I've just started upgrading my 88 GT's sound system and installed the Pontiac CD/Radio with 7-band EQ often used, including the aftermarket wiring adapter (and splicing the Blue & Red wires per several excellent threads.) I was happy to find that the 4 main speakers were already upgraded and the CD sounds great!

The code label indicates a stock sound system (UM6) rather than the premium (UQ6), however the premium courtesy unit w/slider is installed. There is no subwoofer enclosure but in digging behind the radio I discovered what appear to be the amplifier connector and subwoofer speaker wire (see below).



If that is correct then I believe a previous owner started installing the premium system and already has done the wiring harness. That would lead me to conclude that I have to buy:

1-Subwoofer enclosure
2-Subwoofer replacement speaker (Rodney)
3-Amplifier

Is there anything else I have missed? Once I am sure what I need I'll make a WTB post in The Mall.

Sounds about right. See diagrams here:
https://www.fiero.nl/cgi-bin...orum=2&thread=139561

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My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

Back from a trip and can now work on this install again, all parts are in hand. Well, except I noticed I have the Light Blue/Black trace and Dark Blue/White trace wire but not the pigtail going into the sub unit itself. Posted below is another member's wiring diagram showing the speakers as 'A' which is '-' and 'B' which is '+' hence, the positive terminal of Rodney's new subwoofer goes to the Dark Blue/White wire (i.e. B). Reposting the diagram here in case someone else needs to find it.

quote Originally posted by Notorio: I've just started upgrading my 88 GT's sound system and installed the Pontiac CD/Radio with 7-band EQ often used, including the aftermarket wiring adapter (and splicing the Blue & Red wires per several excellent threads.) I was happy to find that the 4 main speakers were already upgraded and the CD sounds great! The code label indicates a stock sound system (UM6) rather than the premium (UQ6), however the premium courtesy unit w/slider is installed. There is no subwoofer enclosure but in digging behind the radio I discovered what appear to be the amplifier connector and subwoofer speaker wire (see below). If that is correct then I believe a previous owner started installing the premium system and already has done the wiring harness. That would lead me to conclude that I have to buy: 1-Subwoofer enclosure 2-Subwoofer replacement speaker (Rodney) 3-Amplifier Is there anything else I have missed? Once I am sure what I need I'll make a WTB post in The Mall.

I've got number 1 and 2 sitting around. Perhaps even number 3. Might be a bit much to ship, but PM me and we can work something out. Just collecting dust here..

Thank you for checking GodSend but I just finished the job and am loving the results!

On a general note for the installation, various posts recommended confirming speaker polarity with a low-voltage battery, which I did with an old C cell reading about 1 volt. Good thing too, I found the front-left speaker had the polarity reversed.

quote Originally posted by Notorio: Thank you for checking GodSend but I just finished the job and am loving the results! On a general note for the installation, various posts recommended confirming speaker polarity with a low-voltage battery, which I did with an old C cell reading about 1 volt. Good thing too, I found the front-left speaker had the polarity reversed.

How is this accomplished with the battery?

I hooked up the leads I borrowed from my multi-meter which have an alligator clip on one end --these were connected to the terminals on the speaker. Then very briefly I touched the battery connections and watched the movement of the speaker cone. If the cone moved 'outward' that indicated the + on the battery was connected to the + on the battery. The speaker from Rodney was already labeled with the polarity so I just confirmed that. The existing Pioneer speakers did not so I checked those and then labeled them for future owners. The pioneers had different sized connections for the + and - so once you confirm the polarity you can't hook them up wrong at some future time (I like that system.)