[HummerJim]

I too have electrical gremlins in my 2006. The only aftermarket electrical item is a backup camera dealer installed when new that displays on the nav panel. I'll be driving along and the red OnStar light will come on, or the red neutral light under the 4 W drive buttons will come on (even though the buttons have been replaced), the lights come on during the day and the nav panel turns to night black, or I'll get in the Hummer and the clock has lost two hours, but it starts right up. Then once in a while the battery will go dead if it sits two days, so I just keep it on the battery tender in the garage now.