ASE A5: How to test vacuum power assist and hydroboost braking systems

摘要

The ASE A5 Test has a large section (about 43%) dedicated to hydraulic, power assist and parking brake system diagnosis and repair. As it specifically pertains to power assist, you must know how to: 1) Check vacuum supply (manifold or auxiliary pump) to vacuum-type power booster, 2) Diagnose vacuum-type power booster units for vacuum leaks and proper operation; inspect the check valve for proper operation; repair, adjust or replace parts as necessary. 3) Diagnose hydroboost systems for leaks and proper operation; repair or replace parts as necessary; refill and bleed system following manufacturers' specifications.