Power Brake Unit Function Check (Simple Method)

Step 1 

1. With the engine stopped, depress the pedal a few times.
2. With the pedal depressed, start the engine.
3. If the pedal moves down slightly immediately after the engine starts, the unit is operating.

Step 2 

1. Start the engine.
2. Stop the engine after it has run for 1 or 2 minutes. 
3. Depress the pedal with the usual force.
4. If the first pedal stroke is long and becomes shorter with subsequent strokes, the unit is operating.
   • If a problem is found, inspect for damage of the vacuum hose, and vacuum tank. Repair if necessary, and inspect it again.

Step 3 

1. Start the engine.
2. Depress the pedal with usual force.
3. If the pedal height does not change, the unit is operating.
4. Hold the pedal down for about 30 s. 
5. If the pedal height does not change, the unit is operating.