Joseph Wery

I just got my truck back from the dealership where I had some service work done on the bu camera. When I left I got the above mentioned rear turn signal message for the first time ever before I left their parking lot. When I activate the turn signal it flashes correctly 3 times then starts flashing rapidly while there is nothing happening with the bulbs. I swapped out the bulbs with the left side and still the same thing with the left working fine with the right side bulbs in. I checked the fuses with a dmm and they are fine then I tried disconnecting the batteries (duramax) hoping that would reset something but it didn't. I called the service dept. and asked if the wiring they fixed on the camera would have anything to do with it and he said that it wouldn't and after looking at their fix I can't see how it would. I have checked for loose connections or corrosion or bent pins everywhere....found nothing obvious. Any ideas or suggestions would help, thanks.