WAS DRIVING VEHICLE 35 MPH SLOWED DOWN TO GO AROUND SHARP CURVE. WHEN VEHICLE DROVE AROUND CURVE THERE WERE VEHICLES IN FRONT OF US THAT STOPPED SUDDENLY. APPLIED BRAKES AND PEDAL PULSED AND REQUIRED ALOT OF EFFORT TO SLOW DOWN. WAS UNABLE TO SLOW VEHICLE DOWN FAST ENOUGH AND REAR ENDED VEHICLE IN FRONT OF US. CAUSED A 3 CAR PILEUP. THE 3 PASSENGERS IN OUR 04 ARMADA SUFFERED WHIPLASH, THE DRIVER SPRAINED HER WRIST AND WAS OUT OF WORK FOR 3 DAYS BECAUSE OF ACCIDENT. THE NISSAN ARMADA WAS TOTALED AND HAD TO PURCHASE ANOTHER VEHICLE. THE BRAKES NOT WORKING CORRECTLY IS WHAT CAUSED THE ACCIDENT. *TR