im guessing you just want to add a dvd player to the radio? thats all well and good.. but your gunna need more than just +12V/ground.. you need audio and video outputs as well.. you wanna hear/see it dont you? ther should most likely be rca's out of the back of the player.. one red, one white, and one yellow??
Also.. you have 4 red and 4 black wires comming off the dvd player? thats wierd.. your going to have to be more specific if you want us to help
