check engine light MERCEDES-BENZ GLS-Class SUV 2017 X166 User Guide

ProblemPossible causes/consequences andMSolutions
Vehicles with a gasoline
engine:
The engine is not running
smoothly and is misfir-
ing.There is a malfunction in the engine electronics or in a mechanical
component of the engine management system.
XOnly depress the accelerator pedal slightly.
Otherwise, non-combusted fuel may get into the catalytic converter
and damage it.
XHave the cause rectified immediately at a qualified specialist work-
shop.
The coolant temperature
gage shows a value
above 248 ‡ (120 †).The coolant level is too low. The coolant is too hot and the engine is no
longer being cooled sufficiently.
XStop as soon as possible and allow the engine and the coolant to
cool down.
XCheck the coolant level (Ypage 322). Observe the warning notes
as you do so and add coolant if necessary.
DYNAMIC SELECT controller
Use the DYNAMIC SELECT controller to change
the drive program. Depending on the drive pro-
gram selected the following vehicle character-
istics will change:
Rthe drive (engine and transmission manage-
ment)
Rthe transmission
Rthe suspension
Rthe steering
Rthe availability of the ECO start/stop function
Each time you start the engine with the Smart-
Key or the Start/Stop button, the Comfortdrive
program is activated. For further information
about starting the engine, see (
Ypage 139).
XAll vehicles (except Mercedes-AMG vehi-
cles): turn DYNAMIC SELECT controller :as many times as necessary until the desired
drive program is selected.
The selected drive program appears in the
multifunction display. After five seconds the
display goes out.
In addition, the current drive program settings
are displayed in the multimedia system dis-
play.
Drive programs available (all vehicles
except Mercedes-AMG vehicles):
IndividualIndividual settings
SportSporty driving characteris-
tics
ComfortComfortable and economi-
cal driving characteristics
SlipperyOptimal driving characteris-
tics on slippery or snow-
covered roads
Off-roadOptimal driving characteris-
tics for easily negotiable off-
road terrain
Offroad Plus
(vehicles with
Off-Road Engi-
neering pack-
age)Optimal driving characteris-
tics for rough terrain
DYNAMIC SELECT controller145
Driving and parking
Z

Opening the fuel filler flap
:Opening the fuel filler flap
;To insert the fuel filler cap
=Instruction label for fuel type to be refueled
?Tire pressure table
XSwitch off the engine.
XRemove the SmartKey from the ignition lock.
or, on vehicles with KEYLESS ‑GO:
XOpen the driver's door.
The vehicle electronics now have status 0.
This is the same as the SmartKey having been
removed.
The driver’s door can be closed again.
XPress the fuel filler flap in the direction of
arrow :.
The fuel filler flap swings up.
XTurn the fuel filler cap counterclockwise and
remove it.
XInsert the fuel filler cap into the holder
bracket on the inside of filler flap ;.
XCompletely insert the filler neck of the fuel
pump nozzle into the tank, hook in place and
refuel.
XOnly fill the tank until the pump nozzle
switches off.
Do not add any more fuel after the pump stops
filling for the first time. Otherwise, fuel may leak
out.
Vehicles with a diesel engine: the filler neck is
designed for refueling at diesel filling pumps.
Closing the fuel filler flap
XReplace the cap on the filler neck and turn
clockwise until it engages audibly.
XClose the fuel filler flap.
Close the fuel filler flap before locking the vehi-
cle.
If you are driving with the fuel filler cap open, the
8 reserve fuel warning lamp flashes. A mes-
sage appears in the multifunction display
(
Ypage 259).
In addition, the ;Check Engine warning
lamp may light up (
Ypage 283).
Refueling155
Driving and parking
Z

This helps you to avoid overheating the
brakes and wearing them out excessively.
When you take advantage of engine braking, a
drive wheel may not turn for some time, e.g.
on a slippery road surface. This could cause
damage to the drive train. This type of damage is not covered by the Mercedes-Benz war-
ranty.
Do not depress the brake pedal continuously
while the vehicle is in motion, e.g. causing the
brakes to rub by constantly applying light pres-
sure to the pedal. This results in excessive and
premature wear to the brake pads.
Use the left-hand steering wheel paddle shifter
to shift into a lower gear in good time on long
and steep downhill gradients. This is especially
important if the vehicle is laden.
This also applies if you have activated cruise
control, the speed limiter 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.
Heavy and light loads
GWARNING
If you rest your foot on the brake pedal while
driving, the braking system can overheat. This increases the stopping distance and can even
cause the braking system to fail. There is a
risk of an accident.
Never use the brake pedal as a footrest. Never
depress the brake pedal and the accelerator
pedal at the same time.
!Depressing the brake pedal constantly
results in excessive and premature wear to
the brake pads.
If the brakes have been subjected to a heavy
load, do not stop the vehicle immediately. Drive
on for a short while. This allows the airflow to
cool the brakes more quickly.
Wet roads
If you have driven for a long time in heavy rain
without braking, there may be a delayed reac-
tion from the brakes when braking for the first time. This may also occur after the vehicle has
been washed or driven through deep water.
You then have to depress the brake pedal more
firmly. Maintain a greater distance from the
vehicle in front.
After driving on a wet road or having the vehicle
washed, brake firmly while paying attention to
the traffic conditions. This will warm up the
brake discs, thereby drying them more quickly
and protecting them against corrosion.
Limited braking performance on salt-
treated roads
If you drive on salted roads, a layer of salt resi-
due may form on the brake discs and brake
pads. This can result in a significantly longer
braking distance.
RBrake occasionally to remove any possible
salt residue. Make sure that you do not
endanger other road users when doing so.
RCarefully depress the brake pedal and the
beginning and end of a journey.
RMaintain a greater distance to the vehicle
ahead.
Servicing the brakes
!The brake fluid level may be too low, if:
Rif the red brake warning lamp lights up in
the instrument cluster and
Ryou hear a warning tone while the engine is
running
Observe additional warning messages in the
multifunction display.
The brake fluid level may be too low due to
brake pad wear or leaking brake lines.
Have the brake system checked immediately.
Consult a qualified specialist workshop to
arrange this.
!A function or performance test should only
be carried out on a 2-axle dynamometer. If
you wish to operate the vehicle on such a
dynamometer, please consult a qualified spe-
cialist workshop in advance. You could oth-
erwise damage the drive train or the brake
system.
!Because ESP®is an automatic system, the
engine and ignition must be switched off
(SmartKey in position 0or 1or Start/Stop
button in position 0or 1) when the electric
Driving tips165
Driving and parking
Z

RLOW RANGE offroad gear (vehicles with the
Offroad Engineering package) (Ypage 219)
RDifferential lock (vehicles with the Off-Road
Engineering package) (Ypage 218)
ROff-road ABS (Ypage 64)
ROff-road 4ETS (Ypage 67)
ROff-road ESP®(Ypage 68)
RAIRMATIC package (vehicle level)
(Ypage 186)
RDSR (Downhill Speed Regulation)
(Ypage 216)
Observe the following notes:
RStop the vehicle before starting to drive along
an off-road route. If necessary, select the off-
road program (
Ypage 218) or shift to the
LOW RANGE off-road gear (Ypage 219).
RSelect a vehicle level that is suitable for the
terrain. To avoid damaging the vehicle, make
sure there is always sufficient ground clear-
ance.
RCheck that items of luggage and loads are
stowed safely and are well secured
(
Ypage 299).
RAlways keep the engine running and in gear
when driving on a downhill gradient. Activate
DSR (
Ypage 216).
RAlways keep the engine running and in gear
when driving on a slope.
RAdapt your speed to the terrain. The rougher,
steeper or more ruts on the terrain, the slower
your speed should be.
RDo not jump with the vehicle as this will inter- rupt the vehicle's propulsion.
RDrive with extreme care on unfamiliar off-road
routes where visibility is poor. For safety rea-
sons, get out of the vehicle first and survey
the off-road route.
RLook out for obstacles, such as rocks, holes,
tree stumps and furrows.
RAlways keep the doors, the tailgate, the side
windows and the sliding sunroof closed whilethe vehicle is in motion.
RDo not shift the automatic transmission to
transmission position N.
RObserve the notes on off-road fording
(Ypage 167).
iDo not use the HOLD function when driving
off-road, on steep uphill or downhill gradients
or on slippery or loose surfaces. The HOLD function cannot hold the vehicle on such sur-
faces.
Checklist before driving off-road
!If the engine oil warning lamp lights up while
the vehicle is in motion, stop the vehicle in a
safe place as soon as possible. Check the
engine oil level. The engine oil warning lamp
warning must not be ignored. Continuing the
journey while the symbol is displayed could
lead to engine damage.
XEngine oil level: check the engine oil level
and add oil if necessary.
When driving on steep gradients, the engine
oil level must be sufficiently high to ensure a
correct oil supply in the vehicle.
XDEF tank (BlueTEC vehicles): check the
level and add if necessary (Ypage 156).
XTire-changing tool kit: check that the jack is
working and make sure you have the lug
wrench, a robust tow cable and a folding
spade in the vehicle.
XWheels and tires: check the tire tread depth
and tire pressure.
XCheck for damage and remove any foreign
objects, e.g. small stones, from the wheels/
tires.
XReplace any missing valve caps.
XReplace dented or damaged wheels.
XRims: dented or bent rims can result in a loss
of tire pressure and damage the tire bead.
Before driving off-road, check the wheels and replace them if necessary.
Checklist after driving off-road
!If you detect damage to the vehicle after
driving off-road, have the vehicle checked
immediately at a qualified specialist work-
shop.
Driving over rough terrain places greater
demands on your vehicle than driving on normal
roads. After driving off-road, check the vehicle.
This allows you to detect damage promptly and
reduce the risk of an accident to yourself and
other road users.
XIf the Offroad orOffroad Plus drive program
is selected: select the Individual,Sport,
Driving tips169
Driving and parking
Z

ComfortorSlippery drive program
(Ypage 145).
XDeactivate the LOW RANGE off-road gear
(Ypage 219).
XDeactivate DSR (Ypage 216).
XLower the vehicle level again to a level suita-
ble to the road conditions, e.g. to the normal
level.
XClean the headlamps and rear lights and
check for damage.
XClean the front and rear license plates.
XClean the wheels and tires with a water jet
and remove any foreign objects.
XClean the wheels, wheel housings and the
vehicle underside with a water jet; check for
any foreign objects and damage.
XCheck whether twigs or other parts of plants
have become trapped. These increase the risk of fire and can damage fuel pipes, brake
hoses or the rubber bellows of the axle joints
and propeller shafts.
XAfter the trip, examine without fail the entire
undercarriage, wheels, tires, brakes, body-
work structure, steering, chassis and exhaust
system for damage.
XAfter driving for extended periods across
sand, mud, gravel, water or in similarly dirty
conditions, have the brake discs, wheels,
brake pads/linings and axle joints checked
and cleaned.
XIf you detect strong vibrations after off-road
travel, check for foreign objects in the wheels
and drive train and remove them if necessary.
Foreign objects can disturb the balance and
cause vibrations.
Driving on sand
Observe the following rules when driving on
sand:
RSelect the Offroaddrive program (vehicles
without Off-Road Engineering package)
(
Ypage 217).
RSelect the Offroaddrive program (vehicles
with Off-Road Engineering package)
(
Ypage 218).
RSelect a higher vehicle level.
RAvoid high engine speeds.
RUse the left-hand steering wheel paddle
shifter to shift to a lower gear appropriate to
the terrain.
RDrive quickly to overcome the rolling resist-
ance. Otherwise the vehicle's wheels could
become stuck in loose ground.
RDrive in the tracks of other vehicles if possi-
ble. Make sure that:
-the tire ruts are not too deep.
-the sand is sufficiently firm.
-the ground clearance of the vehicle is suf-
ficient.
Tire ruts and gravel roads
!Check that the ruts are not too deep and
that your vehicle has sufficient clearance.
Otherwise, your vehicle could be damaged or
bottom out and get stuck.
Observe the following rules when driving along
ruts in off-road terrain or on roads with loose
gravel:
RSelect the Offroaddrive program (vehicles
without Off-Road Engineering package)
(
Ypage 217).
RSelect the Offroaddrive program (vehicles
with Off-Road Engineering package)
(
Ypage 218).
RSelect a higher vehicle level.
RAvoid high engine speeds.
RShift to a lower gear using the left-hand steer-
ing wheel paddle shifter.
RDrive slowly.
RWhere ruts are too deep, drive with the
wheels of one side on the center grassy area,
if possible.
Driving over obstacles
!Obstacles could damage the floor of the
vehicle or components of the chassis. Ask
passengers for guidance when driving over
large obstacles. The passenger should always
keep a safe distance from the vehicle when
doing so in order to avoid injury as a result of
unexpected vehicle movements. After driving off-road or over obstacles, check the vehicle
for possible damage, especially to the under-
body and the components of the chassis.
170Driving tips
Driving and parking

Observe the following rules when driving over
tree stumps, large stones and other obstacles:
RSelect theOffroaddrive program (vehicles
without Off-Road Engineering package)
(
Ypage 217).
RSelect the Offroaddrive program (vehicles
with Off-Road Engineering package)
(
Ypage 218).
RSelect LOW RANGE offroad gear (vehicles
with Off-Road Engineering package)
(
Ypage 219)
RRaise the vehicle level.
RAvoid high engine speeds.
RShift to a lower gear using the left-hand steer-
ing wheel paddle shifter.
RDrive very slowly.
RDrive straight over the center of obstacles.
Traveling uphill
Approach/departure angle
GWARNING
If you drive on a steep incline at an angle or
turn when driving on an incline, the vehicle
could slip sideways, tip and rollover. There is a risk of an accident.
Always drive on a steep incline in the line of
fall (straight up or down) and do not turn the
vehicle.
RObserve the rules on off-road driving.
RDo not drive at an angle on slopes, inclines orgradients, but instead follow the direct line of
fall.
RWhen driving down an incline, make use of the
engine's braking effect. Observe the engine
speed; do not overrev the engine.
RSelect the Offroaddrive program (vehicles
without Off-Road Engineering package)
(
Ypage 217).
RSelect the Offroaddrive program (vehicles
with Off-Road Engineering package)
(
Ypage 218).
RBefore driving on extreme uphill and downhill
gradients, select the LOW RANGE offroad
gear (vehicles with Off-Road Engineering
package) (
Ypage 219).
RDrive slowly.
RAvoid high engine speeds. Drive at appropri-
ate engine speeds (maximum 3,000 rpm).
RUse the left-hand steering wheel paddle
shifter to shift into a lower gear in good time
on long and steep downhill gradients.
RCheck the brakes after prolonged off-road
driving.
Hill start assist will aid you when pulling away on
a hill. For further information about hill start
assist, see (
Ypage 141).
Do not switch to transmission position Nwhen
driving off-road. If you try to brake the vehicle
using the service brake, you could lose control
of the vehicle. If the gradient is too steep for your vehicle, drive back down in reverse gear.
Always observe the approach/departure angle
values (
Ypage 386).
Maximum gradient-climbing capability
Always observe the maximum gradient climbing
ability values (Ypage 386).
Hilltops
When driving up an uphill gradient, slightly
reduce pressure on the accelerator immediately
before reaching the brow of the hill. Make use of
the vehicle's own impetus to travel over the
brow.
This style of driving prevents:
Rthe vehicle from lifting off the ground on the
brow of a hill
Rthe vehicle from traveling too quickly down
the other side
Driving tips171
Driving and parking
Z

Towing a trailer
When you attach a trailer, make sure you have
correctly established the electrical connection.
This can be accomplished by checking the trailer
lighting. In this event, Blind Spot Assist is deac-tivated. The indicator lamp lights up yellow in
the exterior mirrors and the Blind Spot
Assist Not Available When Towing aTrailer See Operator's Manualmessage
appears in the multifunction display.
iYou can deactivate the indicator lamps in
the exterior mirrors.
To do so, switch off Blind Spot Assist when:
Rthe SmartKey is in position 2in the ignition
lock
Rthe engine is not running
Lane Keeping Assist
General notes
:Lane Keeping Assist camera
Lane Keeping Assist monitors the area in front of
your vehicle with camera :, which is mounted
at the top of the windshield. Active Lane Keeping
Assist detects lane markings on the road and
can warn you before you leave your lane unin-
tentionally.
This function is available in the range between
40 mph and 120 mph (60 km/h and 200 km/h).
A warning may be given if a front wheel passes
over a lane marking. It will warn you by means of
intermittent vibration in the steering wheel for
up to 1.5 second s.
Important safety notes
GWARNING
Lane Keeping Assist may not always clearly
recognize lane markings.
In this case, Lane Keeping Assist may:
Rgive an unnecessary warning
Rnot give a warning
There is a risk of an accident.
Always pay particular attention to the traffic
situation and stay in lane, in particular if
warned by Lane Keeping Assist.
GWARNING
The Lane Keeping Assist warning does not
return the vehicle to the original lane. There is
a risk of an accident.
You should always steer, brake or accelerate
yourself, in particular if warned by Lane Keep-
ing Assist.
If you fail to adapt your driving style, Lane Keep-
ing Assist can neither reduce the risk of an acci-
dent nor override the laws of physics. Lane
Keeping Assist cannot take into account the
road, traffic and weather conditions. Lane Keep- ing Assist is merely an aid. You are responsible
for the distance to the vehicle in front, for vehi-
cle speed, for braking in good time and for stay-
ing in your lane.
The Lane Keeping Assist does not keep the vehi-
cle in the lane.
The system may be impaired or may not function
if:
Rthere is poor visibility, e.g. due to insufficient
illumination of the road, or due to snow, rain,
fog or spray
Rthere is glare, e.g. from oncoming traffic, the
sun or reflection from other vehicles (e.g. if
the road surface is wet)
Rthe windshield is dirty, fogged up, damaged or
covered, for instance by a sticker, in the vicin-
ity of the camera
Rthere are no, several or unclear lane markings
for a lane, e.g. in areas with road construction
work
Rthe lane markings are worn away, dark or cov-
ered up, e.g. by dirt or snow
Rthe distance to the vehicle in front is too small
and the lane markings thus cannot be detec-
ted
Rthe lane markings change quickly, e.g. lanes
branch off, cross one another or merge
Driving systems209
Driving and parking
Z

Rthe LOW RANGE offroad gear is activated
(vehicles with the Offroad Engineering pack-
age).
Ra loss of tire pressure or a defective tire is
detected.
Switching on Active Blind Spot Assist
XMake sure that Active Blind Spot Assist is
activated in the on-board computer
(
Ypage 238).
XTurn the SmartKey to position2in the ignition
lock.
Warning lamps :in the exterior mirrors light
up red for approximately 1.5 seconds and
then turn yellow.
Towing a trailer
When you attach a trailer, make sure you have
correctly established the electrical connection.
This can be accomplished by checking the trailer
lighting. Active Blind Spot Assist is then deacti-
vated. The indicator lamp lights up yellow in the
exterior mirrors and the Active Blind Spot
Asst. Not Available When Towing aTrailer See Operator's Manualmessage
appears in the multifunction display.
Active Lane Keeping Assist
General notes
Active Lane Keeping Assist monitors the area in
front of your vehicle by means of multifunction
camera :at the top of the windshield. Various
different areas to the front, rear and side of your
vehicle are also monitored with the aid of the
radar sensor system. Active Lane Keeping
Assist detects lane markings on the road and
can warn you before you leave your lane unin-
tentionally. If you do not react to the warning, a lane-correcting application of the brakes can
bring the vehicle back into the original lane.
This function is available in a speed range
between 40 mph and 120 mph (60 km/h and
200 km/h).
For Active Lane Keeping Assist to assist you
when driving, the radar sensor system must be
operational.
Important safety notes
If you fail to adapt your driving style, Active Lane
Keeping Assist can neither reduce the risk of
accident nor override the laws of physics. Active
Lane Keeping Assist cannot take into account
road, weather or traffic conditions. Active Lane
Keeping Assist is only an aid. You are responsi-
ble for the distance to the vehicle in front, for
vehicle speed, for braking in good time and for
staying in your lane.
Active
Lane Ke
eping Assist cannot continuously
keep your vehicle in its lane.
GWARNING
Active Lane Keeping Assist cannot always
clearly detect lane markings.
In such cases, Active Lane Keeping Assist
can:
Rgive an unnecessary warning and then
make a course-correcting brake application
to the vehicle
Rnot give a warning or intervene
There is a risk of an accident.
Always pay particular attention to the traffic
situation and keep within the lane, especially
if Active Lane Keeping Assist alerts you. Ter-
minate the intervention in a non-critical driv-
ing situation.
The system may be impaired or may not function
if:
Rthere is poor visibility, e.g. due to insufficient
illumination of the road, or due to snow, rain,
fog or spray
Rthere is glare, e.g. from oncoming traffic, the
sun or reflection from other vehicles (e.g. if
the road surface is wet)
Rthe windshield is dirty, fogged up, damaged or
covered, for instance by a sticker, in the vicin-
ity of the camera
Driving system s213
Driving an d parking
Z

Ra driving safety system intervenes, e.g. ESP®,
PRE-SAFE®Brake or Active Blind Spot Assist.
Ryou have adopted a sporty driving style with
high cornering speeds or high rates of accel-
eration.
RESP®is switched off.
Rthe transmission is not in position D.
Ron vehicles with a trailer tow hitch, the elec-
trical connection to the trailer has been cor-
rectly established.
Rthe offroad program is activated (vehicles
without the Offroad Engineering package).
Rthe Offroad or Offroad Plus drive program is
activated (vehicles with the Off-Road Engi-
neering package).
Rthe LOW RANGE offroad gear is activated
(vehicles with the Offroad Engineering pack-
age).
Ran obstacle has been detected in the lane in
which you are driving.
Rwhen a loss of tire pressure or a defective tire
has been detected and displayed.
There is a possibility that the Active Lane Keep-
ing Assist could misjudge the given traffic sit-
uation. An inappropriate brake application may
be interrupted at any time if you:
Rsteer slightly in the opposite direction.
Rswitch on the turn signal.
Rclearly brake or accelerate.
A lane-correcting brake application is interrup-
ted automatically if:
Ra driving safety system intervenes, e.g. ESP®,
PRE-SAFE®Brake or Active Blind Spot Assist.
Rlane markings are no longer detected.
Switching on Active Lane Keeping Assist
XSwitch on Active Lane Keeping Assist using
the on-board computer; to do so, select
Standard
or Adaptive(Ypage 238).
If you drive at speeds above 40 mph
(60 km/h) and lane markings are detected,
the lines in the assistance graphics display
(
Ypage 237) are shown in green. Active Lane
Keeping Assist is ready for use.
If Standard
is selected, no warning vibration
occurs if:
Ryou switch on the turn signals. In this event,
the warnings are suppressed for a certain
period of time.
Ra driving safety system intervenes, such as
ABS, BAS or ESP®.
When Adaptive
is selected, no warning vibra-
tion occurs if:
Ryou switch on the turn signals. In this event,
the warnings are suppressed for a certain
period of time.
Ra driving safety system intervenes, e.g.
ABS, BAS or ESP®.
Ryou accelerate hard, e.g. kickdown.
Ryou brake hard.
Ryou steer actively, e.g. swerve to avoid an
obstacle or change lanes quickly.
Ryou cut the corner on a sharp bend.
Towing a trailer
When you attach a trailer, make sure you have
correctly established the electrical connection.
This can be accomplished by checking the trailer
lighting. Lane-correcting brake application does
not take place when towing a trailer. Active Lane Keeping Assist is not activated and the lines in
the assistance graphic are gray.
Off-road driving systems
4MATIC (permanent four-wheel drive)
4MATIC ensures that all four wheels are perma-
nently driven. Together with ESP®and 4ETS, it
improves the traction of your vehicle whenever
a drive wheel spins due to insufficient grip.
If you fail to adapt your driving style, 4MATIC can
neither reduce the risk of accident nor override the laws of physics. 4MATIC cannot take
account of road, weather and traffic conditions.
4MATIC 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.
!Never tow the vehicle with one axle raised.
This may damage the transfer case. Damage
of this sort is not covered by the Mercedes-
Benz Limited Warranty. All wheels must
remain either on the ground or be fully raised.
Observe the instructions for towing the vehi-
cle with all wheels in full contact with the
ground.
Driving systems215
Driving and parking
Z

XSecure the bolt using spring cotterB.
XCheck the ball coupling, bolt and spring cotter
for correct installation.
If the ball coupling cannot be correctly mounted,
remove the ball coupling. Under these circum-
stances, the ball coupling must not be used for
trailer towing.
Have the entire trailer tow hitch checked at a
qualified specialist workshop.
Coupling up a trailer
!
Do not connect the trailer's brake system (if
featured) to the hydraulic brake system of the
towing vehicle, as the latter is equipped with
an anti-lock brake system. Doing so will result
in a loss of function of the brake systems of
both the vehicle and the trailer.
XShift the transmission to position P.
XApply the vehicle's electric parking brake.
XStart the engine.
XVehicles with AIRMATIC package: select
normal level and the Comfortdrive program.
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 work-
ing.
XPush the combination switch upwards/down-
wards and check whether the corresponding
turn signal on the trailer flashes.
A trailer that is connected is recognized only
when the electrical connection is established
correctly and when the lighting system is work-
ing properly. The function of other systems also
depends on this, for example:
RESP®
RParking Assist PARKTRONIC
RParking Pilot
RActive Blind Spot Assist
RActive Lane Keeping Assist
iVehicles with the AIRMATIC package: if you
couple up a trailer, the vehicle always remains
at normal level. When coupling up a trailer,
please observe the foll
owing:
RIf the normal level has not been set man-
ually, the vehicle is automatically lowered
to normal level. This is the case if a speed of
5 mph (8 km/h) is reached.
RThe
Sport drive program 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 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.
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 tow-
ing vehicle, the safety switch applies the
trailer brakes.
Towing a trailer225
Driving and parking
Z