Sorry for bumping an older post.

In response to joeck76 wire colors. Illumination wire is used on some stereos (all that I have seen in the past 6 years). It dims the screen and the buttons for night driving when you turn your lights on, If you have some cool looking super doooper stereo with brightly back lid buttons, they should dim for night driving so not to blind you. Not a necessity but you might want to check out your set up if you want that feature.