Scott, This is the thread covering my Macintosh->double din facia etc.
viewtopic.php?f=22&t=7702&hilit=svxdcCheck out the data there, and svxdc'slinks to other stuff that might help with pin outs. svxdc provided a cable suitable to plug into white plug in the dash, and to mate with the speaker connector down under the pax seat, and all worked flawlessly. He also provided the bits to allow my HU's sub woofer out to be connected to an amp (and for the power to such an amp), and then fed to sub when I get to it.
This may help - I think its the speaker connector under the seat...
18 pin connector,numbered 1-8 top, 2 dead key places in centre. bottom row numbered 9-18.places 4,12,13,14 vacant
1 and 9 RB +12V (red-black?)
2 V Front right + (violet?)
3 P front left + (purple?)
5 V Sub + (violet?)
6 LG Right rear + (light gray or green?)
7 Or rear left + (orange?)
8 and 18 Ground
10 W front right - (white?)
11 W front left -
15 W Sub -
16 W right rear -
17 W rear left -
as in
1 2 3 4 # # 5 6 7 8
9 10 11 12 13 14 15 16 17 18
When you draw this out you will find + and - in vertical pairs - ie 2&10,3&11.etc. Since you only want speakers connected, make sure you dont have anything to feed the +12V out to where it could come to harm(ie short). You can verify your view of the connector is correct by getting a dry cell with a couple of wires , and flashing them across a pair like 2 and 10, and you should hear static noise from the speaker.
I found I had to remove the pax seat to enable me to run the said speaker cable under the tunnel cover and then down to the speaker connector removed from the Mac output - its a pretty tight fit, and unmanageable with the seat in place, and the plug on the end of the cable. It might be doable if the plug was NOT on the cable end, but I wasnt going to dismantle it to find out, quicker just to pull the seat - 4 bolts and a couple of electrical plugs.
jp 08 gtb 6mt wagon.
PS - 'hth' is Hope that helps'