0204777571 | Genuine GM® Power Brake Booster Assembly 1999-2008

1. Reduce Driver Effort

Without a booster, you’d have to press the brake pedal very hard—especially at higher speeds or in heavy vehicles.
The booster multiplies your foot pressure using vacuum or hydraulic assist, making it possible to stop the car with minimal effort.

2. Improve Braking Control and Comfort

Because the booster smooths out pedal effort, it allows for better modulation (fine control) of braking force.
That means:

• Smoother stops

• More predictable pedal feel

• Easier braking in traffic or emergencies

3. Enhance Safety

A power-assisted brake system helps you apply full braking force faster, which can reduce stopping distance and prevent accidents.
This is especially critical during:

• Sudden stops

• Panic braking situations

• Towing or carrying heavy loads

4. Support Modern Vehicle Systems

In modern vehicles, the brake booster often works together with:

• ABS (Anti-lock Braking System)

• ESC (Electronic Stability Control)

• Brake Assist systems

These systems depend on consistent, boosted hydraulic pressure to function effectively.

1. Hard or Stiff Brake Pedal

• The most obvious symptom.

• When the booster fails, the vacuum or pressure assist is lost.

• You’ll have to press much harder on the pedal to stop the car, especially at low speeds.

2. Increased Stopping Distance

• Because you’re not getting power assist, the brakes don’t engage as quickly or strongly.

• The car may take longer to stop, which is dangerous in emergencies.

3. Hissing Noise When Braking

• A vacuum leak in the booster diaphragm or check valve can cause a hissing sound (like air escaping) when you press the brake pedal.

• This usually means the diaphragm is torn or a hose is cracked.

4. Engine Stalling or Rough Idle When Braking

• The brake booster uses engine vacuum, so a leak can cause too much air to enter the intake system.

• This leads to rough idling, stalling, or even check engine lights when you apply the brakes.

5. “Spongy” or Delayed Brake Pedal Response

• If the booster or its check valve fails partially, the pedal may feel soft or slow to respond before braking engages.

6. High Brake Pedal Position

• A failed booster may cause the brake pedal to sit higher than usual, requiring more travel before braking starts.