The simple fact is that all the newer cars have about 5,000 wires in them, most operating at 12V. To think you can sift through these wires and get the correct ones off the fuse block is nuts.
Furthermore if the plug is already gone and your trying to identify speakers as mentioned you will be there all NIGHT trying to figure out which wires actually go to the same speaker let alone phase.
I hope you can now see some of our frustration and why we are trying to get you to do the easy and smart thing, get the harness!
BuickFreak-
These are good answers. But if you have looked around the person askign the questions did not even know what coninuity is
Lastly for as much credentials as you have and working for RF and all I would think you would be slightly more professional.
This site will remain clean with no mud slinging FYI.