you can catch a remote wire from you ignition harness (steering column). The radio power wire in the back of the head unit is a weird setup through the GM Lan system.
The yellow wire however (i think its yellow, check me on that), but it is the "illumination" wire. What I did was attached my remote wire to this. It sounds weird, but fits my purposes very well. When I am driving around for work, or have people in my car, I typically do NOT want the extra bass, but at night, I almost always want the bass. Well, when the headlights come on, the amp automatically comes on. Basically, the amp is controlled by the light sensor on top of the dash. If I Do want to listen with the amp during the day, I can just turn the fog lights on, or switch the headlights to the on position. I prefer to do the fog lights, because they just turn off when I shut the car off, as opposed to having to switching the headlights back off. I also put a switch in the bottom of my center console, which I can turn the remote wire off completely, so that no matter what my lights are doing, the amp will not be on...
Anyway, if your looking for just a standard setup, you have to go into the ignition harness in the steering column, I believe.
