Bu_man

I notcied yesterday when I was driving thru a parking lot going about 5/10 mph and I would barley just touch my brake I was hear this sound that sounded like a pump or some time of motor. It was pretty loud and would last for 5/10 seconds and would seem to donit every time I would touch the brake. I’m not sure it does it at high speed. My trucks too loud to really hear it then.