Hello looking for some help! I have no sound from my factory rear door speakers! Wondering if there was a factory amplifier that im missing somewhere and its bad or just bad speakers? Can anyone tell me if theres an amp and where it is? I checked behind the glove box there was nothing there, Its not a bose audio system and i do have an after market radio that was wired correctly! I was told that all 4 door tahoes had a factory amplifier regardless if it was bose or not HELP!