trailer MERCEDES-BENZ GLS 2018 Service Manual

For heavier soiling, you can apply a fine paint-
work polish with a microfiber cloth. Remove
the excess polish residue after polishing.
Impurities combined with the effects of road grit
and corrosive environmental factors may cause
flash rust to form on the surface. You can
restore the original shine of the exhaust pipe by
cleaning it regularly, especially in winter and
after washing. X
Clean the exhaust pipe with a chrome care
product tested and approved by Mercedes-
Benz.
Cleaning the trailer tow hitch
H Environmental note
Dispose of rags soaked in oil and grease in an
environmentally responsible manner.
! Do not clean the ball coupling with a power
washer. Do not use solvents.
! Please note the care instructions in the
trailer coupling manufacturer's operating
instructions.
The ball coupling must be cleaned if it becomes
dirty or corroded. X
Remove rust on the ball of the ball coupling,
e.g. with a wire brush. X
Remove dirt with a clean, lint-free cloth or a
brush. X
After cleaning, lightly oil or grease ball cou-
pling C .X
Check that the vehicle's trailer tow hitch is
working properly.
i You can also have the maintenance work on
the ball coupling and the trailer tow hitch car-
ried out by a qualified specialist workshop. Interior care
Cleaning the display
! For cleaning, do not use any of the following: R
alcohol-based thinner or gasoline R
abrasive cleaning agents R
commercially-available household cleaning
agents
These may damage the display surface. Do
not put pressure on the display surface when
cleaning. This could lead to irreparable dam-
age to the display. X
Before cleaning the display, make sure that it
is switched off and has cooled down. X
Clean the display surface using a commer-
cially available microfiber cloth and TFT/LCD
display cleaner. X
Dry the display surface using a dry microfiber
cloth.
Cleaning the plastic trim
G WARNING
Care products and cleaning agents containing
solvents cause surfaces in the cockpit to
become porous. As a result, plastic parts may
come loose in the event of air bag deploy-
ment. There is a risk of injury.
Do not use any care products and cleaning
agents to clean the cockpit.
! Never attach the following to plastic surfa-
ces: R
stickers R
films R
perfume oil container or similar
You could otherwise damage the plastic.
! Do not allow cosmetics, insect repellent or
sunscreen to come into contact with the plas-
tic trim. This maintains the high-quality look of
the surfaces. X
Wipe the plastic trim with a damp, lint-free
cloth, e.g. a microfiber cloth. X
Heavy soiling: use care and cleaning prod-
ucts recommended and approved by
Mercedes-Benz.
The surface may change color temporarily.
Wait until the surface is dry again. Care 335
Maintenance and care Z

i Jumper cables and further information regarding jump-starting can be obtained at any qualified
specialist workshop.
Towing and tow-starting
Important safety notes
G WARNING
Functions relevant to safety are restricted or
no longer available if: R
the engine is not running. R
the brake system or the power steering is
malfunctioning. R
there is a malfunction in the voltage supply
or the vehicle's electrical system.
If your vehicle is being towed, much more
force may be necessary to steer or brake.
There is a risk of an accident.
In such cases, use a tow bar. Before towing,
make sure that the steering moves freely.
G WARNING
When towing or tow-starting another vehicle
and its weight is greater than the permissible
gross weight of your vehicle, the: R
the towing eye could detach itself R
the vehicle/trailer combination could roll-
over.
There is a risk of an accident.
When towing or tow-starting another vehicle,
its weight should not be greater than the per-
missible gross weight of your vehicle.
Details on the permissible gross vehicle weight
of your vehicle can be found on the vehicle iden-
tification plate ( Y
page 385).
! When Active Brake Assist, Distance Pilot
DISTRONIC or the HOLD function is activated,
the vehicle brakes automatically in certain
situations.
To avoid damage to the vehicle, deactivate
these systems in the following or similar sit-
uations: R
when towing the vehicle R
in the car wash ! Make sure that the electric parking brake is
released. If the electric parking brake is faulty,
visit a qualified specialist workshop.
! Only secure the tow rope or tow bar at the
towing eyes, or the trailer tow hitch, if availa-
ble. You could otherwise damage the vehicle.
! Observe the following points when towing
with a tow rope: R
Secure the tow rope on the same side on
both vehicles. R
Make sure that the tow rope is not longer
than legally permitted. Mark the tow rope in
the middle, e.g. with a white c loth
(1
1.8 x 11.8 in). This will make other road
users aware that a vehicle is being towed. R
Only secure the tow cable to the towing
eyes or, if available, to the trailer tow hitch. R
Observe the brake lamps of the towing
vehicle while driving. Always maintain a dis-
tance a distance so that the tow rope does
not sag. R
Do not use steel cables or chains to tow
your vehicle. You could otherwise damage
the vehicle.
! Do not use the trailer tow hitch for recovery
or towing. Do not use the towing eye for
recovery. this could damage the vehicle. If in
doubt, have the vehicle recovered using a
crane.
! When towing, pull away slowly and
smoothly. Pull the towed vehicle as straight as
possible and not at an acute angle. Excessive
tractive power could damage the vehicles.
When towing, it is preferable to use a rigid tow-
ing bar as opposed to a tow rope. A rigid towing
bar helps to keep the tractive power low.
! When towing away vehicles with KEYLESS-
GO, use the key instead of the Start/Stop
button. The automatic transmission may oth-
erwise shift to position ] when you open the
driver's or front-passenger door, which could
damage the transmission.
! Do not tow with sling-type equipment. This
could damage the vehicle.Towing and tow-starting 349
Breakdown assistance Z

! Vehicles with differential locks: make sure
the differential locks are in automatic mode.
When towing, the differential locks must not
be switched on. The transmission may other-
wise be damaged.
! The vehicle can be towed a maximum of
30 miles (50km). The towing speed of 30 mph
(50 km/h) must not be exceeded.
If the vehicle has to be towed more than
30 miles (50km), the entire vehicle must be
raised and transported.
It is better to have the vehicle transported than
to have it towed away.
If the vehicle has suffered transmission damage,
have it transported on a transporter or trailer.
The automatic transmission must be in position
\\ when the vehicle is being towed.
The battery must be connected and charged.
Otherwise, you: R
cannot turn the SmartKey to position H in
the ignition lock R
cannot release the electric parking brake R
cannot shift the automatic transmission to
position \\
Disarm the automatic locking feature before the
vehicle is towed ( Y
page 244). You could other-
wise be locked out when pushing or towing the
vehicle.
Installing/removing the towing eye
Installing the towing eye The brackets for the screw-in towing eye are
located in the bumpers. They are at the front and
rear behind covers CD .X
Remove the towing eye from the vehicle tool
kit ( Y
page 339). X
To open the cover at the front: press the
mark on cover C inwards in the direction of
the arrow. X
To open the cover at the rear: insert a flat,
blunt object into the cutout and lever
cover D out of the bumper. X
Take cover C or D off the opening.X
Screw in the towing eye clockwise as far as it
will go and tighten it.
Removing the towing eye X
Unscrew and remove the towing eye. X
Position cover C or D in the bumper and
press the cover on until it engages. X
Place the towing eye in the vehicle tool kit.
Towing a vehicle with both axles on
the ground The automatic transmission shifts to position
] automatically when you open the driver's or
front-passenger door or when you remove the
SmartKey from the ignition lock.
In order to ensure that the automatic transmis-
sion stays in position \\ when towing away the
vehicle, you must observe the following points: X
Make sure that the vehicle is stationary. X
Turn the SmartKey to position H in the igni-
tion lock. X
Depress and hold the brake pedal. X
Shift the automatic transmission to position
\\ . X
Leave the SmartKey in position H in the igni-
tion lock. X
Release the brake pedal. X
Release the electric parking brake. X
Switch on the hazard warning lamps
( Y
page 117).
In order to signal a change of direction when
towing the vehicle with the hazard warning
lamps switched on, use the combination switch
as usual. In this case, only the indicator lamps
for the direction of travel flash. After resetting350
Towing and tow-starting
Breakdown assistance

the combination switch, the hazard warning
lamp starts flashing again.
Transporting the vehicle
4MATIC vehicles/vehicles with auto-
matic transmission
! When the vehicle is loaded for transport, the
front and rear axles must be stationary and on
the same transportation vehicle. Positioning
over the connection point of the transport
vehicle is not permitted. The drive train may
otherwise be damaged.
All vehicles
! You may only secure the vehicle by the
wheels, not by parts of the vehicle such as
axle or steering components. Otherwise, the
vehicle could be damaged.
The towing eye can be used to pull the vehicle
onto a trailer or transporter for transporting pur-
poses. X
Turn the SmartKey to position H in the igni-
tion lock. X
Shift the automatic transmission to position
\\ .
As soon as the vehicle has been loaded: X
Prevent the vehicle from rolling away by
applying the electric parking brake. X
Shift the automatic transmission to position
] . X
Turn the SmartKey to position

Vehicles with 4MATIC may either be towed away
with both axles on the ground or be loaded up
and transported.
If the vehicle's transmission, front, or rear axle is
damaged, have the vehicle transported on a
truck or trailer.
In the event of damage to the electrical sys-
tem: if the battery is defective, the automatic
transmission will be locked in position P . To shift
the automatic transmission to position N , you
must provide power to the vehicle's electrical
system in the same way as when jump-starting
( Y
page 346).
Have the vehicle transported on a transporter or
trailer.
Tow-starting (emergency engine
starting)
! Vehicles with automatic transmission must
not be tow-started. You could otherwise dam-
age the automatic transmission.
You can find information on "Jump-starting"
under ( Y
page 346).
Fuses
Important safety notes
G WARNING
If you manipulate or bridge a faulty fuse or if
you replace it with a fuse with a higher amper-
age, the electric cables could be overloaded.
This could result in a fire. There is a risk of an
accident and injury.
Always replace faulty fuses with the specified
new fuses having the correct amperage.
! For the fuse boxes in the engine compart-
ment and under the rear bench seat, only use
fuses with the suffix "S". Otherwise, compo-
nents or systems could be damaged.
! Make sure that no moisture can enter the
fuse box when the cover is open.
! When closing the cover, make sure that it is
lying correctly on the fuse box. Moisture seep-
ing in or dirt could otherwise impair the oper-
ation of the fuses. The fuses in your vehicle serve to close down
faulty circuits. If a fuse blows, all the compo-
nents on the circuit and their functions stop
operating.
Blown fuses must be replaced with fuses of the
same rating, which you can recognize by the
color and value. The fuse ratings are listed in the
fuse allocation chart.
The fuse allocation chart is located in the fuse
box under the rear bench seat ( Y
page 353).
If a newly inserted fuse also blows, have the
cause traced and rectified at a qualified special-
ist workshop, e.g. an authorized Mercedes-Benz
Center.
Before changing a fuse Observe the important safety notes
( Y
page 352) X
Switch off the engine. X
Switch off all electrical consumers. X
Remove the SmartKey from the ignition lock.
Or, on vehicles with KEYLESS-GO start function
or KEYLESS ‑ GO: X
Open the driver's door.
The vehicle electronics are now in key posi-
tion

R
incorrectly set tire pressure R
sudden loss of tire pressure, e.g. from a for-
eign object that has penetrated the tire
The data on the Tire and Loading Information
placard and tire pressure table shown here are
examples. Tire pressure specifications are vehi-
cle-specific and may deviate from the data
shown here. The tire pressure specifications
that are valid for your vehicle can be found on
the Tire and Loading Information placard and
tire pressure table on the vehicle.
General notes The recommended tire pressures for the tires
mounted at the factory can be found on the
labels described here.
Operation with emergency spare wheel:
information on operation with the emergency
spare wheel can be found under "Emergency
spare wheel" ( Y
page 380).
Operation with a trailer: the applicable value
for the rear axle is the maximum tire pressure
value stated in the table inside the fuel filler flap.
Further information on tire pressures can be
obtained at a qualified specialist workshop.
Tire and Loading Information placard
C
Recommended tire pressures
The Tire and Loading Information placard is on
the B-pillar on the driver's side ( Y
page 364).
The Tire and Loading Information placard con-
tains the recommended tire pressures for cold
tires. The recommended tire pressures are valid
for the maximum permissible load and up to the
maximum permissible vehicle speed. Tire pressure table The tire pressure table is on the inside of the fuel
filler flap. It shows the tire pressure for all tires
permitted at the factory for this vehicle; see
illustration (example).
The tire pressure table contains the recommen-
ded pressures for cold tires for various operat-
ing conditions, i.e. differing load and speed con-
ditions.
If a tire size precedes a tire pressure, the fol-
lowing tire pressure information is only valid for
that tire size; see illustration (example).
The load conditions "partially laden" and "fully
laden" are defined in the table for different num-
bers of occupants and amounts of luggage. The
actual number of seats may differ.358
Tire pressure
Wheels and tires

able cargo and luggage load capacity is
650 lbs (1400 - 750 (5 x 150) = 650 lbs). X
Step 5: Determine the combined weight of
luggage and cargo being loaded on the vehi- cle. That weight may not safely exceed the
available cargo and luggage load capacity cal-
culated in step 4.
Example: steps 1 to 3 The following table shows examples on how to calculate total and cargo load capacities with varying
seating configurations and number and size of occupants. The following examples use a load limit of
1500 lbs (680 kg). This is for illustration purposes only. Make sure you are using the actual load
limit for your vehicle stated on your vehicle's Tire and Loading Information placard ( Y
page 364).
The greater the combined weight of the occupants, the lower the maximum luggage load.
Additional information when towing a trailer ( Y
page 225).
Step 1
Example 1 Example 2 Example 3
Combined maximum
weight of occupants
and cargo (data from
the Tire and Loading
Information placard) 1500 lbs (680 kg) 1500 lbs (680 kg) 1500 lbs (680 kg)
Step 2
Example 1 Example 2 Example 3
Number of people in
the vehicle (driver and
occupants) 5 3 1
Distribution of the
occupants Front: 2
Rear: 3 Front: 1
Rear: 2 Front: 1
Weight of the occu-
pants Occupant 1: 150 lbs
(68 kg)
Occupant 2: 180 lbs
(82 kg)
Occupant 3: 160 lbs
(73 kg)
Occupant 4: 140 lbs
(63 kg)
Occupant 5: 120 lbs
(54 kg) Occupant 1: 200 lbs
(91 kg)
Occupant 2: 190 lbs
(86 kg)
Occupant 3: 150 lbs
(68 kg) Occupant 1: 150 lbs
(68 kg)
Gross weight of all
occupants 750 lbs (340 kg) 540 lbs (245 kg) 150 lbs (68 kg)366
Loading the vehicle
Wheels and tires

Speed rating The speed rating is part of the tire identification.
It specifies the speed range for which the tire is
approved.
GTW (Gross Trailer Weight) The GTW is the weight of a trailer including the
weight of the load, luggage, accessories etc. on
the trailer.
GVW (Gross Vehicle Weight) The gross vehicle weight includes the weight of
the vehicle including fuel, tools, the spare wheel,
accessories installed, occupants, luggage and
the drawbar noseweight, if applicable. The gross
vehicle weight must not exceed the gross vehi-
cle weight rating GVWR as specified on the vehi-
cle identification plate on the B-pillar on the
driver's side.
GVWR (Gross Vehicle Weight Rating) The GVWR is the maximum permissible gross
weight of a fully loaded vehicle (the weight of the
vehicle including all accessories, occupants,
fuel, luggage and the drawbar noseweight, if
applicable). The gross vehicle weight rating is
specified on the vehicle identification plate on
the B-pillar on the driver's side.
Maximum loaded vehicle weight The maximum weight is the sum of: R
the curb weight of the vehicle R
the weight of the accessories R
the load limit R
the weight of the factory installed optional
equipment
Kilopascal (kPa)
Metric unit for tire pressure. 6.9 kPa corre-
sponds to 1 psi. Another unit for tire pressure is
bar. 100 kilopascals (kPa) are the equivalent of
1 bar.
Load index
In addition to the load-bearing index, the load
index may also be imprinted on the sidewall of
the tire. This specifies the load-bearing capacity
more precisely.
Curb weight
The weight of a vehicle with standard equipment
including the maximum capacity of fuel, oil and
coolant. It also includes the air-conditioning sys- tem and optional equipment if these are instal-
led in the vehicle, but does not include passen-
gers or luggage.
Maximum load rating The maximum tire load is the maximum permis-
sible weight in kilograms or lbs for which a tire is
approved.
Maximum permissible tire pressure Maximum permissible tire pressure for one tire.
Maximum load on one tire Maximum load on one tire. This is calculated by
dividing the maximum axle load of one axle by
two.
PSI (pounds per square inch) A standard unit of measure for tire pressure.
Aspect ratio Relationship between tire height and tire width
in percent.
Tire pressure This is pressure inside the tire applying an out-
ward force to each square inch of the tire's sur-
face. The tire pressure is specified in pounds per
square inch (psi), in kilopascal (kPa) or in bar.
The tire pressure should only be corrected when
the tires are cold.
Cold tire pressure The tires are cold: R
if the vehicle has been parked with the tires
out of direct sunlight for at least three hours
and R
if the vehicle has not been driven further than
1 mile (1.6 km)
Tread
The part of the tire that comes into contact with
the road.
Bead
The tire bead ensures that the tire sits securely
on the wheel. There are several steel wires in the
bead to prevent the tire from coming loose from
the wheel rim.All about wheels and tires 373
Wheels and tires Z

Sidewall The part of the tire between the tread and the
bead.
Weight of optional extras The combined weight of those optional extras
that weigh more than the replaced standard
parts and more than 2.3 kg (5 lbs). These
optional extras, such as high-performance
brakes, level control, a roof rack or a high-per-
formance battery, are not included in the curb
weight and the weight of the accessories.
TIN (Tire Identification Number) This is a unique identifier which can be used by
a tire manufacturer to identify tires, for example
for a product recall, and thus identify the pur-
chasers. The TIN is made up of the manufactur-
er's identity code, tire size, tire type code and
the manufacturing date.
Load bearing index The load bearing index (also load index) is a code
that contains the maximum load bearing capa-
city of a tire.
Traction Traction is the result of friction between the tires
and the road surface.
TWR (Tongue Weight Rating) The TWR specifies the maximum permissible
weight that the ball coupling of the trailer tow
hitch can support.
Treadwear indicators Narrow bars (tread wear bars) that are distrib-
uted over the tire tread. If the tire tread is level
with the bars, the wear limit of

Accelerate carefully and make sure that the
wheels do not spin when driving on steep ter-
rain.
i If the load on the front axle is reduced when
pulling away on a steep uphill slope, the front
wheels have a tendency to spin. 4ETS recog-
nizes this and brakes the wheels accordingly.
The rear wheel torque is increased, making it
easier to drive off.
For further information about the maximum gra-
dient climbing ability, see ( Y
page 173).
Trailer tow hitch
Mounting dimensions
! 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.
C
Anchorage points for the trailer tow hitch
D
Rear axle center line Trailer loads
Permissible trailer load, braked (at a
minimum gradient-climbing capability
of 12% from a standstill) All models
7500 lbs (3402 kg)
Maximum drawbar noseweight (the
drawbar noseweight is not included in
the trailer load) All models
600 lbs (272 kg)
The actual noseweight may not be higher than
the value which is given. The value can be found
on the trailer tow hitch or trailer identification
plates. The lowest weight applies.
The maximum permissible trailer drawbar nose-
weight is the maximum weight with which the
trailer drawbar can be loaded. Limit for
Mercedes-Benz-approved trailer couplings.
Gross rear axle weight rating when tow-
ing a trailer All models
3968 lbs (1800 kg)
Ball position of the ball coupling
C
7.5"
D
2"