1. Check of serviceability of functioning of the vacuum amplifier of brakes is made from the driver's place.
2. At completely squeezed out pedal of a foot brake start the engine, - the pedal has to fail a little more.
3. At the working engine several times squeeze out a pedal of a foot brake. The size of the course of a pedal has to remain a constant.
4. Squeeze out a pedal, kill the engine and continue to hold a pedal pressed within about 30 more seconds during which it should not neither fail below, nor rise.
5. Again start the engine, let's it work for about a minute, then again muffle. Again several times firmly squeeze out a pedal, - the size of the course has to be reduced with each muscleman.
6. In case of negative result of the described check the servo-driver of the vacuum amplifier of brakes is subject to recovery repair or replacement (see the Head the Brake system).