I have a dual brand car monitor stereo tha...

hi there
well to start the e-brake will need to be applied to allow you to see the video if it was installed correctly.................to over ride this feature you need a toggle switch with 3 pins on it
on the toggle switch there should be two logos (power & ground) if you run a small wire from the red wire from the back of your in-dash system to the toggle switch (power) and do the same for the black wire (ground wire)..........the last pin on toggle switch you attach the e-brake wire from the back of your in-dash system to the toggle switch pin and turn it on video will play
if this doesn't work switch the e-brake and ground wire around on the toggle switch
hope this helped