MERCEDES-BENZ R320 2010 W251 Workshop Manual

thresholds and in certain rollovers (window
curtain air bags and ETDs).
R Never wear the shoulder belt under your
arm,
against your neck or off your shoulder.
In a frontal crash, your body would move
too far forward. That would increase the
chance of head and neck injuries. The seat
belt would also apply too much force to the
ribs or abdomen, which could severely
injure internal organs such as your liver or
spleen.
Adjust the seat belt so that the shoulder
section is located as close as possible to
the middle of the shoulder. It should not
touch the neck. Never pass the shoulder
portion of the seat belt under your arm. For
this purpose, you can adjust the height of
the seat belt outlet.
R Position the lap belt as low as possible on
your hips and not across the abdomen. If
the lap belt is positioned across your
abdomen, it could cause serious injuries in
a crash.
R Never wear seat belts over rigid or
breakable objects in or on your clothing,
such as eyeglasses, pens, keys etc., as
these might cause injuries.
R Make sure the seat belt is always fitted
snugly. Take special care of this when
wearing loose clothing.
R Never use a seat belt for more than one
person at a time. Do not fasten a seat belt
around a person and another person or
other objects at the same time.
R Seat belts should not be worn twisted. In a
crash, you would not have the full width of
the seat belt to distribute impact forces.
The twisted seat belt against your body
could cause injuries.
R Pregnant women should also always use a
lap/shoulder belt. The lap belt portion
should be positioned as low as possible on
the hips to avoid any possible pressure on
the abdomen. R
Place the seat backrest in a position that is
as upright as possible.
R Check your seat belt during travel to make
sure it is properly positioned.
R Never place your feet on the instrument
panel, dashboard, or on the seat. Always
keep both feet on the floor in front of the
seat.
R When using a seat belt to secure infant
restraints, toddler restraints, or children in
booster seats, always follow the child seat
manufacturer’s instructions. G
Warning!
Do not pass seat belts over sharp edges. They
could tear.
Do

not allow the seat belt to get caught in the
door or in the seat adjustment mechanism.
This could damage the seat belt.
Never attempt to make modifications to seat
belts. This could impair the effectiveness of
the seat belts.
Fastening the seat belts G
Warning!
According to accident statistics, children are
safer when properly restrained in the rear
seating positions than in the front seating
position. Thus, we strongly recommend that
children

be placed in the rear seats whenever
possible. Regardless of seating position,
children 12 years old and under must be
seated and properly secured in an
appropriately sized infant restraint, toddler
restraint, or booster seat recommended for
the size and weight of the child. For additional
information, see “Children in the vehicle”.
A child’s risk of serious or fatal injuries is
significantly increased if the child restraints
are not properly secured in the vehicle and/
or the child is not properly secured in the child
restraint. Occupant safety
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G
Warning!
Vehicles with BabySmart™ air bag
deactivation system, Canada only: Children
12 years old and under must never ride in the
front seat, except in a Mercedes-Benz
authorized BabySmart™ compatible child
seat, which operates with the BabySmart™
system installed in the vehicle to deactivate
the front passenger front air bag when it is
installed properly. Otherwise they will be
struck by the air bag when it inflates in a
crash. If this happens, serious or fatal injury
will result. X
With a smooth motion, pull the seat belt out
of seat belt outlet :.
X Place the shoulder portion of the seat belt
across the top of your shoulder and the lap
portion across your hips.
X Push latch plate ; into buckle = until it
clicks.
Seat belt adjustment function: The seat
belts on both front seats adjust to the
upper body automatically as necessary
(Y page 51). X
If necessary, adjust the seat belt to the
correct height (Y page 50).
X If necessary, tighten the lap portion to a
snug fit by pulling shoulder portion up.
All lap/shoulder belts except the driver’s seat
belt have special seat belt retractors to
secure child restraints properly. For more
information on special seat belt retractors,
see “Infant and child restraint system”
(Y page 55).
To release the seat belt with seat belt release
button ?, see ( Y page 51).
Seat belt outlet height adjustment X
Raising: Slide seat belt outlet height
adjuster ; upward.
Seat belt outlet height adjuster ; engages
in various positions.
X Lowering: Press and hold release
button :.
X Slide seat belt outlet height adjuster ;
downward.
X Release button : and make sure seat belt
outlet height adjuster ; engages into
place. 50
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Seat belt adjustment function
The seat belt adjustment function adjusts the
seat belts on both front seats to the upper
body
of the respective vehicle occupant. The
seat belt will be pulled slightly tighter for that
purpose when
R you engage the latch plate into the buckle
and then turn the SmartKey in the starter
switch to position 2
R the SmartKey in the starter switch is in
position 2 and you then engage the latch
plate in the buckle
The seat belt adjustment function takes place
with a certain amount of retracting force
when the system senses slack between the
vehicle occupant and the seat belt. Do not
retain the seat belt during this procedure. You
can activate or deactivate the seat belt
adjustment function via the control system
(Y page 138).
Releasing the seat belts X
Press seat belt release button ?
(Y page 50).
Allow the retractor to completely rewind
the seat belt by guiding latch plate ;
(Y page 50).
! Make sure the seat belt retracts
completely.

Otherwise the seat belt and/or
latch plate could get caught or pinched in
the door or in the seat mechanism. This can
damage the seat belt and impair its
effectiveness, and/or cause damage to the
door and/or door trim panel. Such damage
is not covered by the Mercedes-Benz
Limited Warranty.
Damaged seat belts must be replaced.
Contact an authorized Mercedes-Benz
Center.
Enhanced seat belt reminder system When the engine is started, the seat belt
telltale
7 will always illuminate for 6 seconds to remind you and your passengers
to fasten your seat belts.
If the driver’s seat belt is not fastened when
the engine is started, an additional warning
chime

will sound. The warning chime goes out
after approximately 6 seconds or once the
driver’s seat belt is fastened.
If after these 6 seconds the driver’s or the
front passenger’s seat belt (with the front
passenger seat occupied) is not fastened with
front doors closed,
R the seat belt telltale 7 remains
illuminated for as long as either the driver’s
or front passenger’s seat belt is not
fastened.
R and if the vehicle speed once exceeds
15 mph (25 km/h), the seat belt telltale
7 starts flashing and a warning chime
sounds with increasing intensity for a
maximum of 60 seconds or until the
driver’s and front passenger’s seat belt are
fastened.
If you and/or your passenger release the
seat belt during driving, the seat belt
telltale 7 starts flashing and the
warning chime sounds as described before.
If the driver’s or the front passenger’s seat
belt remains unfastened after 60 seconds,
the warning chime stops sounding, the seat
belt telltale 7 stops flashing but
continues to be illuminated.
After a vehicle standstill, the warning chime
is reactivated and the seat belt telltale
7 is flashing again if the vehicle speed
once exceeds 15 mph (25 km/h).
The seat belt telltale 7 will only go out if
both the driver’s and the front passenger’s
seat belt (with the front passenger seat
occupied) are fastened, or the vehicle is
standing still and a front door is opened.
For more information, see “Practical hints”
(Y page 302). Occupant safety
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Emergency Tensioning Device (ETD),
seat belt force limiter
The seat belts for the following seats are
equipped with ETDs and seat belt force
limiters:
R
front seats
R outboard second-row seats
R third-row seats
The ETDs are designed to activate in the
following cases:
R in frontal or rear-end impacts exceeding
the system’s preset deployment threshold
R in side impacts exceeding the system’s
preset deployment threshold on the far
side of the impact
R in certain vehicle rollovers
R if
the restraint systems are operational and
functioning correctly, see “SRS indicator
lamp” (Y page 36)
The ETDs for the front seats will only activate
if the front seat belts are fastened (latch plate
properly inserted into buckle).
The ETDs for the rear outer seats (second-row
seats) or rear seats (third-row seats) will
activate with or without the respective seat
belts fastened.
In an impact, the ETDs remove slack from the
seat belts in such a way that the seat belts fit
more snugly against the body. Seat belt force
limiters, when activated, are employed to
help reduce the peak force exerted by the
seat belts on occupants during a crash.
i The ETDs do not correct an incorrect seat
position or incorrectly worn seat belts.
The ETDs do not pull occupants back
toward the seat backrest. G
Warning!
Pyrotechnic ETDs that were activated must be
replaced.
For your safety, when disposing of the
pyrotechnic ETDs always follow our safety instructions. These are available at any
authorized Mercedes-Benz Center.
The PRE-SAFE
®
system has electrically
operated reversible pre-tensioners that do
not require replacement after activation. Preventive occupant safety (PRE-
SAFE
®
) G
Warning!
The PRE-SAFE ®

system is intended to reduce
the effects of an accident on vehicle
occupants who are wearing their seat belt
properly. Despite your vehicle being equipped
with the PRE-SAFE ®
system, the possibility of
personal injuries occurring as a result of an
accident cannot be eliminated. Therefore,
always drive carefully and adjust your driving
to the prevailing road, weather, and traffic
conditions.
The PRE-SAFE ®
system takes preventive
measures to better protect the occupants
from the possibility of personal injuries in the
following hazardous situations:
R emergency braking maneuvers with the
Brake Assist System (BAS) ( Y page 64)
activated
R critical dynamic driving situations, e.g.
when the vehicle has been caused to
understeer or oversteer because it has
exceeded its physical limitations or in case
of evasive steering maneuvers at speeds
above approximately 85 mph (140 km/h)
PRE-SAFE ®
takes the following measures
when it is activated:
R The front seat belts are pre-tensioned
automatically.
R Vehicles with front passenger seat memory
function: If the passenger seat is in an
unfavorable position, the seat will be
adjusted to a position that seeks to better
protect the occupant. 52
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R
If the vehicle is in a critical dynamic driving
situation, the door windows close, except
for a minimal gap that remains open.
R Vehicles with power tilt/sliding sunroof: If
the vehicle is in a critical dynamic driving
situation, the tilt/sliding sunroof also
closes, except for a minimal gap that
remains open.
If the closing procedure of any of these
elements is blocked, it will stop and open
slightly.
Once the hazardous situation no longer exists
and an accident has been avoided, the seat
belt pre-tensioning is deactivated. All of the
PRE-SAFE ®
settings can be re-adjusted
following the critical driving event.
If the seat belts do not release:
X Adjust the seat backrest or seat slightly to
the rear until the seat belt tension is
reduced.
The locking mechanism releases.
! When moving the seats, make sure there
are no items in the footwell or behind the
seats. Otherwise, you could damage the
seats and/or the items.
For information on the seat belt adjustment
function as an integrated comfort feature of
PRE-SAFE ®
, see ( Y page 51). NECK-PRO active front head
restraints
The NECK-PRO active front head restraints
are intended to offer the driver and front
passenger increased protection from
whiplash-type injuries. In the event of a rear-
end

collision, the NECK-PRO active front head
restraints on the front seats are designed to
move forward in the direction of travel. They
thus provide the head with increased support
earlier on in the collision sequence. The
NECK-PRO active front head restraints will
move forward whether the seats are occupied
or not. G
Warning!
Do not attach any objects (e.g. hangers) to the
head restraint posts. Otherwise, the NECK-
PRO active front head restraints may not be
able

to function properly or offer the intended
degree of protection they were designed for
in the event of a rear-end collision. G
Warning!
Only use seat or head restraint covers which
have
been tested and approved by Mercedes-
Benz for your vehicle model.
Using other seat or head restraint covers may
interfere with or prevent the activation of the
NECK-PRO active front head restraints and/
or the deployment of the front side impact air
bags.
Contact an authorized Mercedes-Benz Center
for availability.
When the NECK-PRO active front head
restraints have been triggered in an accident,
the NECK-PRO active front head restraints
must be reset. Otherwise, the NECK-PRO
active front head restraints cannot offer any
additional protection in the event of another
rear-end collision.
For information on resetting the activated
NECK-PRO active front head restraints, see
“Resetting activated head restraints”
(Y page 310).
You cannot remove the NECK-PRO active
front head restraints. G
Warning!
For your protection, drive only with properly
positioned head restraints.
Adjust

the head restraint so that it is as close
to the head as possible and the center of the
head restraint supports the back of the head
at eye level. This will reduce the potential for
injury to the head and neck in the event of an
accident or similar situation.
For information on head restraint adjustment,
see “Head restraint height” ( Y page 83), or Occupant safety
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see “Head restraint fore and aft adjustment”
(Y page 83).
Correct driver seat adjustment
G
Warning!
In order to avoid possible loss of vehicle
control the following must be done before the
vehicle is put into motion:
R seat adjustment
R head restraint adjustment
R steering wheel adjustment
R rear view mirror adjustment
R fastening of seat belts Steering wheel
G
Observe Safety notes, see page 91.
X Position steering wheel : properly. See
(Y page 92) for manual adjustment and
(Y page 92) for electrical adjustment. Make sure:
R
You can reach the steering wheel with your
arms slightly bent at the elbows.
R You can move your legs freely.
R All displays (including malfunction and
indicator lamps) on the instrument cluster
are clearly visible.
Seat belt G
Observe Safety notes, see page 47.
X Fasten and position your seat belt ;
correctly (Y page 49).
Make sure:
R The seat belt is always fitted snugly.
R Adjust the seat belt so that the shoulder
section is located as close as possible to
the middle of the shoulder.
R Place the lap portion of the seat belt as low
as possible on your hips.
Seat and head restraint G
Observe Safety notes, see page 81.
X Position seat = and head restraint
properly. See ( Y page 82) for seat and
head restraint adjustment.
Observe the following points:
R Always be in a properly seated position.
R The position should be as far rearward from
the front air bag in the steering wheel as
possible, while still permitting proper
operation of vehicle controls.
R Adjust the seat to a comfortable seating
position that still allows you to reach the
accelerator/brake pedal safely.
R The seat must be adjusted so that you can
correctly fasten and position your seat belt.
R The seat backrest must be in a position that
is as nearly upright as possible. 54
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R
Adjust the seat cushion so that the front
edge of the seat cushion lightly supports
your legs.
R Adjust the head restraint so that it is as
close to the head as possible and the
center of the head restraint supports the
back of the head at eye level.
R Never place hands under the seat or near
any moving parts while the seat is being
adjusted. Children in the vehicle
Safety notes If an infant or child is traveling with you in the
vehicle:
X
Secure the child using an infant or child
restraint
appropriate to the age and size of
the child.
X Make sure the infant or child is properly
secured at all times while the vehicle is in
motion. G
Warning!
When leaving the vehicle, always remove the
SmartKey from the starter switch. Always
take the SmartKey with you and lock the
vehicle. Do not leave children unattended in
the

vehicle, even if they are secured in a child
restraint system, or with access to an
unlocked vehicle. A child’s unsupervised
access to a vehicle could result in an accident
and/or serious personal injury. The children
could
R injure themselves on parts of the vehicle
R be seriously or fatally injured through
excessive exposure to extreme heat or cold
R injure themselves or cause an accident with
vehicle equipment that can be operated
even if the SmartKey is removed from the
starter switch or removed from the vehicle,
such as seat adjustment, steering wheel
adjustment, or the memory function If children open a door, they could injure other
persons or get out of the vehicle and injure
themselves or be injured by following traffic.
Do not expose the child restraint system to
direct sunlight. The child restraint system’s
metal parts, for example, could become very
hot, and the child could be burned by these
parts.
G
Warning!
Do not carry heavy or hard objects in the
passenger
or cargo compartment unless they
are firmly secured in place.
Unsecured or improperly positioned cargo
increases a child’s risk of injury in the event
of
R strong braking maneuvers
R sudden changes of direction
R an accident
Infant and child restraint systems G
Observe Safety notes, see page 55.
We recommend all infants and children be
properly restrained at all times while the
vehicle is in motion.
Canada only:
Only use a BabySmart™ compatible child
restraint for the front passenger seat in this
vehicle.
All

lap/shoulder belts except the driver’s seat
belt have special seat belt retractors for
secure fastening of child restraints.
To fasten a child restraint, follow the child
restraint manufacturer’s instructions for
mounting.
To activate the special seat belt retractor:
X Pull the shoulder belt out completely and
let it retract. Occupant safety
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During seat belt retraction, a ratcheting
sound can be heard to indicate that the
special seat belt retractor is activated.
The seat belt is now locked.
X Push down on child restraint to take up any
slack.
To deactivate the special seat belt retractor:
X Release the seat belt buckle and let the
seat belt retract completely.
The
seat belt can then again be used in the
usual manner.
To deactivate the special seat belt retractor
for the front passenger seat, the front
passenger

seat must be in the most backward
position. G
Warning!
Never release the seat belt buckle while the
vehicle
is in motion, since the special seat belt
retractor will be deactivated.
i Information on child seats with mounting
fittings for tether anchorages
(Y page 57).
For information on LATCH-type child seat
anchors (Y page 60).
The use of infant or child restraints is required
by law in all 50 states, the District of
Columbia, the U.S. territories and all
Canadian provinces.
Infants and small children should be seated
in an appropriate infant or child restraint
system. They must be properly secured in
accordance with the manufacturer’s
instructions for the child restraint. All infant
or child restraint systems must comply with
U.S. Federal Motor Vehicle Safety Standards
213 and 225 and Canadian Motor Vehicle
Safety Standards 213 and 210.2.
A statement by the child restraint
manufacturer of compliance with these
standards can be found on the instruction
label on the restraint and in the instruction
manual provided with the restraint. When using any infant restraint, toddler
restraint, or booster seat, make sure to
carefully read and follow all manufacturer’s
instructions for installation and use.
Please read and observe warning labels
affixed to the inside of the vehicle and to
infant or child restraints. G
Warning!
According to accident statistics, children are
safer when properly restrained in the rear
seating positions than in the front seating
position. Thus, we strongly recommend that
children

be placed in the rear seats whenever
possible. Regardless of seating position,
children 12 years old and under must be
seated and properly secured in an appropriate
infant restraint, toddler restraint, or booster
seat recommended for the size and weight of
the child.
The infant or child restraint must be properly
secured with the vehicle’s seat belt, the seat
belt and top tether strap, or lower anchors and
top tether strap, fully in accordance with the
child seat manufacturer’s instructions.
Occupants, especially children, should always
sit as upright as possible, wear the seat belt
properly and use an appropriately sized infant
restraint, toddler restraint, or booster seat
recommended for the size and weight of the
child.
Children can be killed or seriously injured by
an inflating air bag. Note the following
important information when circumstances
require you to place a child in the front
passenger seat:
R USA only: Your vehicle is equipped with air
bag technology designed to deactivate the
front passenger front air bag in your vehicle
when the system senses the weight of a
typical 12-month-old child or less along
with the weight of a standard appropriate
child restraint on the front passenger seat.
R USA only: For children larger than the
typical 12-month-old child, the front
passenger front air bag may or may not be 56
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activated. Always make sure the
42 indicator lamp is
illuminated, indicating that the front
passenger front air bag is deactivated.
R Canada only: Children 12 years old and
under must never ride in the front seat,
except in a Mercedes-Benz authorized
BabySmart™ compatible child seat, which
operates with the BabySmart™ system
installed in the vehicle to deactivate the
front passenger front air bag when it is
installed properly. Otherwise they will be
struck by the air bag when it inflates in a
crash.
If this happens, serious or fatal injury
will result.
R A child in a rear-facing child restraint on the
front passenger seat will be seriously
injured or even killed if the front passenger
front air bag inflates in a collision which
could occur under some circumstances,
even with the air bag technology installed
in your vehicle. The only means to
completely eliminate this risk is to never
place a child in a rear-facing child restraint
in the front seat. We therefore strongly
recommend that you always place a child
in a rear-facing child restraint in a backseat.
R If you must install a rear-facing child
restraint on the front passenger seat
because circumstances require you to do
so, make sure the 42
indicator lamp is illuminated, indicating
that the front passenger front air bag is
deactivated. Should the 42
indicator lamp not illuminate or go out while
the restraint is installed, please check
installation. Periodically check the
42 indicator lamp while
driving to make sure the 42
indicator lamp is illuminated. If the
42 indicator lamp goes out or
remains out, do not transport a child on the
front passenger seat until the system has
been repaired. A child in a rear-facing child restraint on the
front passenger seat will be seriously
injured
or even killed if the front passenger
front air bag inflates.
R If you have to place a child in a forward-
facing child restraint on the front passenger
seat, move the seat as far back as possible,
use the proper child restraint
recommended for the age, size and weight
of the child, and secure child restraint with
the vehicle’s seat belt according to the child
seat manufacturer’s instructions. G
Warning!
Infants and small children should never share
a seat belt with another occupant. During an
accident,

they could be crushed between the
occupant and seat belt.
A child’s risk of serious or fatal injuries is
significantly increased if the child restraints
are not properly secured in the vehicle and/
or the child is not properly secured in the child
restraint.
Children too big for a toddler restraint must
ride in seats using regular seat belts. Position
shoulder belt across chest and shoulder, not
face or neck. A booster seat may be
necessary to achieve proper seat belt
positioning for children over 41 lb (18 kg) until
they reach a height where a lap/shoulder belt
fits properly without a booster.
When the child restraint is not in use, remove
it from the vehicle or secure it with the seat
belt to prevent the child restraint from
becoming a projectile in the event of an
accident.
Installation of infant and child restraint
systems This vehicle is equipped with tether
anchorages for a top tether strap at each of
the

rear seat backrests. The tether anchorage
ring of the second-row middle seat is located
on the rear of the seat base ( Y page 59). Occupant safety
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Top tether straps enable an additional
connection to be made between child
restraint systems secured with LATCH-type
anchors and rear seats. This can further
reduce the risk of injury.
G
Observe Safety notes, see page 55.
Outboard second-row and third-row seats X
Press in lower part of anchorage ring
cover : on the seat backrest on which a
child seat is to be installed.
X Pull on upper part of anchorage ring
cover : to remove cover.
X Store anchorage ring cover : in a
convenient place (e.g. glove box).
X Move the respective head restraint to its
uppermost position ( Y page 88).
X Release the respective seat backrest
(Y page 84).
The seat backrest folds down.
X Guide the top tether strap between head
restraint and top of the seat backrest. X
Securely fasten hook =, which is part of
the tether strap ?, to anchorage ring ;. i
For safety, make sure hook = is attached
to anchorage ring ; beyond the safety
catch, as illustrated.
Make sure
R top tether strap ? is not twisted
R the head restraint is installed and
positioned such that top tether strap ?
can pass freely between the head restraint
and top of the seat backrest
R top tether strap ? is positioned between
the seat backrest and the cargo
compartment cover blind (if installed)
R top tether strap ? is positioned between
the seat backrest and the cargo net (if
installed) G
Warning!
When installing a child seat on a third-row
seat, do not fasten the hook to the strap below
the anchorage ring. Otherwise, the child seat
will not be securely fastened. A child’s risk of
serious or fatal injuries is significantly
increased if the child seat is not properly
secured in the vehicle.
X Fold seat backrest up and push backwards
until it engages audibly.
An outboard second-row seat is locked
properly only when the lock status
indicator is in hinged position and the red
marking is barely visible ( Y page 86).58
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