Active Brake Booster
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
Incorporated into the vacuum brake booster, is an electric solenoid actuator. This actuator can be used to apply the brake booster and thus the master cylinder as commanded by the electronic brake control module (EBCM). During stability events, the EBCM can command the solenoid actuator in the brake booster to apply the booster. This quickly provides a large volume of pressurized brake fluid to the brake pressure modulator valve (BPMV). The BPMV will then control the flow of fluid to the brake corners to obtain the appropriate response for the vehicle.