tow MERCEDES-BENZ GLS 2018 Service Manual

R
is affected more by strong crosswinds R
demands more sensitive steering R
has a larger turning circle
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
your vehicle/trailer combination.
Notes on towing a trailer
General notes
! If you have a trailer tow hitch retrofitted,
changes to the cooling system and drive train
may be necessary, depending on the vehicle
type.
If you have a trailer tow hitch retrofitted,
observe the anchorage points on the chassis
frame. R
Do not exceed the legally prescribed maxi-
mum 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.
More information on availability and installa-
tion can be obtained at any qualified special-
ist workshop. 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 cou-
pling.
When towing a trailer, set the tire pressure on
the rear axle of the towing vehicle for the max-
imum load. You will find the values in the tire
pressure table in the fuel filler flap of the vehicle
( Y
page 372).
Please note that when towing a trailer, the fol-
lowing driving systems have limited availability
or are not available at all: R
Parking Assist PARKTRONIC ( Y
page 192)R
Blind Spot Assist ( Y
page 209)R
Active Lane Keeping Assist ( Y
page 215) 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 395).
Driving tips Also observe the notes on pulling away with a
trailer ( Y
page 143).
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 for your trailer. Observe the
legally permissible maximum speed in the rele-
vant country.
For certain Mercedes-Benz vehicles, the maxi-
mum permissible rear axle load is increased
when towing a trailer. See "Technical data" to
find out whether this applies to your vehicle
( Y
page 395). 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 maximum
permissible speed for car/trailer combinations
is greater than 60 mph (100 km/h).
When towing a trailer, your vehicle's handling
characteristics will be different in comparison
with when driving without a trailer.
Use the left-hand steering wheel paddle shifter
to shift into a lower gear in good time on long
and steep downhill gradients.
This also applies if you have activated cruise
control or Distance Pilot DISTRONIC.
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 sys-
tem 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.Towing a trailer 225
Driving and parking Z

R
Maintain a greater distance from the vehicle
in front than when driving without a trailer. R
Avoid braking abruptly. If possible, brake gen-
tly at first to allow the trailer to run on. Then,
increase the braking force rapidly. R
The values given for gradient-climbing capa-
bilities from a standstill refer to sea level.
When driving in mountainous areas, note that
the power output of the engine and, conse-
quently, the vehicle's gradient-climbing capa-
bility, decreases with increasing altitude.
Installing the ball coupling
G WARNING
If the ball coupling is not correctly installed
and secured, it can come loose during the
journey and endanger other road users. There
is a risk of an 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 descri-
bed in the ball coupling installation instruc-
tions. Make sure that the ball coupling is
installed and secured correctly before every
journey. X
Pull protective cap C in the direction of the
arrow, out of the ball coupling recess. X
Stow protective cap C so that it cannot be
thrown around.
Observe the loading guidelines ( Y
page 300)
and the safety notes regarding stowage
spaces ( Y
page 300).
X
Insert the ball coupling horizontally into ball
coupling recess D in the direction of the
arrow until the holes in ball coupling

Most U.S. 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 fas-
tened 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
A separate brake system for certain types of
trailer. R
Safety switch for braked trailers. Check the
specific legal requirements applicable to your
state.
If the trailer becomes detached from the tow-
ing vehicle, the safety feature triggers the
trailer brakes.
Towing a trailer There are numerous legal requirements con-
cerning the towing of a trailer, e.g. speed restric-
tions. Make sure that your car/trailer combina-
tion complies with the local regulations: R
in your place of residence R
in the location to which you are driving
The police and local authorities can provide reli-
able information.
Observe the following when towing a trailer: R
To gain driving experience and to become
accustomed to the new handling characteris-
tics, you should practice the following in a
traffic-free location: -
cornering -
stopping -
backing up R
Before driving, check: -
trailer tow hitch -
safety switch for braked trailers -
safety chains -
electrical connections -
lights -
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. R
Secure any objects on the trailer to prevent
the cargo from slipping when the vehicle is in
motion. R
When you couple up a trailer, check at regular
intervals that the load is firmly secured. If the
trailer is equipped with trailer lights and
brakes, check the trailer to ensure that these
are working. R
Bear in mind that the handling will be less
stable when towing a trailer than when driving
without one. Avoid sudden steering move-
ments. 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, do not brake suddenly, but instead
depress the brake pedal moderately at first so
that the trailer can activate its brakes. Then
increase the pressure on the brake pedal. R
If the automatic transmission repeatedly
shifts between gears on uphill or downhill gra-
dients, shift to a lower gear using the left-hand
steering wheel paddle shifter.
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 instal-
led, the trailer brakes. R
If the coolant temperature increases dramat-
ically while the air-condition ing system is
switched on, switch off the air-conditioning
system.
Coolant heat can also be dissipated by open-
ing the windows and switching the ventilation
blower and the interior temperature to the
highest level. R
When overtaking, pay particular attention to
the extended length of your vehicle/trailer
combination.
Due to the length of the vehicle/trailer com-
bination, you require additional road space in
relation to the vehicle you are overtaking
before you can change back to the original
lane.228
Towing a trailer
Driving and parking

Decoupling a trailer
G WARNING
If you uncoupl e a trailer wit h th e overrun
brake engaged, you could trap your han d
between th e vehicle and th e trailer drawbar .
There is a ris k of injury.
Do no t uncoupl e a trailer if th e overrun brake
is engaged.
G WARNING
Vehicles wit h level control:
The vehicle is lowered as soo n as you discon-
nect th e trailer cable. Thi s could result in your
limbs or those of other people that are
between th e vehicle bod y and tires or under-
neat h th e vehicle bein g trapped. There is a
ris k of injury.
Mak e sur e that nobod y is in th e immediate
vicinit y of th e whee l housings or under th e
vehicle when you disconnec t th e trailer cable.
! Do no t disconnec t a trailer wit h an engage d
overrun brake . Otherwise , your vehicle could
be damaged by th e reboundin g of th e overrun
brake .X
Shift th e transmissio n to position P .X
Apply th e vehicle' s electric parking brake .X
Start th e engine.X
Clos e th e doors and tailgate.X
Apply th e trailer's parking brake .X
Detach th e trailer cable and decoupl e th e
trailer .X
Switc h of f th e engine.
Permissible trailer loads an d drawbar
loads
Weight specifications
Maximum allowable gross mass
The gross vehicle weight of th e trailer is calcu-
lated by addin g th e weight of th e trailer to th e
weight of th e load and equipmen t on th e trailer .
You will fin d installin g dimensions and load s
under "Technical data" ( Y
page 395). Permissible noseweigh tYou will fin d installin g dimensions and load s
under "Technical data" ( Y
page 395).
Loading a trailer R
Whe n loadin g th e trailer , mak e sur e that nei-
ther th e permissible gross weight of th e trailer
no r th e gross vehicle weight are exceeded.
The permissible gross vehicle weight is indi-
cated on th e identification plat e located on
th e B-pilla r on th e driver's sid e of th e vehicle.
You can fin d th e maximum permissible values
on th e typ e plates of your vehicle and th e
trailer . Whe n calculatin g how muc h weight
th e vehicle and trailer may carry, pay atten-
tion to th e respective lowest values. R
The trailer drawbar load on th e ball couplin g
mus t be adde d to th e rea r axl e load to avoid
exceedin g th e permissible gross axl e weight .
The permissible gross vehicle weight is indi-
cated on th e identification plat e located on
th e B-pilla r on th e driver's sid e of th e vehicle.
i Mercedes-Ben z recommends a trailer load
wher e th e trailer drawbar noseweigh t
accounts fo r 8 % to 15 % of th e trailer's per -
missible gross weight .
i The weight of additional accessories , pas-
sengers, and cargo reduce s th e permissible
trailer load and drawbar load fo r your vehicle.
Checking th e vehicle an d trailer weigh tR
To chec k that th e weight s of th e towin g vehi-
cl e and th e trailer compl y wit h th e maximum
permissible values, hav e th e vehicle/trailer
combination (includin g th e driver , passen -
gers, and cargo wit h a full y lade n trailer )
weighed on a calibrated weighbridge .R
Chec k th e gross axl e weight ratin g of th e fron t
and rea r axles, th e gross weight of th e trailer
and th e trailer drawbar noseweight.
Removin g th e ball coupling X
Remov e th e sprin g cotter.X
Remov e th e bolt from th e ball couplin g
recess . X
Remov e th e ball couplin g from th e ball cou-
plin g recess .Towing a trailer 229
Driving and parking Z

X
Clean the ball co uplin g if it is dirt y.X
St ow the ball co uplin g so that it cannot be
thrown aroun d.
Observe the loading guidelines ( Y
page 300)
and the safety notes regarding stowage spaces
( Y
page 300).
In formation on cleaning and care of the trailer
tow hitch ( Y
page 335).
Trailer power supply
! Accessories wit h a maximum power con-
sumption of 180 W can be connected to the
permanent power supply.
You must not charge a trailer battery using the
power supply.
The trailer socket of your veh icle is equipp ed at
the factory wit h a permanent power supply.
The permanent power supply is suppli ed via
trailer socket pin 4.
The trailer's permanent power supply is
swit ched off in the event of low veh icle supply
voltage and after six hours at the latest.
A qualif ied specialist workshop can pro vide
more information about installing the trailer
electrics.
Bicycle rack
General notes
Trailer tow hitch (example wit h addit ional
guide pin ) Depending on the bicycle rack's design, you can
transport up to four bicycles on it: R
When attached by clamping onto ball cou-
pling C , the maximum payload is 75 kg. You
can transport up to three bicycles. R
When attached to ball coupling C and also
guide pin D , the maximum payload is 100 kg.
You can transport up to three bicycles.
The payload is calculated from the weight of the
bic ycle rack and the load of the bicycle rack.
To transport bicycles wit h a gross weight
between 75 kg and 100 kg, use only bicycle
racks wit h additional anchorage on guide pin D .
Important safety notes
G WARNING
The bicycle rack can detach from the vehicle if
you R
exceed the permissible payload of the
trailer tow hitch R
use the bicycle rack incorrectly R
attach the bicycle rack to the ball coupling
beneath the ball head
There is a risk of an accident.
For your safety and that of other road users,
observe the foll owin g:R
Alwa ys observe the permissible payload of
the trailer tow hitch. R
Use the bicycle rack only to transport bicy-
cles. R
Always attach the bicycle rack correctly by
clamping onto the ball head and, if possible,
to the guide pin on the ball coupling as well. R
To transport four bicycles, always use bicy-
cle racks wit h additional support on the ball
coupling's guide pin. R
Use only bicycle racks appr oved by
Mercedes-Benz. R
Alwa ys comply wit h the bicycle rack's oper-
ating manual.
! Using unsuitab le bicycle racks or using
them incorrectly can cause damage to and
fractures in the trailer tow hitch.230
Bicycle rack
Driving and parking

Use only bicycle racks approved by
Mercedes-Benz.
Bicycle racks cause your vehicle's driving char-
acteristics to change. The vehicle: R
is heavier R
is restricted in its acceleration and gradient-
climbing capability R
has an increased braking distance This could impair the handling characteristics.
Adapt your driving style accordingly. Maintain a
safe distance and drive carefully.
When using bicycle racks, set the tire pressure
on the rear axle of the vehicle for the maximum
load. Further information on tire pressure can be
found on the tire pressure table ( Y
page 357).
Loading instructions The greater the distance between the load's center of gravity and the ball head, the higher the load
exerted on the trailer tow hitch.
Therefore, observe the following notes: R
Attach heavy bicycles as close as possible to the vehicle. R
Always distribute the load on the bicycle rack as symmetrically as possible to the vehicle longi-
tudinal axis.
Before loading the bicycle rack, Mercedes-Benz advises you to remove all add-on parts from the
bicycles, e.g. bicycle baskets, child seats or batteries. This will allow you to improve the aerody-
namic resistance and the bicycle rack's center of gravity.
Always secure bicycles against slipping and check that they are firmly seated at regular intervals.
Do not use tarpaulins or other covers. This could impair the driving characteristics and rear visibility.
The aerodynamic resistance would also rise, and so would the load exerted on the trailer tow hitch
as a result.
Load distribution on the bicycle rack
C
Distance in height between the center of gravity and the ball coupling
D
Distance to the rear between the center of gravity and the ball coupling

When loading the bicycle rack, comply with the following notes:
Number of bicycles Gross weight of bicy-
cle rack and load Max. distance C Max. distance D
3 up to 75 kg 420 mm 300 mm
4 2
up to 100 kg 2
420 mm 400 mm
2
When transporting four bicycles or a gross weight between 75 kg and 100 kg, use only bicycle racks with
additional support on the guide pin of the trailer tow hitch.232
Bicycle rack
Driving and parking

Display messages
Possible causes/consequences and P Solutions
The yellow $ warning lamp and th e red I (US A only) or $
(Canada only) indicator lamp ligh t up.
The electric parking brak e is malfunctioning .
To release: X
Switc h off th e ignition and tur n it bac k on .X
Releas e th e electric parking brak e manually.
or X
Releas e th e electric parking brak e automatically ( Y
page 162).
If th e electric parking brak e still canno t be released:X
Do no t drive on .X
Consult a qualified specialist workshop .
The red I (US A only) or $ (Canada only) indicator lamp flashes
and th e yellow $ warning lamp lights up.
The electric parking brak e is malfunctioning .
To release: X
Switc h off th e ignition and tur n it bac k on .X
Releas e th e electric parking brak e manually.
To apply : X
Switc h off th e ignition and tur n it bac k on .X
Apply th e electric parking brak e manually.
If th e red I (US A only) or $ (Canada only) indicator lamp con-
tinue s to flash: X
Do no t drive on .X
Secur e th e vehicl e against rollin g away ( Y
page 375).X
Shift th e transmission to position ] .X
Turn th e fron t wheels toward s th e curb.X
Consult a qualified specialist workshop .252
Display messages
On-board computer and displays

Display messages
Possible causes/consequences and P Solutions
Blind Spo t Assist
Currently Unavaila‐
ble See Operator' s
Manual or Active
Blind Spo t Assist
Currently Unavaila‐
ble See Operator' s
Manual Blind Spot Assis t or Active Blind Spot Assis t is temporarily inoperative.
Possibl e causes are: R
The radar sensor system is outside th e operating temperature
range. R
The radar sensor system is temporarily inoperative, e.g. due to
electromagneti c radiation emitted by nearby TV or radi o station s or
other source s of electromagneti c radiation .
The yellow c indicator lamp s also ligh t up in th e exterio r mirrors.
Whe n th e causes state d abov e no longer apply, th e display message
disappears.
Blind Spot Assis t or Active Blind Spot Assis t is operational again .
If th e display message does no t disappear :X
Pull ove r and stop th e vehicl e safely as soo n as possible, payin g
attention to roa d and traffic conditions.X
Secur e th e vehicl e against rollin g away ( Y
page 161).X
Restart th e engine.
Blind Spo t Assist
Not Available Whe n
Towing a Traile r
See Operator' s Man ‐
ual or Active Blind
Spo t Assist Not
Available Whe n Tow ‐
ing a Traile r See
Operator' s Manual Blind Spot Assis t or Active Blind Spot Assis t is deactivated while tow-
ing a trailer .
You hav e established th e electrical connection between th e trailer and
your vehicle. X
Press v on th e steering whee l to confirm th e display message .
Blind Spo t Assist
Inoperative or
Active Blind Spo t
Assist Inoperative Blind Spot Assis t or Active Blind Spot Assis t is malfunctioning .
The yellow c indicator lamp s also ligh t up in th e exterio r mirrors.X
Visit a qualified specialist workshop .
Parkin g Pilot Can ‐
celed The driver's door is open .X
Repeat th e parking gap measuremen t and parking process wit h th e
driver's door closed .
You hav e inadvertentl y touched th e multifunction steering whee l while
steering intervention was active .X
Whil e steering intervention is active , mak e sur e that th e multifunc-
tion steering whee l is no t touched unintentionally.
The vehicl e has started to skid and ES P ®
has intervened.X
Use Parking Pilo t again later ( Y
page 195).Display messages 26 9
On-board computer and displays Z

Connecting USB devices X
Connect the USB device to the USB port.
There are two USB ports in the stowage space
under the armrest. X
Select the media source ( Y
page 298).
CD/DVD drive and AUX jacks (Rear Seat
Entertainment System)
C
Disc slotD
AUX, right-hand (R) jack for audio signal
(red)