Do all of the buttons on an 06 GMC SLE 2500 have lights behind them, or is it only the "seek" buttons? Those are the only ones that are lit. Also, the 4X4 buttons are not lit, and the AC button is dark. I just got the truck today, and while driving it home in the dark, I noticed these buttons disappeared! I am guessing the AC light is just burned out, but I am unsure about the other buttons. Maybe if one of you guys notice next time you are in you rig?