Engine MERCEDES-BENZ R-Class 2012 W251 Manual PDF

RDo not install hired trailer couplings or
other detachable trailer couplings on the
bumpers of your vehicle.
R To reduce the risk of damage to the ball
coupling, remove it from the ball coupling
recess when not in use.
Coupling up a trailer
GWARNING
Vehicles with AIRMATIC: While you are
coupling or decoupling a trailer, make sure
nobody locks or unlocks the vehicle and/or
opens or closes doors or the tailgate.
The vehicle's level could change and you
could endanger yourself and/or others as a
result.
Make sure that you do not operate the ADS
switch or the vehicle level control system
when coupling/decoupling the trailer.
Observe the maximum permissible trailer
dimensions (width and length).
Most federal states and all Canadian
provinces 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.
Allow for enough play in the chains to
facilitate turning tight corners.
R a separate brake system for certain types
of trailer.
R a safety switch for braked trailers. Check
the specific legal requirements applicable
to your federal state.
If the trailer detaches from the towing
vehicle, the safety switch applies the
trailer's brakes.
! Do not connect the trailer's brake system
(if featured) to the hydraulic brake system
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.
i The vehicle's wiring harness features a
line to the brake indicator lamp.XMake sure that the automatic transmission
is set to position P.XApply the vehicle's parking brake.XStart the engine.XVehicles with the AIRMATIC package:
select highway level and set ADS to
AUTO or COMF .XSwitch off the engine.XClose all doors and the tailgate.XCouple up the trailer.XEstablish all electrical connections.
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 if highway level has not been set
manually, the vehicle will automatically
sink to highway level as soon as it
reaches a speed of 5 mph (8 km/h).
R high-speed level is not available.
These restrictions apply to all accessories
powered through a connection to the trailer
power socket of your vehicle, e.g. a bicycle
carrier.
Towing a trailer
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.
192Trailer towingDriving and parking

Please observe the following when towing a
trailer:
R To acquaint yourself with driving with a
trailer and with the resulting changes to
handling, you should practice cornering,
stopping and reversing in a traffic-free
location.
R Before driving, check:
- the trailer tow hitch
- the safety switch for braked trailers
- the safety chains
- the 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 features electronically
controlled brakes, pull away the vehicle/
trailer combination carefully, manually
brake using the brake controller, and check
the brakes for correct function.
R Secure any objects on the trailer to prevent
the cargo from slipping when the vehicle is
in motion.
R If you couple up a trailer, regularly check
the cargo for secure fastening 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 continues to
shift back and forth between two gears
when driving up or downhill, restrict the
shift range. Select shift range 4, 3, 2, or 1.
A lower 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 a trailer
GWARNING
Vehicles with AIRMATIC: While you are
coupling or decoupling a trailer, make sure
nobody locks or unlocks the vehicle and/or
opens or closes doors or the tailgate.
The vehicle's level could change and you
could endanger yourself and/or others as a
result.
Make sure that you do not operate the ADS
switch or the vehicle level control system
when coupling/decoupling the trailer.
XMake sure that the automatic transmission
is set to position P.XApply the vehicle's parking brake.Trailer towing193Driving and parkingZ

XStart the engine.XClose all doors and the tailgate.XApply the trailer's parking brake.GWARNING
Vehicles with AIRMATIC: As soon as you
disconnect the electrical connection between
the trailer and the vehicle, the vehicle will
lower. To help avoid personal injury, make
sure no one is near the wheel housing or
underneath the vehicle before the electrical
connection is disconnected.
When you decouple the trailer, the vehicle is
temporarily raised because the springs are
relieved of load. Be especially careful during
this process, as you could otherwise injure
yourself and/or others. Make sure that any
persons remaining in the vehicle do not press
the switches for vehicle level control or the
ADS.
XRemove the trailer cable and decouple the
trailer.XSwitch off the engine.
Permissible trailer loads and drawbar
noseweights
Weight specifications
The Gross Trailer Weight (GTW) is the
combined weight of the trailer together with
the cargo and equipment loaded on the
trailer. Permissible gross weight: 3500 lb
(1588 kg).
The permissible Trailer drawbar Weight
Rating (TWR) is the maximum weight
permitted on the trailer drawbar: 350 lb
(158 kg) limit for Mercedes-Benz-approved
trailer couplings.
Loading a trailer
R When loading a trailer, please note that
neither the permissible gross trailer weight
nor the permissible Gross Vehicle Weight
Rating (GVWR) may be exceeded. The
permissible Gross Vehicle Weight Rating
(GVWR) is specified on the type plate
located on the B-pillar on the driver's side
of your vehicle.
You can find the maximum permissible
values on the type plates of your vehicle
and the trailer. Always observe the lowest
respective value when determining the
maximum weight with which you can load
the vehicle and the trailer.
R The drawbar noseweight acting on the ball
coupling has to be added to the rear axle
weight in order to prevent the permissible
Gross Axle Weight Rating (GAWR) from
being exceeded. The permissible Gross
Vehicle Weight Rating (GVWR) is specified
on the type plate located on the B-pillar on
the driver's side of your vehicle.
i Mercedes-Benz recommends loading the
trailer so that the drawbar noseweight
remains between 8% and 10% of the
permissible gross trailer weight.
i The weight of additional accessories,
passengers, and cargo reduces the
permissible trailer load and drawbar
noseweight for your vehicle.
Checking the vehicle and trailer weight
R To check that 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 axle, the Gross Trailer Weight
(GTW), and the drawbar noseweight.
Trailer power supply
The trailer power socket of your vehicle is
designed for connecting the 7-pin connector
supplied as part of the Mercedes-Benz-
approved trailer coupling.
194Trailer towingDriving and parking

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).
Important safety notes
You will find an illustration of the instrument
cluster in the "At a glance" section
( Y page 29).
GWARNING
A driver's attention to the road and traffic
conditions must always be his/her primary
focus when driving.
For your safety and the safety of others,
selecting features through the multifunction
steering wheel should only be done by the
driver when traffic and road conditions permit
it to be done safely.
Bear in mind that at a speed of just 30 mph
(approximately 50 km/h ), your vehicle is
covering a distance of 44 feet (approximately
14 m) every second.
GWARNING
No messages will be displayed if either the
instrument cluster or the multifunction
display is inoperative.
As a result, you will not be able to see
information about your driving conditions,
such as
R speed
R outside temperature
R warning/indicator lamps
Rmalfunction/warning messages
R failure of any systems
Driving characteristics may be impaired.
If you must continue to drive, do so with added
caution. Contact an authorized Mercedes-
Benz Center as soon as possible.GWARNING
Malfunction and warning messages are only
indicated for certain systems and are
intentionally not very detailed. The
malfunction and warning messages are
simply a reminder with respect to the
operation of certain systems. They do not
replace the owner's and/or driver's
responsibility to maintain the vehicle's
operating safety. Have all required
maintenance and safety checks performed on
the vehicle. Bring the vehicle to an authorized
Mercedes-Benz Center to address the
malfunction and warning messages.
Displays and operation
Tachometer
The red band in the tachometer indicates the
engine's overrevving range.
! Do not drive in the overrevving range, as
this could damage the engine.
The fuel supply is interrupted to protect the
engine when the red band is reached.
Outside temperature display
The outside temperature display is in the
multifunction display ( Y page 200).
GWARNING
The outside temperature indicator is not
designed to serve as an ice-warning device
and is therefore unsuitable for that purpose.
Indicated temperatures just above the
freezing point do not guarantee that the road
198Displays and operationOn-board computer and displays

FunctionETrip computer menu (Y page 210)FTelephone menu (Y page 211)Standard display menu
Standard displayXPress the V or U button on the
steering wheel to select the standard
display.
Standard display
:Trip odometer;Odometer
You can select the following functions in the
Standard display menu using the & or
* button:
R tire pressure loss warning system
( Y page 329) (Canada only)
R tire pressure monitor ( Y page 331) (USA
only)
R coolant temperature ( Y page 202)
R digital speedometer or outside
temperature ( Y page 202)
R ASSYST PLUS service interval display
( Y page 287)
XTo reset the trip odometer: press and
hold the . reset button in the instrument
cluster until the trip odometer is reset.
Displaying the coolant temperature
GWARNING
Driving when your engine is overheated can
cause some fluids which may have leaked into
the engine compartment to catch fire. You
could be seriously burned.
Steam from an overheated engine can cause
serious burns which can occur just by opening
the engine hood. Stay away from the engine
if you see or hear steam coming from it.
Stop the vehicle in a safe location away from
other traffic. Turn off the engine, get out of the
vehicle and do not stand near the vehicle until
the engine has cooled down.XPress the V or U button on the
steering wheel to select the standard
display.XPress the & or * button to select the
coolant temperature.
Under normal driving conditions, with the
correct anti-corrosion and antifreeze additive
concentration, the reading may rise to
248 ‡(120 †).
! If the coolant temperature exceeds
248 ‡(120 †) do not continue driving. The
engine will otherwise be damaged.
Displaying the digital speedometer or
outside temperature
If you have selected the digital speedometer
for the status bar ( Y page 206), the outside
temperature is displayed here.
202Menus and submenusOn-board computer and displays

Settings menu
Introduction
The Settings menu can be used for:
R restoring the factory settings
R changing the instrument cluster settings
R changing the time/date settings 26
R changing the light settings
R changing the vehicle settings
R changing the convenience settings
Resetting to factory settings
For safety reasons, the Daytime Running
Lamps function in the Lighting submenu is
only reset when the engine is switched off.
XPress V or U on the steering wheel
to select the Settings menu.XPress and hold the . reset button on the
instrument cluster for approximately three
seconds.
A prompt appears in the multifunction
display asking you to confirm by pressing
the . reset button again.XPress the . reset button again.
The settings of most functions are restored
to the factory settings.
or
XIf you want to retain the settings, do not
press the . reset button a second time.
After approximately five seconds, the
Settings menu reappears.XPress the V or U button to select a
different menu.Instrument cluster
Selecting the unit of measurement for
distance
This function is only available in Canada.
The Display unit Speedometer/
Odometer function allows you to choose
whether certain displays appear in kilometers
or miles.
The selected unit of measurement for
distance applies to:
R the analog speedometer
R the odometer and the trip odometer
R the trip computer
R the navigation instruction in the
Navigation menu
R DISTRONIC
XPress the V or U button on the
steering wheel to select the Settings
menu.XPress the & button to call up the
selection of submenus.XPress the W or X button to select the
Instrument Cluster submenu.XPress the & button to select Display
Unit Speedometer/Odometer .XPress the W or X button to select
km or Miles as the unit of measurement for
distance.XPress the &, V or U button to
select a different display.
Selecting the unit of distance for the
digital speedometer
XPress V or U on the steering wheel
to select the Settings menu.XPress the & button to select submenus.XPress the W or X button to select the
Instrument cluster submenu.XPress the & button to display Display
unit Digital speedometer .26
This function is not available in vehicles with the navigation module.Menus and submenus205On-board computer and displaysZ

XPress the W or X button to select
km or miles as the unit of measurement for
distance.XPress the &, V or U button to
select a different display.
Selecting the language
The Language: function allows you to select
the language for the instrument cluster.
XPress V or U on the steering wheel
to select the Settings menu.XPress the & button to select submenus.XPress W or X to select the
Instrument cluster submenu.XPress & to select Language .XPress the W or X button to select the
desired language.XPress the &, V or U button to
select a different display.
Selecting the status line display
XPress V or U on the steering wheel
to select the Settings menu.XPress the & button to select submenus.XPress W or X to select the
Instrument cluster submenu.XPress & to select Status line
display .XPress W or X to select the display in
the status line: speed ( Speed) or outside
temperature ( Outside temp. ).
The selected display now appears
constantly in the lower multifunction
display. When you scroll through the
Standard display menu (Y page 202), you
will see the display you have not selected.XPress the &, V or U button to
select a different display.
Time/date
This submenu is only available on vehicles
with no navigation module. To set the time
and the date for vehicles with a navigation
module, see the separate operating
instructions.
In the Time/date submenu, you can set the
time and date.XPress V or U on the steering wheel
to select the Settings... menu.XPress the & button to select submenus.XPress the W or X button to select the
Time/date submenu.XTo set the time: press & to select
Clock Set Hour or Clock Set
Minute(s) .
or
XTo set the date: press & to select
Date Set Day , Date Set Month or Date
Set Year .XPress W or X to set a value.XPress the &, V or U button to
select a different display.
Lights
Switching the daytime running lamps on/
off
This function is not available in Canada.
If you have activated the Daytime Running
Lights function and the light switch is in the
$ or à position, the daytime running
lamps are automatically switched on when
the engine is running.
In the dark, the following also light up:
R the low-beam headlamps
R the parking lamps
R the tail lamps
R the license plate lamp
R the side marker lamps
On vehicles with daytime running lamps, the
factory setting is On
XSwitch off the engine.XPress V or U on the steering wheel
to select the Settings menu.XPress the & button to select submenus.206Menus and submenusOn-board computer and displays

XPress the W or X button to select the
Lighting submenu.XPress & to select Daytime Running
Lamps .XPress W or X to set daytime running
lamps to On or Off .XPress the &, V or U button to
select a different display.
Switching the surround lighting on or off
If you activate the surround lighting function
and the light switch is set to Ã, the
following will light up if it is dark and you
unlock the vehicle using the SmartKey:
R the parking lamps
R the license plate lamp
R the tail lamps
R the fog lamps 27
R the low-beam headlamps 28
R the side marker lamps
R the surround lighting in the exterior mirrors
The surround lighting switches off
automatically after 40 seconds or when the
driver's door is opened.
XPress V or U on the steering wheel
to select the Settings menu.XPress the & button to select submenus.XPress the W or X button to select the
Lighting submenu.XPress & to select Surround lighting
function .XPress W or X to switch the
Surround lighting function on or off.XWhen leaving the vehicle, turn the light
switch to position Ã.
The surround lighting is activated.XPress the &, V or U button to
select a different display.Activating/deactivating the exterior
lighting delayed switch-off
If the Headlamp deactivation function is
activated and the light switch is in the Ã
position, the exterior lighting continues to
light for 15 seconds after the doors have been
closed when it is dark.
If the engine is switched off and then none of
the doors are opened, or if an open door is
not closed, the exterior lighting goes out after
60 seconds.
If you have activated the delayed switch-off
function, the light switch is set to à and
you switch off the engine, the following
remain lit:
R the parking lamps
R the license plate lamp
R the tail lamps
R the fog lamps 29
R the low-beam headlamps 30
R the side marker lampXPress V or U on the steering wheel
to select the Settings menu.XPress the & button to select submenus.XPress the W or X button to select the
Lighting submenu.XPress the & button to select Headlamp
delayed shut-off .XPress the W or X button to activate
or deactivate the Headlamp delayed
shut-off function.XBefore switching off the engine, turn the
light switch to position Ã.
The exterior lighting delayed switch-off is
activated.XPress the &, V or U button to
select a different display.
Deactivating the delayed switch-off
temporarily:
27 Only for vehicles with front fog lamps.
28 Only for vehicles without front fog lamps.
29 Only for vehicles with front fog lamps.
30 Only for vehicles without front fog lamps.Menus and submenus207On-board computer and displaysZ

XBefore leaving the vehicle, turn the
SmartKey to position 0 in the ignition lock.XTurn the SmartKey to position 2 in the
ignition lock and back to position 0.
The delayed switch-off is deactivated.
Delayed switch-off is reactivated the next
time you start the engine.
Activating/deactivating the interior
lighting delayed switch-off
If the Interior lighting Delayed Shut-
off function is activated and you remove the
SmartKey from the ignition lock, the interior
lighting remains on for 10 seconds.
XPress the V or U button on the
steering wheel to select the Settings
menu.XPress the & button to select submenus.XPress the W or X button to select the
Lighting submenu.XPress the & button to select Interior
Lighting Delayed Shut-off .XPress the W or X button to activate
or deactivate the Interior Lighting
Delay function.XPress the &, V or U button to
select a different display.
Vehicle
Activating/deactivating the automatic
door locking feature
If you select the Automatic Door Locking
function, the vehicle is centrally locked above
a speed of around 9 mph (15 km/h).
i For further information on the automatic
locking feature, see ( Y page 80).
XPress the V or U button on the
steering wheel to select the Settings
menu.XPress the & button to call up the
selection of submenus.XPress the W or X button to select the
Vehicle submenu.XPress the & button to select
Automatic Door Locking .XPress the W or X button to switch
Automatic Door Locking on or off.XPress the &, V or U button to
select a different display.
Activating/deactivating the acoustic
locking confirmation
If you activate the Acoustic Lock
Feedback function, an audible signal sounds
when the vehicle is locked or unlocked. When
unlocking, the signal sounds once. When
locking, it sounds three times.
XPress the V or U button on the
steering wheel to select the Settings
menu.XPress the & button to call up the
selection of submenus.XPress the W or X button to select the
Vehicle submenu.XPress the & button to select Acoustic
Lock Feedback .XPress the W or X button to switch
the Acoustic Lock Feedback function on
or off.XPress the &, V or U button to
select a different display.
Activating/deactivating the radar sensor
system
If the radar sensor system is switched off,
Blind Spot Assist (Y page 189) is deactivated.
i USA only: This device has been approved
by the FCC as a "Vehicular Radar System".
The radar sensor is intended for use in an
automotive radar system only. Removal,
tampering, or altering of the device will void
any warranties, and is not permitted by the
FCC. Do not tamper with, alter, or use in
any nonapproved way.
Any unauthorized modification to this
device could void the user's authority to
operate the equipment.
208Menus and submenusOn-board computer and displays

Display messagesPossible causes/consequences and M Solutions$ (USA
only) ! (Canada
only)
Release Parking
BrakeYou are driving with the parking brake applied. A warning tone also
sounds.XRelease the parking brake$ (USA
only) J (Canada
only)
Check Brake Fluid
LevelGRisk of accident
There is not enough brake fluid in the brake fluid reservoir.
Additionally, the red $ (USA only)/ J (Canada only)
warning lamp lights up in the instrument cluster and a warning
tone sounds.
XPull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.XEngage the parking brake.XConsult a qualified specialist workshop.XDo not add brake fluid. This will not correct the malfunction.GWARNING
Driving with the message Check Brake Fluid Level displayed can result in an accident. Have
your brake system checked immediately.
Do not add brake fluid before checking the brake system. Overfilling the brake fluid reservoir can
result in spilling brake fluid on hot engine parts and the brake fluid catching fire. You can be
seriously burned.
Display messages217On-board computer and displaysZ