Important: If any hydraulic component is removed or disconnected, it may be necessary to bleed all or part of the brake system. Refer to Hydraulic Brake System Bleeding .

The power booster is a single diaphragm, vacuum suspended unit. In normal operating mode, with the service brakes in the release position, a vacuum suspended booster operates with a vacuum on both sides of its diaphragm. When the brakes are applied, air at atmospheric pressure is admitted to one side of the diaphragm to provide the power assist. When the brakes are released, atmospheric air is shut off from that side of the diaphragm. The air is then drawn from the booster through the vacuum check valve by the vacuum source.