My brake pedal has no pressure and when pressed it goes to the floor. This morning the brake light was on and I didn't get a chance to check he brake fluid, I was in a rush so I drove the car with the light on and the rake pedal had very little pressure, very spongy and when pressed hard it goes to the floor. I brought it into the garage, checked the level and it was low, way below the min line. I filled the reservoir and the brake light on the dash cleared but there is no pressure on the brake pedal now... Bad master cylinder? Or should I try bleeding the brakes?