I am also having this issue, and I'm pretty sure it is the break pump. In the mornings, or when the car has been parked for a while, I hear the noise when I step on the brake pedal. It usually lasts about 5 seconds, but if I step on the pedal again, the noise comes back, and keeps repeating until after three or four times. My question is this. Someone posted that the service manual recommends replacement if noise is above 70dB. Does anybody know if the service manual has any mention of the distance you should measure it? My pump is clearly louder than 70dB if I stick a meter close to it.