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BASIC BRAKE SYSTEM -
On-vehicle Service
35A-8
2. With the engine stopped, step on the brake pedal several
times.
Then step on the brake pedal and start the engine.
If the pedal moves downward slightly, the booster is in
good condition. If there is no change, the booster is
defective.
3. With the engine running, step on the brake pedal a nd
then stop the engine.
Hold the pedal depressed for 30 seconds. If the pedal
height does not change, the booster is in good condition,
if the pedal rises, the booster is defective.
If the above three tests are okay, the booster performance
can be determined as good.
If one of the above three tests is not okay at last, the
check valve, vacuum hose, or booster will be defective.
CHECK VALVE OPERATION CHECK
35100900151
1. Remove the vacuum hose. (Refer to P.35A-16.)
Caution
The check valve should not be removed from the
vacuum hose.
2. Check the operation of the check valve by using a vacuum
pump.
Vacuum pump connection Accept/reject criteria
Connection at the brake
booster side (A)
A negative pressure (vacu-
um) is created and held.
Connection at the intake
manifold side (B)
A negative pressure (vacu-
um) is not created.
Caution
If the check valve is defective, replace it as an
assembly unit together with the vacuum hose.
When engine is
stopped
When engine is
started
Valve
Spring
Booster
side
Intake
manifold
side
AB