I am starting this because I have been racking my brain to come out with an answer for the best harness to use for an aftermarket head unit install. I already have the GMOS-04 installed but I'm not getting very good sound out of it. I would just like to know what everyone else is using and how it's working for them? (I'm not talking about relocating the factory head unit to the trunk only aftermarket harnesses) PAC,Metra ect.?

 

I went with PAC when I did mine. I didn't stay with the factory amp long either, but everything worked and sounded fine for me.

 

Here I am up early/late again. Which PAC did you use? The OS2-Bose Or Just the OS2? Do you have the warning chimes? Another thing the OS2-Bose say that you cannot fade the radio when its installed?

http://www.pac-audio.com/productSear...2002&YearId=13

 

It's been a while, but I'm almost positive that I used this one. Mine was an older version apparently, because the module doesn't look like the one in the picture. I can't imagine much was changed though.

http://www.pac-audio.com/productDeta...&CategoryID=26

What the OS-2Bose description is saying is that you'll only be using two of the aftermarket head unit's outputs instead of all four, so your front and rear speakers will be playing the same thing (I think). Therefore, you won't be able to adjust front-rear differently, you'll only have left-right adjustments.

 

So your interface has RCA's that plug into the head unit? Mine work the same way with RCA's into the head unit on the GMOS-04. I might have to try one of the new PAC interfaces and see how it goes.

Anyone else have any luck or ideas with other interfaces?

 

I'll have to edit my post to let you know which one I have exactly.. but I was getting very poor sound as well. I read somewhere that if you get a factory amp bypass or something similar it will be like night and day with the sound.

 

I have been researching this and getting nowhere fast. The 4 interfaces I have come up with are:

PAC-

OS-2-Does not have RCA's but may or may not need chime module.
OS-2 BOSE- Does not have RCA's but may or may not need chime module.

Metra/Axxess-

GMOS-04- Has RCA's integrated chime module and Onstar.
GMOS-01- No RCA's integrated chime module and Onstar.

I currently have the GMOS-04 and it sounds like junk. With my Alpine deck it cut the volume level in half compared to the stock radio. I was looking at the amp bypass but I don't think you would get as much power from just the head unit as you would from the stock amp. The thing that suck is I have looked all over the forum and nobody has any posts about using other interfaces. I don't want to keep shelling out $80-100 to check to see if any of the other interfaces work.

 

I got the half sound as well using a "peripheral GMCO"

another thing I was reading is you can run wires directly from your deck to the factory speakers.

 

maby a dumb question but did u turn the **** on the side of the gmos its the amp gain level a may be what ur lookin for the one on the bottom is for door chimes

 

to turn the **** u will need a small phillips and its the small hole i think on th left side. turn it to the rite, i was havin the same problem with sound till i turned it up now its sounds good(better then stock)