Please help with 12v accessory...

Can anyone please give me some advice a dead 12v accessory wire? I
bought my 95 civic used and it came with a garbage radio, but it worked and now I dont know how. When I tried to install mine, I couldn't get it live. My volt meter reads around 3 volts. This is my first problem with
this wire and I'm clueless. Did I miss something?
For now I ran both wires (12v constant and 12v acc.) and it works. My receiver can be manually shut off so I haven't had a problem. This isn't
dangerous is it?
I'm installing my real stereo soon and I dont want the ghetto install on it.
Is there any solution to this problem. Any help is appreciated.first post.

just run 2 wires for the constant and accesories. theres no problem with running 2 wires in the back, its not ghetto, its stock.

the only place i could see to start, is to trace the wire back until you see your voltage rise to the expected 12v. there is a drain on it coming from somewhere, and you need to find out where. other than that, if you found a way that works, live with it until you can find a better way of solving the problem.