I just bought an 05 S2000 and I only have one working speaker. It is one in the head rest behind the driver. Now its not the speakers, I plugged them into the working connection and they worked fine. The speakers are Focal speakers and the head unit is an alpine CDA-9853. I can't get behind the head unit until I find some bracket keys. I am unfamiliar with the wiring of the car and I can not seem to find an amp. Does anyone have any suggestions on what could possible be the issue with my stereo? I will provide more information upon request to further identify the source of the problem. Thank you in advance.

 

What do you mean "working connection?" The leads that connect AT the working headrest speaker?

If so, the next step I'd recommend (when you get the head unit out) is to verify connectivity between the wiring harness at the back of the head unit and the individual speaker connections.