head uni wiring

ok i need your guys help…i have a clarion head unit i just got from a friend and the only wire that i do not know where it goes is coming out of the headunit and it is brown…all of the other ones match up…it must be important because the unit will not work right now…any idea where the brown wire goes?

EDIT: I WAS WRONG ABOUT THIS, SEE POST BELOW

I’m pretty sure that that is the ground you wire through your wiring harness and then the black wire you actually ground to the chassis.
I’m basing this on assumtion, not tangable fact, but I’m %75 sure.

If I were you I’d wait for a second oppinion

Woops, I was wrong. That is the input for phone mute. So if you have a car phone and it rings, the stereo mutes itself. Hope you didn’t rush out to hook it to a ground. Don’t know why the unit isn’t working, that wire should have nothing to do with it. If you need to double check your work check out the FAQ at Clarion.com I would give you a link, but the site is kind of screwy. You’ll see what I mean.