Question

I purchase a wireless backup camera and installed it per the directions to my backup lights on my truck a few weeks ago to use when hooking up my boat. When I used my 5ver for the first time my brake control unit didn't show any numbers but I still seam to have my electric brakes then when I disconnected my 5ver at my site the numbers showed up and every time I hit my truck brake after my truck was disconnected from my 5vr the numbers would go up, like I said earlier the numbers weren't there when I was plugged into my truck but they are now that I'm unhook from my rv, What might be the problem? Thank you for your time.