2000 accord speaker wiring

I recently purchased a 2000 accord and from the start the dealer had to give me a new radio b/c no sound was coming from the original one.  Now only two of the speakers have sound coming from them.  I asked my mechanic to simply check and see if the speakers work, and he said all of them work.  I've tried finding an extensive wiring diagram that shows where the wires run from the harness to the speakers (b/c I do not know if the problem lies somewhere there (perhaps a wire is pinched or something)).  Chilton was no help, and I would rather not spend 60$ on a Honda ETM.  I do not have an owner's manual either as I bought the car used.  I was wondering where to look to fix the wiring so that I can get my front right and rear left speakers as well as the in-dash tweeters working again.

I also bought and installed a Kenwood CD/MP3 player, it did the same thing with only two of the speakers working, but then all of the sudden gave out and has no sound emitting from the system (although it does get power and the illumination and everything else works).  I checked my wiring and everything is right, I took a voltmeter to it and all of them are properly connected.  I put back the old radio and it has sound on the two speakers.  But when I put the Kenwood back in, I get no sound again.  Can someone help?  I have no clue anymore what I'm doing... or where the problem could be.