It's at the top of the brake pedal lever, near connector to the vacuum booster.
From the booster, to a vacuum source on the engine.
Faulty Vacuum Power Brake Booster
you need manifold vacuum for the brake booster.. (intake manifold)
If you have a booster you need a vacuum line to perform effectively, disc or drum.
The power brake vacuum booster is failing.
brake booster vacuum leak,or bad brake booster.
No, the brake booster operates off of vacuum not electricity. If the booster isn't working then check the vacuum line going from the intake manifold to the booster. If the line is ok and not leaking then you need to replace the booster.
If the vacuum leak is small, then yes the brake booster will still function well enough to assist the braking action. However, if the vacuum leak is very large, or if the brake booster rubber diaphragm is ruptured , then the brake booster will be inoperative and you will NOT have power assist to the brakes. It's wise to just replace the power brake booster with a new unit if there is an internal leak in it, to avoid an accident due to a loss of braking power.
behind the brake booster
You may have a vacuum leak at the brake booster. Have the brake booster inspected.
Power brake booster failure or vacuum supply to booster insufficient.