SSANGYONG 1999 Musso Service Manual page 938

PEDAL STROKE INSPECTION
1. Start the engine and stop it after one or two minutes.
Depress the brake pedal several times.
If the pedal goes down furthest the first time, but gradually
rises after the second or third time, brake booster is normal.
If there is no change in pedal stroke, the brake booster is
abnormal.
2. Depress the brake pedal several times with engine stopped,
and depress the brake pedal and start the engine. If the
pedal goes down slightly, the booster is normal.
3. Depress the brake pedal with engine running, and stop it
with the pedal depressed. If there is no change in pedal
height during 30 sec., the booster is normal.
POWER BOOSTER 4C-5