I WAS HAULING A 15,000 LB FIFTH WHEEL WITH THE CRUISE CONTROL SET AT ABOUT 45MPH COMING UP TO THE LIGHT ON HWY. 35 AND HWY. 20 INTERSECTION NORTHBOUND IN INDIANA. I TAPPED MY FOOT ON THE BREAK TO SHUT MY CRUISE CONTROL OFF LIKE I NORMALLY DO AND PUT MY FOOT ON THE THROTTLE TO CONTROL THE ACCELERATION TO THE LIGHT. I REALIZE I WASN'T SLOWING DOWN PROPERLY AND PUT MY FOOT ON THE BRAKE AND STOOD BOTH FEET ON THE BREAK TO TRY TO STOP TO AVOID HITTING THE CAR IN FRONT OF ME. I ENDED UP HITTING THE CAR IN FRONT OF ME EVEN WITH THE TRUCK AND TRAILER BRAKES APPLIED. THE AIRBAGS DID NOT GO OFF IN EITHER VEHICLE. EVERYTHING WENT SO QUICKLY, DIDN'T KNOW WHY THE TRUCK DIDN'T WANT TO SLOW DOWN. I HAVE HAD NO PROBLEM WITH THE TRUCK OR MY 2018 TRUCK. I BELIEVE THE CRUISE CONTROL NOT SHUTTING OFF WAS THE CAUSE OF THE ACCIDENT. I WOULD LIKE YOU TO COME AND INVESTIGATE IT TO SEE IF THAT WAS THE ISSUE OF THE ACCIDENT. I CAN'T THINK OF ANYTHING ELSE THAT WOULD HAVE CAUSED IT.