Vrcd500-sdu color code diagram

You can find the manual for the VRCD500SDU on the VR3 web site: http://roadmasterusa.com/index.php?page=car-stereos#VRCD400SDU

I don't know if it contains a wiring diagram, but installing a head unit is usually easy. Just match up the cables that you are the same color, then use logic and reasoning for the off colored ones. Also I have heard that if you use a 9 volt battery you will hear a pop when the cables are matched correctly, though I would get another source for this.