GMC CHEVROLET Silverado 6500HD 2019 Owner's Manual page 311

310 Vehicle Care
force, via brake fluid, to the main
components of the hydraulic brake
system.
The motor/pumps will run
momentarily with the ignition on or
off to maintain accumulator
pressure. Therefore, whenever the
brake pedal is pressed when the
ignition is off, the motor/pumps may
be heard.
Split System Feature
Warning
To prevent property damage,
personal injury, and/or death,
if part of the brake system fails,
reduce speed and employ safe
driving practices as stopping
distance may increase under the
failed condition since only one
section of the brake system is
operating. Have the brake system
repaired immediately. Loss of
braking capability could cause a
crash.
The system is divided into two
separate but identical channels: the
primary channel (controls front axle)
and the secondary channel (controls
rear axle). The master cylinder
provides brake lines that are routed
to the front and rear brake channels.
With the split brake system, the
vehicle should have reasonable
brake control should one of the two
channels fail. If one of the motor/
pump related systems fails, you
may not detect any difference in the
feel of the pedal, but with a defect in
the master cylinder circuit, you may
experience a longer pedal stroke to
attain desired stopping. With any
system failure, one of the instrument
cluster warning indicators will
turn on.
Hydraulic Brake Booster
System
Warning
To prevent property damage,
personal injury, and/or death,
if part of the brake system fails,
reduce speed and employ safe
driving practices as stopping
distance may increase under the
failed condition since only one
section of the brake system is
operating. Have the brake system
repaired immediately. Loss of
braking capability could cause a
crash.
The system receives fluid pressure
from the power steering pump to
provide power assist during braking.
The hydraulic booster has a backup
pump which will provide hydraulic
boost at a reduced rate if the normal
source of fluid is interrupted. The
signal for operation of the backup
pump comes from the flow switch.
If normal flow is interrupted, the flow