GM Service Manual Online
For 1990-2009 cars only

This booster is a tandem vacuum suspended unit. The tandem vacuum suspended booster operates with a vacuum on both sides of the diaphragms when the following conditions exist:

    • The booster is in normal operating mode.
    • The service brake is in the released position.

When the brakes are applied, air at atmospheric pressure is admitted to one side of each diaphragm to provide the power assist. When the service brake is released, the atmospheric air is shut off from the one side of each diaphragm. The air is then drawn from the booster through the vacuum check valve to the vacuum source.

Important: 

   • Do not use lubricated compressed air on brake parts as damage to rubber parts may result.
   • If any hydraulic component is removed or disconnected, you may need to bleed all or part of the brake system. Refer to Hydraulic Brake System Bleeding .
   • The fastener tightening values specified are for dry, unlubricated fasteners.
   • Perform service operations on a clean bench free from all mineral oil materials.