There are four primary methods for bleeding brakes: gravity, manual, vacuum, and pressure bleeding. Gravity bleeding is simple but ineffective if lines run above the master cylinder. Manual bleeding requires two people. Vacuum and pressure bleeding are one-person jobs, with vacuum pulling fluid through and pressure forcing it through.
Brake bleeding is necessary to remove air, often due to overheating or opening the system. Always bleed from the furthest wheel from the master cylinder (typically right rear, left rear, right front, left front).
For ABS systems, a scan tool might be needed to bleed the system, as air can get trapped in the module’s complexities. Always consult the manufacturer’s specifications.
Regarding the initial question, Technician A is incorrect that a scan tool “must” be used for “all” ABS systems, and Technician B is incorrect that vacuum bleeding requires two people (manual bleeding does). Neither technician is correct.
Brake System Bleeding
