Sephia GS Sedan L4-1.8L (1997)
Vacuum Brake Booster: Testing and Inspection
Power Brake Unit Function Check
NOTE: The power brake unit is not repairable. It must be replaced as a unit.
STEP 1
1. With the engine stopped, depress the brake pedal a few times.
2. With the pedal depressed, start the engine.
3. The unit is operating correctly if the brake pedal moves down immediately when the engine starts.
STEP 2
1. Start the engine.
2. Stop the engine after it has run for 1 to 2 minutes.
3. Depress the brake pedal several times.
4. If the first pedal stroke is long, but becomes shorter with subsequent strokes, the unit is operating correctly.
STEP 3
1. Start the engine.
2. Depress the brake pedal and hold.
3. Stop the engine.
4. Hold the pedal down for about 30 seconds.
5. If the pedal height does not change, the unit is operating correctly.
6. If there is a problem, check for damage to the check valve and vacuum hose. Replace if necessary.
NOTE: If the cause of the problem is still not clear after the three steps above, follow the more detailed check described in Vacuum and Pressure
