towing MERCEDES-BENZ M-Class 2014 W166 Owner's Guide

X
Selector wheel 0002 engaged:
briefly press
selector wheel 0002.
Selector wheel 0002extends.
X To select: turn selector wheel 0002until
indicator lamp 0003comes on.
Trailer indicator 0023appears in the
multifunction display.
R Highway level is set.
R ADS (Adaptive Damping System) adapts
comfortable damping characteristics to
the current operating and driving
conditions.
R The automatic transmission selects the
automatic drive program for a
comfortable driving style that provides
for optimum fuel consumption, changing
gear at optimum points.
R While pulling away, the differential locks
are engaged. Off-road driving systems
4MATIC (permanent four-wheel drive) If you fail to adapt your driving style, 4MATIC
can neither reduce the risk of accident nor
override the laws of physics. 4MATIC cannot
take account of road, weather and traffic
conditions. 4MATIC is only an aid. You are
responsible for the distance to the vehicle in
front, for vehicle speed, for braking in good
time and for staying in your lane.
! Never tow the vehicle with one axle
raised. This may damage the transfer case.
Damage of this sort is not covered by the
Mercedes-Benz Limited Warranty. All
wheels must remain either on the ground
or be fully raised. Observe the instructions
for towing the vehicle with all wheels in full
contact with the ground.
! A function or performance test should
only be carried out on atwo-axle
dynamometer. Before you operate the
vehicle on such a dynamometer, please
consult a qualified workshop .You could otherwise damage the drive train or the
brake system.
4MATIC ensures that all four wheels are
permanently driven. Together with ESP ®
and
4ETS, it improves the traction of your vehicle
whenever a drive wheel spins due to
insufficien tgrip.
i In wintry driving conditions, the maximum
effect of 4MATIC can only be achieved if
you use winter tires (M+S tires), with snow
chains if necessary.
Further information about "Driving off-road"
(Y page 187).
DSR (Downhill Spee dRegulation) Important safety notes
DSR assists you when driving downhill. It
keeps the speed of travel at the speed set on
the on-board computer. The steeper the
downhill gradient, the greater the DSR
braking effect on the vehicle .When driving on
flat stretches of road or on an uphill gradient,
the DSR braking effect is minimal or
nonexistent.
DSR controls the set speed when it is active
and the automatic transmission is in the D,
R or Nposition. By accelerating or braking,
you can always drive at a higher or a lower
speed than that set on the on-board
computer.
Further information about "Driving off-road"
(Y page 187).
If you fail to adapt your driving style, DSR can
neither reduce the risk of accident nor
override the laws of physics. DSR cannot take
account of road, weather and traffic
conditions. DSR is only an aid. You are
responsible for the distance to the vehicle in
front, for vehicle speed, for braking in good
time and for staying in your lane.
You are always responsible for keeping
control of the vehicle and for assessing
whether the downhill gradient can be
managed. DSR may not always be able to
keep to the set speed, depending on road 246
Driving systemsDriving and parking

R
uphill or downhill gradien tinpercentage
R on-road/off-road program selected
R condition of the differential lock for the
transfer case
R the LOW RANGE off-road gear is selected
R condition of the LOW RANGE off-road
gear
R the on-road trailer program is selected Towing
atrailer Notes on towing
atrailer
Important safety notes G
WARNING
If you install a ball coupling other tha nthe one
delivered with the vehicle, the trailer tow hitch
and the rear axle may be overloaded. This
applies especially if the ball coupling in
question is longer or angled differently. This
could seriously impair the driving
characteristics and the trailer can come
loose. There is a risk of an accident.
Only install the ball coupling delivered with
the vehicle or a ball coupling that is designed
to meet your trailer towing requirements. Do
not modify the ball coupling or the trailer tow
hitch. G
WARNING
If the ball coupling is not installed correctly or
not secured with the bolt provided and the
corresponding spring cotter, the trailer may
come loose. There is a risk of an accident.
Always install and secure the ball coupling as
described. Before every journey, ensure that
the ball coupling is secured with the bolt and
the corresponding spring cotter. G
WARNING
If you rest your foot on the brake pedal while
driving, the braking system can overheat. This
increases the stopping distance and can even cause the braking system to fail. There is a
risk of an accident.
Never use the brake pedal as a footrest.N
ever
depress the brake pedal and the accelerator
pedal at the same time. G
WARNING
When the vehicle/trailer combination begins
to lurch, you could lose control of it. The
vehicle/trailer combination could even
rollover. There is a risk of an accident.
On no account should you attempt to
straighten up the vehicle/trailer combination
by increasing the speed. Reduce vehicle
speed and do not countersteer .Apply the
brake as necessary.
! Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
Please observe the manufacturer's operating
instructions for the trailer coupling if a
detachable trailer coupling is used.
Couple and uncouple the trailer carefully. If
you do not couple the trailer to the towing
vehicle correctly, the trailer could become
detached.
Make sure that the following values are not
exceeded:
R the permissible trailer drawbar noseweight
R the permissible trailer load
R the permissible rear axle load of the towing
vehicle
R the maximum permissible gross vehicle
weight of both the towing vehicle and the
trailer
The applicable permissible values, which
must not be exceeded, can be found:
R in the vehicle documents
R on the identification plates of the trailer tow
hitch, the trailer and the vehicle
If the values differ, the lowest value applies.
You will find the values approved by the
manufacturer on the vehicle identification Towing
atrailer
253Driving an d parking Z

plates and those for the towing vehicle under
"Technical data" (Y
page 456).
When towing a trailer, your vehicle's handling
characteristics will be differen tincomparison
with when driving without atrailer.
The vehicle/trailer combination:
R is heavier
R is restricted in its acceleration and
gradient-climbing capability
R has an increased braking distance
R is affected more by strong crosswinds
R demands more sensitive steering
R has a larger turning radius
This could impair the handling
characteristics.
When towing a trailer, always adjust your
speed to the current road and weather
conditions. Do not exceed the maximum
permissible speed for yourv ehicle/trailer
combination.
General notes R
Do not exceed the legally prescribed
maximum speed for vehicle/trailer
combinations in the relevant country.
This lowers the risk of an accident.
R Only install an approved trailer coupling on
your vehicle.
Further information on availability and on
installation is available from any authorized
Mercedes-Benz Center.
R The bumpers of your vehicle are not
suitable for installing detachable trailer
couplings.
R Do not install hired trailer couplings or
other detachable trailer couplings on the
bumpers of your vehicle.
R If you no longer need the ball coupling,
remove it from the ball coupling recess.
This will reduce the risk of damage to the
ball coupling.
i When towing a trailer, set the tire
pressure on the rear axle of the towing vehicle for a maximum load; see the tire
pressure table in the fuel filler flap
(Y
page 419).
Please note that when towing a trailer,
PARKTRONIC ( Ypage 213) and Blind Spot
Assist (Y page 233) are only available with
limitations, or not at all.
i On vehicles without level control, the
height of the ball coupling will alter
according to the load placed on the vehicle.
If necessary, use a trailer with a height-
adjustable drawbar.
You will find installing dimensions and loads
under "Technical data" (Y page 455).
Driving tips i
Observe the information on ESP ®
trailer
stabilization (Y page 73) and on pulling
away with a trailer (Y page 160).
The maximum permissible speed for vehicle/
trailer combinations depends on the type of
trailer. Before beginning the journey, check
the trailer's documents to see what the
maximum permissible speed is. Observe the
legally prescribed maximum speed in the
relevant country.
For certain Mercedes-Benzv ehicles, the
maximum permissible rear axle load is
increased when towing a trailer. See
"Technical data" to find out whether this
applies to your vehicle (Y page 456). If you
utilize any of the added maximum rear axle
load when towing a trailer, the vehicle/trailer
combination may not exceed a maximum
speed of 60 mph (100 km/h) for reasons
concerning the operating permit .This also
applies in countries in which the permissible
maximum speed for vehicle/trailer
combinations is above 60 mph (100 km/h).
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
with when driving without atrailer.
Use the left-hand paddle shifter to shift into
a lower gearing ood time on long and steep
downhill gradients. 254
Towing
atrailerDriving an d parking

i
This also applies if you have activated
cruise control or DISTRONIC PLUS.
This will use the braking effect of the engine,
so that less braking will be required to
maintain the speed. This relieves the load on
the brake system and prevents the brakes
from overheating and wearing too quickly. If
you need additional braking, depress the
brake pedal repeatedly rather than
continuously.
Driving tips If the trailer swings from side to side:
X
Do not accelerate.
X Do not counter-steer.
X Brake if necessary.
R Maintain a greater distance from the
vehicle in frontt han when driving without a
trailer.
R Avoid braking abruptly. If possible, brake
gently at first to allow the trailer to run on.
Then, increase the braking force rapidly.
R The values given for gradient-climbing
capabilities from a standstill refer to sea
level. When driving in mountainous areas,
note that the power output of the engine
and, consequently, the vehicle's gradient-
climbing capability, decreases with
increasing altitude. Installing the ball coupling
G
WARNING
If the ball coupling is not installed and secured
correctly it can become detached while the
vehicle is in motion and fall onto the road.
There is a risk of accident and injury.
Always install and secure the ball coupling as
described. Before every journey, ensure that
the ball coupling is secured with the bolt and
the corresponding spring cotter. G
WARNING
If the ball coupling is not installed correctly or
not secured with the bolt provided and the
corresponding spring cotter, the trailer may
come loose. There is a risk of an accident.
Always install and secure the ball coupling as
described. Before every journey, ensure that
the ball coupling is secured with the bolt and
the corresponding spring cotter. G
WARNING
If the ball coupling is not installed and secured
correctly the trailer may come loose. There is
a risk of an accident.
Install and secure the ball coupling as
described in the ball coupling installation
instructions. Make sure that the ball coupling
is installed and secured correctly before every
journey. Cover cap
X
Pull protective cap 0002in the direction of the
arrow, out of the ball coupling recess.
X Place protective cap 0002in the ball coupling
recess. Towing
atrailer
255Driving an d parking Z

Ball coupling recess
Holes in the ball coupling and ball coupling recess
X
Insert the ball coupling horizontally into ball
coupling recess 0003in the direction of the
arrow until the holes in ball coupling 0023are
in line with the holes in ball coupling
recess 0022. Bolt
X
Slide bolt 0020into the hole in the ball
coupling recess and the ball coupling to the
stop. Bolt and spring cotter
X
Secure the bol tusing spring cotter 0021. Correctly installed and secured ball coupling
X
Check the ball coupling, bolt and spring
cotter for correct installation.
If the ball coupling cannot be correctly
mounted, remove the ball coupling. Under
these circumstances, the ball coupling must
not be used for trailer towing.
If the ball coupling cannot be locked and the
key cannot be removed, remove the ball
coupling and clean it. If the ball coupling can
still not be installed (locked) after it has been
cleaned, remove the ball coupling. The trailer
tow hitch must then not be used to tow a
trailer, as safe operation cannot be
guaranteed.
Have the entire trailer tow hitch checked at a
qualified specialist workshop. Coupling up a trailer
! Do not connect the trailer's brake system
(if featured) to the hydraulic brake system 256
Towing
atrailerDriving an d parking

of the towing vehicle, as the latter is
equipped with an anti-lock brake system.
Doing so will result in a loss of function of
the brake systems of both the vehicle and
the trailer.
X Make sure that the automatic transmission
is set to position P.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Vehicles with the AIRMATIC package:
select highway level.
X Vehicles with ADS: set ADS toAUTOor
COMF.
X Switch off the engine.
X Close all doors and the tailgate.
X Couple up the trailer.
X Establish all electrical connections.
X Check that the trailer lighting system is
working.
i Vehicles with the AIRMATIC package:
with a trailer attached, the vehicle will
always remain at highway level. When
coupling up a trailer, please observe the
following:
R Unless highway level has been set
manually, the vehicle is automatically
lowered to highway level. This is the case
if a speed of 5mph(8km/h) is reached.
R High-speed level is not available.
These restrictions apply to all accessories
powered through a connectio nto the trailer
power socket of your vehicle, e.g. a bicycle
carrier.
Observe the maximum permissible trailer
dimensions (width and length).
Most U.S. states and all Canadia nprovinces
require by law:
R Safety chains between the towing vehicle
and the trailer. The chains should be cross-
wound under the trailer drawbar. They must
be fastened to the vehicle's trailer
coupling, not to the bumper or the axle. Leave enough play in the chains to make
tight cornering possible.
R As eparate brake system for certain types
of trailer.
R As afety switch for braked trailers. Check
the specific legal requirements applicable
to your state.
If the trailer detaches from the towing
vehicle, the safety switch applies the
trailer's brakes. Towing
atrailer
There are numerous legal requirements
concerning the towing of a trailer, e.g .speed
restrictions. Make sure that your vehicle/
trailer combination complies with the local
requirements not only in your area of
residence but also at any location to which
you are traveling. The police and local
authorities can provide reliable information.
Please observe the following when towing a
trailer:
R In order to accumulate driving experience
and accustom yourself to the new handling
characteristics, practice the following at a
location where there is no traffic:
-Cornering
- Stopping
- Backing up
R Before driving, check:
-the trailer tow hitch
- the safety switch for braked trailers
- the safety chains
- electrical connections
- the lights
- the wheels
R Adjust the exterior mirrors to provide an
unobstructed view of the rear section of the
trailer.
R If the trailer has electronically controlled
brakes, pull away carefully. Brake manually
using the brake controller and check
whether the brakes function correctly. Towing
atrailer
257Driving an d parking Z

R
Secure any objects on the traile rto prevent
the cargo from slipping when the vehicle is
in motion.
R If you couple up a trailer, regularly check
that the cargo is securely fastened and
make sure that the trailer lamps and (if
applicable) the trailer brakes are
functioning correctly.
R Bear in mind that the handling will be less
stable when towing a trailer than when
driving without one. Avoid sudden steering
movements.
R The vehicle/trailer combination is heavier,
accelerates more slowly, has a decreased
gradient climbing capability and a longer
braking distance.
It is more susceptible to side winds and
requires more careful steering.
R If possible, avoid abrupt braking. Depress
the brake pedal moderately at first, so that
the trailer can activate its own brakes. Then
increase the pressure on the brake pedal.
R If the automatic transmission repeatedly
shifts between gears on uphill or downhill
gradients, shift to a lower gear using the
left-hand steering wheel paddle shifter.
Al ower gear and lower speed reduce the
risk of engine failure.
R When driving downhill, shift to a lower gear
to utilize the engine's braking effect.
Avoid continuous brake application as this
may overheat the vehicle brakes and, if
installed, the trailer brakes.
R If the coolant temperature increases
dramatically while the air-conditioning
system is switched on, switch off the air-
conditioning system.
Coolant heat can additionally be dissipated
by opening the windows and by setting the
blower fan and the interior temperature to
maximum.
R When overtaking, pay particular attention
to the extended length of your vehicle/
trailer combination. Due to the length of your vehicle/trailer
combination, you will have to travel an
additional distance beyond the vehicle you
are overtaking before returning to the
previous lane. Decoupling
atrailer G
WARNING
If you uncouple a trailer with the overrun
brake engaged, you could trap your hand
between the vehicle and the trailer drawbar.
There is a risk of injury.
Do not uncouple a trailer if the overru nbrake
is engaged. G
WARNING
Vehicles with level control:
The vehicle is lowered as soon as you
disconnect the trailer cable. This could result
in yourl imbs or those of other people that are
betwee nthe vehicle body and tires or
underneath the vehicle being trapped. There
is a risk of injury.
Make sure that nobody is in the immediate
vicinity of the wheel housings or under the
vehicle when you disconnectt he trailer cable.
! Do not disconnect a trailer with an
engaged overrun brake. Otherwise, your
vehicle could be damaged by the
rebounding of the overrun brake.
X Make sure that the automatic transmission
is set to position P.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Close all doors and the tailgate.
X Apply the trailer's parking brake.
X Detach the trailer cable and decouple the
trailer.
X Switch off the engine. 258
Towing
atrailerDriving an d parking

Permissible trailer loads and drawbar
loads
Weight specifications Maximump
ermissible gross vehicle
weight rating
The gross trailer weight is calculated by
adding the weight of the trailer to the weight
of the load and equipment on the trailer.
You will find installing dimensions and loads
under "Technical data" ( Ypage 455).
Permissible noseweight
You will find installing dimensions and loads
under "Technical data" ( Ypage 455).
Loading atrailer R
When loading the trailer, make sure that
neithe rthe permissible gross weight of the
trailer nor the gross vehicle weight is
exceeded. The permissible gross vehicle
weight is indicated on the identification
plate on the B-pillar on the driver's side of
the vehicle.
You can find the maximum permissible
values on the type plates of your vehicle
and the trailer. When calculating how much
weight the vehicle and trailer may carry,
pay attention to the respective lowest
values.
R The trailer drawbarl oad on the ball coupling
must be added to the rear axle load to avoid
exceeding the permissible gross axle
weight. The permissible gross vehicle
weight is indicated on the identification
plate on the B-pillar on the driver's side of
the vehicle.
i Mercedes-Benz recommends atrailer
load where the trailer drawbar noseweight
accounts for 8% to 15% of the trailer's
permissible gross weight.
i The weight of additional accessories,
passengers, and cargo reduces the
permissible trailer load and drawbar load
for yourv ehicle. Checking the vehicle and trailer weight R
To chec kthat the weights of the towing
vehicle and the trailer comply with the
maximum permissible values, have the
vehicle/trailer combination (including the
driver, passengers, and cargo with a fully
laden trailer) weighed on a calibrated
weighbridge.
R Check the gross axle weight rating of the
front and rear axles, the gross weight of the
trailer and trailer drawbarl oad. Removing the ball coupling
X Remove the spring cotter.
X Remove the bolt from the ball coupling
recess.
X Remove the ball coupling from the ball
coupling recess.
X Clean the ball coupling if it is dirty.
Information on cleaning and care of the trailer
tow hitch can be found at (Y page 374). Storing the ball coupling
G
WARNING
Do not carry the ball coupling in the vehicle
interior if it is not secured.
Otherwise, you and others could be injured by
the ball coupling being thrown around if you:
R brake sharply
R change direction suddenly
R are involved in an accident Trailer power supply
! You can connect accessories with a
maximum power consumption of 240 Wto
the permanent powe rsupply.
You must no tcharge a trailer battery using
the power supply.
The trailer socket of your vehicle is equipped
at the factory with apermanen tpower supply. Towing
atrailer
259Driving an d parking Z

The permanen
tpower supply is supplied via
trailer socket pin 4.
The trailer's permanent power supply is
switched off in the event of low vehicle supply
voltage and after six hours at the latest.
Aq ualified specialist workshop can provide
more information about installing the trailer
electrics. 260
Towing
atrailerDriving an d parking

Display messages Possible causes/consequences and
0001 Solutions
0002
Drive More Slowly You canno
tchange the vehicle level. Possible causes are:
R you are driving too fast for the selected vehicle level.
R you are towing a trailer.
R the trailer-coupling socket is being used, e.g. for a bicycle rack.
X Drive more slowly and then select the desired vehicle level
again.
R
Vehicles with the ON&OFFROAD package (Y page 202)
R Vehicles with the AIRMATIC package (Y page 209)
X Observe the notes on towing a trailer (Y page 253).0002
Compressor Is
Cooling You have selected a higher vehicle level. The compressor first
needs to cool down because of frequent level changes.
X
Drive in a manner appropriate for the current vehicle level.
X Make sure that there is sufficient ground clearance.
X Allow the compressor to cool down.
When the compressor has cooled down, the display message
disappears. The vehicle then continues rising to the selected
level. 0002
Malfunction AIRMATIC is malfunctioning.
X
Drive as appropriate for the current vehicle level, but do not
exceed 50 mph (80 km/h).
X Make sure that there is sufficient ground clearance.
X Have the vehicle checked at a qualified specialist workshop. 0002
Max. Speed12 mph You are exceeding the speed permissible for the selected off-road
level.
In addition, the vehicle level display appears between the vehicle
icon and the display message, and a warning tone sounds.
G WARNING
The vehicle could tip and rollover.
There is a risk of an accident.
X Adjust your driving style to the altered handling characteristics.
X Only make slight steering movements and avoid fast steering
movements.
X Do not exceed 12 mph (20k m/h )until the vehicle has reached
off-road level 2. 302
Display messagesOn-board computer and displays