I WAS FOLLOWING MY DAUGHTER WHO WAS EXITING THE GAS STATION AND PULLING OUT ONTO ROUTE 149. AS SHE PULLED UP TO ROUTE 149 SHE STOPPED TO CHECK TRAFFIC. I WAS BEHIND HER IN MY 2015 GMC SIERRA 1500, GOING APPROX. 2 MPH. WHEN I HIT THE BRAKES, NOTHING HAPPENED. THE TRUCK KEPT MOVING FORWARD AND I HIT THE REAR OF MY DAUGHTERS CAR, CRACKING THE REAR BUMPER. NO DAMAGE TO THE TRUCK BECAUSE I WAS ONLY GOING A COUPLE MPH, LUCKILY MY DAUGHTER HAD HER FOOT ON THE BREAK OF HER CAR, OTHERWISE I WOULD HAVE PUSHED HER RIGHT INTO ONCOMING TRAFFIC. THE FACT THAT SHE HAD HER FOOT ON THE BRAKE IS WHAT STOPPED MY TRUCK. WE BOTH BACKED UP AND GOT OUT OF THE INTERSECTION, WHEN BACKING UP THE BRAKES WORKED FINE. THERE WASN'T A SPOT TO LEAVE THE TRUCK SO I HAD TO DRIVE 3 MILES BACK TO MY HOUSE. THE BRAKES WORKED PERFECTLY AFTER, NO ISSUES WHAT SO EVER. IT SEEMED LIKE AT THE SLOW SPEED THAT BRAKES DIDN'T HAVE ANY BOOST (OR PRESSURE), THE PEDAL WAS VERY VERY STIFF, IT FELT LIKE IT WAS PUSHING BACK AGAINST ME WHEN I HIT THE REAR OF MY DAUGHTERS CAR. BUT DRIVING HOME EVERYTHING WORKED PERFECT. I'M BRINGING THE TRUCK IN (APPROX. 72K MILES) TO HAVE IT LOOKED AT BUT I'M CONCERNED THE DEALER WILL NOT KNOW WHAT TO FIX AS THE ISSUE SEEMS TO BE INTERMITTENT. THIS WAS A VERY DANGEROUS INTERSECTION AND I COULD HAVE PUSHED MY DAUGHTER INTO ONCOMING TRAFFIC AND THE RESULT WOULD HAVE BEEN MUCH MUCH WORSE. SOMETHING SEEMS TO BE SERIOUSLY WRONG WITH THE BRAKES AND WHEN GOOGLING THIS ISSUE, I FOUND MANY