MERCEDES-BENZ S-Class 2012 W221 Service Manual

Overhead control panelFunctionPage:Eyeglasses compartment433;p Switches the left-
hand reading lamp on/off
281
=u Switches the rear
interior lighting on/off
282
?c Switches the front
interior lighting on/off
282
A3 Opens/closes the
sliding sunroof
96
3 Opens/closes the
panorama roof with power
tilt/sliding panel and roller
sunblinds
97
BG SOS button (mbrace
system)
444
C| Switches the
automatic interior lighting
control on/off
282
FunctionPageDy Extends/retracts the
rear roller sunblind of the
panorama roof with power
tilt/sliding panel
97
Ep Switches the right-
hand reading lamp on/off
281
FRear-view mirrorGButtons for the garage door
opener
451
HMicrophone for mbrace
(emergency call system),
telephone and the Voice
Control System 22
Observe the additional operating instructions.Overhead control panel39At a glance

Door control panel
Front
FunctionPage:Opens the door86;%& Unlocks/locks
the vehicle
86
=Adjusts the seat electrically104?r 45=
Memory function
113
w Adjusts the front-
passenger seat from the
driver’s seat
105
Ac Seat heating108s Seat ventilation109B7Zª\
Adjusts and folds the
exterior mirrors in/out
electrically
111
FunctionPageCW Opens/closes the
side windows
92
t Opens/closes the
roller sunblinds in the rear
side windows
93
Do Opens the trunk lid90p Vehicles with trunk lid
remote closing feature:
opens/closes the trunk lid
90
En Override feature for
the controls in the rear
compartment
67
40Door control panelAt a glance

RearFunctionPage:v Adjusts the front-
passenger seat from the
rear
105
;r 45=
Memory function
113
=Adjusts the seat electrically104?Opens the door86Au Roller sunblind439By Operates the rear
roller sunblind of the
panorama roof with power
tilt/sliding panel from the
rear
98
FunctionPageCW Opens/closes the
side windows
92
t Opens/closes the
roller sunblinds in the rear
side windows
93
Dc Adjusts seat heating108s Adjusts seat
ventilation
109
Door control panel41At a glance

Rear seatsFunctionPage:Cup holder underneath the
rear seat armrest
437
;Cup holder in the rear seat
armrest
437
=Control panel for
multicontour seat in the
rear compartment
108
?Stowage compartment in
the rear seat armrest
434
AStowage box in the seat
backrest
434
42Rear seatsAt a glance

Useful information ..............................44
Occupant safety .................................. 44
Children in the vehicle ........................62
Panic alarm .......................................... 68
Driving safety systems .......................68
Theft deterrent locking systems .......7543Safety

Useful information
i This Operator's Manual describes all
models and all standard and optional
equipment of your vehicle available at the
time of publication of the Operator's
Manual. Country-specific differences are
possible. Please note that your vehicle may
not be equipped with all features
described. This also applies to safety-
related systems and functions.
i Please read the information on qualified
specialist workshops ( Y page 31).
Occupant safety
Overview of occupant safety
In this section, you will learn the most
important facts about the restraint system
components of the vehicle.
The restraint system consists of:
R seat belts
R child restraint systems
R LATCH-type (ISOFIX) child seat anchors
Additional protection is provided by:
R SRS (Supplemental Restraint System)
R NECK-PRO head restraints/NECK-PRO
luxury head restraints
R PRE-SAFE ®
R Air bag system components with:
- PASSENGER AIR BAG OFF indicator lamp
- front-passenger seat with Occupant
Classification System (OCS)
The different air bag systems work
independently of each other. The protective
functions of the system work in conjunction
with each other. Not all air bags are deployed
in an accident.
GWARNING
Modifications to or work improperly
conducted on restraint system components
or their wiring, as well as tampering with
interconnected electronic systems, can lead
to the restraint systems no longer functioning
as intended.
Air bags or Emergency Tensioning Devices
(ETDs), for example, could deploy
inadvertently or fail to deploy in accidents
although the deceleration threshold for air
bag deployment is exceeded. Therefore,
never modify the restraint systems. Do not
tamper with electronic components or their
software.
i See "Children in the vehicle"
( Y page 62) for more information on
infants and children traveling with you in
the vehicle and restraints for infants and
children.
SRS (Supplemental Restraint System)
Introduction
SRS consists of:
R the 6 SRS warning lamp
R air bags
R air bag control unit (with crash sensors)
R Emergency Tensioning Devices
R belt force limiters
SRS reduces the risk of occupants coming
into contact with the vehicle's interior in the
event of an accident. It can also reduce the
effect of the forces to which occupants are
subjected during an accident.
SRS warning lamp
SRS functions are checked regularly when
you switch on the ignition and when the
engine is running. Therefore, malfunctions
can be detected in good time.
The 6 SRS warning lamp in the instrument
cluster lights up when the ignition is switched
on. It goes out no later than a few seconds
after the engine is started.
44Occupant safetySafety

The SRS components are in operational
readiness when the 6 SRS warning lamp
is not lit while the engine is running .GWARNING
The SRS self-check has detected a
malfunction if the 6 SRS warning lamp:
R does not come on at all
R fails to go out approximately 4 seconds
after the engine was started
R comes on after the engine was started or
while driving
For your safety, Mercedes-Benz strongly
recommends that you have the system
checked as soon as possible at an authorized
Mercedes-Benz Center. Otherwise the SRS
may not be activated when it is needed in an
accident, which could result in serious or fatal
injury. The SRS might also deploy
unexpectedly and unnecessarily which could
also result in injury.
In addition, improper work on the SRS creates
a risk of rendering the SRS inoperative or
causing unintended air bag deployment. Work
on the SRS must therefore only be performed
by qualified technicians. Contact an
authorized Mercedes-Benz Center.
If it is necessary to modify an air bag system
to accommodate a person with disabilities,
contact an authorized Mercedes-Benz Center
for details. USA only: Call our Customer
Assistance Center at 1-800-FOR-MERCedes
(1-800-367-6372) for details.
Safety guidelines for seat belts,
Emergency Tensioning Devices (ETDs)
and air bags
GWARNING
R Damaged seat belts or seat belts that have
been subjected to stress in an accident
must be replaced. Their anchoring points
must also be checked. Only use seat belts
installed or supplied by an authorized
Mercedes-Benz Center.
R Air bags and pyrotechnic Emergency
Tensioning Devices (ETDs) contain
perchlorate material, which may require
special handling and regard for the
environment. Check your national disposal
guidelines. California residents, see
www.dtsc.ca.gov/HazardousWaste/
Perchlorate/index.cfm .
R Air bags and ETDs are designed to function
on a one-time-only basis. An air bag or ETD
that has deployed must be replaced. PRE-
SAFE ®
has electrically operated reversible
belt tensioners in addition to the
pyrotechnic ETDs.
R Do not pass seat belts over sharp edges.
They could tear.
R Do not make any modification that could
change the effectiveness of the seat belts.
R Do not bleach or dye seat belts as this may
severely weaken them. In a crash they may
not be able to provide adequate protection.
R No modifications of any kind may be made
to any components or wiring of the SRS.
R Do not change or remove any component
or part of the SRS.
R Do not install additional trim material, seat
covers, badges, etc. to the:
- padded steering wheel boss
- front-passenger air bag cover
- outer side of front seat bolsters
- side trim next to the rear seat backrest
- roof lining trim
R Do not install additional electrical/
electronic equipment on or near SRS
components and wiring.
R Keep area between air bags and occupants
free of objects (e.g. packages, purses,
umbrellas, etc.).
R Do not hang items such as coat hangers
from the coat hooks or handles over the
door. These items may be thrown around in
the vehicle and cause head and otherOccupant safety45SafetyZ

injuries when the window curtain air bag is
deployed.
R Air bag system components will be hot after
an air bag has inflated. Do not touch them.
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 Improper repair work on the SRS creates a
risk of rendering the SRS inoperative or
causing unintended air bag deployment.
Work on the SRS must therefore only be
performed by qualified technicians.
Contact an authorized Mercedes-Benz
Center.
R For your protection and the protection of
others, when scrapping the air bag unit or
ETD, our safety instructions must be
followed. These instructions are available
from any authorized Mercedes-Benz
Center.
R Given the considerable deployment speed,
required inflation volume, and the material
of the air bags, there is the possibility of
abrasions or other, potentially more serious
injuries resulting from air bag deployment.
If you sell your vehicle, Mercedes-Benz
strongly recommends that you inform the
subsequent owner that the vehicle is
equipped with SRS. Also, refer them to the
applicable section in the Operator's Manual.
Air bags
Important safety notes
GWARNING
Air bags are designed to reduce the incidence
of injuries and fatalities in certain situations:
R frontal impacts (driver's and front-
passenger front air bags)
R side impacts (side impact air bags and
window curtain air bags)
R rollover (window curtain air bags)
However, no system available today can
completely eliminate injuries and fatalities.
When the air bags are deployed, a small
amount of powder is released. The powder
generally does not constitute a health hazard
and does not indicate that there is a fire in the
vehicle. In order to prevent potential
breathing difficulties, you should leave the
vehicle as soon as it is safe to do so. If you
have any breathing difficulty but cannot get
out of the vehicle after the air bag inflates,
then get fresh air by opening a window or
door.GWARNING
To reduce the risk of injuries during front air
bag inflation, the driver and front-passenger
must always be seated correctly and have
their seat belts fastened accordingly.
For maximum protection in the event of a
collision, you must always be in the normal
seat position with your back against the
backrest. Fasten your seat belt and make sure
that it is correctly positioned on your body.
Since the air bag inflates with considerable
speed and force, a proper seating position
and correct positioning of the hands on the
steering wheel will help to keep you at a safe
distance from the air bag. Occupants who are
not wearing their seat belt, are not seated
properly or are too close to the air bag can be
seriously injured or killed by an air bag as it
inflates with great force instantaneously:
R Sit with the seat belt properly fastened in a
position that is as upright as possible with
your back against the seat backrest.
R Move the driver's seat as far back as
possible, still permitting proper operation
of vehicle controls. The distance from the
center of the driver's chest to the center of
the air bag cover on the steering wheel
must be at least 10 inches (25 cm) or more.
You should be able to accomplish this by
adjusting the seat and steering wheel. If
you have any difficulties, please contact an
authorized Mercedes-Benz Center.
46Occupant safetySafety

RDo not lean your head or chest close to the
steering wheel or dashboard.
R Only hold the steering wheel by the rim.
Placing hands and arms inside the rim can
increase the risk and potential severity of
hand/arm injury when the driver front air
bag inflates.
R Adjust the front-passenger seat as far back
as possible from the dashboard when the
seat is occupied.
R Occupants, especially children, should
never place their bodies or lean their heads
in the area of the door where the side
impact air bag inflates. This could result in
serious injuries or death should the side
impact air bag be deployed. Always sit as
upright as possible, wear the seat belt
properly and use an appropriately sized
child restraint, infant restraint or booster
seat recommended for the size and weight
of the child.
Failure to follow these instructions can result
in severe injuries to you or other occupants.
If you sell your vehicle, it is important that you
make the buyer aware of this safety
information. Be sure to give the buyer this
Operator's Manual.GWARNING
Accident research shows that the safest place
for children in an automobile is in a rear seat.
There is a possibility for a side impact air bag-
related injury if occupants, especially
children, are not properly seated or restrained
when next to a side impact air bag which
needs to deploy rapidly in a side impact in
order to do its job.
To help avoid the possibility of injury, please
follow these guidelines:
(1)Occupants, especially children,
should never place their bodies or
lean their heads in the area of the
door where the side impact air bag
inflates. This could result in
serious injuries or death shouldthe side impact air bag be
deployed.(2)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. and
for children 12 years old and
under, use an appropriately sized
infant restraint, toddler restraint,
or booster seat recommended for
the size and weight of the child.(3)Always wear seat belts properly.
If you believe that, even with the use of these
guidelines, it would be safer for your rear seat
occupants to have the rear mounted side
impact air bags deactivated, then
deactivation can be carried out upon your
written request at an authorized Mercedes-
Benz Center at an additional cost.
Please contact an authorized Mercedes-Benz
Center or call the Customer Assistance
Center (in the USA) at 1-800-FOR-MERCedes
(1-800-367-6372), or Customer Service (in
Canada) at 1-800-387-0100 for details.
The air bags are only deployed if the air bag
control unit detects the need for deployment.
Only in the event of such a situation will they
provide their supplemental protection.
The driver and passenger should always wear
their seat belts. Otherwise, it is not possible
for the air bags to provide their supplemental
protection.
In the event of other types of impacts and
impacts below air bag deployment
thresholds, the air bags will not deploy. The
driver and passengers will then be protected
to the extent possible by a properly fastened
seat belt. A properly fastened seat belt is also
needed to provide the best possible
protection in a rollover.
Air bags provide additional protection; they
are not, however, a substitute for seat belts.
All vehicle occupants must fasten their seat
Occupant safety47SafetyZ

belts regardless of whether your vehicle is
equipped with air bags or not.
It is important for your safety and that of your
passenger to have deployed air bags replaced
and to have any malfunctioning air bags
repaired. This will help to make sure the air
bags continue to perform their protective
function for the vehicle occupants in the
event of a crash.
Front air bags
The front air bags increase protection for the
driver's and front-passenger's head and
chest.
Driver's air bag : deploys in front of the
steering wheel; front-passenger front air
bag ; deploys in front of and above the glove
box.
They are deployed:
R in the event of certain frontal impacts
R if the system determines that air bag
deployment can offer additional protection
to that provided by the seat belt
R if the seat belt is fastened
R independently of other air bags in the
vehicle
If the vehicle overturns, the front air bags are
generally not deployed unless the system
detects high vehicle deceleration in a
longitudinal direction.
Your vehicle has adaptive, two-stage front air
bags. In the event of a collision, the air bag
control unit evaluates the vehicle
deceleration. In the first deployment stage,
the front air bag is filled with enough
propellant gas to reduce the risk of injuries.
The front air bag is fully deployed if a second
deployment threshold is exceeded within a
few milliseconds.
The deployment of the front-passenger front
air bag is also influenced by the weight
category of the front passenger, which is
determined by the Occupant Classification
System (OCS) ( Y page 50).
The lighter the passenger side occupant, the
higher the vehicle deceleration rate required
(predicted at the start of the impact) for
second stage inflation of the front-passenger
front air bag. In the second stage, the front
air bags are inflated with the maximum
amount of propellant gas available.
The front air bags are not deployed in
situations where a low impact severity is
predicted. You will then be protected by the
fastened seat belt.
The front-passenger front air bag will only
deploy if:
R the system, based on the OCS weight
sensor readings, detects that the front-
passenger seat is occupied.
R the 42 indicator lamp in the
center console is not lit, ( Y page 50).
R the air bag control unit predicts a high
impact severity.
Side impact air bagsGWARNING
The pressure sensors for side impact air bag
control are located in the doors. Do not
modify any components of the doors or door
trim panels including, for example, the
addition of door speakers.
Improper repair work on the doors or the
modification or addition of components to the
doors create a risk of rendering the side
impact air bags inoperative or causing
unintended air bag deployment. Work on the
doors must therefore only be performed by
48Occupant safetySafety