Xbox 360 RCA (video as well) to mini. xbox wont turn on?

i have installed and xbox in my car in a attempt to connect it to my head unit, a Kenwood DNX6180. Only problem is that i had to put it through 3 way rca (yellow, red and white) to mini but the xbox doesn't seem to recognize the video source so it turns on, but it wont send out a video signal. is there a way to bypass it all or am i just completely off in my diagnosis.