Here's GM's general speaker wiring colors are as follow
Driver's Front (+) Tan (-) Gray

Passenger Front (+) L Green (-) D Green

Driver's Rear (+) Brown (-) Yellow

Passenger Rear (+) D Blue (-) L Blue



...Ox

Is this from the main plug on the back of the factory radio. I have an Infinity Bass-Link T to install and might help with the intall.
Mark