Power Brake Unit Function Check (Simple Method)

Step 1 

1. With the engine stopped, depress the pedal several times.
2. With the pedal depressed, start the engine.
   • If the pedal moves down slightly, immediately after the engine starts, the unit is operating.
   • If a problem is found, inspect for damage on the check valve or vacuum hose, and examine the installation. Repair as necessary, and inspect it again.

Step 2 

1. Start the engine.
2. Stop the engine after idling for 1 or 2 minutes. 
3. Depress the pedal with the usual force.
   • 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 on the check valve or vacuum hose, and examine the installation. Repair as necessary, and inspect it again.

Step 3 

1. Start the engine.
2. Depress the pedal with the usual force.
3. Stop the engine with the pedal held depressed.
4. Hold the pedal down for about 30 seconds. 
   • If the pedal height does not change, the unit is operating.
   • If a problem is found, inspect for damage on the check valve or vacuum hose, and examine the installation. Repair as necessary, and inspect it again.