vss is not needed. Only 1 power wire. and the temp sensor just run to the temp sensor. the blue/red is just for dimmer, so the display would dim with the dimmer, I dont use it. the display is not that bright anyhow. light wires just run from the dome. granted you have to run a solid power, but that'd be easy. Just run it along with the OHC power and run it back to the dome.