If this is the cause of your rv 12 volt system not working issue you could take care of it in a blink of an eye.
Rv 12 volt system not working when plugged in.
Also take a reading off the feeds to your circuits from the feed side of the fuses.
Troubleshooting the rv 12 volt system.
Many times it s the actual power system itself that s broken down somewhere between the source and the appliance.
Likewise your inverter converter is also essential to your 12 volt electrical system and that could be the source of the problem.
When your rv appliances aren t working it s not always right to assume the appliance itself is broken.
From there it feeds into all of the slides switches lights etc.
Without a properly working 12 volt dc house battery power source the rv interior lights will not work the water pump will not function the appliance control boards will not have the power they need to allow the gas electric refrigerator to work the air conditioning units will not function the furnace will not provide heat and the slide outs and leveling systems will not function.
You may have to take the cover off to get to one.
These vibrations can shake electrical connections loose.
A bad connection in the 12 volt system can cause failures of various appliances including slides and lights which run on 12 volt power.
Overworked overheat batteries run short of water from time to time which disrupts the operation of the rv 12 volt system.
To get an accurate reading make sure the rv is not plugged into electricity and turn on a couple of overhead lights to place a small load on the battery.
Check the reading at the monitor panel.
A 12 volt problem can cause failure of other appliances and systems if they have 12 volt power to their controls.
Problems can occur in either one of these systems because rvs vibrate when traveling.
With it plugged in take a reading at your converter off the red battery lead and a good ground which can be in the power center.
Typically the output of your 12 volt converter runs through two 30 amp fuses that supply the 12 volt fuse panel.
Your rv s 12 volt system runs off of the batteries and if they are dead damaged or undercharged that could stop your 12 volt system from working.
If you re boondocking or dry camping and not plugged in you can use your batteries to power anything that runs off 12 volt.