The easiest way to do this is to buy a gm aftermarket harness for around 15$. You are going to connect it up to the aftermarket head unit and then to the factory harness. Then you will have to run the power wire from the harness to an accessory fuse and tap into it. The windshield wiper one would work just fine. This way the radio will only come on when the ignition is on. This is how I installed my alpine head unit in my 2005 and my 2008 chevy cobalt. Hope this helps