We have a Roadtrek Camping van built on a Chevy 3500 chassis. The ashtray has no light, fixture, or wires nearby. I found a 12 vdc miniature light at Radio Shack that will fit the area where a light is supposed to go, and I can route the wiring so it is hidden. I would like to hook the + wire on the light to the instrument panel dimmer, but I can’t find any info identifying which color code the wire would be. I purchased a repair manual for the van, but the schematic is unclear. I have already disassembled the lower dash unit, and I can clearly see/access the headlight switch. Any help would be greatly appreciated.