Problem With Bose System Only The Sub Works

[Z71 Kris]

Hey a friend has a 04 siverado and his factory bose sub is the only speaker working right now, we tested the head unit in my truck and it worked fine(weird that it worked and did not lock, I know) we had highs and lows, we even swapped out bose amps and had the same results. Any ideas?
Does anybody have a complete wiring diagram of the audio system, before and after the bose amp?