Hello, I own a 2006 G6 GT with the 3.5L V6, sitting at about 135k. Also has the Monsoon sound system. Joined because I am trying to install an aftermarket radio, the harness says it's supposed to match, matched all the wires, have power, but no sound. Trying to test everything and getting no luck, even plugged the old radio back in and sound works then. Any ideas?