Audio Systems: instalation problem, pioneer deh p7700mp, pioneer radio

Question
hello,
i have just bought a pioneer deh-p7700mp car stereo to
install in my 1999 chrysler lhs. i have wired about 15 stereos in my life so i at least know how to do them. i
wired my harness up and plug it in and the deck will work
everything is fine but i have zero sound out of the
speakers i dont understand why my triple checked my wires
and the are connected right. but as soon as i plug the
factor stereo back in all works fine. does this have
something to do with the infinity amp on my car
speakers(factory installed) i just dont understand if my
connections are right and it lights up and functions right
why it is not putting out any sound. i hope you can help
thank you very much

matthew stier

Answer
use the blue wire from the pioneer radio to turn on the amplifier
sometimes there is a blue wire in the harness if not look on the other side of the factory harness and cut the cable

this will turn on the relay that activates the 4 amplifiers