The most common type of brake booster uses engine vacuum to add force to the pressure being applied to the master cylinder. It is installed between the brake master cylinder and the driver's brake pedal and is located in the engine compartment.
How to Replace the Brake Booster
1. Empty the brake master cylinder of all brake fluid
2. Remove the brake master cylinder and disconnect the brake booster vacuum hose
3. Remove the brake booster, which may require decoupling from the brake pedal
4. Install the new brake booster and re-install the brake master cylinder
5. Connect the vacuum hose and bleed the entire brake system
6. Test drive the vehicle to verify the repair