That Sob

i just installed a new sony xav-a1 flip out tv head unit. i connected all the appropriate parts for the speakers and power ground etc. the light green wire comming fron the harness is supposed to go to the parking break. i m trying to override that so i can have dvd's playing when car is parked AND in motion. i tried to just ground it but its not playing the dvd's. it says picture off for you safety. anyone know how to fix this problem???? where i can run the wire that suppossed to go to the parking brake so i can play dvd anytime??? all the wires except 2 are being used from the cars radio harness ..there are 2 black and reddish wires i think..(not sure what they are there for) ...other than that everything is connected and the cd player works and all...thanks