Hi Everyone.
I just bought my first Grand Prix (2004 GTP), and I'm curious about doing a stereo install. I've done stereo installs myself on previous vehicles that I've owned, but when I discovered everything that comes into play on an 04 GTP, I was actually overwhelemed. So here's the deal. I want to remove the stock CD player and replace it with a Pioneer SPH-DA120 (with Apple CarPlay and all that fancy crap). After doing my research, It is to my understanding that it fits in my vehicle. My main concern is, since my vehicle has both a Monsoon system, and OnStar, do I absolutely NEED to get a special wiring harness? I understand that if I get a normal harness, I will lose OnStar (Which I am more than completely fine with). But will I need to get a special harness just because of the sole fact that I have a Monsoon system? And If so, does that special harness need to be the one that retains OnStar and all of that? I was a bit confused when I saw the stock headunit has two ports in the back, whereas my new headunit only has one. Do I just let the black one hang there? I also have the PAC steering wheel control adapter to retain steering wheel functions (if that's even possible). Sorry about the lengthy post. This is my first time posting on a car forum.
