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218Driving and operatingsufficient. Turn steering wheel gently
into opposite direction, if lane change
is intended.
When crossing a lane marking
significantly, lane keep assist starts a visual and acoustic warning.
Unintended lane departure is
assumed
● without using turn signal
● using the turn signal in the opposite direction of the lane
departure
● without braking
● without acceleration
● without active steering.
Notice
The system is switched off during
detection of ambiguous lane
markings, e.g. in construction areas.
Notice
The system may be switched off if it
detects lanes which are too narrow,
too wide or too curved.Activation
The lane keep assist is activated by
pressing a. The LED in the button
illuminates to indicate that the system
is switched on.
When the control indicator a in the
instrument cluster illuminates green,
the system is ready to assist.
The system is operational at vehicle
speeds between 37 mph and
112 mph and if lane markings are
available.
The system gently turns the steering
wheel and the control indicator a
changes to yellow, if the vehicle
approaches a detected lane marking
without using the turn signal in that
direction.
The system alerts by flashing a
together with three chimes, from the
respective direction, if the lane is
departed significantly.
The system is only operable when a
lane marking is detected.
If the system only detects lane
markings on one side of the road, it
will only assist for this side.
Lane keep assist detects hands-free
driving. In this case a message in the
Driver Information Centre pops-up
and a chime sounds as long as lane
keep assist detects hands-free
driving.
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Driving and operating219DeactivationThe system is deactivated by
pressing a; the LED in the button
extinguishes.
The system is deactivated
automatically when a trailer is
detected.
Fault
The system performance may be affected by:
● Windscreen not clean or affected
by foreign items, e.g. stickers
● Close vehicles ahead
● Banked roads
● Winding or hilly roads
● Road edges
● Roads with poor lane markings
● Sudden lighting changes
● Adverse environmental conditions e.g. heavy rain or
snow
● Vehicle modifications, e.g. tyres.Switch off the system if the system is
disturbed by tar marks, shadows,
road cracks, temporary or
construction lane markings, or other
road imperfections.9 Warning
Always keep your attention on the
road and maintain proper vehicle
position within the lane, otherwise
vehicle damage, injury or death
could occur.
Lane keep assist does not
continuously steer the vehicle.
The system may not keep the
vehicle in the lane or give an alert,
even if a lane marking is detected.
The steering of the lane keep
assist may not be sufficient to
avoid a lane departure.
The system may not detect hands-
off driving due to external
influences (road condition and
surface, weather etc). The driver
has full responsibility to control the
vehicle and is always required to keep the hands on the steeringwheel while driving.
Using the system while towing a
trailer or on slippery roads could
cause loss of control of the vehicle
and a crash. Switch the system off.
Page 227 of 317

Driving and operating225Trailer hitch
General information
Only use towing equipment that has
been approved for your vehicle.
Entrust retrofitting of towing
equipment to a workshop. It may be
necessary to make changes that
affect the cooling system, heat
shields or other equipment.
The bulb outage detection function for trailer brake light cannot detect a
partial bulb outage, e.g. in case of four
times five watt bulbs, the function only detects lamp outage when only a
single five Watt lamp remains or none remain.
Fitting of towing equipment could
cover the opening of the towing eye.
If this is the case use the coupling ball
bar for towing. Always keep the
coupling ball bar in the vehicle when
not in use.Driving characteristics and
towing tips
Before attaching a trailer, lubricatethe coupling ball. However, do not do
so if a stabiliser, which acts on the coupling ball, is being used to reduce snaking movements.
During trailer towing do not exceed a
speed of 50 mph. A maximum speed
of 60 mph is only appropriate if an oscillation damper is used and the
permissible gross trailer weight does
not exceed the vehicle's curb weight.
For trailers with low driving stability
and caravan trailers, the use of an
oscillation damper is strongly
recommended.
If the trailer starts snaking, drive more
slowly, do not attempt to correct the
steering and brake sharply if
necessary.
When driving downhill, drive in the
same gear as if driving uphill and
drive at a similar speed.
Adjust tyre pressure to the value
specified for full load 3 296.Trailer towing
Trailer loadsThe permissible trailer loads are
vehicle and engine-dependent
maximum values which must not be
exceeded. The actual trailer load is
the difference between the actual
gross weight of the trailer and the
actual coupling socket load with the trailer coupled.
The permissible trailer loads are
specified in the vehicle documents. In
general, they are valid for gradients
up to 12%.
The permissible trailer load applies
up to the specified incline and at sea
level. Since engine power decreases
as altitude increases due to the air
becoming thinner, therefore reducing
climbing ability, the permissible gross train weight also decreases by 10%for every 1000 metres of altitude. The gross train weight does not have to be
reduced when driving on roads with
slight inclines (less than 8%, e.g.
motorways).
Page 231 of 317
Driving and operating229Open the protective flap and turn the
key to position c to unlock the
coupling ball bar.
Pull out rotary handle and turn
clockwise as far as it will go. Pull out
coupling ball bar downwards.
Insert sealing plug in opening.
Fold away connecting socket.
On Sports Tourer insert cover into
rear bumper as shown in the
illustration.
Stow the coupling ball bar in the bag
and secure by fixing the strap through the rear right lashing eye. Wrap
around twice and tighten the strap to
secure the bag.
Trailer stability assist
If the system detects snaking
movements, engine power is reduced
and the vehicle/trailer combination is selectively braked until the snaking
ceases. While system is working keep
steering wheel as still as possible.
Trailer stability assist is a function of
the Electronic Stability Control 3 182.
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Vehicle care251No.Circuit33Anti theft warning horn34Horn35Power outlet load compartment36Right high beam (Halogen)/
Right low beam (LED)37Left high beam (Halogen)38LED headlight/Automatic head‐
light range adjustment39Front fog light40Central Gateway Module41Water in fuel sensor/Water
pump42Manual headlight range adjust‐
ment43Fuel pump44Rear view camera/Inside rear
view mirror/Trailer module45LED headlight left/Automatic
headlight range adjustment leftNo.Circuit46Instrument cluster47Steering column lock48Rear wiper49Outside rearview mirror50LED headlight right/Automatic
headlight range adjustment
right51Left low beam (LED)52Engine control module/Trans‐
mission control module53–54Windscreen wiper55Diesel exhaust system56–57–
After having changed defective fuses,
close the fuse box cover and press
until it engages.
If the fuse box cover is not closed
correctly, malfunction may occur.
Instrument panel fuse box
The fuse box is located behind a
cover.
Pull the cover and remove.
Vehicles with power connector:
If the fuse cover has a power
connector, it must be removed by
using an adapter and a screwdriver.
The adapter is stowed in the glovebox 3 70 . The screwdriver is stowed in the
load compartment 3 255.
Page 254 of 317
252Vehicle care
Attach the adapter to the power
connector.
Push the screwdriver through the
recess in the adapter. Remove the
cover by pulling the screwdriver.No.Circuit1–2Climate control system, fan3Power seat driver side4Cigarette lighter/Power outlet
front5–6Power window front7ABS8Heated steering wheel9Body control module 810Power window rear11Sunroof12Body control module 413Seat heating (only on vehicles
without alarm horn)14Exterior mirror15Body control module 116Body control module 7
Page 255 of 317
Vehicle care253No.Circuit17Body control module 618Body control module 319Data link connector20Airbag system21Climate control system22Central locking system, tailgate23Electronic key system24Power seat memory function25Airbag system steering wheel26Ignition switch/Steering column
lock27Body control module 228USB socket29–30Selector lever31Rear window wiper32Transmission control moduleNo.Circuit33Anti-theft alarm system/Power
sounder34Parking assist/Side blind spot
alert/Infotainment system/USB
socket35OnStar36Info display/Instrument cluster/ CD player37Infotainment system, radio
After having changed defective fuses,
close the fuse box cover and press
until it engages.
Vehicles with power connector: 1. Apply the cover on the right side.
2. Fold the left side of the cover forwards. Take care that the
securing clamp is guided as
shown in the illustration.
Load compartment fuse box
The fuse box is located on the left side
of the load compartment behind a
cover.
Page 263 of 317

Vehicle care261Select● Light for comfort pressure up to
three people.
● Eco for Eco pressure up to
three people.
● Max for full loading.
Tyre pressure sensor matching
process
Each tyre pressure sensor has a
unique identification code. The
identification code must be matched
to a new wheel position after rotating
the wheels or exchanging the
complete wheel set and if one or more
tyre pressure sensors were replaced. The tyre pressure sensor matching
process should also be performed
after replacing a spare wheel with a
road wheel containing the tyre
pressure sensor.
The malfunction light w and the
warning message or code should go
off at the next ignition cycle. The
sensors are matched to the wheel
positions, using a relearn tool, in the
following order: left side front wheel,
right side front wheel, right side rearwheel and left side rear wheel. The
turn signal light at the current active
position is illuminated until sensor is
matched.
Consult a workshop for service. There
are two minutes to match the first
wheel position, and five minutes
overall to match all four wheel
positions. If it takes longer, the
matching process stops and must be
restarted.
The tyre pressure sensor matching
process is:
1. Apply the parking brake.
2. Turn the ignition on.
3. On vehicles with automatic transmission: set the selector
lever to P.
On vehicles with manual
transmission: select neutral.
4. Midlevel display: Use MENU on the turn signal
lever to select the Vehicle
Information Menu ? in the
Driver Information Centre.
Uplevel display:Press p on the steering wheel to
open main menu page.
Select the Info page with Q or P.
Confirm with 9.
5. Select the tyre pressure menu. Midlevel display:
Uplevel display: