Isuzu N Series 2008 Owner's Manual page 242

4-114
CONTROLS AND INSTRUMENTS
NOTE
[HYDRAULIC BRAKE BOOSTER CHARACTERISTICS]
In the HBB models, an unusual sound from under the instrument panel may be
heard from the hydraulic system while brakes are used. It does not mean trouble.
It is not a sign of malfunction.
• If you pump the brakes with the engine off, a squeaking sound can be heard.
This comes from the auxiliary accumulator. It is not a malfunction.
With the engine running, a similar sound can be heard during sudden braking.
• Another characteristic of the HBB system is that the brake pedal may be
depressed easily to the floor with the vehicle at a stop. This is not a sign of
malfunction.
• When the engine is running, the system automatically charges the accumulator
whenever pressure has been reduced after braking.
Auto charge may be activated without braking, depending on temperature
changes in the accumulator.
During auto charge, a hissing and clicking sound can be heard.
This is not a malfunction.
• With the engine running, a booming sound can be heard during hard braking.
This comes from the brake-fluid pump. It is not a malfunction.
Applying continuous hard braking for a long time will lead to considerable
temperature rise in the hydraulic booster pump. Such overworking of the brakes
is best avoided.
[VACUUM OR HYDRAULIC POWER ASSISTED BRAKES]
If the engine stops, do not pump the brakes. The system is designed to stop the
vehicle with reserve power assist if the brake pedal is held down. This reserve is
greatly reduced each time you apply and release the brakes. If, when you turn the
steering wheel during braking, the vehicle does not turn, release some pressure
from the brake pedal.
Without power assist the vehicle can still be stopped by pushing much harder on
the brake pedal, however, the stopping distance may be longer.
2008N_sec04-2_print2.indd 114 3/09/2008 5:31:54 PM