Hi guys,
I have been searching for a while if anyone had a similar problem, but it seems that I am the only one

Basically I installed a backup camera and it seems to only work when I start my brz in reverse gear (when the camera is activated and the headunit can detect it), then it works normaly, whenever i backup. But if I start the car in lets say neutral, the camera dosent work. So I thought that I should wire a 12V impulse to headunit.
Maybe anyone knows where could I find a power source that only lasts a few seconds when starting the car?
Any help is appreciated!