Brake booster
The brake booster uses engine manifold vacuum to assist braking force. Do not turn off the engine while driving because that will turn off the brake booster, resulting in poor braking power.
The brakes will continue to work even when the brake booster completely stops functioning. If this happens, however, you will have to depress the pedal much harder than normal and the braking distance will increase.
See also:
Engine
...
Use of engine braking
Remember to make use of engine braking
in addition to foot braking. When descending
a grade, if only the foot brake is used,
the brakes may start working improperly
because of brake fluid over ...
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