Subaru IMPREZA 2002 Service Manual page 410

BRAKE BOOSTER
BRAKE
C: INSPECTION
ES)
1.
OPERATION CHECK (WITHOUT GAUG-
CAUTION:
When checking operation, be sure to securely
apply the hand brake.
Checking without gauges
This method cannot determine the exact portion
which has failed, but it can provide a rough under-
standing of the nature of the failure if checking is
conducted in accordance with the following proce-
dures.
Air tightness check
Start the engine, and run it for 1 to 2 minutes, then
turn it off. Depress the brake pedal several times
applying the same pedal force as that used in ordi-
nary braking operations. The pedal stroke should
be greatest on the 1 st depression, and it should be-
come smaller with each successive depression. If
no change occurs in the pedal height while in a de-
pressed state, the brake booster is faulty.
S4M0465A
(1)
OK
(2) NOTOK
(3) 1st
(4) 2nd
(5) 3rd
NOTE:
In the event of defective operation, inspect the
condition of the check valve and vacuum hose.
Replace them if faulty and conduct the test
again.
If no improvement is observed, check precisely
with gauges.
Operation check
1)
With the engine off, depress the brake pedal
several times applying the same pedal force and
make sure that the pedal height does not vary with
each depression of the pedal.
S4M0466A
(1)
When engine is stopped
(2) When engine is started
2) With the brake pedal depressed, start the en-
gine.
3) As engine starts, the brake pedal should move
slightly toward the floor. If no change occurs in the
pedal height, the brake booster is faulty.
NOTE:
If faulty, check precisely with gauges.
Loaded air tightness check
Depress the brake pedal while engine is running,
and turn off the engine while the pedal is still de-
pressed. Keep the pedal depressed for 30 sec-
onds; if no change occurs in the pedal height, the
brake booster is functioning normally; if the pedal
height increases, it is faulty.
NOTE:
If faulty, check precisely with gauges.
BR-40