4runner Stereo issues

So I recently installed subwoofers in my 4runner. The rear speakers hadn’t worked at all under my ownership, and when installing my amp remote turn on wire to my stereo harness I noticed the blue wires (power antenna wires?) were already disconnected, meaning the old owners had subs in the car before. Connected those wires with the turn on wire, still nothing from the rear speakers. Can someone who’s experienced with stereos give me some tips? Do I use that blue wire that loops back into the harness? Any help appreciated thanks