POWER BRAKE UNIT INSPECTION

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Power Brake Unit Function Inspection (Inspection using gauges)

1.  Connect the SST gauges, a vacuum gauge, and a pedal depression gauge as shown in the figure. Bleed the air from the SST gauges before performing the following tests.

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Checking for vacuum loss (unloaded condition)

1.  Start the engine.

2.  Stop the engine when the vacuum gauge indicates 67 kPa {500 mmHg, 20 inHg}.

3.  Observe the vacuum gauge for 15 s.

•  If the gauge indicates 64—66 kPa {476—499 mmHg, 18.8—19.6 inHg}, the unit is operating.

Checking for vacuum loss (loaded condition)

1.  Start the engine.

2.  Depress the brake pedal with a force of 200 N {20 kgf, 45 lbf}.

3.  With the brake pedal held depressed, stop the engine when the vacuum gauge indicates 67 kPa {500 mmHg, 20 inHg}.

4.  Observe the vacuum gauge for 15 s.

•  If the gauge indicates 64—66 kPa {476—499 mmHg, 18.8—19.6 inHg}, the unit is operating.

Checking for hydraulic pressure

1.  If the engine is stopped (vacuum 0 kPa {0 mmHg, 0 inHg}) and the fluid pressure is within the specification, the unit is operating.

2.  Start the engine. Depress the brake pedal when the vacuum reaches 67 kPa {500 mmHg, 20 inHg}.

•  If the fluid pressure is within the specification, the unit is operating.

•  If the fluid pressure is not as specified, inspect for damage to the check valve or vacuum hose, and fluid leakage of the hydraulic line. Repair as necessary, and inspect again.