ON 12 JULY 2018 AT 0530 AM I WAS DRIVING DOWN COUNTY ROAD 26 MANKATO MN TO PICKUP MY SEMI AS I WAS APROACHING 3RD AVE STOP SIGN I APPLIED THE BRAKES PEDAL WENT TO FLOOR I WENT THROUGH INTERSECTION SLAMMED INTO A BOULDER WALL HEAD ON AT AN ESTIMATED SPEED OF 40-45MPH. AIR BAGS DID NOT DEPLOY,SEAT BELT TENSIONER BROKE,WONT RETRACT BACK INTO HOLDER. AFTER GETTING CAR TOWED CAN SEE THAT THE AIR BAG SENSOR WAS CRUSHED BUT NO DEPLOYMENT SPENT 2 DAYS IN HOSPITAL. THANKFULLY NOTHING BROKE JUST ALOT OF BRUISING. CANNOT FIGURE OUT WHY BRAKES DIDNT WORK ENDED UP USING EMERGENCY BRAKE TO TRY SLOWING DOWN IMPACT.