I have the two parts installed.  My headunit doesn't seem to know that I have a CD changer.  The car was pre-wired for the changer.  I found the two wires and plugged the unit in.  I know it has power.  I got the headunit installed at a local stereo shop.  The previous owner had installed a Jensen unit and cut out the OE harness and antenna lead and spliced in his own stuff.  The stereo place ordered a new a connector pigtail and did the install for me.  Everything on the headunit works, AM, FM, Weatherband and tape deck.  All the buttons; scan, program, modes and balance, pre-sets, everything works.  According to the guy I got it from you just toggle the band switch and it should offer you AM, FM and CD.  CD never comes up.  I didn't tell the stereo shop that I had a changer in the trunk.  I figured it was part of the harness.  It there something extra I need to hook-up?  Here is what I installed.