pioneer KEH-M6500 speaker wire colors?

Boy is that an old one :-) If memory serves,

Green = LF Green/black = Left Common Green/red = LR Grey = RF Grey/Black = R Common Grey/red = RR

Thanks for the info, it is an older unit. I had a feeling black was a common speaker negative but the red stripe threw me off. Just for a longshot, this radio has an intermittent backlight on the display but the rest of the face lights work. Any pointers? I already cleaned the faceplate contacts but it still blinks off sometimes - I was thinking maybe the flat ribbon cable inside that feeds the faceplate connector strip.