white/black is negative
grey/black is positive
white/red is amp turn on
the way I do it is get an rca end (male) and cut it and tap the negative side to the white/black wire and the positive side to the grey/black wire and then plug it inot the sub out from your aftermarket deck. as far as the amp turn on goes; put a 1k ohm resistor inline with it. it will work without that, but you'll get a popping sound everytime it turns on. and this is all the the thrid plug behind the radio. and questions let me know, and GL