Peterbilt 579 - Page 202

OPERATING THE BRAKE SYSTEM
4
detected and the ASR or ATC system
is applying the drive wheel brakes or
reducing engine torque. Engine torque
or vehicle speed should be reduced
to eliminate wheel spin and prevent
excessive application of the ASR/ATC
system. Except for checking for proper
illumination of the ABS and traction
control warning lamps when rst
starting the vehicle, and for monitoring
these lamps while driving, no special
operating procedures are required.
For detailed system description, see
literature for your specic ABS that
was provided with your vehicle.
This feature
helps improve traction
when vehicles are on slippery surfaces
or surfaces with poor traction (i.e.
mud or snow) by reducing drive wheel
overspin. Wheel spin control works
automatically in two different ways:
• If a drive wheel starts to spin,
wheel spin control applies air
pressure to brake the wheel. This
transfers engine
torque to the
wheels with
better traction.
• If all drive wheels spin, wheel spin
control reduces engine torque to
provide improved traction.
Wheel spin
control turns itself on and
off, you do not have to select this
feature. If drive wheels spin during
acceleration, the ASR Warning Lamp
comes on, indicating wheel spin control
is active.
Do not
allow the ASR Warning Lamp
to remain on continuously for an
extended length of time. Extended,
continuous use of the ASR/ATC can
cause overheating of the drive wheel
brakes.
Deep Snow
and Mud Switch (option)
A deep
snow and mud switch is
included with Wheel Spin Control. The
Deep Snow and Mud feature is helpful
during acceleration. This function
increases available
traction on extra
soft surfaces like snow, mud or gravel,
by slightly increasing the permissible
wheel spin. When this function is in
use, the ASR Warning Lamp blinks
continuously.
Off-Road ABS
Function Switch
(option)
Your
vehicle may be equipped with
a separate switch to activate an
Off-Road ABS function. This function
is NOT to be used for On-Highway
driving but is intended to be used
to improve stopping performance in
Off-Highway conditions (e.g., loose
gravel and mud). The Off-Road ABS
function is accomplished by allowing a
“wedge” of material to build-up in front
of momentarily locked wheels.
Features and
Benets
• Changes the ABS control limits to
allow for a more aggressive ABS
function while off-road.
4-30 Y53-6047–2C (04/13)