I have a 2015 Impala LS, that only the rear driver side speaker plays music. The radio turns on and works, but only for that one speaker. The voice command on the wheel doesnt work either. I've had it looked at and tested all the speakers, and that are all fine just not playing sound form the radio. The place that worked on it switched the amplifier but they said it still didnt work. I tested an external speaker to the pins on the wiring harness coming in form the radio and none of the pairs play sound except for the pins that go to the rear Driver side speaker ( the only one that play sound). So it seem like the radio isnt sending the outputs to the amplifier to have the other speakers play sound also. The balance in the setting is fine and in the middle. Is this a possible issue? And is it reasonable to fix? Why would the radio only be sending outputs for one spearker?

 

maybe it's fried

 

Question, have you tried to pull the fuses for the amp and radio, wait a few minutes, put them back in and try again? While at it, make sure they are all good.