I have a sony cdx - gt 500 with a few plugs hanging in the trunk [ may be a disc changer / amp. 1991 bmw the remote works ok but I need a op. man. can u help me Mike

I have a sony CDX-505RF changer, i need to know how to hook up the 3 wires on the box. Theres a black, red, and a yellow wire. Whats power and ground and whats the other wire for?

We have this CDX505RF Srvice manual. for further information pl. email me. Regards, Sharmila