200 Intelligent technology
vertical axis, vehicle acceleration in the fore-
and-aft and lateral directions, the brake pres-
sure, and the steering ang le are all measured .
The direction in which the driver wishes to
travel is determined with the aid of the stee r-
ing angle and vehicle speed and is continually
compared with the actual behavior of the ve-
hicle. If the two do not match, for examp le,
when the vehicle starts hydroplaning on a wet
road, ESP will automatically brake the appro -
priate wheel to correct the problem .
The vehicle is then stabilized by the forces act-
ing on the wheel during braking. If the vehicle
is
oversteering (the vehicle turns too sharply
and the rear wheels slide toward the outside
of a curve), the brakes are mainly applied on
the wheel that is on the outside of the curve.
In the case of a vehicle that is
understeering
(the vehicle does not turn sharply enough and
pushes out of a curve), the brakes are applied
as needed on the wheel that is on the inside of
the curve or addit iona lly on the other wheels.
An acoust ic signal indicates when ESP brake
application cuts in ¢ &,..
The system operates across the entire speed
range in combination with the ABS system
¢
page 203. If the Anti-Lock Brake System
(ABS) malfunctions, the ESP will be out of ac-
tion as well.
Activating
When you turn on the engine, ESP will auto-
matica lly be activated and will perform a se lf-
test. As soon as the test is completed, the sys-
tem is in normal operating mode .
You can activate a deactivated ESP or deacti-
vated ESP/ASR if required by pressing the
¢
fig. 194 ¢ fig . 193 button. When they are
activated, the message
Stabilisation program
on
appears briefly in the display.
Deactivating
The ESP shou ld normally be activated all the
time. If necessary, you can deactivate Anti-
Slip Regulation (ASR) or the Electronic Stabili-
zation Program (ESP) by pressing the button
<::;,fig . 194 .
- Deactivating ASR: Tap the button. In cer-
tain exceptional situations (e.g. driving with
tire chains), the Anti-Slip Regulation (ASR)
can be deactivated ¢
page 201. The mes-
sage
ASR off Caution! Limited driving sta-
bility
appears in the display as well.
- Deactivating ESP/ASR Press the button for
more than 3 seconds. With the ESP/ASR de-
activated, the indicator light comes on, see
r:::;, page 15 . The message Warning! Restrict-
ed stability
appears in the display as well.
,&. WARNING
-
The Electronic Stabilization Program is
nevertheless subject to the laws of phys-
ics.
It is particularly important to pay at-
tention to this fact on wet and slippery
roads. It is therefore important that you
always adapt your driving to the condition
of the road and traff ic conditions. Do not
allow the increased safety provided by the
Electronic Stabilization Program system to
lull you into accepting addit ional safety
risks.
Electronic differential lock (EDL)
The electronic differential lock monitors the
rotational speed of the drive wheels .
General notes
The electronic differential lock (E0L) helps the
car to start moving, accelerate and climb a
gradient on surfaces providing poor or almost
no grip. Without EDL, this would be difficult,
if not impossible .
How the system works
The EDL operates automatically. It mon itors
the rotational speed of wheels with the help
of the ABS sensors¢
page 203 . If a noticea-
ble
slip is detected at the wheels (e.g. on slip-
pery ground
on one side), the sp inning wheels
are braked and power is transferred to the
other whee ls. This is done up to a speed of
about 60 mph (100 km/h) . Noises from the
brake system signa l that whee l spin is being
controlled.
ll-
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