Working on 07/97 toyota tacoma radio swap

Yes but the connection at the back of the radio is bad and cut in and out all the time that's why I decided to change it. Now I even have a subwoofer wired in that's real simple wiring, and I'm not getting any output to the sub either. I figured the sub would at least kick if there was a power differentiation headed out. And I'm connecting these directly to the radio receiver wiring. Next thing is too take door panels off and completely rerun the speaker wiring maybe there's a bad ground somewhere where does the brown ground lead to? And I keep seeing this thing about reverse positive. But I have no idea which wires of mine are the reverse positive.