The orange single wire is constant power. It has power even when the key is removed from the car.
The two black wires are the grounds. One is a constant ground allowing you to turn on the dome light whenever you'd like. The other ground is managed by the door ajar system; when a door is opened, it connect the ground which activates the dome light. I don't remember which ground is which but a tester or trial and error will find them.
Hatch Nation #13 : Rally Revolution #13 : ROTM Jan '13
It's Bryan, not Brian
RSVT-170 Build in Progress
Derusting Rusty Build in Progress