Antilock Brake System (Abs); Warning Light - Chevrolet 4500HD Series 2019 Manual

76 Instruments and Controls
Brake Low Vacuum Warning
Light
This light should come on briefly
when the engine control switch is
turned to the ON position, and then
should go out after the engine is
started. If the light does not come
on when the engine control switch is
turned to ON, it could indicate a
burned out bulb or a blown fuse.
Have the system repaired if the light
does not come on during this check.
The warning light and buzzer will
come on simultaneously when the
brake booster s vacuum or pressure
becomes insufficient either during
driving or when the engine control
switch is in the ON position, or when
there is an abnormality in the
charging system, such as an
alternator malfunction or loosening
or splitting of the fan belt or
whenever the hydraulic brake
booster (HBB) becomes faulty. The
warning buzzer will stop sounding
when the parking brake is engaged.
On 4500HD and 4500XD, the brake
low vacuum warning light and
warning buzzer should come on to
indicate low vacuum reserve for
brake power assist. At the same
time, the Back up Electric Vacuum
Pump operates.
(5500HD, 5500XD models) When
the HBB pressure is low, and/or the
HBB fluid (Dexron VI) level is low,
the light and warning buzzer should
come on. Do not use brake fluid in
the brake booster reservoir. Use
only Dexron VI ATF.
If this happens while driving:
Do not pump the brakes. The
system is designed to stop the
truck with reserve power assist if
the pedal is held down. This
reserve is greatly reduced each
time you apply and release the
brakes.
Stopping distance may be
longer.
You may have to push much
harder on the brake pedal.
Have the vehicle repaired before
you continue driving.
The buzzer stops when the selector
lever is shifted to the P position.
{
Warning
Do not drive while the buzzer
sounds as the brakes are not
operating to their full capacity.
You and others could be seriously
injured.
Antilock Brake System
(ABS) Warning Light
This light comes on briefly when the
engine control switch is turned to
the ON position, and then should go