REAR BRAKES LOCKED UP WHILE DRIVING FIVE TIMES IN THE PAST YEAR, CAUSING THE REAR BRAKE PADS TO SMOKE AND CATCH ON FIRE. CONSUMER REPLACED THE REAR CALIPERS/ROTORS AND MASTER CYLINDER. CONSUMER CALLED GMC, AND WAS TOLD THAT WARRANTY EXPIRED, AND THERE WAS NOTHING THEY COULD DO. EACH TIME THIS HAPPENED CONSUMER WAS IN HEAVY TRAFFIC, AND WAS ALMOST REAR ENDED. *AK