2014 GMC Terrain Driver Assist & ADAS Problems

"SERVICE SIDE DETECTION SYSTEM" WARNING UPON STARTUP AND SPORADICALLY WHEN DRIVING AT NORMAL SPEEDS. THE BLIND SPOT MONITOR LIGHTS IN THE SIDE MIRRORS DO NOT FUNCTION ANYMORE. UPON STARTING THE VEHICLE, BOTH SIDES USED TO ILLUMINATE WHILE RUNNING THRU SYSTEMS CHECK. NOW ONLY THE DRIVER'S SIDE LIGHTS UP. TO CONFIRM, THE BLIND SPOT MONITORING DOES NOT WORK FOR EITHER SIDE OF THE VEHICLE NOW. THE SENSOR IS UNDERNEATH THE REAR BUMPER COVER, EXPOSED TO THE ELEMENTS. THERE ARE SEVERAL FORUMS MENTIONING THIS ON THE GMC TERRAIN DENALI MODEL ALONG WITH CADILLAC AND CHEVROLET MODELS THAT HAVE THE SENSOR IN THE SAME PHYSICAL LOCATION OF THE CAR. THE SENSOR IS EXPOSED TO RAIN, SNOW, DIRT, DUST, MUD. I HAVE CHECKED RECALLS ON THIS BUT IT DOESN'T APPEAR TO HAVE ANY OUT THERE DESPITE FORUM COMPLAINTS. THERE SEEMS TO HAVE BEEN "SERVICE BULLETINS" SENT OUT FOR CADILLAC AND CHEVROLET MODELS DUE TO CUSTOMERS COMPLAINING ABOUT THIS SAME ISSUE. THOSE HAVE BEEN REPLACED AT NO COST TO THE CONSUMER FROM WHAT I UNDERSTAND. AFTER DOING SOME RESEARCH, TYPICAL COST FOR THIS PIECE DIRECT FROM ONLINE SELLERS IS $250+. TO HAVE THE DEALER REPLACE, IT'S LOOKING AT A COST UPWARDS OF $750+. THE NUMBER OF TERRAIN DENALI (THE ONLY TERRAIN TRIM WITH THE SIDE BLIND ZONE ALERT) ARE RELATIVELY LOW COMPARED WITH THE QUANTITY OF THE CADILLAC AND CHEVROLET MODELS WITH THIS ISSUE. I'M WONDERING IF THIS IS POSSIBLY WHY THERE WERE NO "SERVICE BULLETINS" ON THE TERRAIN. THE TERRAIN HAS A HORRIBLE BLIND SPOT AND I UTILIZED THIS FEATURE ALL THE TIME WHEN IT WAS WORKING PROPERLY. I FEEL LIKE SAFETY IS COMPROMISED FOR MYSELF AND MY FAMILY WITH THIS NOW NOT WORKING. I APPRECIATE ANY AND ALL ASSISTANCE.