Seat belts
156
The physical principle of a frontal
collision
The physical principle of a frontal accident can be explained quite simply: Motion energy, so-called kinetic energy, is produced as soon as the
vehicle is moving, both for the vehicle and its occupants. The magnitude
of this kinetic energy depends essentially on the speed at which the
vehicle is travelling and on the weight of the vehicle and the occupants.
The greater the speed and weight increase, the greater the amount of
energy which has to be absorbed in the event of an accident.
The speed of the vehicle is, nevertheless, the most important factor.
Doubling the speed of the vehicle from 25 km/h up to 50 km/hour
increases the kinetic energy four times.
The common opinion that it is possible to support your body in a minor
accident with your hands, is incorrect. Even in a collision at only a low
speed, the forces acting on the body are such that it is no longer possible
to support your body.
Even if you only drive at a speed within the range from 30 km/hour to 50
km/hour, the forces which are produced on your body in the event of an
accident can easily exceed 10.000 N (Newton). This equals a weight of
one tonne (1 000 kg).
In the event of a frontal collision, occupants of the car not wearing a seat
belt, are thrown forward and strike in an uncontrolled way parts of the inte-
rior of the car, such as steering wheel, dash panel, windscreen,
⇒fig. 135 .
The occupants of a vehicle who have not fastened their seat belts may
even be thrown out of the vehicle. This can result in fatal injuries.
It is also important that rear seat occupants fasten their seat belts as they
will otherwise be thrown through the vehicle in an uncontrolled manner in
the event of an accident A rear seat passenger who has not fastened the
seat belt is a danger not only to himself but also for those seated at the
front ⇒fig. 136 .
Fig. 135 The driver is
thrown forward if not
wearing a belt
Fig. 136 The rear seat
occupant is thrown
forward if not wearing a
belt
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Airbag system
164
− The hazard warning light is switched on,
− All the doors are unlocked.
Front airbags
Description of the front airbags
The airbag system is not a substitute for the seat belt!
The front airbag for the driver is housed in the steering wheel ⇒fig. 141 .
The front airbag for the front passenger is housed in the dash panel above
the storage compartment ⇒fig. 142 . The installation positions are each
marked with the “AIRBAG” logo.
The front airbag system, in combination with three-point safety belts,
offers additional protection for the head and chest area of the driver and
front passenger in the event of a frontal collision of major severity ⇒
in “Important safety information regarding the front airbag system” on
page 166.
The airbag is not a substitute for the seat belt, but is part of the complete
passive vehicle safety concept. Please note that an airbag can only
offer you optimal protection in combination with a seat belt which is
fastened. .
Apart from their normal protective function, a further task of the seat belts
is to also hold the driver and front passenger in a correct seated position
in the event of a frontal collision so as to enable the front airbags to offer
the maximum protection.
Fig. 141 Driver airbag
in the steering wheel
Fig. 142 Front
passenger airbag in the
dash panel
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Airbag system
166
Important safety informat ion regarding the front
airbag system
Correct use of the airbag system considerably reduces the
risk of injury!
WARNING
•Never transport children on the front seat of a vehicle without
using a proper restraint system. If airbags are deployed in the event
of an accident, the child might suff er severe or even fatal injuries!
•For the driver and front passenger it is important to maintain a
distance of at least 25 cm from the steering wheel or dash panel
⇒ fig. 144 . Not maintaining this minimu m distance will mean that
the airbag system will not be able to properly protect you - hazard!
The front seats and the head restraints must always also be
correctly adjusted to match the body size of the occupant.
•It is essential to always switch off ⇒page 171, “Deactivating an
airbag” the front passenger airbag when attaching a child safety seat on the front passenger seat where the child is seated with its
back facing in direction of travel (in some countries also when the
child is facing the direction of travel). If this is not done, there is a
risk of the child suffering severe or
even fatal injuries if the front
passenger airbag is deployed. In certain countries national legal
provisions also require that the side or head passenger airbags be
deactivated. When transporting a child on the front passenger seat,
please comply with the appropriat e national regulations regarding
the use of child safety seats.
•There must not by any further persons, animals or objects posi-
tioned between the front seated occupants and the deployment
area of the airbag.
•The steering wheel and the surface of the airbag module in the
dash panel on the passenger side must not be stuck onto, covered
or modified in any other way. Th ese parts should only be cleaned
with a dry cloth or a cloth moistened with water. No objects such
as cup holders, mobile phone mounts, etc. may be attached to the
covers of the airbag modules or be located within the immediate
area.
•No modifications of any kind may be made to parts of the airbag
system. Any work on the airbag system including installing and
removing system components because of other repair work (e.g.
removing the steering wheel) must only be carried out by a
specialist garage.
•Never carry out changes on the front bumper or on the body.
•Never place any objects on the surface of the front passenger
airbag in the dash panel.
Fig. 144 Safe distance
to steering wheel
WARNING (continued)
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Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
•There must not be any other persons (e.g. children) or animals
between the car occupant and the deployment area of the head
airbag. In addition, none of the occupants should lean their head
out of the window when driving, or extend their arms and hands out
of the window.
•The sun visors must not be swivelled to the side windows into
the deployment area of the head airbags if any objects, such as
ball-point pens etc. are attached to them. This might result in inju-
ries to the occupants if the head airbag is deployed.
•Installing impermissible accessories in the area of the head
airbags may considerably impair the protection offered by the head
airbag in the event of it being deployed. When the deployed head
airbag is inflated, parts of the accessories fitted may in certain
circumstances be thrown into the interior of the car and cause inju-
ries to the occupants ⇒ page 243, “Accessories, changes and
replacement of parts”.
•Any work on the head airbag system including installing and
removing system components because of other repair work (e.g.
removing headliner) must only be carried out by a specialist
garage.
Deactivating an airbag
Deactivating airbags
If any airbags have been deactivated, switch them on
again as soon as possible so that they are able to again
provide their proper protection.
There is the technical means installed within your vehicle to switch off the
front, side or head airbag (take out of commission).
This is why you should have the deactivation of the airbags carried out by
a specialist garage.
On vehicles equipped with the switch for deactivation of the airbags, you
can deactivate the front and side passenger airbag by means of this
switch ⇒page 172.
Deactivation of airbags is envisaged only for particular instances,
such as if:
•you must in exceptional cases use a child seat on the front
passenger seat where the child has its back to the direction of travel of the
vehicle (in some countries this must be in the direction of travel due to
other legal regulations applying) ⇒page 174, “Important safety informa-
tion on using child safety seats”
•you are not able to maintain the distance of at least 25 cm between
middle of steering wheel and chest, despite the driver seat being correctly
adjusted,
•special attachments are required in the area of the steering wheel
because of a physical disability,
•you have installed other seats (e.g. orthopaedic seats without side
airbags).
WARNING (continued)
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Intelligent Technology185
Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
Driving Tips
Intelligent Technology
Electronic stability programme (ESP)*
General
General
The ESP aids you maintain control of your vehicle in situations in border-
line driving situations such as when negotiating a curve too fast. The risk
of skidding is reduced and your car 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 indi-
vidual 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 acceleration 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
car 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 understeer (tendency to shift out of the
curve). This braking control cycle is accompanied by noises.
The ESP operates in combination with the ABS ⇒page 189, “Antilock
brake system (ABS)”. If there is a fault in the ABS system, the ESP also
does not operate.
Fig. 160 ESP switch
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Intelligent Technology
186
The ESP warning light ⇒page 35 lights up in the instrument cluster when
there is a fault on the ESP.
Switching off
You can switch the ESP off and on again as you wish, by pressing the
button ⇒page 185, fig. 160 . The ESP warning light ⇒ page 35 lights up
in the instrument cluster when the ESP is switched off.
The ESP should normally always be switched on. It may be good practice
to switch the system off only in particular exceptional situations if you
desire wheel slip.
Examples:
•when driving with snow chains,
•when driving in deep snow or on a loose surface,
•when it is necessary to rock a car free when it has become stuck.
then you should switch on the ESP again.
WARNING
It is also not possible for the E SP 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 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 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 other
assignment of tyres and wheels) can influence the function of the ESP
⇒ page 243.
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 trans-
Fig. 161 TCS switch
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Using the systemSafetyDriving TipsGeneral MaintenanceBreakdown assistanceTechnical Data
mitted 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 189, “Antilock
brake system (ABS)”. The TCS will not function if a fault exists in the ABS
system.
The TCS warning light ⇒page 35 lights up in the instrument cluster when
there is a fault on the TCS.
Switching off
You can switch the TCS off and on again as you wish by pressing the
button ⇒page 186, fig. 161 . The TCS warning light ⇒page 35 lights up
in the instrument cluster when the TCS is switched off.
The TCS should normally always be switched on. It may be good practice
to switch the system off only in particular exceptional situations if you
desire wheel slip.
Examples:
•when driving with snow chains,
•when driving in deep snow or on a loose surface,
•when it is necessary to rock a car free when it has become stuck.
then you should switch on the TCS again.
The EDL ⇒page 187, “Electronic Differential Lock (EDL)” is a part of the
TCS. THE EDL operates independently of the TCS (also when the TCS
has been switched off using the TCS button).
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 other
assignment of tyres and wheels) can influence the function of the TCS
⇒ page 243, “Accessories, changes and replacement of parts”.
Electronic Differential Lock (EDL)
The electronic differential lock prevents an individual
wheel from slipping.
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.
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Intelligent Technology
188
The EDL switches on again automatically as soon as the brake has cooled
down.
WARNING
•Depress the accelerator carefully when accelerating on
uniformly slippery 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 warning light comes on, this may also indicate a fault in the
EDL. Please have the car inspected as soon as possible by a specialist
garage.
•Changes to vehicle (e.g. on engine, on the brakes, on chassis or other
assignment of tyres and wheels) can influence the function of the EDL
⇒ page 243, “Accessories, changes and replacement of parts”.
Brakes
What has a negative effect on braking efficiency?
Wear-and-tear
Wear-and-tear to the brake pads is greatly dependent on the operating
conditions of the vehicle and your style of driving. Particularly if you drive
a great deal in towns and over short distances or if you adopt a sporty style of driving, it may be necessary to have the thickness of the brake pads
inspected at a specialist garage between the service inspections.
Wet roads or road salt
There may be a certain delay before the brakes take full effect under
certain conditions such as when driving through water, during heavy rain
showers or after the vehicle has been washed in an automatic vehicle
wash, since the brake discs and brake pads may be moist or even have a
coating of ice on them in winter. You should dry the brakes as soon as
possible (by applying and releasing the brakes several times, if the road
conditions and the traffic situation allows it).
There also may be a certain delay before the full braking efficiency is
available when driving on roads which have been treated with road salt if
you have not used the brakes for some considerable time beforehand.
The layer of salt on the brake discs and brake pads must first be rubbed
off when you apply the brakes.
Corrosion
Corrosion on the brake discs and dirt on the bake pads occur if the vehicle
has been parked for a long period and if you do not make much use of the
braking system.
We recommend cleaning the brake discs by firmly applying the brakes at
a fairly high speed if you do not make much use of the braking system or
if surface corrosion is present
⇒.
Faults in the brake surface
If you notice that the braking distance has suddenly become longer and
that the brake pedal can be depressed further, it is possible that a brake
circuit of the dual-circuit brake system has failed. Drive, in such cases, to
the nearest specialist garage without delay in order to have the problem
rectified. Drive at a reduced speed while on your way to the dealer and
adapt your style of driving to the higher brake pedal pressure required.
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