what he said boss. Or grab a 12volt test light and check the wires to ground. Obviously 12v constant will light the bulb regardless of voltage, and the ignition controlled voltage will work with keyswitch on or in access. I have no idea why Ford would have an ANTENNA wire on a wiring harness. Never heard of Ford putting a retractable antenna on any mustang...but I could be wrong. Last all you need to do is find a ground wire. Usually ground is green. But to know for sure requires an ohm meter to check for continuity. Or a continuity checker. Good luck.