I Need Help

[raulssilvermustang]

I have a 2002 mustang gt w/ the mach sound system im trying to install myself a amp and subwoofers. the problem is that eveything turns on and i get the voltage on the amplifier and i also installed a capacitor and i get very nominal sound but i swapped the amp ino another car and it works perfectly in the other but in my stang i cant get any loud voice please help me can someone show me the stereo wiring harness colors and which one is what or the diagram in a website thanx