Leak Test
- Press the brake pedal with the engine running, then turn the ignition switch to LOCK (0). The brake pedal height should not vary while pressed for 30 seconds.
- Start the engine, and let it idle for 30 seconds. Turn the ignition switch to LOCK (0), and wait 30 seconds. Press the brake pedal several times using normal pressure. When the pedal is first pressed, it should be low. On consecutive applications, the pedal height should gradually rise.
- If it rises, the brake booster is OK.
- If it does not rise, go to step 3.
- Disconnect the brake booster vacuum hose (A) at the booster. The check valve (B) is built into the hose.NOTE: If the check valve is faulty, replace the brake booster vacuum hose/check valve as an assembly.
- Start the engine, and let it idle. There should be vacuum available.
- If no vacuum is available, the check valve is not working properly. Replace the brake booster vacuum hose and the check valve, and retest.
- If vacuum is found, go to step 5.
- With the ignition switch at LOCK (0), reconnect the vacuum hose to the brake booster.
- Start the engine, and then pinch the brake booster vacuum hose between the check valve and the booster.
- Turn the ignition switch to LOCK (0), and wait 30 seconds. Press the brake pedal several times using normal pressure. When the pedal is first pressed, it should be low. On consecutive applications, the pedal height should gradually rise.
- If the pedal position does not vary, inspect the rod seal between the master cylinder and the brake booster. If the rod seal is OK, replace the brake booster (see BRAKE BOOSTER REPLACEMENT ).
- If the pedal position varies, replace the brake booster vacuum hose/check valve as an assembly.