
X
Slide bolt 0083into the hole in the ball coupling
recess and the ball coupling to the stop. X
Secure the bolt using spring cotter 0084.X
Check 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.
X Shift the transmission to position 005D.
X Apply the vehicle's electric parking brake.
X Start the engine.
X Vehicles with AIRMATIC Package: select
normal level and the Comfortdrive program.
X Switch off the engine.
X Close the doors and tailgate.
X Couple up the trailer.
X Establish the electrical connection between
the vehicle and the trailer.
X Check that the trailer lighting system is work-
ing.
X Push 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:
R ESP ®
R Parking Assist PARKTRONIC
R Active Parking Assist
R Parking Package with rear view camera
R Active Blind Spot Assist
R Active Lane Keeping Assist
i Vehicles 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 following:
R If 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.
R The 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). Towing a trailer
223Driving and parking Z

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-woundunder 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 sothat 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-conditioning 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. 224
Towing a trailerDriving and parking

Safety systems
Display messages
Possible causes/consequences and
0050
0050Solutions 002500E5
Currently Unavaila‐
Currently Unavaila‐
ble See Operator's ble See Operator's
Manual Manual ABS (Anti-lock Braking System) and ESP
®
(Electronic Stability Pro-
gram) are temporarily not available.
Other driving systems and driving safety systems may also malfunc-
tion.
In addition, the 00E5,00BBand0025 warning lamps light up in the
instrument cluster.
Possible causes are:
R Self-diagnosis is not yet complete
R The on-board voltage may be insufficient
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you brake
hard, for example.
The steerability and braking characteristics may be severely affected. The braking distance in an emergency braking situation can increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Carefully drive a suitable distance, making slight steering move-
ments at a speed above 12 mph (20 km/h).
If the display message disappears, the functions mentioned above
are available again.
If the multifunction display still shows the display message:
X Drive on carefully.
X Visit a qualified specialist workshop immediately. 002500E5
Inoperative See Inoperative See
Operator's Manual Operator's Manual ABS and ESP
®
are malfunctioning.
Other driving systems and driving safety systems may also malfunc-
tion.
The 0027 (USA only) or 004D(Canada only), 00E5,00BBand0025
warning lamps in the instrument cluster also light up.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you brake
hard, for example.
The steerability and braking characteristics may be severely affected. The braking distance in an emergency braking situation can increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Drive on carefully.
X Visit a qualified specialist workshop immediately. Display messages
245On-board computer and displays Z

Display messages
Possible causes/consequences and
0050
0050Solutions 00E5
Currently Unavaila‐ Currently Unavaila‐
ble See Operator's ble See Operator's
Manual Manual ESP
®
is temporarily unavailable.
Other driving systems and driving safety systems may also malfunc-
tion.
In addition, the 00E5and00BB warning lamps light up in the instru-
ment cluster.
The self-diagnosis function might not be complete, for example.
ATTENTION ASSIST is deactivated.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you brake
hard, for example.
The braking distance in an emergency braking situation can thus
increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Carefully drive a suitable distance, making slight steering move-
ments at a speed above 12 mph (20 km/h).
If the display message disappears, the functions mentioned above are available again.
If the multifunction display still shows the display message:
X Drive on carefully.
X Visit a qualified specialist workshop immediately. 00E5
Inoperative See Inoperative See
Operator's Manual Operator's Manual ESP
®
is malfunctioning.
Other driving systems and driving safety systems may also malfunc-
tion.
In addition, the 00E5and00BB warning lamps light up in the instru-
ment cluster.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you brake
hard, for example.
The braking distance in an emergency braking situation can thus
increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Drive on carefully.
X Visit a qualified specialist workshop immediately. 246
Display messagesOn-board computer and displays

Display messages
Possible causes/consequences and
0050
0050Solutions 007A
0025
00E5 Inoperative See
Inoperative See
Operator's Manual Operator's Manual EBD (electronic brake force distribution), ABS and ESP
®
are malfunc-
tioning.
Other driving systems and driving safety systems may also malfunc-
tion.
In addition, the 00E5,00BBand0025 warning lamps light up in the
instrument cluster and a warning tone sounds.
G WARNING
The brake system continues to function normally, but without the
functions listed above. The wheels could therefore lock if you brake
hard, for example.
The steerability and braking characteristics may be severely affected. The braking distance in an emergency braking situation can increase.
If ESP ®
is not operational, ESP ®
is unable to stabilize the vehicle.
There is an increased risk of skidding and an accident.
X Drive on carefully.
X Visit a qualified specialist workshop immediately. 0049
(USA
only) 0024 (Canada
only)
Turn On the Igni‐ Turn On the Igni‐
tion tion to
toRelease
Release the
the
Parking Brake
Parking Brake The red
0049(USA only) or 0024(Canada only) indicator lamp lights
up.
You attempted to release the electric parking brake while the ignition
was switched off.
X SmartKey : insert the SmartKey into the ignition lock and turn to
position 0047.
X KEYLESS-GO: switch on the ignition. 0049
(USA
only) 0024 (Canada
only)
Please Please Release Release Park‐
Park‐
ing Brake
ing Brake The red
0049(USA only) or 0024(Canada only) indicator lamp flashes
and a warning tone sounds. A condition for automatic release of the
electric parking brake is not fulfilled (Y page 157).
You are driving with the electric parking brake applied.
X Release the electric parking brake manually. The red
0049(USA only) or 0024(Canada only) indicator lamp flashes
and a warning tone sounds.
You are using the electric parking brake for emergency braking
(Y page 157). 0049
(USA
only) 0024 (Canada
only)
Parking Brake See Parking Brake See
Operator's Manual Operator's Manual The yellow
0024warning lamp lights up.
The electric parking brake is malfunctioning.
To apply:
X Switch the ignition off.
X Press the electric parking brake handle for at least ten seconds.
X Shift the transmission to position 005D.
X Consult a qualified specialist workshop. Display
messages
247On-board computer and displays Z

Display messages
Possible causes/consequences and
0050
0050Solutions The yellow
0024warning lamp and the red 0049(USA only) or 0024
(Canada only) indicator lamp light up.
The electric parking brake is malfunctioning.
To release:
X Switch off the ignition and turn it back on.
X Release the electric parking brake manually.
or X Release the electric parking brake automatically (Y page 157).
If the electric parking brake still cannot be released:
X Do not drive on.
X Consult a qualified specialist workshop. The red
0049(USA only) or 0024(Canada only) indicator lamp flashes
and the yellow 0024warning lamp lights up.
The electric parking brake is malfunctioning.
To release:
X Switch off the ignition and turn it back on.
X Release the electric parking brake manually.
To apply: X Switch off the ignition and turn it back on.
X Apply the electric parking brake manually.
If the red 0049(USA only) or 0024(Canada only) indicator lamp con-
tinues to flash:
X Do not drive on.
X Secure the vehicle against rolling away (Y page 372).
X Shift the transmission to position 005D.
X Turn the front wheels towards the curb.
X Consult a qualified specialist workshop. 248
Display
messagesOn-board computer and displays

Display messages
Possible causes/consequences and
0050
0050Solutions The yellow
0024warning lamp lights up. The red 0049(USA only)
or 0024 (Canada only) indicator lamp flashes for about ten seconds
after the electric parking brake has been applied or released. It then
goes out or remains lit.
The electric parking brake is malfunctioning.
X Switch off the ignition and turn it back on.
X Apply the electric parking brake.
If it is not possible to apply the electric parking brake:
X Shift the transmission to position 005D.
X Visit a qualified specialist workshop.
If it is not possible to release the electric parking brake:
X Release the electric parking brake automatically (Y page 157).
If the electric parking brake still cannot be released:
X Consult a qualified specialist workshop. The yellow
0024warning lamp lights up. If you manually apply or
release the electric parking brake, the red 0049(USA only) or 0024
(Canada only) indicator lamp flashes.
The electric parking brake is malfunctioning. It is not possible to apply
the electric parking brake manually.
X Shift the transmission to position 005D.
X Visit a qualified specialist workshop. 0049
(USA
only) 0024 (Canada
only)
Parking Brake Inop‐ Parking Brake Inop‐
erative erative The yellow
0024warning lamp lights up. The red 0049(USA only)
or 0024 (Canada only) indicator lamp flashes for about ten seconds
after the electric parking brake has been applied or released. It then
goes out or remains lit.
The electric parking brake is malfunctioning, e.g. because of over-
voltage or undervoltage.
X Remove the cause for the overvoltage or undervoltage, e.g. by
charging the battery or restarting the engine.
X Apply or release the electric parking brake.
If it remains impossible to apply or release the electric parking brake:
X Switch off the ignition and turn it back on.
X Apply or release the electric parking brake.
If the electric parking brake still cannot be released: X Consult a qualified specialist workshop.
If the electric parking brake still cannot be applied:
X Visit a qualified specialist workshop. Display
messages
249On-board computer and displays Z

Display messages
Possible causes/consequences and
0050
0050Solutions The yellow
0024warning lamp lights up and the red 0049(USA only)
or 0024 (Canada only) indicator lamp flashes.
It is not possible to apply the electric parking brake manually.
X Shift the transmission to position 005D.
X Visit a qualified specialist workshop. 0027
(USA only)
004D (Canada only)
Check Brake Fluid
Check Brake Fluid
Level
Level There is not enough brake fluid in the brake fluid reservoir. In addition,
the 0027 (USA only) or 004D(Canada only) warning lamp lights up in
the instrument cluster and a warning tone sounds.
G WARNING
The braking effect may be impaired.
There is a risk of an accident.
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions. Do not continue driving
under any circumstances.
X Secure the vehicle against rolling away (Y page 156).
X Consult a qualified specialist workshop.
X Do not add brake fluid. This does not correct the malfunction. 0026
Check Check
Brake
Brake Pad
PadWear
Wear The brake pads/linings have reached their wear limit.
USA only: the red
0027brake system warning lamp is lit while the
engine is running.
X Visit a qualified specialist workshop. 0053
Inoperative Inoperative One or more main features of the mbrace system are malfunctioning.
X Visit a qualified specialist workshop. Active
Active
Brake
Brake Assist
Assist
Functions
Functions Currently
Currently
Limited See Opera‐
Limited See Opera‐
tor's Manual tor's Manual Active Brake Assist with cross-traffic function is temporarily inopera-
tive.
Possible causes are:
R the radar sensor system is temporarily inoperative, e.g. due to elec-
tromagnetic radiation emitted by nearby TV or radio stations or
other sources of electromagnetic radiation
R the system is outside the operating temperature range
R the on-board voltage is too low
When the causes stated above no longer apply, the display message
disappears.
Active Brake Assist with cross-traffic function or PRE ‑SAFE®
PLUS is
functional again.
If the display message does not disappear:
X Pull over and stop the vehicle safely as soon as possible, paying
attention to road and traffic conditions.
X Secure the vehicle against rolling away (Y page 156).
X Restart the engine. 250
Display
messagesOn-board computer and displays