Possible both ideas may be correct but that does take a bit of jump done on faith!
If we go with the wire that is reported to be labeled JP1 as being wire JP, then both ideas might be correct as JP does go to several different items on the roof!
If we accept that JP is ground and it is associated with JA for battery, those two wires show up here.
Click for best view or go direct for the whole story as we are seeing it?
Several things that it might be but I find no firm info beyond taking the leap and testing needed to confirm!
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Richard
Why no RV year, make and floorplan on MY signature as we suggest for others?
I currently DO NOT have one!