Chevrolet Equinox Service Manual: Brake Booster Vacuum Assist Description and Operation Hydraulic Brakes Brake Booster

System Component DescriptionHydraulic Brakes Block Diagram

B19BBrake Booster Vacuum SensorK17Electronic Brake Control ModuleM9Brake Booster Pump MotorHard-Wired

B19B-Brake Booster Vacuum Sensor

K17-Electronic Brake Control Module

M9-Brake Booster Pump Motor

The Brake Booster Vacuum Assist system consists of the following:

The Brake Booster Vacuum Pump is a secondary vacuum supply to the brake booster usedto maintain sufficient vacuum for brake assist.

The vacuum sensor is used to measure the level of vacuum available in the brake booster.The Electronic Brake Control Module supplies a 5-V reference and a low reference circuitto the brake booster vacuum sensor. The vacuum sensor is located in the brake boosteror vacuum hose. The Brake Booster Vacuum Sensor supplies a voltage signal in relationto the pressure in the brake boosterto the Electronic Brake Control Module.

The Electronic Brake Control Module monitors the vacuum in the brake booster usingthe Brake Booster Vacuum Sensor. When the vacuum within the system drops the ElectronicBrake Control Module turns ON the Brake Booster Auxiliary Vacuum Pump.

When brake system input force is applied, air at atmospheric pressure is admittedto the rear of both vacuum diaphragms, providing a decrease in brake pedal effortrequired. When input force is removed, vacuum replaces the atmospheric pressure withinthe booster. The booster uses source vacuum to decrease the effort required by driverwhen applying the brake.

Vacuum is supplied by the engine vacuum or by the Brake Booster Auxiliary Vacuum Pump.

The pump can be switched on and off by the Electronic Brake Control Module based onthe required vacuum. Pressure variations during braking can be measured, and the pumpcan be activated to generate additional vacuum if required to increase the brakingforce.