ECU MERCEDES-BENZ S-Class 2011 W221 Owner's Manual

When the OCS senses that the front-
passenger seat occupant is classified as
being heavier than the weight of a typical 12-
month-old child seated in a standard child
restraint or as being a small individual (such
as a young teenager or a small adult), the
42 indicator lamp will illuminate
for approximately 6 seconds when the engine
is started and then, depending on occupant
weight sensor readings from the front-
passenger seat, remain illuminated or go out.
With the 42 indicator lamp
illuminated, the front-passenger front air bag
is deactivated. With the 42
indicator lamp out, the front-passenger front
air bag is activated.
When the OCS senses that the front-
passenger seat occupant is classified as an
adult or someone larger than a small
individual, the 42 indicator lamp
will illuminate for approximately 6 seconds
when the engine is started and then go out,
indicating that the front-passenger front air
bag is activated.
If the 42 indicator lamp is
illuminated, the front-passenger front air bag
is deactivated and will not be deployed.
If the 42 indicator lamp is not
illuminated, the front-passenger front air bag
is activated and will be deployed:
R in the event of certain frontal impacts
R if impact exceeds a preset deployment
threshold
R independently of the side impact air bags
If the front-passenger front air bag is
deployed, the rate of inflation will be
influenced by:
R the rate of vehicle deceleration as assessed
by the air bag control unit
R the front passenger's weight category as
identified by OCS
For further information, see the section
regarding air bag display messages
( Y page 386).GWarning
According to accident statistics, children are
safer when properly restrained on the rear
seats than on the front-passenger seat. 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
child restraint system or booster seat
recommended for the size and weight of the
child.
The infant or child restraint system 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 appropriate 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 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 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 eliminate
this risk completely is never to place a child
in a rear-facing child restraint in the front-
passenger seat. We therefore strongly
Occupant safety49SafetyZ

recommend that you always place a child
in a rear-facing child restraint on the rear
seat.
RIf you install a rear-facing child restraint on
the front-passenger seat, 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.
RIf you 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
-secure child restraint with the vehicle's
seat belt according to the child seat
manufacturer's instructions
RFor children larger than a typical 12-month-
old child, the front-passenger front air bag
can be activated or deactivated.
Deployment of the driver front air bag does
not mean that the front-passenger front air
bag should also have deployed.
OCS may have determined:
Rthat the seat was unoccupied or occupied
by a weight of up to or less than that of a
typical 12-month-old child seated in a
standard child restraint
Rthat the seat was occupied by a small
individual (e.g. a young teenager or a small
adult) or a child who weighs more than a
typical 12-month-old child in a standard
child restraint system
These are examples of when OCS deactivates
the front-passenger front air bag. The air bag
is deactivated despite the impact fulfilling the
criteria for deploying the driver's front air bag.
If the SmartKey has been removed from the
ignition lock or is in position 0, indicator lamp
42: does not light up.
GWarning
If the red SRS 6 indicator lamp in the
instrument cluster and the 42
indicator lamp are lit at the same time, there
is a malfunction in the OCS. The front
passenger front air bag will be deactivated in
this case. Have the system checked by
qualified technicians as soon as possible.
Contact an authorized Mercedes-Benz
Center.
Only have the seat repaired or replaced at an
authorized Mercedes-Benz Center.
In order to ensure proper operation of the air
bag system and OCS:
RSit with the seat belt properly fastened in a
position that is as upright as possible with
your back against the seat backrest.
RWhen seated, a passenger should not
position him/herself in such a way as to
cause the passenger's weight to be lifted
from the seat cushion as this may result in
the OCS being unable to correctly
50Occupant safetySafety

RMake sure the seat belt is always routed
snugly. Take special care of this when
wearing loose clothing.
RNever 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.
RSeat 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.
RPregnant 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.
RPlace the seat backrest in a position that is
as upright as possible.
RCheck your seat belt during travel to make
sure it is properly positioned.
RNever place your feet on the instrument
panel, dashboard, or on the seat. Always
keep both feet on the floor in front of the
seat.
RWhen using a seat belt to secure infant
restraints, toddler restraints, or children in
booster seats, always follow the child seat
manufacturer's instructions.
GWarning
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 seat belts
GWarning
According to accident statistics, children are
safer when properly restrained on the rear
seats than on the front-passenger seat. Thus,
we strongly recommend that children be
placed in the rear seat whenever possible.
Regardless of seating position, children 12
years old and under must be seated and
properly secured in an appropriately sized
child restraint system or booster seat
recommended for the size and weight of the
child. For additional information, see the
"Children in the vehicle" section.
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.
XAdjust the seat and move the backrest to
an almost vertical position (Y page 100).
XPull the seat belt smoothly through belt
sash guide :.
XWithout twisting it, guide the shoulder
section of the seat belt across the middle
of your shoulder and the lap section across
your hips.
Occupant safety57SafetyZ

XEngage belt tongue ; in buckle =.
Seat-belt adjustment: if necessary, the
driver's and front-passenger seat belts
automatically adjust to the upper body
(Y page 58).
XIf necessary, adjust the seat belt to the
appropriate height (Y page 58).
XIf necessary, pull upwards on the shoulder
section of the seat belt to tighten the belt
across your body.
All seat belts in the vehicle, except the
driver's seat belt, are equipped with a special
seat belt retractor to secure child restraint
systems properly. For further information on
"Special seat belt retractors", see
(Y page 62).
For more information about releasing the seat
belt with release button ?, see "Releasing
seat belts" (Y page 58).
Seat belt adjustment
The seat-belt adjustment function adjusts the
driver's and front-passenger seat belt to the
upper body of the occupants.
The belt strap is tightened slightly when:
Ryou engage the belt tongue in the belt
buckle and you then turn the SmartKey to
position 2 in the ignition lock.
Rthe SmartKey is in position 2 in the ignition
lock and you then engage the belt tongue
in the buckle.
The seat-belt adjustment will apply a certain
tightening force if any slack is detected
between the occupant and the seat belt. Do
not hold on to the seat belt tightly while it is
adjusting. You can switch the seat-belt
adjustment on and off in the on-board
computer (Y page 378).
Seat belt outlet height adjustment
You can adjust the seat belt height on the
driver's seat and the front-passenger seat.
Adjust the height so that the upper part of the
seat belt is routed across the center of your
shoulder.
XTo raise: slide the belt sash guide upwards.
The belt sash guide engages in various
positions.
XTo lower: press and hold belt sash guide
release :.
XSlide the belt sash guide downwards.XRelease belt sash guide release : and
make sure that the belt sash guide has
engaged.
The outer seat belts in the rear compartment
are adjusted automatically.
Releasing seat belts
XPress release button ? (Y page 57) and
guide belt tongue ; back towards belt
sash guide :.
! Make sure that the seat belt is fully rolled
up. Otherwise, the seat belt or belt tongue
will be trapped in the door or in the seat
mechanism. This could damage the door,
the door trim panel and the seat belt.
Damaged seat belts can no longer fulfill
their protective function and must be
replaced. Consult an authorized Mercedes-
Benz Center.
Belt warning for driver and front
passenger
Regardless of whether the driver's and front-
passenger seat belts have already been
58Occupant safetySafety

The belt tensioners are triggered depending
on the type and severity of an accident:
R in the event of a head-on or rear-end
collision, if the vehicle decelerates or
accelerates rapidly in a longitudinal
direction during the initial stages of the
impact
R in the event of a side impact, on the side
opposite the impact if the vehicle
decelerates or accelerates rapidly in a
lateral direction
R in certain situations, if the vehicle
overturns and the system determines that
it can provide additional protection
If the air bags are deployed, you will hear a
bang and a small amount of powder may also
be released. Only in rare cases will the bang
affect your hearing. The powder that is
released generally does not constitute a
health hazard. The 6 SRS warning lamp
lights up.GWarning
Pyrotechnic Emergency Tensioning Devices
that have been deployed must be renewed.
For your safety, when disposing of Emergency
Tensioning Devices, always observe the
safety instructions. These are available from
any authorized Mercedes-Benz Center.
The PRE-SAFE ®
system has electrically
operated reversible pre-tensioners that do
not require replacement after activation.
Automatic comfort-fit feature
The front seat belts have an automatic
comfort-install feature. In vehicles with a rear
bench seat with electrically adjustable outer
seats, the seat belts for the outer seats have
an automatic comfort-install feature. The
automatic comfort-install feature reduces the
retraction force of the seat belts. This results
in increased seat belt comfort.
Children in the vehicle
Important safety notes
GWarning
When leaving the vehicle, always remove the
SmartKey from the ignition lock. 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
ignition lock 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 on these
parts.
GWarning!
Do not carry heavy or hard objects in the
passenger compartment or trunk 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
60Children in the vehicleSafety

If an infant or child is traveling in the vehicle:XSecure the child using an infant or child
restraint system appropriate to the age and
weight of the child.XMake sure that the infant or child is
properly secured at all times while the
vehicle is in motion.
Child restraint systems
Important safety notes
GWarning
Observe "Important safety notes"
( Y page 60).
We recommend all infants and children be
properly restrained using the child restraint
systems at all times while the vehicle is in
motion.
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 always be
seated in an infant or child seat restraint
system appropriate for the size and weight of
the child. They must be properly secured in
accordance with the manufacturer's
installation instructions for the infant or child
seat restraint system. All infant and child seat
restraint systems must comply with the US
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 system. You will also
find the statement in the instruction manual
provided with the child restraint system.
When using an infant restraint system, child
restraint system or booster seat, make sure
to carefully read and follow all manufacturer's
instructions for installation and use.
Please read the warning labels affixed to the
interior of the vehicle or to the infant restraint
or child restraint system.GWarning
According to accident statistics, children are
safer when properly restrained on the rear
seats than on the front-passenger seat. 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
child restraint system or booster seat
recommended for the size and weight of the
child.
The infant or child restraint system 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 appropriate 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 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 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 eliminate
Children in the vehicle61SafetyZ

this risk completely is never to place a child
in a rear-facing child restraint in the front-
passenger seat. We therefore strongly
recommend that you always place a child
in a rear-facing child restraint on the rear
seat.
R If you install a rear-facing child restraint on
the front-passenger seat, 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 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
- secure child restraint with the vehicle's
seat belt according to the child seat
manufacturer's instructions
R For children larger than a typical 12-month-
old child, the front-passenger front air bag
can be activated or deactivated.GWarning
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
the shoulder belt across the 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.
Special seat belt retractorGWarning
Observe "Important safety notes"
( Y page 60).
All seat belts in the vehicle, except the
driver's seat belt, are equipped with a special
seat belt retractor. When activated, the
special seat belt retractor ensures that the
seat belt cannot slacken after being fastened.
Installing a child restraint system:
XAlways comply with the manufacturer's
installation instructions.XPull the seat belt smoothly from the inertia
reel.XEngage the seat belt tongue in the belt
buckle.
Activating the special seat belt retractor:
XPull the seat belt out fully and let the inertia
reel retract it again.
While the seat belt is retracting, you should
hear a ratcheting sound. The special seat
belt retractor function is enabled.XPush down on the child restraint system to
take up any slack.62Children in the vehicleSafety

Removing a child restraint system/
deactivating the special seat belt retractor:XAlways comply with the manufacturer's
installation instructions.XPress the seat belt release button and
guide the belt tongue to the belt outlet.
The special seat belt retractor function is
deactivated.GWarning
Never release the seat belt buckle while the
vehicle is in motion, since the special seat belt
retractor will be deactivated.
LATCH-type child restraint (ISOFIX) in
the rear
GWarning
Observe "Important safety notes"
( Y page 60).
GWarning
Children that are too large for a child restraint
must travel in seats using normal seat belts.
Position shoulder belt across the chest and
shoulder, not face or neck.
In order to attain the correct seating position
for children weighing over 41 lb (18 kg), it may
be necessary to use a booster seat until they
reach a height where a normal lap/shoulder
seat belt lies properly across their bodies
without the need for a booster seat.
Install the child restraint system according to
the manufacturer's instructions.
The child restraint system must be installed
firmly on both brackets.
An incorrectly installed child restraint system
can come loose in the event of an accident,
causing the child to be severely or fatally
injured.
Child restraint systems/child restraint
retaining brackets that are damaged or have
suffered damage due to an impact must be
replaced.
ISOFIX is a standardized securing system for
specially designed child restraint systems on
the rear seats. Securing rings for two LATCH-
type (ISOFIX) child restraint systems are
installed on the left and right of the rear seats.
Use the vehicle's seat belts to install child
restraint systems without the ISOFIX
securing system. Follow the manufacturer's
instructions for of child restraint systems.
! Vehicles with a center seat in the rear:
when installing the LATCH-type (ISOFIX)
child restraint system, make sure that the
seat belt for the center seat does not get
trapped. Otherwise, the seat belt could be
damaged.
Installation instruction : indicates the
installation point of securing ring 2.
XMove the rear seat backrest of the
electrically adjustable rear seat to the
upright position ( Y page 102).XFold upholstered lining = and the Velcro
fastener upwards.XTurn installation aid ? to a vertical
position, so that upholstered lining = does
not fold back down.XInstall the LATCH-type (ISOFIX) child
restraint system on both securing
rings ;. Comply with the manufacturer's
instructions when installing the LATCH-
type (ISOFIX) child restraint system.GWarning!
Vehicles with rear power seats:
Children in the vehicle63SafetyZ

All of the above will lessen the
effectiveness of the child restraint and thus
increase the chance or severity of injury in
an accident.
Child-proof locks
Child-proof locks for the rear doors
GWarning
Observe "Important safety notes"
(Y page 60).
GWarning
Children could open a rear door from inside
the vehicle. This could result in serious
injuries or an accident. Therefore, when
children ride in the rear always secure the rear
doors with the child-proof locks.
You can secure each door individually with
the child-proof locks on the rear doors. A door
secured with a child-proof lock cannot be
opened from inside the vehicle. When the
vehicle is unlocked, the door can be opened
from the outside.
XTo activate: press the child-proof lock
lever up in the direction of arrow :.
XMake sure that the child-proof locks are
working properly.
XTo deactivate: press the child-proof lock
lever down in the direction of arrow ;.
Override feature for the rear side
windows
GWarning
Observe "Important safety notes"
(Y page 60).
GWarning
When children ride on the vehicle's rear seats,
activate the override switch. Otherwise, the
children could be injured, e.g. by trapping
themselves in the rear side window.
For the rear compartment, you can disable
operation of:
Rthe rear side windows
Rthe cigarette lighter in the rear
Radjustment of the front-passenger seat
from the rear compartment
Rthe sunblinds:
-in the roof
-of the rear window
-of the rear side windows
XTo activate/deactivate: press button :.
If indicator lamp ; is lit, the rear-
compartment functions are disabled. The
rear side windows can then only be
operated using the switches on the driver's
door. If indicator lamp ; is off, the
functions are enabled. The rear side
windows can be operated using the
switches in the rear compartment.
Children in the vehicle65SafetyZ

Vehicle equipment
i This manual describes all the standard
and optional equipment of your vehicle
which was available at the time of
purchase. Country-specific differences are
possible. Bear in mind that your vehicle
may not feature all functions described
here. This also refers to safety-related
systems and functions.
SmartKey
Important safety notes
GWarning!
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.
GWarning
Do not carry heavy or hard objects in the
passenger 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
General information
If you cannot open or lock the vehicle with the
SmartKey, either the battery in the SmartKey
is empty, the SmartKey is faulty, or the starter
battery is discharged.
XCheck the battery in the SmartKey and
replace it if necessary ( Y page 80).XUnlock the driver's door with the
mechanical key ( Y page 84).XLock the vehicle ( Y page 84).XHave the starter battery and battery
contacts checked by an authorized
Mercedes-Benz Center.
If the SmartKey is faulty, contact Roadside
Assistance or an authorized Mercedes-Benz
Center.
SmartKey functions
General notes
i USA only:
This device complies with Part 15 of the
FCC regulations. Operation is subject to
the following conditions:
1. This device must not cause any harmful
interference, and
2. This device must be able to
accommodate interference that is
received, including interference which
could cause unwanted functions.
76SmartKeyOpening and closing