Troubleshooting guide

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For more information, visit www.bendix.com or www.foundationbrakes.com • 1-800-AIR-BRAKE (1-800-247-2725)
See section 12 for other system schematics.
Advanced ABS
Yaw Stability
Yaw stability counteracts the tendency of a vehicle to spin
about its vertical axis. During operation, if the friction at
the tires is not suffi cient to oppose lateral (side) forces,
one or more of the tires can slide, causing the truck/
tractor to spin. These are referred to as under-steer
or over-steer situations. Generally, shorter wheelbase
vehicles (tractors, for instance) have less yaw stability,
while longer wheelbase vehicles (straight trucks) have
greater natural yaw stability. Factors that infl uence yaw
stability are: wheelbase, suspension, steering geometry,
weight distribution front to rear and vehicle tracking.
Stability Systems
During operation, the ECU of the Bendix Advanced ABS
system constantly compares performance models to
the vehicle’s actual movement, using the wheel speed
sensors of the ABS system, as well as lateral, yaw and
steering angle sensors. If the vehicle shows a tendency
to leave an appropriate travel path, or if critical threshold
values are approached, the system will intervene to
assist the driver.
Advanced ABS
The Bendix
®
ESP
®
Electronic Stability Program Full
Stability System
The ESP/ESC Electronic Stability Program/Electronic
Stability Control functionality of the Bendix Advanced
ABS system responds to a wide range of low- to high-
friction surface scenarios including rollover, jackknife
and loss-of-control. It is the recommended system for
all power vehicles and especially critical for tractors
pulling trailers. In the case of vehicle slide (over-steer
or under-steer situations), the system will reduce the
throttle and then brake one or more of the “four corners
of vehicle” (in addition to potentially braking the trailer),
thus applying a counter-force to better align the vehicle
with an appropriate path of travel. For example, in an
over-steer situation, the system applies the “outside”
front brake; while in an under-steer situation, the “inside”
rear brake is applied.
In the case of a potential roll event, the system will
reduce the throttle and quickly apply the brakes to slow
the vehicle combination below the threshold.
Driving Scenario:
Driving speed exceeds the threshold,
and the resulting lateral force causes
the vehicle to slide or jackknife on
lower-friction surfaces.
Action by Bendix
Stability Solutions:
System applies the appropriate
brakes to reduce speed and properly
align the vehicle, thereby reducing
the tendency to slide or jackknife.