2012 MERCEDES-BENZ M-Class towing

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

G
WARNING Do
not disconnect atrail erwith anengag ed
overru nbrake. Otherwi se,you rhand could
bec ome trapped between thebumpe rand
trai lerd rawb ar.
Observe themaximu mpermissible trailer
dimension s(width andlengt h).
Most federal statesand allCanadian
provin cesrequire bylaw:
R safety chains between thetowing vehicle
and thetrailer. Thechains should becross -
wound underthetrailer drawbar. Theymust
be fasten edtothe vehicle's trailer
coupling, nottothe bumper orthe axle.
Allow forenough playinthe chains to
facilitat eturn ingtight corners.
R aseparate brakesystem forcert aintypes
of trailer.
R asafety switch forbraked trailers. Check
the specific legalrequirement sapplicable
to your federal state.
If the trailer detaches fromthetowing
vehicle, thesafety switch applies the
trailer's brakes.
! Donot connectthe trailer's brakesystem
(if featured) tothe hydrau licbrake system
of the towing vehicle, asthe latter is
equipp edwith ananti-lock brakesystem.
Doing sowill result inaloss offunct ionof
the brake systems ofboth thevehicle and
the trailer.
X Make surethattheautomatic transmission
is set toposition P.
X Apply thevehicle's electricparking brake.
X Start theengine.
X Vehicles withtheAIRMATIC package:
select highway level.
X Vehicles withtheadaptive damping
system: setADS toAUTO orCOMF.
X Switch offthe engine.
X Close alldoors andthetailgate.
X Coupl eup the trailer.
X Est ablish allelectrical connections. i
Vehicles
withtheAIRMATIC package:
if you couple upatrailer, thevehicle always
remains athighway level.When coupling up
a trailer, please observe thefollowing:
R ifhighway levelhasnotbeen set
manually ,the vehicle willautomatically
sink tohighway levelassoon asit
reaches aspeed of5m ph(8km/ h).
R high-spe edlevel isnot available.
These restrictions apply toall access ories
powered through acon nection tothe trailer
power socketofyour vehicle, e.g.abicycle
carrier . Towing
atrail er
Th ere arenum erouslega lreq uirem ents
conce rning the towingofatra iler, e.g.speed
rest rictions. Make surethatyour vehicle/
trailer combin ationcomplies withthelocal
requiremen tsnot only inyour areaof
residen cebut also atany location towhich
you aretrav eling. Thepolice andlocal
authorit iescan provide reliableinformation .
Please observe thefollowing whentowinga
trailer:
R To acquaint yourselfwithdrivin gwith a
trailer andwith theresultin gchang esto
handling, youshould practicecorn ering,
stoppin gand backin gup inatraf fic-free
location .
R Befor edrivin g,chec k:
- the trailer towhitch
- the safety switchfor braked trailers
- the safety chains
- the elect ricalconnection s
- the lights
- the wheels
R Adj ust the exterior mirror sto provide an
unobst ructedview ofthe rear sectionofthe
trailer.
R Ifthe trailer features electronic ally
con trolled brakes, pullaway thevehicle/
trailer combin ationcarefully, manually 216
Tr
ailer towingDriving and parking

brake
usingthebrake controller, andchec k
the brakes forcorr ectfunc tion.
R Sec ureany objec tson the trailer topreven t
the cargo fromslipping whenthevehicle is
in mot ion.
R Ifyou couple upatrailer, regularly check
the cargo forsecure fasteningand make
sure thatthetrailer lamps and(if
applicable) thetrailer brakes are
func tioningcorr ectly.
R Bear inmind thatthehandling willbeless
stable whentowingatrailer thanwhen
drivin gwithout one.Avoid sudden steering
movem ents.
R The vehicle/ trailercombin ationisheavier,
acceler atesmore slowly, hasadecreased
gradient climbingcapability andalonger
brakin gdistan ce.
It is more suscept ibletoside winds and
requires morecareful steering.
R Ifpossible, avoidabrupt braking.Depres s
the brake pedalmoderat elyatfirst ,so that
the trailer canactiv ateitsown brakes. Then
incr ease thepressure onthe brake pedal.
R Ifthe automatic transmission continues to
shift back andforthbetween twogears
when drivingup ordownhill, restrict the
shift range. Selectshiftrange 4,3,2,or 1.
Al ower gearandlower speed reduce the
risk ofengine failure.
R On long andsteep gradients thatare
difficult todrive down inshift range 1,
switch tothe off-road program orengage
the LOW GEAR off-road gear.
R When driving downhill, shifttoalower gear
to utilize theengine's brakingeffect.
Avoid continuous brakeapplication asthis
may overheat thevehicle brakesand,if
installed, thetrailer brakes.
R Ifthe coolant temperat ureincreases
dramatically whiletheair-con ditioning
system isswitched on,switch offthe air-
condit ioning system.
Coolant heatcanadditionally bedissipated
by opening thewindows andbysett ingthe blower
fanand theinterior temperat ureto
maximum.
R When overtak ing,payparticular attention
to the exten dedlength ofyour vehicle/
trailer combinat ion.
Due tothe length ofyour vehicle/t railer
combinat ion,youwillhave totravel an
additional distancebeyondthevehicle you
are overtak ingbefore returningtothe
previous lane. Deco
upling atrail er G
WA
RNI NG Ve
hicle swi th airs uspen sionprogram :While
you arecoupling ordecoupling atrailer, make
sure nobody locksorunlocks thevehicle and/
or opens orcloses doorsorthe tailgate.
The vehicle's levelcould change andyou
could endanger yourselfand/orothersasa
result.
Make surethatyoudonot operate theADS
switch orthe vehicle levelcontrolsystem
when coupling/decoupling thetrailer.
! Donot disconnec ta trailer withan
engaged overrunbrake.Otherwise, your
vehicle couldbedamaged bythe
rebounding ofthe overrun brake.
X Make surethattheautomatic transmission
is set toposition P.
X Apply thevehicle's electricparking brake.
X Start theengine.
X Close alldoors andthetailgate.
X Apply thetrailer's parkingbrake. G
WARNING Vehicles
withairsuspension program:As
soon asyou disconnec tthe electrical
conn ection between thetrailer andthe
vehicle, thevehicle willlower. Tohelp avoid
personal injury,makesurenoone isnear the
wheel housing orunderneath thevehicle
before theelectrical connection is
disconnec ted. Tr
ailer towing
217Driving and parking
Z

When
youdecouple thetrailer, thevehicle is
tempor arilyraised because thesprings are
relieved ofload. Beespecially carefulduring
this process, asyou could otherwise injure
yourself and/orothers.Make sure that any
pers onsrem ainin gin theveh icle donotp ress
the switches forvehicl elevel control orthe
ADS.
X Remo vethe trail ercabl eand decou plethe
trail er.
X Switch offthe engine. Permissi
bletrailer loadsanddrawbar
nos eweig hts
Weig htspec ifications The
gross trailerwei ght iscalcu lated by
add ingthe weight ofthe trail erto the weight
of the loadand equipme nton the trail er.
Maximu mgross vehicl ewei ght: 17
.
The maximu mpermissible trailerdrawbar
noseweight isthe maximum weightwith
which thetrailer drawbar canbeloaded: 17
Threshold forMercedes- Benzapproved
trailer towhitches.
Loading atrail er R
Wh enload ing the trailer, makesure tha t
nei the rthe permissible grossweight ofthe
trailer northegross vehicle weightare
exceeded. Thepermissible grossvehicle
weight isindicated onthe identification
plate onthe B-pillar onthe driver's sideof
the vehicle.
You canfind themaximum permissible
values onthe type plates ofyour vehicle
and thetrailer. Always observe thelowest
respective valuewhen determining the
maximum weightwithwhich youcan load
the vehicle andthetrailer.
R The trailer drawba rload onthe ball coupling
must beadded tothe rear axle load toavoid exceeding
thepermissible grossaxle
weight. Thepermissible grossvehicle
weight isindicated onthe identificat ion
plate onthe B-pillar onthe driver's sideof
the vehicle. i
Mercedes-B
enzrecomm endsloading the
trailer sothat thedrawbar noseweight
remains between 8%and 15% ofthe
permissible grosstrailer weight. i
The
weight ofadditional accessories,
passengers, andcargo reduces the
permissible trailerloadanddrawbar
noseweight foryour vehicle.
Checking thevehicle andtrailer weight R
To check thattheweights ofthe towing
vehicle andthetrailer comply withthe
maximum permissible values,havethe
vehicle/t railercombinat ion(including the
driver, passengers, andcargo withafully
laden trailer) weighed onacalibrated
weighbridge.
R Check thegross axleweight ratingofthe
front andrear axles, thegross weight ofthe
trailer andtrailer drawbar noseweight. Removing
theball coupling
X Remove thespring cotter.
X Remove thebolt from theball coupling
recess.
X Remove theball coupling fromtheball
coupling recess.
X Clean theball coupling ifit is dirty.
Infor mation oncleaning andcare ofthe trailer
tow hitch canbefound at(Y page 322). Storing
theball coupling G
WARNIN
G Do
not carry theball coupling inthe vehicle
interior ifit is not secured.
17 Missing valueswerenotavailabl eattime ofgoing toprin t. 218
Tr
ailer towingDriving and parking

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

Disp
laymessa ges Poss
iblecauses/c onseq uences and M Solu
tions Lan
eKee ping Ass
ist Ino
perative or Act
ive Lane Kee
pingAss ist Ino
perative Lan
eKee pingAs sis torA ctive Lane Keeping Assi stisdef ectiv e.
X Vis itaqu alifi ed spe cialist wo rksho p. Blin
dSpot Assist Curr
ently Unav
ailableSee Oper
ator'sManu al or Acti
veBlin d Spot
Assist Curr
ently Unav
ailableSee Oper
ator'sManu al Bli
nd Spot Assistor Active Blind Spot Assististemp orarily
inop erative .Possible causesare:
R you have established theelectric alconn ection between the
trailer andyour vehicle.
R the sensors aredirty.
R funct ionisimpaired duetoheavy rainorsnow.
R the radar sensor system isoutside theoperating temperature
range.
R the radar sensor system istemporarily inoperative, e.g.due to
electrom agneticradiation emittedbynearby TVorradio
station sor other sources ofelectrom agneticradiation.
The yellow 9indicator lampsalsolight upinthe exter ior
mirrors.
X When towing atrailer, confirmthedisplay message witha.
If you aredriving without atrailer andthedisplay message does
not disappea r:
X Pull over andstop thevehicle safelyassoon aspossible, paying
atten tiontoroad andtraffic conditions.
X Apply theelectric parking brake.
X Clean thesensors (Ypage 322).
X Restart theengine.
If the system detectsthat thesensors arefully operational, the
display message disappears.
Blind SpotAssist orAct ive Blind SpotAssist isoperational again. Blind
SpotAssist Inoperative
or Active
Blind Spot
Assist Inoperative Blind
SpotAssist orAct ive Blind SpotAssist isdefectiv e.
The yellow 9indicator lampsalsolight upinthe exter ior
mirrors.
X Visit aquali fiedspecialist workshop. Park
Assist Canceled The
driver's doorisopen andthedriver's seatbelthasnotbeen
fasten ed.
X Repeat theparking process withtheseat beltfastened andthe
driver's doorclosed. 260
Display
messagesOn-board computer and displays