Make sure you have no loose connectors just as a quick check.
The plug at the site is one of those with the little test button/fuse things in it. Trips instantly. Worked briefly last night. Is the van simply too much for it? Picture of inside fuse panel all fuses are okay. It often doesn’t play nice with 15 Amp sources but is fine with 30 amp sources.
May not be applicable in your case, but I had a similar issue with a GFCI tripping and it turned out to be the water heater. I had an add-on (lightning rod) to use it as electric along with propane. Once I unplugged the add-on, the GFCI stopped tripping.
I figured I’d mention it, because in my search during the issue everything pointed to a neutral/ground issue with outlets or wiring. Never really thought to check the water heater.
Water in an outlet could cause this. Check your outlets, especially outside ones.
I know this is unrelated but You should really consider replacing your power converter to a newer system. Those old ones are hard on new batteries and on sensitive electronics.
Could be drawing more than 15 A or the circuit breaker itself could be malfunctioning.
A long extension cord laying on the ground can sometimes leak enough power to trip a GFCI. Maje sure the cord is heavy enough, in good shape, and not too long, or on wet ground.
Source: Question: My 1995 B-Class campervan is causing a 15 amp power source to trip, why?
