I have a 2007 IS250 with Navigation screen. I have a video and audio input on the screen using a aftermarket interface. I've connected a car PC to this video input but i'm trying to find a way to somehow find out which pins at the back of the navigation unit are resposible for the touch response and see if I can somehow tap in to this and make a USB connection to my car PC so that the touch screen can control the car PC. Can anyone help?