Occasionally in the summer my Engine Service Required Light comes on. Dealer stated that it is my Brake Position sensor. So I replaced it but the problem still exists. Sometimes it impacts my ability to use cruise control. Also, I can hear a humming/buzzing for a sec when I take my foot off the brake when the car is not running (year round). I read that is probably my brake booster. Does anyone know for sure before I get too crazy with the booster? Thanks

 

Not sure about your issue but I too have been getting a humming coming from just behind the dash on the driver's side. It happens semi-consistently and only when I either press the brake or release the brake. It is a buzzing sound. I've been guessing that it is my brake vacuum pump vs. the booster but maybe I'm wrong. I thought a bad booster made a different sound (not a buzz).

 

A bad brake booster will typically make a hissing sound as air leaks at the pushrod seal.