kwoody

I am installing a DVD stereo with steering control built in and the stereo has 4 wires coded as AD / GND / +5V / AD. Which wires do I hook them up to on the Ford Edge factory Wiring Harness. On a diagram it has steering control (+) and steering control (-) not sure if any other wires are needed on a Ford Edge. The receiver also has Illumination control 1 wire but the ford has illumination (+) and illumination (-). Which of these do I use?