Whats up everyone? Bewby looking for info. I proudly drive a 03' Silverado w/ 48000 mi. Yesterday while going down the road i notice a loud buzz or hum that could be felt in the peddles coming from under the hood i pulled over and opened the hood and noticed the cylinder attached to the break booster buzzing. After about minute it stopped, but now every time i start the truck it does the same thing for about a 30 secs. I also noticed the " driver info center" on the dash says "service break booster" after the buzz stops so the ecmis picking up the problem. My questions are, Is the break booster servicable? I always thought you had to replace them when they went bad. Also what is the cylinder attached to the booster, and can this be replaced? The truck still stops fine so im hoping this a simple fix. Also has anyone heard of a break booster crapping out so soon? I'd just like to somewhat informed before i call the shop and they try to soak me for a new break booster. Any and all help/info would be much appreciated. THANK YOU.