warning light MERCEDES-BENZ R-Class 2012 W251 Owner's Guide

Ensure that:
R Top Tether hook = is hooked into Top
Tether anchorage ; as shown
R Top Tether belt ? is not twisted
R Top Tether belt ? is routed between the
seat backrest and the cargo
compartment cover if the cargo
compartment cover is installed.
R Top Tether belt ? is routed between the
seat backrest and the cargo net if the
cargo net is installed.GWARNING
Do not secure the Top Tether hook to the loop
underneath the Top Tether anchorage if you
are securing a child restraint system in the
third row of seats. The child restraint system
is not secured if you do so. An incorrectly
fitted child restraint system cannot perform
its intended protective function in the event
of an accident, and could lead to injuries.
XSwing back the seat backrest until it
engages ( Y page 253).
The outer seats in the second row are only
locked if the lock verification indicator is
folded in and the indicator area is barely
visible ( Y page 253).GWARNING
Make sure that the seats are locked and that
the backrests are locked in a vertical position
after fitting the Top Tether belt.
The outer seats in the second row are only
locked if the lock verification indicator is
folded in and the indicator area is barely
visible.
If the backrests are not locked, they could fold
forwards in the event of an accident, sudden
braking or a sudden change of direction.
Instead of restraining an occupant, they could
cause additional serious or even fatal injury.
XMove the head restraint back down again
slightly if necessary ( Y page 100). Makesure that you do not interfere with the
correct routing of Top Tether belt ?.XInstall the LATCH-type (ISOFIX) child
restraint system with Top TetherComply
with the manufacturer's installation
instructions when doing so. Make sure that
Top Tether belt ? is tight.
Center seat in the 2nd row
GWARNING
Only secure a child restraint system on the
center seat in the second row when the belt
buckles of the outer seats are not obstructed
or overlapped by the child restraint system.
Not all child restraint systems, including some
Mercedes-Benz approved child restraint
systems, can be used in this seat position. For
further information contact an authorized
Mercedes-Benz Center.
Do not use the LATCH-type anchors (ISOFIX)
or seat belt buckles for the outer seats in
conjunction with a child seat in the second-
row center seat. Child seats in the center
seating position must only be secured by the
center seat position seat belt inserted into the
seat belt buckle for the second-row center
seat.
GWARNING
Please be aware that installation of a child
seat in the second-row center seat position
can prevent the folding forward of the outer
second-row seats which can obstruct access
to and exit from the third-row seats. This
could affect the occupants' on the third-row
seats ability to exit the vehicle. In case of an
accident it will be difficult for occupants of the
third-row seats to leave the vehicle. Serious
injuries could be the result.
Install a child seat in one of the outer seating
positions according to the installation
instructions if access to the third-row seats is
required.
XMove the head restraint upwards.Children in the vehicle61SafetyZ

XPull release loop : in the direction of the
arrow.XFold seat backrest ; forward in the
direction of seat cushion = until Top
Tether anchorage ? is accessible.XRoute Top Tether belt B under the head
restraint between the two head restraint
bars.XHook Top Tether hook A of Top Tether belt
B into Top Tether anchorage ?.Ensure that:
R Top Tether hook A is hooked into Top
Tether anchorage ? as shown
R Top Tether belt B is not twisted
R Top Tether belt B is routed between the
seat backrest and the cargo
compartment cover if the cargo
compartment cover is installed.
R Top Tether belt B is routed between the
seat backrest and the cargo net if the
cargo net is installed.XSwing back the seat backrest until it
engages audibly ( Y page 253).GWARNING
Always lock the rear seat backrests in their
upright position when the rear seats are
occupied by passengers. Lock the rear seat
backrests in their upright position after
installing the TopTether straps or when the
extended cargo compartment is not in use.
Make sure that rear seat backrests are
secured properly by pushing and pulling on
the seat backrests. If the seat backrest is not
locked properly, the seat backrest could fold.
The child restraint system is no longer
supported properly or held in position and can
no longer fulfill its function. That could cause
serious or even fatal injuries.
XMove the head restraint back down again
slightly if necessary ( Y page 100). Make
sure that you do not interfere with the
correct routing of Top Tether belt B.XInstall the LATCH-type (ISOFIX) child
restraint system with Top Tether. Comply
with the manufacturer's installation
instructions when doing so. Make sure that
Top Tether belt B sits taut.62Children in the vehicleSafety

Child-proof locks
Important safety notesGWARNING
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.
Child-proof locks for the rear doors
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 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 down in the direction of arrow ;.XMake sure that the child-proof locks are
working properly.XTo deactivate: press the child-proof lock
lever up in the direction of arrow :.
Override feature for the rear side
windows
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.
XTo activate/deactivate: press switch :.
Switch : is pushed in or extended. If the
switch has engaged, operation of the rear
side windows is deactivated. Operation is
then only possible using the switches in the
driver's door.Children in the vehicle63SafetyZ

Panic alarmX To activate: press ! button : for at
least one second.
An alarm sounds and the exterior lighting
flashes.XTo deactivate: press ! button :
again.
or
XInsert the SmartKey into the ignition lock.
or
XPress the KEYLESS-GO Start/Stop button.
The KEYLESS-GO key must be in the
vehicle.
i USA only:
This device complies with Part 15 of the
FCC Rules. Operation is subject to the
following two conditions:
1. This device may not cause interference,
and
2. this device must accept any interference
received, including interference that may
cause undesired operation.
Any unauthorized modification to this
device could void the user's authority to
operate the equipment.
The product label with FCC ID and IC
certification number can be found in the
battery case of the SmartKey.
i Canada only:
This device complies with RSS-Gen of
Industry Canada. Operation is subject to
the following two conditions:
1. This device may not cause harmful
interference, and
2. this device must accept any interference
received, including interference that may
cause undesired operation.
Any unauthorized modification to this
device could void the user's authority to
operate the equipment.
The product label with FCC ID and IC
certification number can be found in the
battery case of the SmartKey.
Driving safety systems
Driving safety systems overview
In this section, you will find information about
the following driving safety systems:
R ABS ( Anti-lock Braking System)
R BAS ( Brake Assist System)
R ESP ®
(E lectronic Stability Program)
R EBD ( Electronic Brake force Distribution)
R Distance warning function (vehicles with
DISTRONIC)
Important safety notes
GWARNING
The following factors increase the risk of
accidents:
R Excessive speed, especially in turns
R Wet and slippery road surfaces
R Following another vehicle too closely
The driving safety systems described in this
section cannot reduce these risks or prevent
the natural laws of physics from acting on the
vehicle. They cannot increase braking or
steering efficiency beyond that afforded by
the condition of the vehicle brakes and tires
or the traction afforded.
Only a safe, attentive, and skillful driver can
prevent accidents.
The capabilities of a vehicle equipped with the
driving safety systems described in this
64Driving safety systemsSafety

section must never be exploited in a reckless
or dangerous manner which could jeopardize
the user's safety or the safety of others.
Always adjust your driving style to the
prevailing road and weather conditions and
keep a safe distance to other road users and
objects on the street.
If a driving system malfunctions, other driving
safety systems may also switch off. Observe
indicator and warning lamps that may come
on as well as messages in the multifunction
display that may appear.
i Please note that the driving safety
systems described only work as effectively
as possible when there is adequate contact
between the tires and the road surface. Pay
particular attention to the information
regarding tires, recommended minimum
tire tread depths etc. in the "Wheels and
tires" section ( Y page 322).
In wintry driving conditions, always use
winter tires (M+S tires) and if necessary,
snow chains. Only in this way will the
driving safety systems described in this
section work as effectively as possible.
ABS (Anti-lock Braking System)
Important safety notes
i Observe the "Important safety notes"
section ( Y page 64).
ABS regulates brake pressure in such a way
that the wheels do not lock when you brake.
This allows you to continue steering the
vehicle when braking.
ABS works from a speed of about
5 mph(8 km/h) upwards, regardless of road-
surface conditions. ABS works on slippery
surfaces, even when you only brake gently.
GWARNING
If the ABS malfunctions, other driving systems
such as the BAS or the ESP ®
are also switched
off. Observe indicator and warning lamps that
may come on as well as messages in the
multifunction display that may appear.
If the ABS malfunctions, the wheels may lock
during hard braking, reducing the steering
capability and extending the braking distance.
The ! warning lamp in the instrument
cluster lights up when the ignition is switched
on. It goes out when the engine is running.
Braking
If ABS intervenes when braking, you will feel
a pulsing in the brake pedal.
XIf ABS intervenes: continue to depress the
brake pedal with force until the braking
situation is over.XTo make a full brake application:
depress the brake pedal with full force.
The pulsating brake pedal can be an
indication of hazardous road conditions, and
functions as a reminder to take extra care
while driving.
GWARNING
Do not pump the brake pedal. Use firm, steady
brake pedal pressure instead. Pumping the
brake pedal defeats the purpose of the ABS
and significantly reduces braking
effectiveness.
BAS (Brake Assist System)
i Observe the "Important safety notes"
section ( Y page 64).
BAS operates in emergency braking
situations. If you depress the brake pedal
quickly, BAS automatically boosts the braking
force, thus shortening the stopping distance.
XKeep the brake pedal firmly depressed until
the emergency braking situation is over.
ABS prevents the wheels from locking.
The brakes will function as usual once you
release the brake pedal. BAS is deactivated.
Driving safety systems65SafetyZ

ESP®
is activated automatically when the
engine is started.
It may be best to deactivate ESP ®
in the
following situations:
R when using snow chains
R in deep snow
R on sand or gravelGWARNING
Switch on ESP ®
immediately if one of the
previously stated conditions is no longer met.
Otherwise, ESP ®
cannot stabilize the vehicle
if it begins to lurch or when a wheel spins.
When you deactivate ESP ®
:
R ESP ®
no longer improves driving stability.
R the engine's torque is no longer limited and
the drive wheels can spin. The spinning of
the wheels results in a cutting action, which
provides better grip.
R traction control is still activated.
R ESP ®
still provides support when you
brake.
If ESP ®
is deactivated and one or more wheels
start to spin, the ÷ ESP®
warning lamp in
the instrument cluster flashes. In such
situations, ESP ®
will not stabilize the vehicle.
XTo deactivate: press button :.
The å ESP®
OFF warning lamp in the
instrument cluster lights up.GWARNING
When the å ESP®
OFF warning lamp is lit,
ESP ®
is deactivated.
If the ÷ ESP®
warning lamp and the
å ESP®
OFF warning lamp remain lit,
ESP ®
is not available due to a malfunction.
When ESP ®
is deactivated or not operational,
vehicle stability in standard driving
maneuvers is reduced.
Adapt your speed and driving to the prevailing
road conditions and to the non-operating
status of the ESP ®
.
! Avoid spinning the driven wheels for an
extended period with ESP ®
deactivated.
You could otherwise damage the drivetrain.
XTo activate: press button :.
The å ESP®
OFF warning lamp in the
instrument cluster goes out.
ESP ®
trailer stabilization
If your vehicle with trailer (vehicle/trailer
combination) begins to lurch, you can only
stabilize the vehicle/trailer combination by
depressing the brake firmly.
In this situation, ESP ®
assists you and can
detect if the vehicle/trailer combination
begins to lurch. ESP ®
slows the vehicle down
by braking and limiting the engine output until
the vehicle/trailer combination has
stabilized.
Trailer stabilization is active from a speed of
approximately 40 mph(65 km/h).
GWARNING
The system will not be able to assist when the
trailer jackknifes
R if the ESP ®
has switched off due to a
malfunction
R on wet or icy roads
R on roads with slippery surface
R in sand or gravel
Driving safety systems67SafetyZ

Trailers with a high center of gravity may tip
over before the system recognizes swaying of
the trailer.
Trailer stabilization does not work if ESP ®
is
deactivated or disengaged because of a
malfunction.
EBD (electronic brake force
distribution)
i Observe the "Important safety notes"
section ( Y page 64).
EBD monitors and controls the brake
pressure on the rear wheels to improve
driving stability while braking.
GWARNING
If EBD has malfunctioned, the braking system
remains available with full brake boosting
effect. However, the rear wheels can still lock,
e.g. under full braking. This could cause you
to lose control of your vehicle and cause an
accident. You should therefore adapt your
driving style to the different handling
characteristics.
XObserve the notes on warning and indicator
lamps ( Y page 240) as well as display
messages ( Y page 216).
Distance warning function (vehicles
with DISTRONIC)
This function provides a warning from a speed
of approximately 20 mph(30 km/h), if:
R for a period of several seconds, the
distance to the vehicle in front is too short
for the speed at which you are traveling.
The · distance warning lamp in the
instrument cluster will light up.
R you are rapidly approaching the vehicle in
front. An intermittent warning tone will
then sound and the · distance warning
lamp will light up in the instrument cluster.
You must apply the brakes yourself in order
to maintain the appropriate distance to the
vehicle in front and prevent a collision.GWARNING
If the distance warning lamp · in the
instrument cluster comes on while driving
and/or an intermittent warning sounds,
immediate attention on the part of the driver
is required. As required by the traffic
situation, apply the brakes and navigate
around a possible obstacle. However, do not
drive by relying on the distance warning
function, as this will result in an emergency
braking application. This will not always
enable you to avoid a collision, especially
when traveling on varying road surface
conditions and with varying driver reaction.
Complex driving situations are not always
fully recognized by the distance warning
function. This could result in wrong or missing
distance warnings.
XTo activate/deactivate: activate or
deactivate the distance warning function in
the on-board computer ( Y page 210).
After activation, the Ä symbol is
displayed in the lower multifunction
display.
Theft deterrent locking systems
Immobilizer
The immobilizer prevents your vehicle from
being started without the correct SmartKey.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. The
engine can be started by anyone with a valid
SmartKey that is left inside the vehicle.
XTo activate with the SmartKey: remove
the SmartKey from the ignition lock.XTo activate with KEYLESS-GO: switch the
ignition off and open the driver's door.XTo deactivate: switch on the ignition.68Theft deterrent locking systemsSafety

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 24).
SmartKey
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 unsupervised in the
vehicle, even if they are secured in a child
restraint system, and do not give them access
to an unlocked vehicle. A child's unsupervised
access to a vehicle could result in an accident
and/or serious personal injury. They could:
R injure themselves on vehicle parts
R be seriously or fatally injured by extreme
heat or cold
R injure themselves or have an accident with
vehicle equipment that may still be in
operation even after the SmartKey has
been removed from the ignition, such as the
seat adjustment, steering wheel
adjustment or memory function.
If children open a door, they could cause
severe or even fatal injury to other persons; if
they get out of the vehicle, they could injure
themselves when doing so or be seriously or
even fatally injured by any passing 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 a child could be burned on these
parts.GWARNING
If a key ring is too heavy or too large, the
weight acting on the key could cause it to turn
in the ignition lock or catch on the steering
wheel. This could cause the engine to be
switched off suddenly. You could lose control
of the vehicle and cause an accident. Do not
attach any heavy or large key rings to the key
that is inserted in the ignition.
General information
If you cannot lock or unlock the vehicle with
the SmartKey, either the battery in the
SmartKey is discharged, the SmartKey is
faulty or the starter battery is discharged.
XCheck the battery in the SmartKey and
replace it if necessary ( Y page 76).XUnlock the driver's door using the
mechanical key ( Y page 81).XLock the vehicle ( Y page 81).XHave the starter battery and battery
contacts checked at 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 Rules. Operation is subject to the
following two conditions:
1. This device may not cause harmful
interference, and
2. this device must accept any interference
received, including interference that may
cause undesired operation.
72SmartKeyOpening/closing

Removing the mechanical keyXPush release catch : in the direction of
the arrow and at the same time, remove
mechanical key ; from the SmartKey.
SmartKey battery
Important safety notes
It is advisable to have batteries replaced at a
qualified specialist workshop, e.g. at an
authorized Mercedes-Benz Center.
GWARNING
Batteries contain toxic and caustic
substances. For this reason, keep batteries
out of the reach of children.
If a battery has been swallowed, seek medical
help immediately.
GWARNING
The SmartKey batteries contain perchlorate
material, which may require special handling
and regard for the environment. Observe
government disposal guidelines. California
residents, see www.dtsc.ca.gov/
HazardousWaste/Perchlorate/
index.cfm .
Checking the batteryXPress the & or % button.
The SmartKey battery is working properly if
battery check lamp : lights up briefly.
If battery check lamp : does not light up
briefly during the test, the SmartKey battery
is discharged.
XChanging the battery ( Y page 76)
i
The battery can be obtained from any
authorized Mercedes-Benz Center.
i If the SmartKey battery is checked within
the signal reception range of the vehicle,
pressing the & or % button locks or
unlocks the vehicle.
Changing the battery
You require a CR 2025 3 V cell battery.
XTake the mechanical key out of the
SmartKey ( Y page 75).XPress mechanical key ; into the opening
in the SmartKey in the direction of the76SmartKeyOpening/closing

ProblemPossible causes/consequences and M SolutionsYou have lost the
mechanical key.XReport the loss immediately to the vehicle insurers.XIf necessary, have the locks changed as well.The engine cannot be
started using the
SmartKey.The on-board voltage is too low.XSwitch off non-essential consumers, e.g. seat heating or interior
lighting, and try to start the engine again.
If this does not work:
XCheck the starter battery and charge it if necessary
( Y page 310).
or
XJump-start the vehicle ( Y page 313).
or
XConsult a qualified specialist workshop.The engine cannot be
started using KEYLESS-
GO. The SmartKey is in
the vehicle.A door is open. Therefore, the SmartKey cannot be detected as
easily.XClose the door and try to start the vehicle again.There is interference from a powerful source of radio waves.XStart your vehicle with the SmartKey in the ignition lock.Doors
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 unsupervised in the
vehicle, even if they are secured in a child
restraint system, and do not give them access
to an unlocked vehicle. A child's unsupervised
access to a vehicle could result in an accident
and/or serious personal injury. They could:
R injure themselves on vehicle parts
R be seriously or fatally injured by extreme
heat or cold
R injure themselves or have an accident with
vehicle equipment that may still be in
operation even after the SmartKey has
been removed from the ignition, such as the
seat adjustment, steering wheel
adjustment or memory function.
If children open a door, they could cause
severe or even fatal injury to other persons; if
they get out of the vehicle, they could injure
themselves when doing so or be seriously or
even fatally injured by any passing 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 a child could be burned on these
parts.GWARNING
Do not carry heavy or hard objects in the
passenger compartment or cargo
compartment unless they are firmly secured
in place.
Doors79Opening/closingZ