TL*THE CONTACT OWNS A 2002 GMC SONOMA. WHILE DRIVING APPROXIMATELY 15 MPH AND APPROACHING A STOP LIGHT, THE VEHICLE DID NOT STOP WHEN THE BRAKE PEDAL WAS DEPRESSED. THE BRAKE PEDAL EXTENDED TO THE FLOOR AND THE CONTACT REAR ENDED ANOTHER VEHICLE. THERE WERE NO INJURIES. THE CONTACT'S SON DIAGNOSED THE VEHICLE AS HAVING BRAKE LINE FAILURE. THE AIR BAGS DID NOT DEPLOY AT THE TIME OF IMPACT. THE CURRENT AND FAILURE MILEAGES WERE 30,000.