Brake Booster Vacuum Assist

Brake Booster Vacuum Assist Description and Operation

System Component Description

The brake booster vacuum assist system consists of the following:

Auxiliary Brake Booster Pump
- The auxiliary brake booster pump is a secondary vacuum supply to the brake booster to maintain sufficient vacuum needed for brake assist.

Vacuum Brake Booster
- Uses source vacuum to decrease effort required by driver when applying the brake.
When brake system input force is applied, air at atmospheric pressure is admitted to the rear of both vacuum diaphragms, providing a decrease in brake pedal effort required. When input force is removed, vacuum replaces atmospheric pressure within the booster.

Vacuum Source
- Vacuum is supplied by engine vacuum or by the auxiliary brake booster pump.

Brake Booster Vacuum Sensor
- The brake booster vacuum sensor is mounted on the vacuum brake booster and provides feedback to the electronic brake control module relative to the amount of vacuum available for the vacuum brake booster. When the vehicle is equipped with Stop/Start System the brake booster vacuum sensor provides also feedback to the engine control module.

System Operation

The electronic brake control module (EBCM) actuates the auxiliary brake booster pump to generate additional vacuum to the vacuum brake booster if low vacuum is detected by brake booster vacuum sensor.