GM Service Manual Online
For 1990-2009 cars only

Checks

Action

Inspect for the following conditions:

    • Broken or damaged hydraulic pipes or hoses
    • A damaged or loose vacuum hose
    • A collapsed vacuum hose

Replace any faulty pipes or hoses.

Inspect for a plugged or loose vacuum fitting.

Clean and correctly tighten the vacuum fitting.

Inspect for the following conditions:

    • A faulty vacuum check valve or grommet
    • Faulty air valve seal or support plate
    • Damaged floating control valve
    • Bad stud welds on the front or rear housing or power head
    • Faulty booster diaphragm
    • Worn or distorted reaction plate or levers
    • Cracked or broken power pistons or retainer

Replace the vacuum booster. Refer to Power Vacuum Brake Booster Replacement in Hydraulic Brakes.

Inspect for the following conditions:

    • A blocked passage in the power piston
    • An air valve sticking shut
    • A broken piston return spring or air valve spring

Replace the vacuum booster. Refer to Power Vacuum Brake Booster Replacement in Hydraulic Brakes

Inspect for a tight brake pedal linkage.

Repair or replace any faulty component.

Inspect for malfunctioning stoplamp switch.

Repair or replace the stoplamp switch. Refer to Stop Lamp Switch Replacement in Hydraulic Brakes.