APPROACHING AN INTERSECTION AND OBSERVED A YELLOW LIGHT. I WAS TRAVELING 35MPH AS POSTED AND APPLIED THE BRAKES ONLY TO HAVE THE PEDAL GO ALL THE WAY DOWN TO THE FIRE WALL. THE TRUCK HAD NO BRAKING POWER AND ONLY SLOWED TO ABOUT 15MPG AFTER APPLYING FOR ROUGHLY 40-50 YARDS. I ENDED UP RUNNING INTO THE INTERSECTION COLLIDED WITH ANOTHER VEHICLE THAT PROCEEDED ON GREEN.