Been doing some research on the GMLAN data bus system, but can't seem to find a direct answer. I purchased an aftermarket stereo and $5 wiring harness to install in my 06 Silverado. While I was reading about the wiring I came across the device known as the GMLAN data bus system. What exactly does this GMLAN do, where is it located and what functions will I lose by removing my factory radio? My truck doesn't have OnStar or the Bose audio system.