WHILE DRIVING ON DRY PAVEMENT, DRIVER MOVED KNOB ON VEHICLE TO SWITCH FROM AWD TO 2WD. VEHICLE WENT INTO AN IMMEDIATE SPIN WHICH COULD NOT BE CORRECTED. (OR MAYBE IT WAS BECAUSE OF WHAT HAPPENED NEXT). VEHICLE CAREENED OVER TWO LANES ("PRESUMABLY" WOULD NOT STOP - DRIVER DOES NOT RECALL TRYING TO HIT THE BRAKES REPEATEDLY OR AT ALL AS THE "NEXT PROBLEM" WAS IN FRONT OF DRIVER AND DRIVER WAS FOCUSING ON SURVIVAL).. DRIVER QUICKLY SMASHED THROUGH METAL SAFETY BARRIER AND CRASHED THROUGH TREES OVER A 30 FT EMBANKMENT INTO A RESERVOIR. DRIVER ABLE TO OPEN ROOF WHILE "STEERING" WITH LEFT HAND AND OPENING ROOF WITH RIGHT HAND AS DRIVER KNEW WATER WAS FAST APPROACHING. DRIVER SMASHED THROUGH TREES, TRUCK WAS DEMOLISHED BUT DRIVER WAS ABLE TO MAKE IT OUT OF CAR ALIVE AS CAR TOOK ON WATER THROUGH OPENED ROOF. VIN NUMBER REPORTS BRAKE ISSUES. DRIVER NOT AWARE OF "BRAKE RECALL" OR ANY ISSUES AND DID NOT REPORT BRAKE ISSUE AS AN ISSUE ON SCENE AS INCIDENT HAPPENED SO FAST AND DRIVER WAS ATTEMPTING TO STAY ALIVE AND WAS EVER FOCUSED ON THE NEXT 'OBSTACLE" AS IT WAS IN THE WAY PER DESCRIPTION HEREIN. AIRBAGS DEPLOYED AS EXPECTED AND DRIVER EXITED WATER-FILLED VEHICLE VIA OPENED ROOF UNHARMED. GMC SENT INVESTIGATORS OUT BUT NO REPORT HAS BEEN ISSUED TO DRIVER. CHUBB LEAD INVESTIGATOR ACCOMPANIED THE GMC INVESTIGATOR AND REPORTED "NO VEHICLE MALFUNCTION". AFTER THIS INCIDENT, AND READING OTHERS' PROBLEMS, DRIVER IS NOW NOT CONVINCED OF THAT REPORT.. NO MENTION OF BRAKE RECALL S