I recently bought an aftermarket amplified antenna for my 99 i30 to replace the one i broke in the carwash. i dont want to replace it with a new one, i just want to replace this one with the aftermarket one. well when i figured out how to get the radio out i found that the antenna wire has 2 wires, with 2 sets of wires inside. heres a pic:

sorry if the pic is too big. now im gonna assume that the larger wire is for the antenna and the smaller wire is power, but you know what happens when people make assumptions... so if anyone has a clue, that would be awesome.

 

Your working in the wrong area to replace your power antenna.
Watch this video for a 4th gen:
One wire is for the rear windows built in antenna, small one iirc, and the larger is for the power antenna.

 

i already said i didnt want to replace the stock antenna with a new one, i want to use the after market one, sorry if i confused you. i figured out that the big wire coming out of the back is the antenna wire, the lil one i still cant seem to figure it out and i dont wanna fry my already skippy radio by trying to read it with a multimeter.

 

Nissan/Infiniti used 2 antennas for the radio. This is referred to as the "diversity" antenna. As Fakie said in post #2, you have 2 antennas. One is the metal rod in the rear fender and the other is a wire in the rear window. Therefore, the plug that goes into the back of the radio has 2 prongs.

If you are bound and determined to run a new cable, instead of repairing the existing antenna, then you need to get an adapter. Metra makes one. http://www.metraonline.com/part/40-NI21

A local car audio store may carry it or you could order on-line. Fry's Electronics carries some of the Metra line. There is one in Downers Grove, but I would call or something before making the drive.

Otherwise, a good place for repair parts is http://www.antennamastsrus.com/Nissa...01995-1999.htm