Power Brake Unit Function Check (Simple Method)
WARNING: This page is about a different car, the 2005 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
- Replace power brake unit component if necessary.
Step 1
- With the engine stopped, depress the pedal a few times.
- With the pedal depressed, start the engine.
- If the pedal moves down slightly, immediately after engine starts, the unit is operating.
- If not, inspect for damage on the check valve or vacuum hose, and examine the installation. Repair if necessary, and inspect it again.
Step 2
- Start the engine.
- Stop the engine after it has run for 1 or 2 minutes.
- Depress the pedal with usual force.
- If the first pedal stroke is long and becomes shorter with subsequent strokes, the unit is operating.
- If not, inspect for damage on the check valve or vacuum hose, and examine the installation. Repair if necessary, and inspect it again.
Step 3
- Start the engine.
- Depress the pedal with usual force.
- Stop the engine with the pedal held depressed.
- Hold the pedal down for about 30 seconds.
- If the pedal height does not change, the unit is operating.
- If not, inspect for damage on the check valve or vacuum hose, and examine the installation. Repair if necessary, and inspect it again.