Mirror Map Lights

[daytonboi]

Can someone tell me how they work. I see three wires and from what i can tell with a multi meter two are ~12 volts until i open the door when one drops to ~0-1 volts...My thing is that i bought an overhead console from a Acura TL but its only got two wires one + one - and I wanted to add a third wire that would make it light up when I opened the doors.

[Crazy K]

The three wires should be:

 

black = ground

white = switched ground

orange = constant