Subaru 2009 IMPREZA Service Manual page 2601

BRAKE
• AIR TIGHTNESS CHECK
Start the engine, and idle it for 1 to 2 minutes, then
turn it OFF. Depress the brake pedal several times
applying the normal pedal force. The pedal stroke
should be the longest at the 1st depression, and it
should become shorter at each successive depres-
sion. If no change occurs in the pedal height when
pressed, the brake booster is faulty.
(1)
(5)
(4)
(3)
(1) Normal operation
(2) Not OK
(3) 1st
(4) 2nd
(5) 3rd
NOTE:
• In case of defective operation, inspect the condi-
tion of the check valve and vacuum hose as well.
• Replace them if faulty, and perform the test
again.
• If no improvement is observed, check precisely
with gauges.
• OPERATION CHECK
1) While the engine is OFF, depress the brake ped-
al several times applying the same pedal force, to
check for a change in pedal height.
(1)
(1) When engine is stopped
(2) When engine is started
2) With the brake pedal depressed, start the en-
gine.
Brake Booster
(2)
BR-00080
(2)
BR-00081
BR-34
3) As the engine starts, the brake pedal should
move slowly toward the floor. If the pedal height
does not change, the brake booster is faulty.
NOTE:
If faulty, check precisely with gauges.
• LOADED AIR TIGHTNESS CHECK
Depress the brake pedal while the engine is run-
ning, and turn the engine to OFF while the pedal is
depressed. Keep the pedal depressed for 30 sec-
onds. If the pedal height does not change, the func-
tion of brake booster is normal. If the pedal height
increases, it is faulty.
NOTE:
If faulty, check precisely with gauges.
2. OPERATION CHECK (WITH GAUGE)
CAUTION:
When checking operation, be sure to apply the
parking brake securely.
• CHECK WITH GAUGE
Connect the gauge as shown in the figure. After
bleeding air from the pressure gauge, perform each
check.
(1) (2)
(3) (4)
(1) Pressure gauge
(2) Vacuum gauge
(3) Adapter hose
(4) Vacuum hose
(5) Pedal force gauge
(5)
BR-00082