Help me find backup camera wiring!

[sasq40]

So I've had a long go with the truck trying to get my stupid backup camera.hasn't really worked since I bought the truck.I have a 2017 gmc 3500 denali drw, and about 90% of the time i get the blue service camera system error. I had the intellihaul system installed when i bought the truck from a different dealer(5 hrs away) so my local dealer won't work on my truck to fix the camera. I've been back to the original dealer 5 hrs away 3 times now and the system still doesn't work. I removed the intellihaul system because I know it's not the issue to try and get my local dealer to work on the truck but of course the camera system was working for the time it was at the dealer so they charged me 100$ to say nothing wrong. I get home and of course, the camera isn't working. I'm sure its a wiring issue since the dealer 5hrs away has apparently replaced the camera, hmi module, and the factory screen. Since there so useless I want to try to make my own wiring harness for the camera so does anyone know what plug and wires are for the camera at the hmi module and which wire are the camera wires in the plug near the tailgate? Thanks I'm about to burn this stupid truck