I had the factory unit in my 95 Civic, no sound going to the speakers, except occassionally when I hit a bump. From some of the posts I read, I thought it could be the head unit and wanted a new one any way. So after replacing the head unit (with KenwoodKDC-528)I have the same problem. I then continued to remove speakers one at a time to see if it was grounded. (Do I need to remove the factory hookups for the speakers--those little clamps to make sure there is no connection to anything? I didn't) What should I do next?

 

If it works when you hit a bump you have loose wires
just check everywhere possible this may be the issue
or as stated, one of the wires may have come loose, or are bare, and are touching the metal of your car
if the speaker wires touch metal, your head unit will not put out sound
so either you have loose connections somewhere, or somewhere your speaker wires are grounding
i say it's the latter

 

a easy way to tell were your problem is to take a meter and do a continuity to ground check on your speaker leads behind the deck.... this way you know which run has the short in it