Put in an aftermarket head unit (OGM1) and back up camera in a 2012 Sierra around 2013/14, and the back up system has worked fine since then.
A couple months ago, the monitor started showing intermittent anomalies such as horizontal coloured lines, interference-like stuff and darkens more than usual at night, when the vehicle was backing up. It has progressively got worse to the point where it is sometimes difficult to make out what it is supposed to be showing on the screen. Other times it works OK, but not perfect.
In other modes, radio etc and GPS map, the screen is fine and is as good as when installed.
My question is:
Is there a relatively easy way to diagnose the system to see whether the issue is in the camera, the connecting wiring or somewhere else in the system? Although I installed the entire system, myself (with good installation instructions), I know pretty well nothing about electrical systems, so wouldn't even know where to start.
As I don't want to take a chance and buy/install a new camera and harness, just to find out it is not the camera, I'm wondering how to diagnose the problem.
Looking for any advice,
Marv