Wires, Stock Radio Options

[Guest_Matthew_*]

Does anybody know what wire that goes to the stock radio that controls the power antenna? Mine came with a premium factory system, and I haven't figured out which wire it is. I need help. I really like the power antenna and since I have replaced the stereo with a new one my FM reception sucks. I have a 98 GT Hatchback. Oh and there are only like 6 or 7 wires back there. There wasn't a wiring harness that could fit my car either so I had to run a wire direct from the battery and directly to all the speakers. The stock wires are just sitting back there tapped up.