View Full Version : 2003 Cadillac STS - Want to install aftermarket radio and subs

06-16-12, 04:27 PM
Hi, I have a 2003 Cadillac Seville STS. I would like to install a Kenwood aftermarket radio and hook up an aftermarket amp with two 12" subs. The factory radio is a BOSE. And I DO want to keep the factory door speakers. I've read many different blogs and forums about this install. I just wanted to ask a few questions.

On the back of the Kenwood HU, it has one set (red and white) of RCA plugins for a sub output. Which I was going to use to plug in the aftermarket amp. Any problems here?

I know I have to have, either a GMOS-06 or PAC-OS2-GM32 module. Which one is better?

I also read that some have had to rewire some things when adding either module. Is this true?

And you have to keep the factory radio somewhere inside the car?

And if adding one of these modules, Will it mess up my remote start?

Thank You very much for your time. Have a nice day.

06-16-12, 06:20 PM
You're gonna hate this reply but I have to ask: Why ruin a rare car ? Your Seville Touring Sedan is one of very few Sevilles built with the Corvette/Ferrari F55 Magnetic Ride Control system. The sound system as-is is perfectly good and a new one won't make the car any faster than it already is.

Do some more homework - this is NOT a cut-and-dried "upgrade". The electrical and electronic gremlins may well come to haunt you.........If the car still operates correctly after installing a remote start (why ?) you're ahead of the game.........

You might want to enter your VIN into the build data site: www.compnine.com (http://www.compnine.com), look at what's in YOUR car, then follow the directions to move the list of RPO features in YOUR car to the "included" box. For comparison, of the 11,440 STS built in 2002, mine is one of 256 identical. Your paint color, sunroof (?), and sound system RPO will give the "rarity" figure - all STS had basically the same trim packages..........and ALL 2003 STS were F55 - our cars were test mules for later cadillac/GM suspension work.

06-16-12, 06:44 PM
Well I thank you for telling me this. Honestly. But I still want to put the aftermarket system in the car. I know its not a easy upgrade, but I want to install it. Let me ask this. Is it possible to KEEP the factory BOSE radio and still be able to add the aftermarket amp and subs??

06-16-12, 07:04 PM
I'm not a car audio guru - they'll be here.........I'm a maintenance and performance gearhead. BUT, the Bose systems use some really weird speaker impedances and drive voltages to several amplifiers. It's not like a good ol' Head unit, sound controls, line out, interconnect, amp(s), speaker cables, and a bunch of Infinity speakers. Bose is a PITA to work on.

06-16-12, 07:22 PM
I am the same! lol. I thank you so much for your help!

06-17-12, 10:43 AM
U can Definitely add aftermarket subs and a amp to your factory Bose system. As long as its installed correctly, It won't mess anything up. I know this from experience, I have my 2002 factory Bose system hooked up to a t1000 with some 10" L7's, & it beats..(10's bc my wife drives this car more then me, i usually drive my 1992 Brougham)

If u add a aftermarket HU, idk. But I believe that's a different story. I know on my friends 2001 he said he had to change out everything bc nothing worked after he put the new HU in. I mean speakers & everything.. But if u find out let me know.. My radio in my 2002 sts has been acting up and not wanting to come on all the time. So I think my HU might be goin bad.. So either I have to get a new factory 1 or do what your planning to do and put a aftermarket in... But it's a big decision. The factory bose Just looks & sounds so beautiful with those 8 speakers

06-17-12, 11:00 AM
I added my mtx audio sledgehammer 8500 12" sub and mtx ported enclosure to my 02 DTS with factory Bose Nav for a while ~a month and while it was really loud and you could see the back seat backrest vibrating / flexing with the bass thanks to caddy you could hardly feel anything in the front buckets. I tried different orientations of the sub and different gain levels but in the end it was not much better in the driver seat than what the factory sub did. In the end it wasn't worth it and if I had purchased the sub specifically for the DTS I would have been disappointed and returned it. But it was just left overs from a previous car that I put a system in. Perhaps I'm getting old but the stock Bose in the caddys is good enough for me. I have the 15 speaker Bose system in my new to me 08 STS and it's doing just fine without adding another sub. That same sub hit really hard and well in the monte Carlo that it's in and did quite well in the cutlass it was in before it was moved to the DTS.

06-17-12, 11:31 AM
15 speaker... Wooooh!!! I'd be kool too lol...
I was thinking bout getting a new to me 2008-2010 caddy too. Or a used sts v.

06-17-12, 11:33 AM
Oops sry didn't mean to press send.. But I would def keep the factory system & just add a sub. I wouldn't replace the HU if I didn't have too. Cadillacs look so luxurious & changing them up can make a beautiful car look horrible

06-17-12, 12:39 PM
Thanks for all the replys! Is anyone here that knows how to add the aftermarket amp and subs to the factory BOSE radio? Any help with this will be greatly appreciated! Thanks.

06-17-12, 05:26 PM
I have a '03 DeVille (with non-Bose), and this January I installed a new Pioneer H/U. I used all the appropriate adapters and retained all steering wheel controls. The H/U had two RCA jacks in the back for a subwoofer - and I spent most of the day yesterday installing a 12" sealed-box sub; running wires (under carpet) to those RCA jacks and then back to trunk (that was a little challenging, had to remove front seat), then splicing into power/neg leads by battery, and I found an ignition source in the fuse box for the amp remote trigger. It all came out very nicely. I have been tweaking and adjusting, trying to find that Goldilocks sound level. I am an old man (60), but I still like some genuine bass (at moderate levels) when listening to music.

As already stated, my DeVille is non-Bose, so I cannot comment on direct wiring for your particular Bose system.

However, I owned/own two cars with Bose systems (a Lincoln Mark VII and a 2004 Corvette Coupe, I still have the Corvette). On both of those vehicles I had the same problem you are having. I DID find a wiring adapter for the Corvette's Bose system, which was designed specifically to allow the addition of a amp and subwoofer. That adapter worked perfectly.

But on the Lincoln Mark VII, there were no adapters available. On that car, I used a method where you simply splice into existing speaker wires and tap off a signal for the amp. That worked beautifully. I would suspect that this MIGHT be an option for you, but of course, do your homework first.

Good luck with your project. I will say that both of my Bose systems sounded MUCH better with the addition of a real subwoofer! :happyhappy:


06-18-12, 12:12 AM
Not much is needed to add a aftermarket sub & woofers to the factory system.. Alls u really need besides uafaik & subs is a scoche amp interface like a fai3a or (whatever brand or model u want)... If I was you I'd take it to someone that knows what they're doing. I paid a friend of mine 50$ to do it, but watching, taking out the back seat and doing the install wasn't too difficult. Everything's in the back so it shouldn't take long. Here in TX, My friend did everything in less then a hr.

06-18-12, 12:14 AM
Sry a few type o's.. Its late... Lol

Factory bose system*

Your subs and amp*

06-18-12, 01:09 PM
So, does anybody have a wiring diagram for the 2003 Cadillac Seville STS Bose sound system? And what wires do I need to splice into? So I can wire the aftermarket amp, into the system. Thank you.

02-06-16, 07:58 PM
I am late with this one Hutu should of done this by now for the car, or for other readers to read this:
The Bose sys is set up with the best speakers out there, nothing and I mean nothing will compaire to the sound and Dolby digital that the speakers makes, they had lowered the sound though for thr 2000 plus models unfortunately and in the 80's they could break windows, gm got to much hate mail and decided to lower the music but keep the sound the same:

Simply just take out the amp, the 2 plug in prones that connect to it, take them out,
There will be a series of wires in the left plug in: u will see 16 wires wrapped by 2 of a total of 8 thoes are your speakers (if u have a 8 speaker sys or 6 times 2 of 12 wires ) and 3 other wires that are 1 of your intermite wire for the bass to radio set: the others wires are your ground and hot and just use them instead of running up your ground and your hot wire, simple job as it's all there, I agree with you on the bass set up, it's not as strong as they was, especially since the 80's and now the 2016's are back and sound amazing like back in the day, hope this helps

Ps- u can use the factory Bose amp to run any front and side speakers and just splice into the same speaker wires for a more amazing sound and clarity to your ride, or keep the same and just run a 400 plus amp to only run your 2-4 base speakers like 10's on up to 15's
Just my 2 cents
I have a Camaro (90) and got your same set up from a sts Seville that mi got from my local yard for a few hundred and speakers from a Denali and not doing nothing dos but Bose with a seperate amp for my kickers 10's and Bose amp for my fronts and reads with tweeters,
Almost done and it will sound clear, crisp and clean music, no just boom boom again best of luck and all readers