Could be for a radar detector. Follow it and see where it goes?

It is definitely aftermarket something. If it goes to the OBD2 connector then it may have been for a scan gauge. http://www.scangauge.com/ A friend of mine has one in his Nissan and it uses the same connector on it.

interesting. Ill have to see where it goes.

I've seen those connectors for radar detectors, subwoofer or light controls and alarm remote sensors. Other than that I don't know, Good luck!

Most likely a bass control Knob. Opti drive amps from lanzar had a cord like that it ran from a bass ajd Knob back to the amp that allowed u to turn bass up or down on a system

some how i think its subwoofer bass knob like briansmith said before

I would assume since it came out of the visor, it would be for a radar detector that was mounted high on the windshield. If you do not have the other end plugged into the lighter and don't see one around, it may be hard wired in.