 50 watt MR-16
And a 50 watt 12 volt "Trouble Light" (Long cord makes it harder to use though)
These all test under differing load conditions, making for a much better test.
Clip the wire lead on to a known good ground and probe with the point of the ice pick type. As I said, Light = Power
Follow the wires, check both ends of the wire.. I had one solid length of wire that showed BRIGHT light at one end, 12 volts on the volt meter at the other end but... No light Yup, wire was bad.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times
