I have a 2004 Silverado 2500HD extended cab. On the dash board there is a button for your typical roof mounted yellow "gumball" light. I would like to know where GM placed the roughed in wires that correspond to this button. I am planning on hooking up a yellow light for plowing. I removed the 3rd brake light lense but do not see any wires in there.

On my 99 it was behind the headliner just reach up above the drivers side there is a pigtail in there towards the middle.