This is for my 04 Forester XT, but I suspect the same thing may be found in other Subarus too.

I bought the car used recently and one of the selling points was the premium sound with an optional factory sub in one of the "stuff compartments" back by the rear hatch.
The factory head unit (in-dash cd changer) wasn't cutting it for me because I wanted a head with a line-in for my MP3 player. So I got an inexpensive Aiwa with a line in jack on the front. It's very convenient and does fine for me except one thing.

When I swapped the heads, I had one plug left over that nowhere to plug into on the new head or wiring harness. Also, that sub doesn't work, so it seems likely that extra wire (that plugged directly into the old head) goes to the sub (plug has eight contacts). The new head unit has preamp outs, so if the sub is powered or has an amp somewhere (nothing under tha passenger seat though) then it seems these outs could feed that sub.

I bought the stuff from Crutchfield thinking they'd know all of this kind of stuff, but they don't. I took photos and sent them in but no joy. So I need to figure it out myself. Hopefully one of you has already done this and can help.

I also went to take apart the sub enclosure to get a look at it, but I can't get the rear trim panels out. There's these plastic rivet looking things that don't release like the dash clips and I'm afraid I'll break them. Anyone know how to get those unhooked? My dealer is 1.5 hours away, so I'd really like to not break anything in the course of this project. Any info or ideas would be appreciated!

Matt

 

I have a 04 Forester and the factory subwoofer is under the passengers seat.

 

Interesting. Which Forester is it? There's nothing under my passenger seat, and definitely an extra speaker in the back. Mine's an XT.

I seem to have some kind of weird version.