All of the Internal DC wires on my camper are white. On each pair one is solid white and the other is white with a color. I am assuming that the white with color is the Positive? I am wiring in some DC power ports and with some devices the Polarity matters.
2019 Cedar Creek 29RE
2017 Silverado Duramax 3500
With the DC wiring on these rigs I assume nothing! To be sure I always use a digital multimeter to check the polarity. If your meter reads 12.8 then your red test lead is positive and the black is negative. If your meter reads - 12.8 then your meter is sensing a reverse polarity. That's the only way to know for sure.
'07 K3500 Silverado LT Crew Duramax (LBZ)
2016 Salem 27RKSS
1984 CHEV SCOTTSDALE K20 2GCGK24J0E1XXXXXX (Chevrolet Legends-Class of 2019) "...exhaust fluid? We don't need no stinkin' exhaust fluid"