I just installed an aftermarket head unit in my 2001 Z3 coupe which has the Harman Kardon system, and everything works 100% (radio, CD player, blue tooth, front and rear speakers), except for the subwoofer. I can adjust the fader all the way to the rear, and the rear speakers work, but again, no subwoofer.


Is there special wiring that needs to be hooked up for the subwoofer to work, or does it just get its signal from the other speaker lines? I'm pretty sure I avoided the common issue of hooking up the antenna wiring incorrectly, because everything works when I use an audio source other than the radio...except for the subwoofer. Thoughts?


The head unit is a Pioneer DEH-X8700BH, and I used a Metra 70-8590 Radio Wiring Harness.


While researching, I was under the impression that I would have to wire the speakers to the RCA outputs on the back of the new head unit, because it seemed like that signal needed to be line level. However, I found this thread:


http://www.bimmerforums.com/forum/sh...rca+line+level


Which suggested that you can just wire the speakers to the speaker outputs on the head unit. This is how I wired it up, and the speakers sound normal and don't sound like the signal is clipping or anything. I'm not sure if this is of any relevance, so I figured I'd add it.

Thoughts? Thanks in advance for any help.

- - - Updated - - -

Another potential source of the problem could be the extra plug that's underneath the main plug that goes to the stock head unit. There's the big main plug, and under it is a small white plug. That now has nothing going to it. Maybe that's the feed to the subwoofer?