workshop MERCEDES-BENZ M-Class 2012 W166 Owner's Guide

Check
listbefor edr iving off-road X
Engine oillevel: check theen gin eoil and
add oilifne ces sary.
When drivingonsteep grad ients,th eoil
leve lmust besuff iciently high toensure a
co rrect oilsupply inthev ehicle.
X DEF tank (BlueTEC vehicles): checkthe
fluid level and,ifnec essary, refilltothe
maximum (13l)(Y page 152).
X Wheel-changing toolkit:chec kthat the
jack isworkin gand make sureyouhave the
lug wrenc h,arobust towcable andafolding
spade inthe vehicle.
X Wheels andtires: chec kthe tire tread
depth andtirepressure.
X Check fordamage andremove anyforeign
objec ts,e.g. small stones,from the
wheels/tir es.
X Replace anymissing valvecaps.
X Replace dentedordamaged wheels.
X Rims: dentedorbent rimscanresult ina
loss oftire pressure anddamage thetire
bead. Therefor e,chec kyour rims before
driving off-road andreplace themas
required.
! Ifthe engine oilwarning lamplights up
while thevehicle isin motion ,stop the
vehicle inasafe place assoon aspossible.
Check theengine oillevel. Theengine oil
warning lampwarning mustnotbeignored.
Continuing thejourney whilethesymbol is
display edcould leadtoengine damage.
Checklist afterdriving off-road G
WARNIN
G If
you notic esudden significant vibrationsor
unusual handling performanc eor ifyou
suspect thatdamage hasoccurred tothe
vehicle, youshould activate thehazard
warning lamps,gentlyreduce speedand
carefully headforanarea thatislocated ata
safe distance fromtheroad.
Check thetires andtheunderside ofthe
vehicle fordamage. Ifthe vehicle seems unsafe,
havethevehicle towedawaytothe
nearest Mercedes-B enzCenter ortire dealer
to be repaired.
! Ifyou detect damage tothe vehicle after
driving off-road, havethevehicle checked
immediately ataquali fiedspecialist
workshop.
Drivin gover rough terrain placesgreater
demands onyour vehicle thandriving on
normal roads.Afterdriving off-road, check
the vehicle. Thisallows youtodetect damage
promptly andreduce therisk ofan accident
to yourself andother roadusers.
X Deact ivateDSR(Ypage 208).
X Vehicles withtheAIRMATIC package:
lower thevehicle toaride height suitable
for the road condit ions,e.g.tothe
highway /high-speed level.
X Clean theheadlamps andrear lights and
check fordamage.
X Clean thefront andrear license plates.
X Clean thewheels/tires withawater jetand
remove anyforeign objects.
X Clean thewheels, wheelarches andthe
vehicle underside withawater jet;check
for any foreign objectsand damage.
X Check whether twigsorother partsof
plants havebecome trapped. These
increase therisk offire and candamage
fuel pipes, brakehoses orthe rubber
bellows ofthe axle jointsand propeller
shafts.
X Aft erthe trip, examine withoutfailthe
entire undercarriage, wheels,tires,brakes,
bodywork structure,steerin g,chassis and
exhaust systemfordamage.
X Aft erdriving forexten dedperiods across
sand, mud,gravel, waterorinsimilarly dirty
condit ions,havethebrake discs, wheels,
brake pads/linings andaxle jointscheck ed
and cleaned.
X Ifyou detect strongvibrations afteroff-road
travel, checkforforeign objectsin the
wheels anddrive trainandremove themif 164
Driving
tipsDriving and parking

Problems
withPARKTRONIC Problem Possible
causes/co nsequences andM Solutions
Only
thered segments
in the PARKTRONIC
warning displaysare lit.
You also hear awarning
tone forapproximately
two seconds.
PARKTRONIC is
deactivated after
approximately
20 seconds, andthe
indicator lampinthe
PARKTRONIC button
lights up. PARKTRONIC
hasmalfunction edand hasswitched off.
X Ifproblems persist,havePARKTRONIC checkedataqual ified
specialist workshop. Only
thered segments
in the PARKTRONIC
warning displaysare lit.
PARKTRONIC is
deactivated after
approximately 20
seconds. The
PARKTRONIC sensorsaredirty orthere isinterf erence.
X Clea nthe PARKTRONIC sensors(Ypage 322).
X Switch theignition backon. The
problem maybecaused byan extern alsource ofradio or
ultrasound waves.
X See ifPARKTRONIC functionsinadifferent location. Active
Parking Assist
Import antsafety notes Act
ive Parking Assistisan electronic parking
aid with ultrasound. Ultrasoundisused to
measure theroad onboth sides ofthe vehicle.
As uitable parkingspac eis ind icat edbythe
park ingsymb ol.Active steer ing interv ention
can assis tyou during parking. Youmay also
use PARKTRONIC (Ypage 183). When
PARKTRONIC isswitched off,Active Parking
Assist isalso unavailab le. G
WARNIN
G Act
iveParking Assistismerely anaid and may
sometimes recommendparking spacesthat
are not suitable forparking. Forexample,
these might bespaces whereparking is
prohibited, driveways,unsuitablesurfaces,
etc. Act
ive Parking Assistmeasures theparking
space asyou drive pastit.Any later changes
to the parking spacearenot taken into
account .For instan ce,this may bethe case
when thevehicle parkedinfront ofor behind
the space changes itsposition orwhen an
obstacle ismoved intotheparking space.
Act ive Parking Assistdoesnotrelieve youof
the responsibility ofpaying attention.Ifyou
rely solely onAct ive Parking Assist,you could
cause anaccident andinjure yourself and
others.
You arealway sresponsible forsafety and
must continue topay atten tiontoyour
immediate surroundings whenparking and
maneuvering. 186
Driving
systemsDriving and parking

Rear
viewcame ra
Impo rtant safetynotes The
rearview came raisan opt ical park ingand
mane uverin gaid. Itshows thearea behin d
your vehic lewith guide linesinthe COMA ND
display. G
WARN
ING Make
surethatnoperso nsoranimals arein
the mane uverin grang e.Oth erwise, they
could beinjured.
The rear view came raisin the handle onthe
tailgat e. :
Rear viewcame ra
View throu ghthecam era The
area behin dthe vehic leisdisplayed ina
mirr or-inv erted mann er,asinthe rear- view
mirr or. G
WARN
ING The
rear view came raisonly anaid and may
display obstacles
R fro madistort edperspect ive
R inacc urately
R may notdisplay obstaclesatall The
rear view camera doesnotrelieve youof
the respon sibility tobe cautious. Takecare
and paycareful attention. Therear view
camera maynotshow objectswhich are
R very close tothe rear bumper
R under therear bumper
R above thetailgate handle
You arerespon sibleforsafety atall times and
must continue topay attention tothe
immediate surroundingswhen parkin gand
maneuver ing.This includes thearea behind,
in fron tof,and besidethe vehicl e.Otherwi se
you couldendange ryourself and/or others. G
WARNING Under
thefollowing circumstances,therear
view camera willnotfunct ion,orwill funct ion
in alimited manner :
R the tailgate isopen
R in heavy rain,snow orfog
R at night orinvery dark places
R ifthe camera isexposed tovery bright light
R ifthe area islit by fluorescent lightorLED
lighting (thedisplay mayflicker)
R ifthere isasudden changeintemperature,
e.g. when driving intoaheated garagein
winter
R ifthe camera lensisdirty orobstruct ed
R ifthe rear ofyour vehicle isdamaged. Inthis
event ,have thecamera position andsetting
check edataquali fiedspecialist workshop.
Mercedes-B enzrecommen dsthat youuse
an authorized Mercedes-B enzCenter for
this purpose.
Do not use therear view camera inthese
types ofsituation. Youcould otherwise injure
others ordamage objectsand your vehicle
while youareparking. 190
Driving
systemsDriving and parking

alte
ringof thedevi cewill void any
warr anties, and isno tp ermit tedbythe
FCC. Donot tamper with,alter, oruse in
any non-approved way.
An yunauthoriz edmodificat iontothis
device couldvoidtheuser’s authorit yto
operate theequipment.
For Blind SpotAssist toassist youwhen
driving, theradar sensor system mustbe
activat ed(Ypage 236)and operation al.
Monitoring rangeofthe sensors
Blind SpotAssist monitorsthe area shown in
the figure upto10 ft(3 m) behind and
immediately adjacenttoyour vehicle. G
WARNIN
G Blind
SpotAssist monitorscert ainareas inthe
immediate vicinityof your vehicle. Vehicles
that approach anddrive pastathigh speeds
are not detect ed.There isno display andno
warning.
If the lanes arevery wide, itmay notbe
possible tomonit orthe complete widthofthe
neighboring lane.Forthis reason, vehicles in
the next lanemaynotbedetect ed,especially
if they aredriving inastaggered formation.
This may bethe case ifvehicles aredriving at
that edge oftheir lanewhich isfurthest away
from yourvehicle. Always
payatten tiontotraffic conditionsand
your surroundings. Otherwise,youmay failto
recogn izedangers intime, cause anaccident
and injure yourself andothers.
If the lanes arenarrow, vehicles drivinginthe
lane beyond thelane next toyour vehicle may
be indicated, especially ifthe vehicles arenot
driving inthe middle oftheir lane. Thismay
be the case ifthe vehicles aredriving onthe
inner sideoftheir lane.
Due tothe nature ofthe system:
R warnings maybeissued inerror when
driving closetocrash barriers orsimilar
solid laneborders.
R warnings maybeinterr upted whendriving
alongside longvehicles, suchastruck s,for
a prolonged time.
The two sensors forBlind SpotAssist are
integr atedintothesides ofthe rear bumper.
Make surethatthebumper isfree from dirt,
ice orslush around thesensors. Therear
sensors mustnotbecovered, forexample by
bicycle racksoroverhanging loads.Following
a severe impact orinthe event ofdamage to
the bumpers, havethefunct ionofthe radar
sensors checkedataquali fiedspecialist
workshop, e.g.anauthorized Mercedes-B enz
Center. BlindSpotAssist mayotherwise not
work properly.
Indicator andwarning display :
Yellow indicator lamp/red warninglamp
When BlindSpotAssist isactivated, indicator
lamp :lights upyellow inthe exter ior
mirrors uptoavehicle speedof20 mph Driving
systems
199Driving and parking Z

i
USA
only:
This device hasbeen approved bythe FCC
as a“Vehicula rRadar System”. The radar
sen sor isint ended foruse inan auto motive
radar systemonly. Remo val,tampering,or
alte ringof thedevi cewill void any
warr anties, and isno tp ermit tedbythe
FCC. Donot tamper with,alter, oruse in
any non-approved way.
An yunauthoriz edmodificat iontothis
device couldvoidtheuser’s authorit yto
operate theequipment.
For Active Blind SpotAssist toassist you
when driving, theradar sensor system must
be activat ed(Ypage 236)and operation al.
Monitoring area
Ac tive Blind SpotAssist monitorsthe area
shown inthe figure upto10 ft(3 m) behind
and immediately adjacenttoyour vehicle. For
this purpose, Active Blind SpotAssist uses
radar sensors inthe rear bumper. G
WARNIN
G Act
ive Blind SpotAssist monitorscert ain
areas inthe immediate vicinityof your vehicle.
Vehicles thatapproach anddrive pastathigh
speeds arenot detect ed.Novisual nor
audibl ewarnings areemitt edand thesystem
does notbrake thevehicle tocorrec tyour
course. If
the lanes arevery wide, itmay notbe
possible tomonit orthe complete widthofthe
neighboring lane.Forthis reason, vehicles in
the next lanemaynotbedetect ed,especially
if they aredriving inastaggered formation.
This may bethe case ifvehicles aredriving at
that edge oftheir lanewhich isfurthest away
from yourvehicle.
Always payatten tiontotraffic conditionsand
your surroundings. Otherwise,youmay failto
recogn izedangers intime, cause anaccident
and injure yourself andothers.
If the lanes arenarrow, vehicles drivinginthe
lane beyond thelane next toyour vehicle may
be indicated, especially ifthe vehicles arenot
driving inthe middle oftheir lane. Thismay
be the case ifthere arevehicles drivingatthe
inner edgeoftheir lanes.
Due tothe nature ofthe system:
R warnings maybeissued inerror when
driving closetocrash barriers orsimilar
solid laneborders.
R warnings maybeinterr upted whendriving
alongside longvehicles, suchastruck s,for
a prolonged time.
Two Active Blind SpotAssist radarsensors
are integrat edinto thefront andrear bumpers
respect ively.Anadditional radarsensor is
located behindthecover inthe radiator grill.
Make surethatthesensor areasonthe
bumpers andthesensor coverinthe radiator
grill arefree ofdirt, iceand slush. Therear
sensors mustnotbecovered, forexample by
cycle racks oroverhanging cargo.Following
a severe impact orinthe event ofdamage to
the bumpers, havethefunct ionofthe radar
sensors checkedataquali fiedspecialist
workshop. BlindSpotAssist mayotherwise
not work properly. Driving
systems
203Driving and parking Z

Please
notethat when towing atrailer,
PARKTRONIC (Ypage 183)andBlind Spot
Assist (Ypage 198)areonly availabl ewith
limitations ,or not atall. i
On
vehicles withoutlevelcontrol,the
height ofthe ball coupling willalter
accordin gto the load placed onthe vehicle.
If necess ary,useatrailer withaheight-
adjustable drawbar.
Driving tips i
Observe
theinform ationonESP®
trailer
stabilization (Ypage 64)and onpulling
away withatrailer. (Ypage 141).
The maximum permissible speedforvehicle/
trailer combinat ionsdepends onthe type of
trailer. Before beginnin gthe journ ey,check
the trailer's document sto see what the
maximum permittedspeed is.Observe the
legally prescribed maximumspeedinthe
relevant country.
For cert ainMercedes- Benzvehicles, the
maximum permissible rearaxle load is
incr eased whentowing atrailer. Refertothe
"Technical data"sectiontofind outwhether
this applies toyour vehicle. Ifyou utilize any
of the added maximum rearaxle load when
towing atrailer, thevehicle/t railer
combinat ionmay notexceed amaximum
speed of60 mph(100 km/h)for reasons
conc ernin gthe operating permit.Thisalso
applies incount riesinwhich thepermissible
maximum speedforvehicle/t railer
combinat ionsisabove 60mph(100 km/h).
When towing atrailer, yourvehicle's handling
charact eristics willbedifferen tinc omparison
with when driving without atrail er.
On long andsteep downhill gradients, you
must selectshift range 1,2or 3in good time. i
This
alsoapp liesif you have activated
cruise control orDISTRONIC PLUS.
This willuse thebraking effectofthe engine,
so that lessbraking willbe requ iredto
maintai nthe speed. Thisrelieves theload on
the brake system andprevents thebrakes from
overheating andwearing tooquickly. If
you need additional braking,depressthe
brake pedalrepeatedly ratherthan
cont inuously .
Driving tips R
Maintain agreater distance fromthe
vehicle infront thanwhen driving without a
trailer.
R Avoid braking abruptly. Ifpossible, brake
gently atfirst toallow thetrailer torun on.
Then, increase thebraking forcerapidly .
R The values givenforgradient-c limbing
capabil itiesfrom astandst illrefer tosea
level. When driving inmountainous areas,
note thatthepower output ofthe engine,
and consequent lythe vehicle's gradient-
climbing capability,decrease with
increasing altitude.
If the trailer swings fromsidetoside:
X Do not accelerate.
X Do not counter- steer.
X Brake ifnecessary. Assemblin
gthe ball coupling
! Mercedes-Ben zrecomm endsthatyou
have theball coupling assembled ata
qualified specialist workshop.Only a
qualified specialist workshophas the
nec essary specialist knowledge andtools
to carry outthework required. Youcould
other wiseincorrectlyassemble theball
coupling ortight enthe nut with the
incor recttorque. Thiscould leadtothe ball
coupling andtheball coupling carrier
becomin gdetached whiletowing atrailer.
As aresult, youcould cause anacciden t.
Therefor e,have theball coupling
assembled ataqualified specialist
worksho p.
If the assembled ballcoupling hasbeen
permanen tlymount edon the vehicle, have
the ball coupling regularly checkedfor 212
Tr
ailer towingDriving and parking

corre
ctinsta llati on and torqu eat aqu alifi ed
spe cialist wo rksho p. G
WARNI
NG The
ballcou pling can bedamag edifthe nut is
tigh tened onthe ballcou pling with the
incor recttorqu e.Thi scou ldcau sethe trailer
to deta chwhi ledri ving andanacci dent could
occu rasa result.
Therefore, pleaseobserve thefollowi ng:
R do not exceed themaximum permitted
noseweight ofthe ball coupling, thetrailer
coupling andthetrailer towhitch.
R when installing, alwaysuse aretainin gring
between thenut and themount ingsurface
of the ball coupling carrier.
R ifthe assembled ballcoupling hasbeen
permanen tlymount edon the vehicle, have
the ball coupling regularly checkedfor
corr ectinst allation andtorque ataqualified
specialist workshop.
R check thatthethread underthenut isof
the corr ectlengt h.
! Mercedes- Benzrecom mends thatyou
only useball couplings testedand
approved foruse onMercedes- Benz
vehicles. Thishelps toavoid damage tothe
vehicle.
Observe themanufact urer'sinstallation
inst ruct ions ifyou useaball coupling other
than theone supplied. i
Also
observe theheight ofthe trailer
coupling andthetrailer manufact urer's
inst ruct ions. i
Depen
dingonthe height ofthe trailer
coupling, itis possible thattheball coupling
will have tobe rotat edby180° onthe ball
coupling carrierforcorr ectinst allation. The
assembly isother wiseidentic al. X
Inser tball couplin g: throug hth ehole in
ball couplin gcar rier ;asfar asitwill go. X
Slid eret aini ngring? onto theth read of
ball couplin g= asfar asitwill go.
X Sc rew onnut Aastightly as poss ible. X
Wit hato rque wrench,tig hten nut Btoa
to rque of516 lb-ft(700 Nm).
X Check thatproje cting thread Chas the
requisite lengthof 0.32 in(8 mm )beneath
nut B.
X Check theassembled ballcoupling for
corr ectinstallation. Tr
ailer towing
213Driving and parking Z

Inst
alling thebal lcoup ling G
WAR
NING If
th eveh icle/t raile rco mbin ation isno t
sec ured ,th etrailer maycome loos e.As a
res ult,you could caus ean acc iden t.
Ther efore, mak esur eth at theball couplin gis
sec ured withth ebolt suppl iedand the
co rrespo nding spring cotter. G
WAR
NING The
ballcouplin gcan bedamag edifth enut is
ti ght ened on theball couplin gwiththe
inc orre cttor que. Thiscould cause thetrailer
to detac hwhile drivingand anacc ident could
occ uras aresult .
There fore,please observethe followin g:
R do not exceed themaxim umperm itted
nos eweight ofthe ball couplin g,the trailer
couplin gand thetrailer towhitch.
R when installing, always usearetainin gring
between thenut and themount ingsurface
of the ball coupling carrier.
R ifthe assembled ballcoupling hasbeen
permanen tlymount edon the vehicle, have
the ball coupling regularly checkedfor
corr ectinst allation andtorque ataqualified
specialist workshop.
R check thatthethread underthenut isof
the corr ectlengt h.
The detachable ballcoupling islocated inthe
stowage wellunder thecargo compart ment
floor (Ypage 292).
X Open thecargo compart mentfloor
(Y page 292). Ball
coupling andballcoupling stowagewell
(example)
X Remove ballcoupling :with thebolt and
spring cotter from ballcoupling stowage
well ;. Protec
tivecap
X Pull protec tivecap=inthe direct ionofthe
arrow, outofthe ball coupling recess.
X Place protec tivecap=into theball
coupling stowagewell. Ball
coupling recess 214
Tr
ailer towingDriving and parking

Hole
inthe ballcoup lingand ballcoup lingreces s
X Insert theballcoup ling hori zontall yinto ball
coup ling reces s? inthe direction ofthe
arro w,until theholein ba llcoup ling A and
the holein ba llcoup ling reces sB align. Bolt
X
Slid ebol tC allthe wayinto theholein the
ba llcoup ling reces sand theballcoup ling. Bolt
andspringcotter
X Secure theboltusing spring cotterD. Correctly
installedandsecured ballcoupling
X Check theball coupling, boltandspring
cott erfor correct installation. G
WARNING If
the ball coupling isnot correct lyinstalled
and secured, theball coupling andthetrailer
could come loose. Asaresult, youcould
cause anaccident.
Therefore, pleaseobserve thefollowi ng:
R Make surethattheball coupling issecured
with thebolt suppli edand the
corresponding springcotter.
R Ifthe ball coupling cannotbecorrect ly
mounted, removetheball coupling. Under
these circumstanc es,the ball coupling
must notbeused fortrailer towing.
Have theentire trailer towhitch checked ata
qual ified speciali stworkshop. Coupling
upatra iler G
WARNING Vehicles
withairsuspension program:While
you arecoupling ordecoupli ngatrailer, make
sure nobody locksorunlocks thevehicle and/
or opens orcloses doorsorthe tailgate.
The vehicle's levelcould change andyou
could endanger yourselfand/o rothe rsas a
res ult.
Ma kesure tha tyou do not operate theADS
switch orthe vehicle levelcontrolsystem
when coupling/decoupling thetrailer. Tr
ailer towing
215Driving and parking Z

Otherwise,
youand others couldbeinjured by
the ball coupling beingthrown around ifyou:
R brake sharply
R change direction suddenly
R are involved inan accident
X Open thestowage wellunder thecargo
compartment floor.
X Remove theprotective capfrom theball
coupling recess.
X Press theprotective capinto theball
coupling recessuntilitengages.
X Make surethattheprotective capisfirmly
in place.
X Store theball coupling inthe ball coupling
recess withthebolt andspring cotter
inserted. Tra
iler power supply
The trailer socket ofyour vehicle isequi pped
at the factory withapermanen tpower supply .
The permanent powersupply issupplied via
trailer socket pin4.
! You canconn ectaccessories witha
maximum powerconsumpt ionof240 Wto
the permanent powersupply.
You must notcharge atrailer battery using
the power supply.
The trailer's permanent powersupply is
switched offinthe event oflow vehicle supply
voltage andafter sixhours atthe latest.
You canobtain further informationabout
installing thetrailer electric sfrom aquali fied
specialist workshop, e.g.anauthorized
Mercedes-B enzCenter. Tr
ailer towing
219Driving and parking Z