I installed a sony head unit in my chevrolet colorado (2005) and I cannot get the stereo to turn on. I used a wiring harness, made all the correct connections and there is just no power. No fuses are blown and the battery was disconnected during all work. The stock radio still has power and works perfectly. I tested the sony head unit straight to the battery of the car and it worked perfectly. Does the Colorado run an obscure voltage to the stereo or possible trouble with the harness? The harness is a metra for GM 98-08. Metra Car Stereo Wire Harness CF-WHGM#.