2
Stability and Safety Enhancement Systems
6
WABCO
Maintenance Manual MM-0112 (Revised 07-18)
2 Stability and Safety Enhancement Systems
ATC
Automatic Traction Control is available as an option on all E version
ECUs and is standard on most. ATC helps improve traction in low
traction road conditions. ATC reduces the potential of jackknifing
caused by excessive wheel spin during acceleration or in curves.
ATC works automatically in two different ways.
A.
When one drive wheel is spinning at a different speed than the
other, ATC momentarily applies the brake until traction is
regained.
B.
When both drive wheels are spinning on a poor-traction
surface, ATC automatically reduces engine power to attain
optimum tire-to-road traction.
ATC will automatically turn on and off. Driver input is not required to
turn this feature on. If the vehicle experiences a traction control
event, the ATC indicator lamp will come on, indicating ATC is active.
The light turns off when the event has ended. Figure 2.1.
Figure 2.1
NOTE:
Some vehicle manufacturers may refer to ATC as Anti-Spin
Regulation (ASR).
If ATC is installed, there will be an indicator lamp on the vehicle dash
or instrument panel marked ATC, ASR, or potentially Stability
Control, depending on the application.
ATC Components
ATC uses the base ABS components plus an active braking valve
that can be installed with individual modulator valves, or installed as
part of the rear valve package.
When installed with individual modulator valves, the active braking
valve is mounted on the frame or cross member, near the rear of the
vehicle.
When it is part of the rear valve package, the active braking valve is
attached to the relay valve. Figure 2.2.
Figure 2.2
ATC Switch
If the vehicle manufacturer offers an ATC switch to control the ATC
functionality, there are two common types of configuration settings
as follows.
앫
Deep snow and mud option:
This function helps to increase
available traction on extra soft surfaces like snow, mud or gravel,
by slightly increasing the permissible wheel spin.
앫
ATC momentary override option:
This function allows the
driver to momentarily disable/override ATC for the duration of the
ignition cycle.
When either option is in use, the ATC indicator lamp blinks
continuously to inform the driver. Figure 2.3.
Figure 2.1
NORMAL
VEHICLE
OPERATION
EXCESSIVE WHEEL
SPIN ATC
OPERATIONAL
(ATC LAMP COMES ON)
1002015a
(ATC LAMP IS OFF)
WHEELS
STOP
SPINNING
(ATC LAMP GOES OUT)
Figure 2.2
4010605
a
