!A function or performance test should
only be carried out on a two-axle dyna-
mometer. 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.
iIn 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"
(
Ypage 198).
DSR (Downhill Speed Regulation)
General notes
DSR is an aid to assist you when driving down-
hill. It keeps the speed of travel at the speed
selected on the on-board computer. The
steeper the downhill gradient, the greater the
DSR braking effect on the vehicle. When driv-
ing on flat stretches of road or on an uphill
gradient, the DSR braking effect is minimal or
nonexistent.
DSR controls the vehicle’s speed when it is
activated and the transmission is in position
D ,R or N. You can drive at a higher or a lower
speed than that set on the on-board computer
at any time by accelerating or braking.
Important safety notes
GWARNING
If the speed driven and the set speed deviate and you activate DSR on a slippery road sur-
face, the wheels may lose traction. There is an
increased danger of skidding and accidents.
Before switching DSR on, please take into
consideration the road surface and the differ- ence between driving speed and the set
speed.
If you fail to adapt your driving style, DSR can
neither reduce the risk of accident nor over-
ride the laws of physics. DSR cannot take
account of road, weather and traffic condi-
tions. 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 con-
trol 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 surface and tire
conditions. Select a set speed suitable for the
prevailing conditions and when necessary,
apply the brakes manually.
Activating DSR
XPress button
:.
Indicator lamp ;lights up.
The à DSR symbol appears in the mul-
tifunction display.
You can only activate DSR when driving at
speeds at or below 28 mph (40 km/h).
If the current vehicle speed is too high, the
à DSR symbol appears in the multifunc-
tion display with the Max. Speed 28 mph
message (Canada:40 km/h).
If you have activated DSR and you change the drive program, DSR is deactivated. If you
switch between the Offroad and Offroad Plus
drive programs, DSR remains activated.
Deactivating DSR
XPress button :.
Indicator lamp ;goes out.
The à DSR symbol appears in the mul-
tifunction display with the Off
message.
DSR switches off automatically if you drive
faster than 28 mph (Canada: 45 km/h). The
Driving systems257
Driving and parking
Z
so will result in a loss of function of the
brake systems of both the vehicle and the
trailer.
XShift the transmission to positionP.
XApply the vehicle's electric parking brake.
XStart the engine.
XVehicles with the AIRMATIC package:
select highway level.
XVehicles with ADS:set ADS toAUTOor
COMF .
XSwitch off the engine.
XClose the doors and tailgate.
XCouple up the trailer.
XEstablish the electrical connection
between the vehicle and the trailer.
XCheck that the trailer lighting system is
working.
iVehicles with the AIRMATIC package:
with a trailer attached, the vehicle will
always remain at highway level. When cou-
pling up a trailer, please observe the fol-
lowing:
RUnless highway level has been set man-
ually, the vehicle is automatically low-
ered to highway level. This is the case if a
speed of 5 mph (8 km/h) is reached.
RHigh-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.
Observe the maximum permissible trailer
dimensions (width and length).
Most U.S. states and all Canadian provinces
require by law:
RSafety 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 cou-
pling, not to the bumper or the axle. Leave enough play in the chains to make
tight cornering possible.
RA separate brake system for certain types
of trailer.
RSafety switch for braked trailers. Check the
specific legal requirements applicable to
your state.
If the trailer becomes detached from the
towing vehicle, the safety switch applies
the trailer brakes.
Towing a trailer
There are numerous legal requirements con-
cerning the towing of a trailer, e.g. speed
restrictions. Make sure that your car/trailer
combination complies with the local regula-
tions:
Rin your place of residence
Rin the location to which you are driving
The police and local authorities can provide
reliable information.
Observe the following when towing a trailer:
RTo gain driving experience and to become
accustomed to the new handling charac-
teristics, you should practice the following
in a traffic-free location:
-cornering
-stopping
-backing up
RBefore driving, check:
-trailer tow hitch
-safety switch for braked trailers
-safety chains
-electrical connections
-lights
-wheels
RAdjust the exterior mirrors to provide an
unobstructed view of the rear section of the
trailer.
RIf the trailer has electronically controlled
brakes, pull away carefully. Brake manually
Towing a trailer267
Driving and parking
Z
using the brake controller and check
whether the brakes function correctly.
RSecure any objects on the trailer to prevent
the cargo from slipping when the vehicle is
in motion.
RWhen you couple up a trailer, check at reg-
ular intervals that the load isfirmly secured.
If the trailer isequipped with trailer lights
and brakes, check the trailer to ensure that
these are working.
RBear inmind that the handlin g will be less
stable when towing a trailer than when driv-
ing without one. Avoid sudden steering
movements.
RThe vehicle/trailer combination isheavier,
accelerates more slowly, has a decreased
gradient cli mbing capability and a longer
braking distance.
It is more susceptible to side winds and
requires more careful steering.
RIf possible, do not brake suddenly, but
instead depress the brake pedal moder-
ate lyat first so that the trailer can activate
it s brakes. Then increase the pressure on
the brake pedal.
RIf the automat ictransmission repeatedly
shifts between gears on uphill or downhill
gradients, shift to a lower gear using the
left-hand steering wheel paddleshifter.
A lower gear and lower speed reduce the
risk of engine failure.
RWhen drivingdown hill, shift to a lower gear
to uti lize the engine's braking effect.
Avoid co ntin
uous brake application as this
may overheat the vehicle brakes and, if
instal led,the trailer brakes.
RIfthe coolant temperature increases dra-
matical ly while the air-cond itioning system
is swit ched on, switch off the air-condition-
ing system.
Coolant heat can also bedissipated by
opening the windows and switching the ventilation
blower and the interior temper-
ature to the highest leve l.
RWhen overtaking, pay particular attention
to the extended length of your vehicle/
trailer combination.
Due to the length of the vehicle/trailer
combination, you require additional road
spaceinrelation to the vehicle you are
overtaking before you can change back to
the original lane.
Decoupling a trailer
GWARNIN G
If you uncouple atrailer wit hth eoverrun
brak eengaged ,you could trap your han d
between th evehicl eand th etrailer drawbar.
Ther eis aris kof injury.
Do no tuncouple atrailer if th eoverrun brak e
is engaged .
GWARNING
Vehicles wit hleve lcontrol :
The vehicl eis lowered as soo nas you discon -
nect th etrailer cable. This could result in your
limb sor those of other people that are
between th evehicl ebody and tires or under-
neath th evehicl ebein gtrapped .Ther eis a
ris kof injury.
Mak esure that nobody is in th eimmediat e
vicinity of th ewhee lhousing sor under th e
vehicl ewhen you disconnect th etrailer cable.
!Do not disconnect a trailer with an
engaged overrun brake. Otherwise, your
vehicle could bedamaged bythe rebound-
ing of the overrun brake.
XSh ift the transmission to position P.
XApply the vehicle's electr icparking brake.
XStart the engine.
XClose the doors and tailgate.
XApply the trailer's parking brake.
268Towing a trailer
Driving and parking
Safety systems
Display messagesPossible causes/consequences andMSolutions
!÷
Currently Unavail‐
able See Opera‐
tor's Manual
ABS (Anti-lock Brake System), BAS (Brake Assist), ESP®(Elec-
tronic Stability Program), ESP®trailer stabilization, PRE‑SAFE®,
the HOLD function, hill start assist, Crosswind Assist, STEER CON-
TROL, Active Lane Keeping Assist and Active Blind Spot Assist are
temporarily unavailable.
COLLISION PREVENTION ASSIST, BAS PLUS and
PRE‑SAFE
®Brake may also have failed.
In addition, the ÷,åand! warning lamps light up in the
instrument cluster.
ATTENTION ASSIST is deactivated.
Possible causes are:
RSelf-diagnosis is not yet complete.
Rthe on-board voltage may be insufficient.
GWARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you
brake hard, for example.
The steerability and braking characteristics may be severely affec-
ted. The braking distance in an emergency braking situation can
increase.
If ESP
®is not operational, ESP®is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
XCarefully drive a suitable distance, making slight steering move-
ments at a speed above 12 mph (20 km/h).
If the display message disappears, the functions mentioned
above are available again.
If the multifunction display still shows the display message:
XDrive on carefully.
XVisit a qualified specialist workshop.
!÷
Inoperative See
Operator's Manual
ABS, BAS, ESP®, ESP®trailer stabilization, PRE ‑SAFE®, the HOLD
function, hill start assist, Crosswind Assist, STEER CONTROL,
Active Lane Keeping Assist and Active Blind Spot Assist are
unavailable due to a malfunction.
COLLISION PREVENTION ASSIST, BAS PLUS and
PRE‑SAFE
®Brake may also have failed.
The $ (USA only) or J(Canada only), ÷,åand!
warning lamps in the instrument cluster also light up.
ATTENTION ASSIST is deactivated.
Display messages291
On-board computer and displays
Z
Display messagesPossible causes/consequences andMSolutions
GWARNING
The brakesystem continues to function normally, but without th e
function slisted above. The wheels could therefore loc kif you
brak ehard, fo rexample.
The steerabilit yand brakin gcharacteristics may be severely affec -
ted. The brakin gdistanc ein an emergenc ybrakin gsituation can
increase .
If ES P
®is no toperational, ES P®is unable to stabiliz eth evehicle.
There is an increase dris kof skiddin gand an accident.
XDrive on carefully.
XVisit aqualified specialist workshop immediately.
÷
Currently unavail‐
abl eSee Opera‐
tor's Manual
ES P®,ES P®trailer stabilization ,BAS, PRE ‑SAFE®, th eHOLD func-
tion ,hill start assist ,Crosswin dAssist, STEE RCONTROL ,Active
Lan eKeepin gAssis tand Active Blind Spot Assis tare unavailable
due to amalfunction .
COLLISION PREVENTION ASSIST ,BA SPLU Sand
PRE ‑S AF E
®Brake may also hav efailed.
In addition ,th e÷ andå warnin glamp sligh tup in th e
instrumen tcluster.
The self-diagnosi sfunction might no tbe complete, fo rexample.
ATTENTION ASSIST is deactivated.
GWARNIN G
The brakesystem continues to function normally, but without th e
function slisted above. The wheels could therefore loc kif you
brak ehard, fo rexample.
The brakin gdistanc ein an emergenc ybrakin gsituation can thus
increase .
If ES P
®is no toperational, ES P®is unable to stabiliz eth evehicle.
There is an increase dris kof skiddin gand an accident.
XCarefull ydrive asuitable distance, makin gslight steerin gmove-
ments at aspeed abov e12 mph (20 km/h).
If th edisplay message disappears, th efunction smentioned
abov eare available again .
If th emultifunction display still shows th edisplay message :
XDrive on carefully.
XVisitaqualified specialist workshop .
292Display messages
On-board computer and displays
Display messagesPossible causes/consequences andMSolutions
F(USA
only)
!(Canada
only)
Tur nOn the Igni‐
tio nto Releas e
the Parkin gBrake
The red F(USAonly) or !(Canada only) indicato rlamp
lights up.
You attempte dto release th eelectric parkin gbrak ewhile th eigni-
tion was switched off.
XSmartKey: turnth eSmartKey to position 1in th eignition lock.
XKEYLESS-GO: switch on theignition .
F(USA
only)
!(Canada
only)
Please Releas e
ParkingBrake
The red F(USAonly) or !(Canada only) indicato rlamp
flashes and awarnin gtone sounds. Acondition fo rautomati c
release of th eelectric parkin gbrak eis no tfulfilled (
Ypage 190).
You are drivin gwit hth eelectric parkin gbrak eapplied.
XReleas eth eelectric parkin gbrak emanually.
The red F(USAonly) or !(Canada only) indicato rlamp
flashes and awarnin gtone sounds.
You are usin gth eelectric parkin gbrak efo remergenc ybrakin g
(
Ypage 190).
F(USA
only)
!(Canada
only)
Parkin gBrake See
Operator' sManual
The yello w! warnin glamp lights up.
The electric parkin gbrak eis malfunctioning.
To apply:
XSwitc hth eignition off.
XPress th eelectric parkin gbrak ehandle fo rat leas tte nseconds.
XShift th etransmissio nto position P.
XConsultaqualified specialist workshop .
The yellow! warnin glamp and th ered F (USAonly)
or ! (Canada only) indicato rlamp ligh tup.
The electric parkin gbrak eis malfunctioning.
To release:
XSwitc hof fth eignition and tur nit bac kon .
XReleas eth eelectric parkin gbrak emanually.
or
XReleas eth eelectric parkin gbrak eautomatically (Ypage 190).
If th eelectric parkin gbrak estill canno tbe released:
XDo no tdrive on .
XConsult aqualified specialist workshop .
294Display messages
On-board computer and displays
Display messagesPossible causes/consequences andMSolutions
The redF(USAonly) or !(Canada only) indicato rlamp
flashes and th eyello w! warnin glamp lights up.
The electric parkin gbrak eis malfunctioning.
To release:
XSwitc hof fth eignition and tur nit bac kon .
XReleas eth eelectric parkin gbrak emanually.
To apply:
XSwitc hof fth eignition and tur nit bac kon .
XApply th eelectric parkin gbrak emanually.
If th ered F (USAonly) or !(Canada only) indicato rlamp
continues to flash:
XDo no tdrive on .
XSecureth evehicl eagainst rollin gaway (Ypage 428).
XShift th etransmissio nto position P.
XTurnth efron twheels toward sth ecurb.
XConsult aqualified specialist workshop .
The yellow! warnin glamp lights up. The red F(USAonly)
or ! (Canada only) indicato rlamp flashes fo rabout te nsec -
onds after th eelectric parkin gbrak ehas been applied or released.
It then goe sout or remain slit .
The electric parkin gbrak eis malfunctioning.
XSwitc hof fth eignition and tur nit bac kon .
XApply th eelectric parkin gbrake.
If it is no tpossibl eto engage th eelectric parkin gbrake:
XShift th etransmissio nto position P.
XVisitaqualified specialist workshop .
If it is no tpossibl eto release th eelectric parkin gbrake:
XReleas eth eelectric parkin gbrak eautomatically (Ypage 190).
If th eelectric parkin gbrak estill canno tbe released:
XConsult aqualified specialist workshop .
Display messages295
On-board computer and displays
Z
Display messagesPossible causes/consequences andMSolutions
The yellow! warnin glamp lights up. If you manually apply or
release th eelectric parkin gbrake, th ered F (USAonly) or !
(Canada only) indicato rlamp flashes .
The electric parkin gbrak eis malfunctioning. It is no tpossibl eto
apply th eelectric parkin gbrak emanually.
XShift th etransmissio nto position P.
XVisitaqualified specialist workshop .
F(USA
only)
!(Canada
only)
Parkin g
BrakeInop‐
erative
The yello w! warnin glamp lights up. The red F(USAonly)
or ! (Canada only) indicato rlamp flashes fo rabout te nsec -
onds after th eelectric parkin gbrak ehas been applied or released.
It then goe sout or remain slit .
The electric parkin gbrak eis malfunctioning, e.g. because of over-
voltag eor undervoltage.
XRemove th ecaus efo rth eovervoltage or undervoltage, e.g. by
chargin gth ebattery or restarting th eengine.
XEngage or release th eelectric parkin gbrake.
If it remain simpossible to apply or release th eelectric parkin g
brake:
XSwitc hof fth eignition and tur nit bac kon .
XEngage or release th eelectric parkin gbrake.
If th eelectric parkin gbrak estill canno tbe released:
XConsult aqualified specialist workshop .
If th eelectric parkin gbrak estill canno tbe applied:
XVisit aqualified specialist workshop .
The yellow! warnin glamp lights up and th ered F (USA
only) or !(Canada only) indicato rlamp flashes .
It is no tpossibl eto apply th eelectric parkin gbrak emanually.
XShift th etransmissio nto position P.
XVisit aqualified specialist workshop .
296Display messages
On-board computer and displays