my rear view camera stop working when put in reverse only white lines come a cross.

When reversing from a cold start (sp. backing up from parking spot in the morning), there is an audible groan associated with a vibration that I can feel in the steering wheel. It resolves after cycling the brakes by pressing the peddle down several times. I have taken my care to 2 GMC dealerships now: 1st stated they could not reproduce the problem... 2nd stated that it was most likely due to breaks sticking because of moisture in my break line. The second dealership replaced my brake fluid and said that the issue had been resolved. The issue has not been resolved. Any advice on how to proceed or thoughts on possible causes? Thanks for any help.