Service Information

Spark

Brake Booster Vacuum Assist Description and Operation

System Component Description

The brake booster vacuum assist system consists of the following:

Brake Booster Auxiliary Vacuum Pump: The brake booster vacuum pump is a secondary vacuum supply to the brake booster to maintain sufficient vacuum 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 brake booster vacuum pump.

System Operation

The brake booster vacuum switch is activated by the amount of vacuum available to the power brake booster. When the ignition switch is at the ON position and the vacuum within the system drops, the switch within the brake booster vacuum switch closes allowing voltage to be supplied to the brake booster pump motor.