Brake Booster Operating Test; Check Valve Operation Check - Mitsubishi MOTORS Space Runner 1999 Workshop Manual Supplement

35A-8
Good
When engine is
stopped
BASIC BRAKE SYSTEMS –

BRAKE BOOSTER OPERATING TEST

No good
For simple checking of the brake booster operation, carry
out the following tests:
1. Run the engine for one or two minutes, and then stop
2. With the engine stopped, step on the brake pedal several
When engine is
started
3. With the engine running, step on the brake pedal and

CHECK VALVE OPERATION CHECK

1. Remove the vacuum hose. (Refer to P.35A-17.)
On-vehicle Service
it.
If the pedal depresses fully the first time but gradually
becomes higher when depressed succeeding times, the
booster is operating properly, if the pedal height remains
unchanged, the booster is defective.
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.
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, the check
valve, vacuum hose, or booster will be defective.
Caution
The check valve should not be removed from the
vacuum hose.
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