I have a cable behind my head unit thats really bugging me. It has four cables, Red, Red, Blue and Black. I have tested with a meter and one cable is the reverse signal to put the head unit rear camera on. Another is the brake signal, to stop you watching videos while driving, the other two seem to be and earth and 12v, but I cant see any point for them as the head unit feed is on a different plug. Im kinda thinking its some sort of signal voltage but i can see any voltage change.
Does anybody have an idea what these two wires are actually for because its starting to drive me mad