I have it coming from the amp but I don't know where to plug it in the head unit. I have the RCA cords plugged in. Ive read that im supposed to plug it into the blue one but theres three blue cords. I have an Alpine deck also

 

we usually hook the blue from the deck harness, blue white from the factory harness, and remote wire all together. blue white is for power antenna, which doesnt matter since our trucks dont have them, but we still wire them all together as habit.

 

Blue/White - Remote wire

Blue - Power Antenna.

You had that backwards.