1997 Mercedes Benz SL600

WE TOOK A ROAD TRIP TO SAN ANTONIO, TX, ON 10/15/2019, AND WERE RETURNING HOME ON 10/17/2019 WHEN THE INCIDENT OCCURRED. SAN ANTONIO IS ABOUT 2 HOURS AWAY FROM LLANO, TX, WHERE WE LIVE. WE HAD DRIVEN IN SAN ANTONIO TRAFFIC FOR ABOUT 45 MINUTES AND STOPPED FOR BREAKFAST AT IHOP AROUND 10:30 AM. AFTER LEAVING IHOP, WE HEADED NORTH ON THE FRONTAGE ROAD OF HIGHWAY 281. ALMOST IMMEDIATELY, WE STOPPED AT A RED LIGHT IN THE MIDDLE LANE. AS SOON AS WE PULLED AWAY, WE HEARD A LOUD BANG THAT SOUNDED LIKE A GUN SHOT. MY HUSBAND, GLEN, WAS DRIVING AND I WAS IN THE PASSENGER SEAT. MY SEATBELT RETRACTED AND I SAW AND SMELLED SMOKE COMING FROM THE HARNESS AREA BY MY RIGHT SHOULDER. GLEN MERGED OVER AS SOON AS POSSIBLE AND WE PULLED OVER ON A SIDE ROAD. WE TALKED ABOUT WHAT HAPPENED AND I GOOGLED "MERCEDES SEATBELT EXPLOSION" AND FOUND THAT IT HAD HAPPENED TO OTHERS IN THE PAST WHICH ACTUALLY MADE ME FEEL BETTER ABOUT CONTINUING ON WITH OUR DRIVE HOME. I COULD NOT WEAR MY SEATBELT. I THOUGHT GLEN'S HAD ALSO LOCKED UP BECAUSE I CHECKED IT WHEN WE STOPPED BUT LATER IN THE TRIP HE TRIED IT AND HE WAS ABLE TO WEAR HIS. ONE THING WE NOTICED: THE CHECK ENGINE LIGHT HAD COME ON THAT MORNING FOR THE FIRST TIME SINCE DECEMBER 2017 WHEN WE HAD THE CAR SERVICED. IT WENT OFF IMMEDIATELY AFTER THE EXPLOSION BUT THE SRS LIGHT CAME ON.