freightliner 108SD, Driver Manual

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valve (or combination modulator valve) is damaged
and inoperative. As these components are an integral
part of the air brake system, normal braking may be
impaired or inoperative.
During emergency or reduced-traction stops, fully
depress the brake pedal until the vehicle comes to a
safe stop.
Do not pump the brake pedal . With the
brake pedal fully depressed, the ABS will control all
wheels to provide steering control and a reduced
braking distance.
Although the ABS improves vehicle control during
emergency braking situations, the driver still has the
responsibility to change driving styles depending on
existing traffic and road conditions. For example, the
ABS cannot prevent an accident if the driver is
speeding or following too closely.
Trailer ABS Compatibility
The Meritor WABCO ABS is designed to communi-
cate with a trailer ABS, if they are compatible. Com-
patibility will result in the illumination of the TRAILER
ABS lamp during vehicle start-up and fault detection.
The TRAILER ABS lamp will not illuminate unless a
compatible trailer is connected to the tractor. The
dash-mounted lamp will operate as follows when a
compatible trailer is properly connected to the tractor:
•
When the ignition key is turned to the ON posi-
tion, the TRAILER ABS lamp will illuminate mo-
mentarily, then turn off.
•
If the lamp illuminates momentarily during ve-
hicle operation, then shuts off, a fault was de-
tected and corrected.
•
If the lamp illuminates and stays on during ve-
hicle operation, there is a fault with the trailer
ABS. Repair the trailer ABS system immedi-
ately to ensure full antilock braking capability.
IMPORTANT: If a compatible trailer is con-
nected, and the lamp is not illuminating momen-
tarily when the ignition key is turned to the ON
position, it is possible that the lamp is burnt out.
Automatic Traction Control
Vehicles with electronic engines and ABS may have
Automatic Traction Control (ATC). On these vehicles,
the ATC system automatically limits wheel spin dur-
ing reduced-traction situations. In normal braking ap-
plications, the standard air brake system is in effect.
An additional solenoid valve is installed. During
reduced-traction situations, the ATC solenoid valve
controls air pressure to the modulator valves and
they in turn increase, hold, or reduce pressure to the
appropriate brake chambers to provide better traction
whenever wheel spin occurs.
When the ATC system is in the NORMAL mode, it
will apply gentle braking to the spinning wheel, to
feed power to the wheel(s) with better traction. If
both wheels are spinning, the system will signal the
engine to reduce power.
ATC includes a deep snow and mud option to in-
crease available traction on extra soft surfaces like
snow, mud, or gravel. A momentary contact rocker
switch labeled ATC will be located on the dash.
Pressing the switch will temporarily allow more drive
wheel spin. The activation of the deep snow and
mud option is indicated by a flashing WHEEL SPIN
lamp. Pressing the switch again will cycle the system
back to normal operation.
NOTICE
The deep snow and mud option is intended to be
used under specific slippery conditions that re-
quire momentary increased wheel spin. Using
this option for an extended period of time may
damage the vehicle brake system.
After the ignition switch is turned on, the TRACTOR
ABS lamp and the WHEEL SPIN indicator lamp
come on for about three seconds. After three sec-
onds, the warning lights go out if all of the tractor’s
ABS components are working.
IMPORTANT: If any of the ABS warning lights
do not work as described above, or come on
while driving, repair the ABS immediately to en-
sure full antilock braking capability.
Enhanced Stability Control
WARNING
The Enhanced Stability Control system is in-
tended only as an aid for a conscientious and
alert driver and is not a substitute for safe driv-
ing procedures. Failure to drive safely, and use
the system properly, could result in personal in-
jury and/or death and property damage.
Brake Systems
12.4