DRIVING MY 2003 CHEVY SILVERADO IN THE LEFT LANE OF THE CITY FREEWAY APPROXIMATELY 50 MPH IN HEAVY TRAFFIC. PUSHED BRAKE TO STOP FOR VEHICLES CHANGING LANES AHEAD. BRAKE PEDAL INITIALLY HAD PRESSURE BUT AFTER ABOUT 2 SECONDS WENT TO THE FLOOR WITH NEARLY NO PRESSURE AND NO BRAKING EFFECT AT ALL. THERE WAS NO PRIOR INDICATION OF A PROBLEM AND NO WARNING LIGHT SIGNALING AN ISSUE. SWERVED INTO THE LEFT BERM TO AVOID HITTING CARS AHEAD. TRAVELED 20 PLUS CAR LENGTHS WHILE DROPPING AUTOMATIC TRANSMISSION INTO LOWEST GEAR AND PUMPING BRAKE PEDAL TO NO AFFECT. FORCED TRUCK AGAINST BARRIER WALL TO AVOID HITTING OTHER VEHICLES. BRAKE WARNING LIGHT CAME ON AS TRUCK STOPPED. A LARGE PUDDLE OF BRAKE FLUID WAS DUMPED BELOW RT REAR WHEEL AND LEAKED WHEN THE BRAKE PEDAL WAS PRESSED. THERE HAD BEEN NO PREVIOUS ISSUES WITH THE BRAKES AND BRAKE PADS WERE REPLACED 20,000 MILES AGO. THE DUAL CIRCUIT SYSTEM PROVIDED NO PARTIAL BRAKING EFFECT AT ALL. I HAD THE VEHICLE TOWED HOME AND DISCOVERED A STEEL BRAKE LINE BURST FROM CORROSION AND ALL BRAKE LINES SIGNIFICANTLY DEGRADED. THIS TRUCK HAS BEEN METICULOUSLY MAINTAINED, IS DRIVEN EVERYDAY AND HAS BEEN GARAGE KEPT SINCE IT WAS PURCHASED NEW IN DEC 2002. *TR