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Good logical view of RV/TT diagram is below diagram.
If your RV has a good battery and sometimes its 12V system works and sometimes it doesn't, do investigate its converter. Confirm if its converter is working properly. If these 2 areas test fine, then investigate its wiring area (between its AC panel, to Converter, to 12V battery area). A few months back, I remember reading a post where the guy's 110/120 Plug on his TT's converter vibrated out (from road bumps). He had intermitting problem that was very hard to find. But, he eventually found the problem (with no flipped breakers or blown fuses either).
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Source file:
- Click Here - Note: Diagram updated with corrected Text. re: Power Invertor (connected to 12V battery) is for 12V power to 110V power devices.