Intelligent Technology155
Using the system
Safety
Driving Tips
General Maintenance
Breakdown assistance
Technical Data
Driving TipsIntelligent TechnologyElectronic stability programme (ESP)*GeneralGeneral
The ESP aids you maintain control of your vehicle in situations in borderline driving
situations such as when negotiating a curve too fast. The risk of skidding is reduced
and your vehicle thus offers greater driving stability depending on the conditions of
the road surface. This occurs at all speeds.
The following systems are integrated into the electronic stability programme:•
Electronic Differential Lock (EDL);
•
Traction control system (TCS);
•
Antilock brake system (ABS);
•
Brake Assist.Operating principle
The ESP switches on automatically when the engine is started and then conducts a
self-test. The ESP control unit processes data from the individual systems. It also
processes additional measurement data which are supplied by highly sensitive
sensors: the rotational velocity of the vehicle about its vertical axis, the lateral accel-
eration of the vehicle, the braking pressure and the steering angle.
The direction which the driver wishes to take is determined based on the steering
angle and the speed of the vehicle and is constantly compared with the actual
behaviour of the vehicle. If differences exist, such as the vehicle beginning to skid,
the ESP will automatically brake the appropriate wheel.
The car is stabilised again by the forces which take effect when the wheel is braked.
Intervention into the brake system takes place primarily on the outer front wheel of
a vehicle which tends to oversteer (tendency for the rear of the vehicle to break
away) while occurs this is on the inner rear wheel of a vehicle which tends to under-
steer (tendency to shift out of the curve). This braking control cycle is accompanied
by noises.
The ESP operates in combination with the ABS ⇒page 159, “Antilock brake system
(ABS)*”. If there is a fault in the ABS system, the ESP also does not operate.
The ESP warning light lights up in the instrument cluster when there is a fault on the
ESP
⇒page 32.
Switching off
You can switch the ESP off and on again as you wish, by pressing the button
⇒fig. 170. The ESP warning light lights up in the instrument cluster when the ESP is
switched off
⇒page 32.
The ESP should normally always be switched on. It may be good practice in certain
exceptional cases, such as when you wish to have wheel slip, to switch off the
system.
Examples:
Fig. 170 ESP switch
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Intelligent Technology 156•
when driving with snow chains;
•
when driving in deep snow or on a loose surface;
•
when it is necessary to rock a vehicle when it has become stuck.
then you should switch on the ESP again.
WARNING
It is also not possible for the ESP to overcome the physical limits of the
vehicle. Even if a vehicle fitted with ESP you should still always adapt your
style of driving to the condition of the road surface and the traffic situation.
This particularly applies when driving on slippery and wet roads. The
increased safety offered must not tempt you to take greater risks than other-
wise - risk of an accident!
Note
•
All four wheels must be fitted with the same tyres in order to achieve problem-
free operation of the ESP. Differing rolling circumferences of the tyres can lead to an
undesirable reduction in the engine output.
•
Changes to vehicle (e.g. on engine, on the brakes, on chassis or another combi-
nation of tyres and wheels) can influence the function of the ESP ⇒page 204,
“Accessories, changes and replacement of parts”.
Traction control system (TCS)*
The traction control system prevents the driven wheels from spinning
when accelerating.General
The TCS makes it much easier, and sometimes at all possible, to start off, accelerate
and climb a steep hill when the conditions of the road surface are unfavourable.
Operating principle
The TCS switches on automatically when the engine is started and then conducts a
self-test. The system monitors the speeds of the driven wheels with the aid of the
ABS sensors. If the wheels are spinning, the force transmitted to the road surface is
automatically adapted by reducing the engine speed. This occurs at all speeds.
The TCS operates in combination with the ABS ⇒page 159, “Antilock brake system
(ABS)*”. The TCS will not function if a fault exists in the ABS system.
The TCS warning light lights up in the instrument cluster when there is a fault on the
TCS
⇒page 31.
Switching off
You can switch the TCS off and on again as you wish by pressing the button
⇒fig. 171. The TCS warning light lights up in the instrument cluster when the TCS is
switched off
⇒page 31.
Fig. 171 TCS switch
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Intelligent Technology157
Using the system
Safety
Driving Tips
General Maintenance
Breakdown assistance
Technical Data The TCS should normally always be switched on. It may be good practice in certain
exceptional cases, such as when you wish to have wheel slip, to switch off the
system.
Examples:
•
when driving with snow chains;
•
when driving in deep snow or on a loose surface;
•
when it is necessary to rock a vehicle when it has become stuck.
then you should switch on the TCS again.
WARNING
You should always adjust your style of driving to the conditions of the road
surface and the traffic situation. The increased safety offered must not tempt
you to take greater risks than otherwise - risk of an accident!
Note
•
All four wheels must be fitted with the same tyres in order to achieve problem-
free operation of the TCS. Differing rolling circumferences of the tyres can lead to
an undesirable reduction in the engine output.
•
Changes to vehicle (e.g. on engine, on the brakes, on chassis or another combi-
nation of tyres and wheels) can influence the function of the TCS ⇒page 204,
“Accessories, changes and replacement of parts”.
Electronic Differential Lock (EDL)*
The electronic differential lock prevents an individual wheel from
slipping.Models fitted with ESP are equipped with electronic differential lock (EDL).
General
The EDL makes it much easier, and sometimes at all possible, to start off, accelerate
and climb a steep hill when the conditions of the road surface are unfavourable.Operating principle
The EDL is activated automatically, that is without any action on the part of the
driver. It monitors the speeds of the driven wheels with the aid of the ABS sensors.
Should only one drive wheel begin spinning on a slippery surface there will be an
appreciable difference in the speed of the driven wheels. The EDL function brakes
the slipping wheel and the differential transmits a greater driving force to the other
driven wheel. This control process is also accompanied by noises.
Overheating of the brakes
The EDL switches off automatically if unusually severe stresses exist in order to
avoid excessive heat generation in the disc brake on the wheel which is being
braked. The vehicle can continue to be driven and has the same characteristics as a
vehicle not fitted with EDL.
The EDL switches on again automatically as soon as the brake has cooled down.
WARNING
•
Carefully depress the accelerator when accelerating on uniformly slip-
pery road surfaces, such as ice and snow. The driven wheels might still spin
despite the EDL and affect the stability of the vehicle - risk of an accident!
•
You should always adapt your style of driving to the condition of road
surface and to the traffic situation even when your vehicle is fitted with EDL.
The increased safety offered must not tempt you to take greater risks than
otherwise - risk of an accident!Note
•
If the ABS or TCS or ESP warning light comes on, this may also indicate a fault in
the EDL. Please have the vehicle inspected as soon as possible by a specialist
garage.
•
Changes to vehicle (e.g. on engine, on the brakes, on chassis or another combi-
nation of tyres and wheels) can influence the function of the EDL ⇒page 204,
“Accessories, changes and replacement of parts”.
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Intelligent Technology 160brake pedal firmly and hold it in this position in order to achieve the shortest
possible braking distance.
The Brake Assist is able to help you achieve a shorter braking distance in emergency
situations by rapidly producing the pressure required in the brake system. It fully
exploits the attributes of the ABS. After you release the brake pedal, the function of
the Brake Assist is automatically switched off and the brakes operate in the normal
way.
The Brake Assist is part of the ESP system. If a fault occurs in the ESP, the Brake Assist
function is also not available. Further information on the ESP ⇒page 155.
WARNING
•
The Brake Assist is also not able to overcome the physical limits of your
vehicle in terms of the braking distance required.
•
Adapt your speed to the conditions of the road surface and to the traffic
situation.
•
The increased safety offered by the Brake Assist must not tempt you to
take a greater safety risk than otherwise.
Electrohydraulic power steeringThe power steering enables you to steer the vehicle with less physical force.
The steering characteristics can be changed by a specialist garage.
You will place great stresses on the power steering system if the steering is turned
to full lock when the vehicle is stationary. Turning the steering to full lock in such a
situation will be accompanied by noises.
It is still possible to fully steer the vehicle if the power steering fails or if the engine
is not running (vehicle being towed in). The only difference is that greater physical
effort is required.
It is possible that the hydraulic pump of the power steering will not run due to the
low vehicle network voltage if the battery has gone flat and the engine must started
with the help off jump leads. This condition will be indicated by lighting up of the
warning light.The power steering operates again if the battery is charged to a specific range when
engine is running. It also operates again, if the engine can be started with its own
battery.
If there is a fault in the power steering, the warning light lights up in the instrument
cluster
⇒page 26.
Caution
Do not leave the steering at full lock for more than 15 seconds when the engine is
running - risk of damaging the power steering!
Note
Have the steering inspected as soon as possible by a specialist garage if there is a
leak or fault in the system.Tyre inflation pressure-control system*The tyre inflation pressure-control system compares with the aid of the ABS sensors
the speed and also the rolling circumference of the individual wheels. If the tyre
inflation pressure is significantly changed and thus the rolling circumference of a
wheel, the warning light
lights up in the instrument cluster ⇒page 32. The tyre
inflation pressure-control system functions late or too sensitively if:
Fig. 172 Button for setting
the tyre inflation pressure
control value
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