Vacuum Brake Booster: Testing and Inspection

Brake Booster Brake Assist, Checking Function, from 12.01

Depress brake pedal with engine running to ensure full vacuum support.

A "clicking" must be heard with the brake pedal fully depressed, mechanical brake assist is activated.

When subsequently releasing brake pedal, a significant lower foot pressure is noticeable.

It is not possible to repair mechanical brake assist, the entire brake booster must be replaced.