i dont know if you already got the answers you were looking for but............the third projector is definately for the the turn signal light. and the wires on the back are for the halo lights that light around the other two projector lights. the way you want to set them up is............first the some of the insullation from your turn signal wire............then wrap the wires (the ones coming out of the housing that are shown in the picture above) wrap those wires around the turn signal wire where you cut off some of the insullation. then wrap electrical tape around it. what is going to happen is that when you turn on your turn signal light, only your turn signal lights, the halo around the projector lights will light up. and it will have that BMW look to it