WHILE DRIVING ALONG, GETTING OFF OF AN EXIT RAMP ONTO A MAIN HWY, I REACHED OVER TO TURN MY DEFROSTER OFF, WHEN THE WHEEL JERKED TO THE LEFT, I ATTEMPTED TO GAIN CONTROL BUT NEVER GOT TOTAL CONTROL ALTHOUGH I DID GET BACK ONTO THE ROAD. A FEW SECONDS LATER THE CAR JERKED AGAIN AND THIS TIME I REALIZED THE STEERING WHEEL WAS NOT MOVING-IT WAS LOCKED UP AND I COULD NOT TURN IT. I THEN HIT THE GUARD RAIL ON THE NORTH SIDE OF THE HWY AND THEN CAME ACROSS TO THE SOUTH SIDE HITTING THE CONCRETE BRIDGE RAILING. THE IGNITION SWITCH RECALL HAD SUPPOSEDLY BEEN CORRECTED BUT THE IGNITION LOCKED UP ON THIS VEHICLE. *TR