YC 1 wrote:
You are getting fooled using a digital voltmeter and no load on the outlet. Go to an outlet that is giving you problems and put your voltmeter to work. Now plug anything in to the other outlet on the same outlet. That is, measure one of the outlets while you have a load on the one above or below the one you are measuring. There are two outlets per wall plate so this should be easy. I bet your voltage goes to zero.
Now the fun part, tracking back to where the problem is. I too suggest turning off your AC breakers one at a time. Press them into the off position. Sometimes one will feel fine but actually be tripped.
If resetting does not solve it you likely have a bad connection. Since I don't know what RV you have do you have an inverter? If so it may have breakers on it too.
Back to a possible outlet issue. Outlets generally daisy chain from one to another. You may need to do some guesswork to find where those outlets are fed from. There are devices "fox and hound", that make the job a lot easier.
He isn't even using a meter, just a voltage detecting lamp type tester. Probably a neon bulb voltage sensor.