12 volt..no lights

If the batteries are indeed good (12V present?) then you need to trace the wiring back to where the voltage ends. Starting at those battery's, follow the wiring. You may have a loose ground, a failed DC breaker or something else but he'll have to follow the wiring.

Has he tried operating the house battery disconnect switch.Do you hesr anything clicking when operating switch

I'm going to ask. Thank you so much for quick replies. Everything was working fine until he started the dang engine this morning. Then everything went off when he turned engine off.

I would try starting engine again assuming you still have chassia 12v,could be an intermittent solenoid .

The house switch cannot operate cause it's 12 volt. The engine starts just fine. We just don't know what we are missing. Again I thank you for helping to sort this through. We have some space heaters. We have the coach plugged into 5o amp. :( At one point the auto start tried to start generator which said we had low voltage but we apparently arent getting juice back to batteries.

I'm guessing your battery disconnect switch got turned off. OR, if the generator won't start, your house batteries are dead.

If the genset won't start, I would start the engine, use the booster switch on the dash then start the genset. Let it run for an hour or so and then recheck the batteries.

The generator does start. He did exactly what you said but still can't get 12 volt to kick in. We are baffled and can't get an RV help out here till Monday. Sigh

converter bad ?
Converter converts 115 AC voltage to 12 Vdc ?

Is the salesman's switch by the exit door on? If so you need to find the relay that it controls and check the voltage on both sides to see if it is working. Or you could just jumper across it and see if the 12 volts is restored. These relays have a history of failing.

You need to address if the 12 volt disconnect switch is turned on and working. We're kinda stuck until that is answered.