I was driving on an empty two lane road going 35-40 mph. The car braked suddenly and the BRAKE warning light came on but no sound. On the way to the service department at the dealership it happened again, only this time I was going 20 mph and in traffic. There was a car in front of me at least 3 car lengths but was moving. I heard the brakes of the car behind me squeal as he avoided hitting me. No sound from my car, the brake light came on, I also put my foot on the brake thinking maybe the car sensed an encroachment I didnt notice. But there was none, so I released the brake before coming to a complete stop. The service department inspected the system and could not reproduce or confirm any issues. There was no warning sound, the brake came on at the same time as the light. There was no warning, the light came on at the same time as the brake