This issue is somewhat confusing for older RV's...
wiring colors used to be:
Pos = Red
Neg = Black
As RV mfg's began to conform to RVIA standards they changed their wiring colors to conform:
Pos = Black
Neg = white
As you can see, the BLACK went from Neg (old) - to Pos (new, current) in wiring harness'...
I found this out in grand style when installing the battery in our 2000 vintage Lance truck camper...Whoa - no red Pos wire - what gives...till I looked at the wiring diagram...Surprise on me...!