As others have said, If you Brake Buddy has a test feature or button, hit that 3 or 4 times before you tow. if it doesn't, just hit the brake pedal a few times before you install the Brake Buddy, and this process must be repeated after, any time you start the engine to bleed off the residual vacuum.
Bill & Denise
2014 Bay Star 3103 - 5 Star Tune
2016 Jeep Grand Cherokee 4X4 Limited