ground to plus 12v?

So I'm guessing you didn't properly check the signals with a volt meter before running the wire? 

If you find out what the voltage is doing at the head unit you can most likely "fix" the issue with a relay.

Actually, I checked the signal from the PAC green wire to see if it was outputting 12v like it was supposed to. It wasn't. So I just ran the wire back to the back assuming that since the camera powers on with that wire then it will work. I didn't. So, you are half correct Kevin. I did check signal but not on the new wire.

I have actually spoken with a Pioneer support person and the guy was actually really nice. He explained how the unit works first (which was interesting) but then he said to make sure that PURPLE / white wire was getting either positive or negative 12v and then set the HU based on that. So, now I'll give that a try and see what it's doing. He said if it's getting some kind of signal and it still doesn't work then I'd have to send the HU in for service.

Well, I'm not a pro at this stuff so I'm not completely ashamed to admit that it was a user error. One of my connections wasn't crimped well enough. I re-crimped and I finally got a 12v reading. Sure enough, the HU works the way it's supposed to.

I'm not one to give up immediately and blame one part or another so taking the time to look into it and get some help here was very much a learning experience. Thanks for the help!