MERCEDES-BENZ M-Class 2014 W166 Repair Manual

and
R if a vehicle speed of 15 mph (25 km/h) is
exceeded, the 0020seat belt warning lamp
begins to flash. Awarning tone also sounds
with increasing intensity for a maximum of
60 seconds or until the driver or front
passenger have fastened their seat belts.
If the driver/front passenger unfasten their
seat belt while the vehicle is in motion, the
0020 seat belt warning lamp lights up and a
warning tone sounds again.
The warning tone ceases eve nifthe driver or
front-passenger seat belt has still not been
fastened after 60 seconds. The 0020seat belt
warning lamp stops flashing but remains
illuminated.
After the vehicle comes to a standstill, the
warning tone is reactivated. The 0020seat
belt warning lamp flashes again if the vehicle
speed exceeds 15 mph (25 km/h).
The 0020 seat belt warning lamp only goes
out if:
R both the driver and the front passenger
have fastened their seat belts.
or
R the vehicle is stationary and a door is open.
i For more information on the 0020seat
belt warning lamp, see "Warning and
indicator lamps in the instrument cluster,
seat belts" (Y page 317).
Emergency Tensioning Devices, seat
belt force limiters G
WARNING
Pyrotechnic Emergency Tensioning Devices
that have been deployed are no longer
operational and are unable to perform their
intended protective function. This poses an
increased risk of injury or even fatal injury.
Therefore, have pyrotechnic Emergency
Tensioning Devices which have been
triggered immediately replaced at a qualified
specialist workshop. !
If the front-passenger seat is not
occupied, do not engage the seat belt
tongue in the buckle on the front-
passenger seat. Otherwise, the Emergency
Tensioning Device could be triggered in the
event of an accident.
i Vehicles with PRE-SAFE ®
: Emergency
Tensioning Devices that are triggered by an
electric motor can be deployed as often as
desired and do not need to be replaced.
The front seat belts and the outer seat belts
in the rear are equipped with Emergency
Tensioning Devices and seat belt force
limiters.
The Emergency Tensioning Devices on the
driver's and front-passenger seat consist of
pyrotechnic belt buckle tensioners and belt
anchor installation tensioners that are
triggered together. The belt buckle tensioner
is mounted on the B-pillar and the belt anchor
installation is mounted on the side of the seat.
After deploying, both tensioners must always
be replaced.
Emergency Tensioning Devices tighten the
seat belts in an accident, pulling them close
against the body.
Emergency Tensioning Devices do not
correct incorrect seat positions or incorrectly
fastened seat belts.
Emergency Tensioning Devices do not pull
vehicle occupants back towards the
backrest.
When triggered, seat belt force limiters help
to reduce the force exerted by the seat belt
on the vehicle occupant.
The seat belt force limiters for the front seats
are synchronized with the front air bags,
which take on a part of the deceleration force.
This results in the force exerted on the
occupant being distributed over a greater
area. Occupant safety
59Safety Z

Emergency Tensioning Devices can only be
activated when:
R
the ignition is switched on.
R the restraint systems ar eoperational; see
"SRS warning lamp" (Y page 43)
R the belt tongue is engaged in the buckle on
each of the lap-shoulder belts in the front
R the front-passenger seat is occupied and
the belt tongue is engaged in the buckle on
the front-passenger side
The ETDs on the outside seats in the rear
compartment are triggered independently of
the lock status of the seat belts.
The ETDs are triggered depending on the type
and severity of an accident:
R if, in the event of a head-on or rear-end
collision, the vehicle decelerates or
accelerates rapidly in a longitudinal
direction during the initial stages of the
impact.
R if, in the event of a side impact, on the side
opposite the impact the vehicle
decelerates or accelerates rapidly in a
lateral direction.
R if, in certain situation swhere the vehicle
rolls over, the system determines that it
can provide additional protection.
If the ETDs 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 and does not indicate that there
is a fire in the vehicle. The dust might cause
some temporary breathing difficulty for
people with asthma or other breathing
trouble. To avoid this, you may wish to get out
of the vehicle as soon as it is safe to do so.
You can also open the window to allow fresh
air to enter the vehicle interior. The 001FSRS
warning lamp lights up. Children in the vehicle
Child restraint systems
Important safety notes 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 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 For children larger than the typical
12-month-old child, the front passenger
front air bag may or may not be activated.
Always make sure the 001A001Cindicator
lamp is illuminated, indicating that the front
passenger front air bag is deactivated. 60
Children in the vehicleSafety

R
Ac hild 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 001A001Cindicator
lamp is illuminated, indicating that the front
passenger front air bag is deactivated.
Should the 001A001Cindicator lamp not
illuminate or go out while the restraint is
installed, please chec kinstallation.
Periodically check the 001A001Cindicator
lamp while driving to make sure the 001A
001C indicator lamp is illuminated. If the
001A001Cindicator lamp goes out or
remains out, do not transport a child on the
front passenger seat until the system has
been repaired.
Ac hild 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
If the child restraint system is installed
incorrectly on a suitable seat, it cannot
protect as intended. The child cannot then be
restrained in the event of an accident, heavy braking or sudden changes of direction. There
is an increased risk of injury, possibly even
fatal.
Make sure that you observe the child restraint
system manufacturer's installation
instructions and the notes on use. Please
ensure, that the base of the child restraint
system is always resting completely on the
seat cushion. Never place objects, e.g.
cushions, under or behind the child restraint
system. Only use child restraint systems with
the original cover designed for them. Only
replace damaged covers with genuine covers.
G
WARNING
If the child restraint system is installed
incorrectly or is not secured, it can come
loose in the event of an accident, heavy
braking or a sudden change in direction. The
child restraint system could be thrown about,
striking vehicle occupants. There is an
increased risk of injury, possibly even fatal.
Always install child restraint systems
properly, even if they are not being used.
Make sure that you observe the child restraint
system manufacturer's installation
instructions. G
WARNING
Child restraint systems or their securing
systems which have been damaged or
subjected to a load in an accident can no
longer protect as intended. The child cannot
then be restrained in the event of an accident,
heavy braking or sudden changes of direction.
There is an increased risk of injury, possibly
even fatal.
Replace child restraint systems which have
been damaged or subjected to a load in an
accident as soon as possible. Have the
securing systems on the child restraint
system checked at a qualified specialist
workshop, before you install a child restraint
system again. Children in the vehicle
61Safety Z

G
WARNING
Infants and small children should never share
a seat beltw ith another occupant .Inthe event
of an accident, they could be crushed
between the occupant and seat belt.
Ac hild'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 that are too large for a child restraint
must travel in seats using normal seat belts.
Position the shoulder belt across the chest
and shoulder, not face or neck.Ab ooster 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. G
WARNING
If children are left unsupervised in the vehicle,
they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment.
Additionally, children could set the vehicle in
motion if, for example, they:
R release the parking brake.
R shifting the automatic transmission out of
park position P
R Start the engine.
There is a risk of an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children or animals unattended in the
vehicle. Always keep the SmartKey out of
reach of children. G
WARNING
If persons, particularly children are subjected
to prolonged exposure to extreme heat or
cold, there is a risk of injury, possibly even
fatal. Never leave children unattended in the
vehicle. G
WARNING
If the child restraint system is subjected to
direct sunlight, parts may get very hot.
Children may burn themselves on these parts,
particularly on the metal parts of the child
restraint system. There is a risk of injury.
If you leave the vehicle, taking the child with
you, always ensure that the child restraint
system is not exposed to direct sunlight.
Protect it with a blanket, for example. If the
child restraint system has been exposed to
direct sunlight, let it cool down before
securing the child in it. Never leave children
unattended in the vehicle.
If an infant or child is traveling in the vehicle:
R secure the child with a child or infant seat
restraint system appropriate to the age and
weight of the child.
R make sure that the infant or child is
properly secured at all times while the
vehicle is in motion.
Mercedes-Benz recommends that you always
properly secure all infant sand children with
a child or infant seat restraint system for the
trip.
The use of sea tbelts and infan tand child
restraint systems is required by law in:
R all 50 states
R the U.S. territories
R the District of Columbia
R all Canadia nprovinces
Infants and children must always be seated in
an appropriate infant or child restraint system
recommended for the size and weight of the
child .The infant or child restraint system
must be properly secured in accordance with
the manufacturer's instructions. 62
Children in the vehicleSafety

All infant or child restraint systems must meet
the following standards:
R U.S. Federal Motor Vehicle Safety
Standards 213 and 225
R Canadia nMotor Vehicle Safety Standards
213 and 210.2
Confirmation that the child restraint system
corresponds to the standards can be found
on an instruction label on the child restraint
system. This confirmation can also be found
in the installation instructions that are
included with the child restraint system.
Always read and follow the manufacturer's
instructions when using an infant or child
restraint system or booster seat.
Observe the warning labels in the vehicle
interior or on the infant or child restraint.
Special seat belt retractor G
WARNING
If you release the seat belt when driving, the
special seat belt retractor is deactivated.
The released seat belt cannot be engaged
again while driving, because the inertia reel
pulls in the seat belt a small distance. The
child restraint system is no longer properly
secured. There is an increased risk of serious
injury or even fatal injury.
Always keep the seat belt of the activated
special seat belt retractor engaged when
driving.
All seat belts 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 will not
slacken once the child restraint system has
been secured. Installing a child restraint system:
X
Always comply with the manufacturer's
installation instructions.
X Pull the seat belt smoothly from the seat
belt retractor.
X Engage the seat belt tongue in the belt
buckle.
Activating the special seat belt retractor:
X Pull the seat belt out fully and let the seat
belt retractor retract it again.
While the seat belt is retracting, you should
hear a ratcheting sound. The special seat
belt retractor is activated.
X Push down on the child restraint system to
take up any slack.
Removing a child restraint system/
deactivating the special seat belt retractor:
X Always comply with the manufacturer's
installation instructions.
X Press the seat belt release button and
guide the belt tongue to the belt outlet.
The special seat belt retractor is
deactivated.
LATCH-type (ISOFIX) child seat anchors
in the rear G
WARNING
LATCH-type (ISOFIX) child restraint systems
do not offer sufficient protective effect for
children whose weight is greater than 48 lbs
(22 kg) who are secured using the safety belt
integrated in the child restraint system. In the
event of an accident, a child might not be
restrained correctly. This poses an increased
risk of injury or even fatal injury.
If the child weighs more than 48 lbs (22 kg),
only use LATCH-type (ISOFIX) child restraint
systems with which the child is also secured
with the vehicle seat belt. Also secure the
child restraint system with the Top Tether
belt, if available.
When installing a child restraint system, be
sure to observe the manufacturer's Children in the vehicle
63Safety Z

installation instructions and the instructions
for correct use of the child restraint system.
! 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. X
Install the LATCH-type (ISOFIX) child
restraint system on both LATCH-type
(ISOFIX) securing rings 0002.Comply with the
child restraint system manufacturer's
instructions when installing the LATCH-
type (ISOFIX) child restraint system.
LATCH-type (ISOFIX) is a standardized
securing system for specially designed child
restraint systems on the rear seats. Securing
rings 0002for two LATCH-type (ISOFIX) child
restraint systems are installed on the left and
right of the rear seats.
Non-LATCH-type (ISOFIX) child seats may
also be used and can be installed using the
vehicle's seat belt system. Install the child
seat according to the manufacturer's
instructions.
Top Tether Top Tether anchorages
G
WARNING
If the rear seat backrests are not locked, they
could fold forwards in the event of an
accident, heavy braking or sudden changes of
direction .As a result, child restraint systems
cannot perform their intended protective
function. Rear seat backrests that are not locked can also cause additional injuries, e.g.
in the event of an accident. This poses an
increased risk of injury or even fatal injury.
Always lock rear seat backrests after
installing a Top Tether belt. Observe the lock
verification indicator. Adjust the rear seat
backrests so that they are positioned
vertically.
Top Tether provides an additional connection
between the LATCH-type (ISOFIX) child
restraint system secured with LATCH-type
(ISOFIX) and the rear seat. This helps reduce
the risk of injury even further. If the LATCH-
type (ISOFIX) child restraint system is
equipped with Top Tether, this should always
be used.
The Top Tether anchorage points are installed
on the rear side of the rear seat backrests. X
Move head restraint 0023upwards.
X Install the LATCH-type (ISOFIX) child
restraint system with Top Tether. Always
comply with the child restraint system
manufacturer's installation instructions
when doing so. 64
Children in the vehicleSafety

X
Route Top Tether belt 0021under head
restraint 0023between the two head restraint
bars.
X Guide Top Tether belt 0021downwards
between cargo compartmen tcover 0002and
rear seat backrest 0003.
X Hook Top Tether hook 0020of Top Tether belt
0021 into Top Tether anchorage 0022.
Make sure that:
R Top Tether hook 0020is hooked into Top
Tether anchorage 0022as shown.
R Top Tether belt 0021is not twisted.
R Top Tether belt 0021is routed between rear
seat backrest 0003and cargo
compartment cover 0002if cargo
compartment cover 0002is installed.
R Top Tether belt 0021is routed between the
rear seat backrest 0003and the cargo net
if the cargo net is installed.
X Tension Top Tether belt 0021.Comply with
the manufacturer's installation
instructions when doing so.
X Move head restraint 0023back down again
slightly if necessary (Y page 108). Make
sure that you do not interfere with the
correc trouting of Top Tether belt 0021.Child-proof locks
Important safety notes G
WARNING
If children are left unsupervised in the vehicle,
they could:
R open the doors, thus endangering other
people or road users.
R get out and disrupt traffic.
R operate the vehicle's equipment. Additionally, children could set the vehicle in
motion if, for example, they:
R
release the parking brake.
R shifting the automatic transmission out of
park position P
R Start the engine.
There is a risk of an accident and injury.
When leaving the vehicle, always take the
SmartKey with you and lock the vehicle. Never
leave children or animals unattended in the
vehicle. Always keep the SmartKey out of
reach of children. G
WARNING
If persons, particularly children are subjected
to prolonged exposure to extreme heat or
cold, there is a risk of injury, possibly even
fatal. Never leave children unattended in the
vehicle. G
WARNING
If children are traveling in the vehicle, they
could:
R open doors, thus endangering other people
or road users
R exit the vehicle and be caught by oncoming
traffic
R operate vehicle equipment and become
trapped
There is a risk of an accident and injury.
Always activate the child-proof locks and
override feature if children are traveling in the
vehicle. When leaving the vehicle, always take
the key with you and lock the vehicle. Never
leave children unattended in the vehicle.
You can activate the following child-proof
locks:
R rear doors (Y page 66)
R rear side windows (Y page 66) Children in the vehicle
65Safety Z

Child-proof locks for the rear doors
G
WARNING
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.
Adoor
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.
X To activate: press the child-proof lock
lever up in the direction of arrow 0002.
X Make sure that the child-proof locks are
working properly.
X To deactivate: press the child-proof lock
lever down in the direction of arrow 0003.
Override feature for the rear side
windows G
WARNING
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. X
To activate/deactivate: press button0002.
If indicator lamp 0003is lit, operation of the
rear side windows is disabled. Operation is
only possible using the switches in the
driver's door. If indicator lamp 0003is off,
operation is possible using the switches in
the rear compartment. Driving safety systems
Overview of driving safety systems
In this section, you will find information about
the following driving safety systems:
R ABS (Anti-lock BrakingSystem)
(Y page 67)
R BAS (Brake AssistSystem) (Y page 67)
R BAS PLUS ( BrakeAssist System Plus)
(Y page 68)
R COLLISION PREVENTION ASSIST (distance
warning function and adaptive Brake
Assist) (Y page 69)
R ESP ®
(Electronic StabilityProgram)
(Y page 72)
R EBD ( Electronic Brake force Distribution)
(Y page 74)
R ADAPTIVE BRAKE (Y page 74)
R PRE-SAFE ®
Brake (Y page 74)
R STEER CONTROL (Y page 76) Important safety notes
If you fail to adapt your driving style or
become distracted, the driving safety 66
Driving safety systemsSafety

systems can neither reduce the risk of
accident nor override the laws of physics.
Driving safety systems are merely aids
designed to assist driving. You are
responsible for the distance to the vehicle in
front, for vehicle speed and for braking in
good time. Always adapty our driving style to
suit the prevailing road and weather
conditions and maintain asafe distance from
the vehicle in front. Drive carefully.
i The driving safety systems described only
work as effectively as possible when there
is adequate contact between the tires and
the road surface. Please pay special
attention to the note son tires,
recommended minimu mtire tread depths,
etc. (Y page 398).
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)
General information AB
Sr egulates 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.
The 0019 ABSw arning lamp in the instrument
cluste rlights up when the ignition is switched
on. It goes out when the engine is running.
Important safety notes i
Observe the "Importan tsafety notes"
sectio n(Ypage 66). G
WARNING
If ABSi s faulty, the wheels could lock when
braking. The steerability and braking
characteristics may be severely impaired.
Additionally, further driving safety systems
are deactivated. There is an increased danger
of skidding and accidents. Drive on carefully. Have ABS checked
immediately at a qualified specialist
workshop.
When ABS is malfunctioning, other systems,
including driving safety systems, will also
become inoperative. Observe the information
on the ABS warning lamp (Y page 318) and
display messages which may be shown in the
instrument cluster (Y page 283).
ABS works from a speed of about 5 mph
(8 km/h), regardless of road-surface
conditions. ABS works on slippery surfaces,
even if you only brake gently.
Braking X
If ABS intervenes: continue to depress the
brake pedal vigorously until the braking
situation is over.
X To make a full brake application:
depress the brake pedal with full force.
If ABS intervenes when braking, you will feel
a pulsing in the brake pedal.
The pulsating brake pedal can be an
indication of hazardous road conditions, and
functions as a reminder to take extra care
while driving.
Off-road ABS An ABS system specifically suited to off-road
terrain is activated automatically once the off-
road program is activated (Y
page 248).
At speeds below 20 mph (30 km/h), the front
wheels lock cyclically during braking. The
digging-in effect achieved in the process
reduces the stopping distance on off-road
terrain. This limits steering capability. BAS (Brake AssistS
ystem)
General information BAS operates in emergency braking
situations. If you depress the brake pedal Driving safety systems
67Safety Z

quickly, BASa
utomatically boosts the braking
force, thus shortening the stopping distance.
Important safety notes i
Observe the "Importan tsafety notes"
sectio n(Ypage 66). G
WARNING
If BASi s malfunctioning, the braking distance
in an emergency braking situation is
increased. There is a risk of an accident.
In an emergency braking situation, depress
the brake pedal with full force. ABS prevents
the wheels from locking.
Braking X
Keep 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.B AS is deactivated.BAS PLUS (Brake Assist System
PLUS)
General information i
Observe the "Important safety notes"
sectio n(Ypage 66).
BASP LUS is only available in vehicles
equipped with DISTRONIC PLUS.
For BAS PLUS to assist you, the radars ensor
system must be operational.
With the help of the radar sensor system, BAS
PLUS can detect obstacles that are in the
path of your vehicle for an extended period of
time.
If the radar sensor system is malfunctioning,
BASP LUS will not be available. The brake
system is still available with complete brake
boosting effect and BAS.
BAS PLUS can help you to minimize the risk
of a collision with a vehicle or reduce the
effects of such a collision. If BAS PLUS detects a danger of collision, you are assisted
when braking.
Important safety notes G
WARNING
BAS PLUS cannot always clearly identify
objects and complex traffic situations.
In such cases, BAS PLUS may:
R intervene unnecessarily
R not intervene
There is a risk of an accident.
Always pay careful attention to the traffic
situation and be ready to brake. Terminate the
intervention in a non-critical driving situation. G
WARNING
BAS PLUS does not react:
R to people or animals
R to oncoming vehicles
R to crossing traffic
R when cornering
As aresult, BAS PLUS may not intervene in all
critical situations. There is a risk of an
accident.
Always pay careful attention to the traffic
situation and be ready to brake.
In the event of snowfall or heavy rain, the
recognition can be impaired.
Recognition by the radar sensor system is
also impaired in the event of:
R dirt on the sensors or anything else
covering the sensors
R interference by other radar sources
R there are strong radar reflections, for
example in parking garages
R a narrow vehicle traveling in front, e.g. a
motorbike
R a vehicle traveling in fron tonadifferent line
relative to the center of your vehicle
Following damage to the fron tend of the
vehicle, have the configuratio nand operation
of the rada rsensors checked at a qualified 68
Driving safet
ysystemsSafety