Suzuki GA413 Service Manual page 217

2) Start engine while depressing brake pedal. If pedal travel in-
creases a little, operation is satisfactory. But no change in pedal
travel indicates malfunction.
Check Air Tightness Under Load
1) With engine running, depress brake pedal. Then stop engine
while holding brake pedal depressed.
2) Hold brake pedal depressed for 30 seconds. If pedal height
does not change, condition is good. But it isn't if pedal rises.
BRAKES 5-21