CONVENTIONALBRAKESYSTEM
P
1 SUOPX-001
03UOPX-03
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POWER BRAKE UNIT
Quick Inspection, On-vehicle
Power brake unit function check
k:;;p{e method)
1. With the engine stopped, depress the pedal a few times.
2. With the pedal depressed, start the engine.
3. If immediately after the engine starts the pedal moves down
slightly, 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.
5. If a problem is found, inspect for damage of the check valve
or vacuum hose and examine the installation. Repair if
necessary, and inspect it once 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.
5. If the pedal height does not change, the unit is operating.
6. If there is a problem, check for damage to the check valve
or vacuum hose, and check the connection. Repair if neces-
sary and check once again.
If the nature of the problem is still not clear after the 3 steps
above, follow the more detailed check described in “Method-
using tester,” below.
(Method-using tester)
Connect a pressure gauge, vacuum gauge, and pedal depres-
sion force gauge as shown in the figure. After bleeding the
air from the pressure gauge, conduct the test as described
in the 3 steps below.
Note
l
Use commercially available gauges and pedal
depression force gauge.
a) Checking for vacuum loss
Unloaded condition
1. Start the engine.
2. Stop the engine when the vacuum gauge reading reaches
500 mmHg (19.7 inHg).
3. Observe the vacuum gauge for
15 seconds.
If the gauge
shows 475-500
mmHg (18.7-19.7 inHg),
the unit is
operating.
P-13
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