hmm what kind of gauge is it. Did it not come with any directions? I wired mine to the fuse box so they light up any time the accessories have power. I used the power window fuse.
its for the dimmer, the gauge when wired properly will dim when headlights are dimmed that what my extra wire was for anyway.vtf1 said:i just got my boost gauge and i know where to hook up the the vaccum line but need help with the lighting part. where do you hook it up to where the light will go on when you trun your head lights? also i know that the red wire is for the 12volt, and the black for ground but there is also a yellow wire? what could it be for? thanks!