Special wiring harness for aftermarket stereo for newer gp

**MattTheBaker123** · 12-26-2009

So i got a new stereo for my 2004 grand prix for christmas and it turns out i bought the wrong wiring harness for it and i cant find one anywhere. My friend tells me the newer gm cars need a special harness. Does anyone know where i can get one online for grand prixs 04 and up?
Thanks.

**I800C0LLECT** · 12-26-2009

Axxess GMOS-01 - Car data bus interface

There's cheaper ones that utilize an internal speaker vs. integrating w/your factory speakers but I can never find it online. I grabbed one from a local audio shop for ~$25

**offroadfury6** · 12-27-2009

its a bia....I bought one it was $120 bucks...and still didnt work right...had to tweak with it, man...the chime one and non-chime are uselss...they couldn't have made this part any harder.

**MattTheBaker123** · 12-29-2009

Originally Posted by I800C0LLECT

Axxess GMOS-01 - Car data bus interface

There's cheaper ones that utilize an internal speaker vs. integrating w/your factory speakers but I can never find it online. I grabbed one from a local audio shop for ~$25

So when it says its supported for a non amplified gm vehicle what does that mean?

**I800C0LLECT** · 12-29-2009

That means it is designed to be inline between the head unit and the speakers. Monsoon setups employ an amplifier. Therefore, instead of being placed inline w/wires, it uses RCA's.

The link I provided pointed towards a GMOS-01 w/o RCA's.

**GP04GT2** · 12-31-2009

Originally Posted by MattTheBaker123

So i got a new stereo for my 2004 grand prix for christmas and it turns out i bought the wrong wiring harness for it and i cant find one anywhere. My friend tells me the newer gm cars need a special harness. Does anyone know where i can get one online for grand prixs 04 and up?
Thanks.

I read all kinds of bad reviews about these harnesses, so I picked up a GMOS-04 at Best Buy for $99 cuz I wanted to be able to exchange it if it was defective. Turned out it was just fine - lots of wires to fuss with, but no cutting/splicing of my factory wires needed. I also got the PAC SWI-JACK (~$40 at Amazon) to keep the steering wheel controls working.

@I800COLLECT got it right - if you have a Monsoon system and want to keep using the amp, then get the GMOS-04. If your new radio doesn't have two sets of pre-outs, you'll need line converters as well since it does use RCAs. If you don't have a factory amp, then get the GMOS-01 - but if you use this harness with a factory amp, I'm pretty sure you'll be sending an already-amplified signal to the amp - not a good thing. The GMOS does require some tweaking, but once you get it right you'll still have the chimes that ding when your fuel is low - I'd run out of gas if I didn't have that.