My buddys 02 with non bose system has no audio on the right side front and back the entire time in CD or FM. I checked the balance and its on 0 I put it on R5 which is all the way right side and I get nothing. I swapped the right speaker to the left side and it works. So speakers are good. Whats the problem?

 

The head unit or the wiring to the speaker.

If you had a Bose unit, it would be a 99.9% chance it was the head unit. I suppose non-Bose could be the same. Check the wire continuity before replacing the head unit.

 

It was the actual head unit, replaced with a 2001 headunit for cheap it was plug and play even the steering controls work.