POWER BRAKE UNIT INSPECTION

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Note

•  The following inspection methods are simple inspection methods to judge the function of the power brake unit.

•  If there is any malfunction in the power brake unit, replace the power brake unit as a single component.

Without Using SST

Operation inspection

1.  Depress the pedal several times with the engine stopped.

2.  With the pedal depressed, start the engine.

3.  If the pedal moves down slightly immediately after engine start, the unit is normal.

Vacuum function inspection

1.  Start the engine.

2.  Stop the engine after driving the vehicle for 1—2 min.

3.  Depress the pedal with normal force.

4.  If the first pedal stroke is long and becomes shorter with subsequent strokes, the unit is normal.

•  If a malfunction is found, inspect for damage to or improper installation of the check valve and vacuum hose. After repairing, inspect again.

Vacuum loss function inspection

1.  Start the engine.

2.  Depress the pedal with normal force.

3.  Stop the engine under this condition.

4.  Hold the pedal depressed for approx. 30 s.

5.  If the pedal height does not change during this time, the unit is normal.

When using SST

Note

•  When performing the inspection using the SST, inspect the brake pipe on the left or right front wheel.

•  The following procedure and figures show the inspection for the brake pipe on the left front wheel.

Preparation before inspection

1.  Loosen the brake pipe flare nut using the commercially available flare nut wrench.

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2.  Disconnect the brake pipe.

3.  Remove the clamp and disconnect the brake hose.

4.  Install the SSTs to the brake pipe as shown in the figure.

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5.  Perform air bleeding of the SST and brake line from bleeder screw A.

6.  Install the pedal force gauge to the brake pedal.

7.  Connect the vacuum piping to the vacuum gauge.

Checking for vacuum loss (loaded condition)

1.  Start the engine.

2.  Depress the brake pedal with a force of 200 N {20.4 kgf, 44.9 lbf}.

3.  With the brake pedal depressed, turn off the engine when the vacuum gauge reaches 68 kPa {510 mmHg, 20.1 inHg}.

4.  Within 15 s right after stopping the engine, measure the lowest amount of vacuum.

5.  If the lowest amount is 3.3 kPa {25 mmHg, 1.0 inHg} or less, the system is normal.

Lack of hydraulic pressure inspection

1.  With the engine stopped and the vacuum amount at 0 kPa {0 mmHg, 0 inHg} if the pedal force and fluid pressure correlation is within the specification, the system is normal.

Hydraulic pressure inspection

1.  Start the engine and when the vacuum amount reaches 66.7 kPa {500 mmHg, 19.7 inHg}, depress the brake pedal.

2.  At this time, apply the indicated pedal force and if the fluid pressure is within the specification, the unit is normal.

Procedure after inspection

1.  Remove the SSTs after the inspection and install the brake hose, clamp and brake pipe to their original positions.

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2.  Perform air bleeding of the brake line. (See AIR BLEEDING.)