most factory GM HUs are provided by Delco Electronics. as far as loss of sound to all speakers means the HU is shot. if you dont have a warrenty just buy an aftermarket and a wiring harness and a mount bracket and do it yourself. its easy to do. here is the 4 steps to doing it. #1. pull out the metal clip on the factory shift knob and pull up. #2. the plastic base around the shifter comes right up without any prying just grab the edge of the cupholder and pull up. #3. grab at the bottom of the facing around the HVAC\HU piece and start pulling as there are about 8 clips holding that in. #4. take a wratchet set and undo the bolts holding the stock HU in place. the screws will work with a 7mm head. the hu will just slide out and you can easily pull the wiring off the back and unhook the factory antena plug. then with the new HU in a new mount bracket and wiring harness already prewired just reverse these 4 steps. make sure if you have a factory amp but no Class 2 system that you hook up the amp turnon lead from the aftermarket HU wires to the turnon lead on the wiring harness.
