I have a 2012 Chevy Silverado LTZ with the type B radio system in it. Since buying from a dealership, its had a Kenwood DDX374BT head unit and the factory Bose 1.9 ohm speakers in it. I lost sound output to the front speakers and the pillers. Only the back door speakers are still functional. After weeks of reading and researching the subject, I replaced the door speakers with the same results. I'm lost at this point, Please help.