2018 GMC Canyon Exterior Lighting

Backup lights are not working; bulbs are good. No apparent chafing/wear on wiring harness. Removed ground strap, cleaned and reattached. Still not working. 48,000 miles on 2018 GMC Canyon SLT, diesel engine.

AT NIGHT, THE BACK-UP CAMERA DISPLAY ON THE DASH IS SO BRIGHT, IT LIGHTS UP THE WHOLE CAB AND THIS CAUSES THE DRIVER NOT TO BE ABLE TO SEE ANYTHING OUTSIDE THE CAB OR AROUND THE VEHICLE WHEN REVERSING. I ALMOST BACKED OVER MY WIFE BECAUSE I COULD NOT SEE HER BECAUSE OF THE BRIGHTNESS. THERE IS NO WAY TO ADJUST THE BRIGHTNESS WHEN IT IS IN REVERSE AND IN THE DARK YOU CAN NOT SEE MUCH IN THE SCREEN BECAUSE OF THE BRIGHTNESS. I TOOK IT TO THE DEALER AND HE SAID THEY HAVE SEEN THIS PROBLEM ON THE FULL SIZED TRUCKS BUT NOT THE MID-SIZED AND HE SAID IT WAS IN WORKING CONDITION. I FEEL THIS IS VERY DANGEROUS IF YOU CAN'T SEE WHEN YOU ARE REVERSING.