head unit wiring

I've got a '99 grand am se with an AC Delco CD player in it. None of the holes in the back are labeled so how do I know if the wires from each speaker are going in to the right place? I ask because one of my speakers isn't puting out any sound at all but looks as if it's plugged in correctly and everything. I checked the insulation and it doesn't look like the wire is shorted or anything so it must just be plugged in wrong.

I'm also puting in a new head unit soon so how will I know what wires go to what speakers (without taking off door panels and looking manually) and how do I know what holes to put the wires into on the new head unit? The head unit I'm getting is going to be used so it won't have any documentation with it.

It's my first time with this kind of thing. So any advice or resources would be great.

Thanks,
Aaron

what kind of CD player are you going to get ?

I'm not sure what kind it is. I'm getting it from my buddy when he replaces his in a couple of weeks. I can find out tomorrow or something.

Still, regardless of what player I get how do I find out what holes I'm supposed to put the speaker wires into on my current CD player? I'd like to get it working until I get the new one.

the place I used to go is a pay-per-view site now, see if the guys in the Pontiac forum know the wiring code.

Since the car is a '99, could be the speaker is just blown or the wire is disconnected at the speaker.