I may have the solution to changing out the headunit and using the stock amp. I have an '04 Pac with amplified stereo no subwoofer.

Question is: RAH radio - what is the 2nd harness that goes into the back for? I have the antenna plug and two harnesses that plug in. No cd changer. I have navigation, memory seats/mirrors.

As soon as I have this info, I'll be able to share what I have come across!!!

 

cd changer harness.

 

I don't have a CD changer. Therefore it can't be a CD changer harness.
I'm thinking it's the navigation harness for voice or something of that nature.

But anyway metra now has the harness that will allow you to use your factory amp with an aftermarket radio

CHTO-02 and yes it will work in a 2004.

Thanks