I'm just trying to get a cheap HU installed with the factory speakers. I'm confused because there are 2 sets of pink and blue wires in the factory harness. One pair goes to the right rear speaker and pink is neg. The other pair goes to front left speaker and blue is neg. How can I tell which one goes where? Also on my new HU, there is no 'amp on' wire. (light green/red stripe) on the factory harness. How do I get that to work? Obviously I'm noob at this. lol Thanks