I have quite a few toys installed on my 8500 and everything is working.  The last thing on my list is a front-facing camera.  I tried the camera by plugging in the yellow RCA cable and then giving it 12v power by attaching the red to positive and black to negative on a 12v car battery just to make sure it works before I wire it.  I did not connect the trigger wire by the rca plug.  To make the camera work, does this have to be plugged into the Accessory power (red wire on harness)?  I have added the video input setting on the head unit and changed the settings to allow for the 2nd camera, but the camera isn't working when I just connect the red/black wire to the battery.  Before I start splicing wires, I'm wondering if I have to tie the trigger wire into a 12v source.  Does anyone know?