Assist systems
Brake assist systems
Introduction
This chapter contains information on the following subjects:
Electronic Stability Control (ESC)
137
Antilock Braking System (ABS)
138
Traction Control System (TCS)
138
Electronic Differential Lock (EDL and XDS)
139
Driver Steering Recommendation (DSR)
139
Hydraulic Brake Assist (HBA)
139
Hill Hold Control (HHC)
139
Multicollision brake
140WARNING■ A lack of fuel can cause irregular engine running or cause the engine to shut
down. The brake assist systems would then fail to function – risk of accident!■
Adjust the speed and driving style to the current visibility, weather, road and
traffic conditions. The increased safety offered by the brake assist systems must not tempt you to take greater risks than otherwise – risk of accident!
■
In the event of an ABS fault, visit a specialist garage immediately. Adjust
your style of driving according to the damage to the ABS as you will not know
how great the damage is and the limitation it is placing on the braking effi-
ciency.
CAUTION
■ All four wheels must be fitted with the same tyres approved by the manufactur-
er to ensure the brake assist systems operate correctly.■
Changes to the vehicle (e.g. to the engine, brakes, chassis) can influence the
functionality of the brake assist systems » page 200.
■
If a fault occurs in the ABS system, the ESC, ASR and EDL also do not work. An
ABS fault is indicated with the warning light » page 18 .
Electronic Stability Control (ESC)Fig. 127
ESC button
First read and observe the introductory information and safety warn-
ings on page 137.
The ESC system helps to maintain control of the vehicle in situations where it is
being operated at its dynamic limits, such as a sudden change to the direction of
travel. The risk of skidding is reduced and your car thus offers greater driving sta-
bility depending on the conditions of the road surface.
The ESC system is automatically activated each time the ignition is switched on.The direction which the driver wishes to take is determined based on the steering angle and the speed of the vehicle and is constantly compared with the actualbehaviour of the vehicle. If differences exist, such as the car beginning to skid,
the ESC system will automatically brake the appropriate wheel.
During an intervention of the system, the warning light
flashes in the instru-
ment cluster.
The following systems are integrated into the Electronic Stability Control (ESC).
› Antilock Brake System (ABS)
» page 138.
› Traction control (TCS)
» page 138.
› Electronic Differential Lock (EDL and XDS)
» page 139.
› Driver Steering Recommendation (DSR)
» page 139.
› Hydraulic Brake Assist (HBA)
» page 139.
› Hill Hold Control (HHC)
» page 139.
› Multicollision brake
» page 140.
› Trailer stabilisation (TSA)
» page 173, Driving with a trailer .
The ESC system cannot be deactivated. Only some systems with built-in ESC
can be deactivated or activated.
137Assist systems
During an intervention of the system, the TCS warning light flashes in the in-
strument cluster.
The TCS should normally always be enabled. The system should be deactivated
only in the following situations, for example.
› When driving with snow chains.
› When driving in deep snow or on a very loose surface.
› When it is necessary to “rock” a car free when it has become stuck.
The TCS can be deactivated in the Infotainment or with the symbol button
» Fig. 128 » Infotainment manual , chapter Vehicle settings (CAR button) .
The warning light lights up in the instrument cluster when the TCR is deactiva-
ted.
Ensure the TCS is activated again afterwards.
Electronic Differential Lock (EDL and XDS)
First read and observe the introductory information and safety warn-
ings
on page 137.
EDL
If one of the wheels starts to spin, the EDL system brakes the spinning wheel and
transfers the driving force to the other wheels. This ensures the stability of the
vehicle and a quick journey.
The EDL switches itself off automatically, in order to avoid excessive heat genera-
tion in the disc brake of the wheel being braked. The vehicle can continue to be
driven and has the same characteristics as a vehicle not fitted with EDL. The EDL
switches on again automatically as soon as the brake has cooled down.
XDS
XDL is an extension to the electronic differential lock. XDL does not respond to traction, but to the load relief of the inner front wheel of the driving axle during
fast cornering.
The automatic brake intervention on the brake of the wheel with reduced load prevents the wheel from spinning. Thus, the traction is improved and the vehicle can continue to follow the desired track.
Driver Steering Recommendation (DSR)
First read and observe the introductory information and safety warn-ings
on page 137.
The DSR indicates to the driver in critical situations a steering recommendation in
order to stabilise the vehicle. The DSR is activated, for example, on the right and
left vehicle side when braking sharply on different road surfaces.
Hydraulic Brake Assist (HBA)
First read and observe the introductory information and safety warn-ings
on page 137.
HBA increases the braking effect and helps to shorten the braking distance.
The HBA is activated by the very quick operation of the brake pedal. To achieve
the shortest possible braking distance, the brake pedal must be applied firmly un-
til the vehicle has come to a complete standstill.
The HBA is automatically switched off when the brake pedal is released.The ABS is activated faster and more effectively with the intervention of the HBA.
Hill Hold Control (HHC)
First read and observe the introductory information and safety warn-ings
on page 137.
HHC allows you, when driving on slopes, to move your foot from the brake pedal
to the accelerator pedal without having to use the handbrake.
The system holds the brake pressure produced by the activation of the brakepedal for approx. 2 seconds after the brake pedal is released.
The brake pressure drops gradually the more you operate the accelerator pedal. Ifthe vehicle does not start off within 2 seconds, it starts to roll back.
The HHC is active from a 5% slope if the driver's door is closed. HHC is always ac-tive on slopes when in forward or reverse start off. When driving downhill, it is in- active.
139Assist systems
Multicollision brakeFirst read and observe the introductory information and safety warn-
ings
on page 137.
The multifunction brake deploys automatic braking after a collision in order to re- duce the risk of further collisions. Automatic braking can only be deployed at
speeds of over 10 km/h in the event of a frontal or side impact.
The vehicle is slowed down automatically by the ESC system as long as the brakes, the ESC and the relevant electrical system remain operational after the impact.
Automatic braking is not applied if the driver presses the accelerator during the
accident.
Parking aid
Introduction
This chapter contains information on the following subjects:
Function
141
Automatic system activation when moving forward
142
Road display
142WARNING■ The parking aid is not a substitute for the driver paying proper attention and
it is always the driver's responsibility to take care when reversing the vehicle
or carrying out similar manoeuvres. Pay particular attention to small children
and animals as they may not be recognised by the system sensors.■
You should satisfy yourself before reversing that there is no small obstacle,
such as a rock, thin post, trailer drawbar etc., in front or behind your vehicle.
Such obstacles may not be recognised by the system sensors.
■
Under certain circumstances, surfaces of certain objects and types of cloth-
ing cannot reflect the system signals. Thus, these objects or people who wear such clothing are not recognised by the System sensors.
■
External sound sources can have a detrimental effect on the system. Under
adverse conditions, this can cause objects or people to not be recognized by
the system.
CAUTION■ If a warning signal sounds for about 3 seconds after activating the system and
there is no obstacle close to your car, this indicates a system fault. The fault is
also indicated by the symbol flashing » Fig. 129 on page 141 in the button. ! or
appears in the Infotainment display. Seek help from a specialist garage.■
The sensors must be kept clean (free of ice, etc.) to enable the system to oper-
ate properly.
■
The system function may be limited under adverse weather conditions (heavy
rain, water vapour, very low or high temperatures etc.).
■
Additional mounted modules, such as a bicycle carrier, can impair the function of
the parking aid.
Note
■ The signal tones for front obstacle recognition are factory-set to be higher than
for rear obstacle recognition.■
If not all fields around the vehicle are shown after the system is activated, the
vehicle will need to be moved a few metres forwards or in reverse.
■
If the system is activated and the selector lever of the automatic gearbox is in
position P (the vehicle cannot move), the warning tone is interrupted and no ob-
stacles are displayed.
140Driving
WARNING (Continued)■If the ACC does not decelerate fast enough, immediately apply the vehicle's
footbrake.■
Control may only be resumed if the stored speed is not too high for the cur-
rent traffic conditions.
WARNINGFor safety reasons, do not use the ACC under the following conditions.■When driving in turning lanes, motorway exits or construction sites, to avoid
an unwanted acceleration to the stored speed.■
When visibility is poor, (e.g. fog, heavy rain, thick snowfall).
■
When road conditions are poor (e.g. ice, slippery road, gravel, dirt road).
■
When driving around “sharp” bends.
■
When riding on a steep gradient / high slope.
CAUTION
■ It is not possible to switch on the control on vehicles fitted with a manual
transmission if the first gear or reverse gear is engaged.■
It is not possible to switch on the control on vehicles fitted with an automatic
transmission , if the selector lever is in the position P, N or R .
■
The control may automatically switch off when some brake assist systems (e.g.
ESC) intervene, when the maximum permissible engine speed is exceeded, etc.
Note
■ The speed can only be set and stored when ACC is activated. The stored speed
may differ from the actual speed if a proximity control procedure is in progress at the time.■
Vehicles with an automatic transmission can decelerate to a standstill and start
again using the ACC.
■
The ACC reduces the speed by automatically releasing the accelerator or by
means of a braking procedure as appropriate. If the brakes are used for an auto-
matic speed reduction at any moments, then the brake light illuminates.
■
In case of failure of more than one brake light on the vehicle or on the electri-
cally connected trailer, the ACC becomes unavailable.
Radar sensorFig. 135
Mounting location of the radar
sensor
First read and observe the introductory information and safety warn-
ings on page 148.
The radar sensor » Fig. 135 (From here on referred to as sensor) is used to assess
the traffic situation in front of the vehicle.
The sensor can distinguish objects by radiating and receiving electromagneticwaves.
The sensor function may be impaired in the events of one of the following.
› The sensor is covered by mud, snow or debris, for example.
› The sensor or its immediate surroundings are covered by other objects, for ex-
ample, a sticker is attached.
› When visibility is poor, (e.g. fog, heavy rain, thick snowfall).
If the sensor is dirty or does not have “visibility” for any other reason, the follow- ing message appears in the instrument cluster display.
ACC: no sensor view!
Stop the car, switch off the engine and clean the sensor or eliminate the obstacle
causing the lack of“visibility”. Should the ACC still be unavailable after the engine is restarted,
» Fig. 138 on page 151 push the lever into position. Seek help
from a specialist garage.
149Assist systems
The area monitoring system (From here on only referred to as Front Assist) warns
you of the danger of a collision with an obstacle in front of the vehicle and tries to
avoid a collision or mitigate its consequences by automatically applying the
brakes as appropriate.WARNING■ Front Assist only works as an aid, it does absolve the driver of the responsi-
bility to maintain full control over the vehicle's steering.■
Front Assist has physical and system related limitations. For this reason, the
driver may experience some undesired or delayed system responses in certain
situations. You should therefore always be alert and ready to intervene!
■
Always adapt your speed and safety proximity to the vehicle ahead to the
current visibility, weather, road and traffic conditions.
■
If Front Assist gives a warning, then, depending on the traffic situation, im-
mediately slow down the car by applying the brakes or avoid the obstacle.
■
The increased safety through the Front Assist system must not tempt you
to take greater risks than otherwise – risk of accident!
■
The driver must always be ready to take over steering of the vehicle himself
(brake or accelerate).
■
Front Assist does not respond to crossing or oncoming objects.
Instructions and Information
First read and observe the introductory information and safety warn-ings
on page 154.
Front Assist may become impaired in the following situations, for example.
› When visibility is poor, (e.g. fog, heavy rain, thick snowfall).
› Driving around “sharp” bends.
› When fully pressing down the accelerator pedal.
› If there is a fault with the Front Assist system.
› When one of the brake assist systems (e.g. ESC) intervenes.
WARNINGIn the following situations, Front Assist should be switched off for safety rea-
sons.■
When the vehicle is being towed away.WARNING (Continued)■ When the vehicle is on a rolling test bench.■When an undesired activation has repeatedly occurred.■
When on a truck, train or a car ferry service or the like.
CAUTION
Narrow vehicles or vehicles travelling side by side are not detected by Front As-
sist via the radar sensor until they are within the sensor's range. This is especially
true for narrow vehicles, such as motorcycles.
Note
In case of failure of more than one brake light on the vehicle or on the electrically
connected trailer, Front Assist not available.
Radar sensor
Fig. 141
Mounting location of the radar
sensor
First read and observe the introductory information and safety warn- ings on page 154.
The radar sensor » Fig. 141 (From here on referred to as sensor) is used to assess
the traffic situation in front of the vehicle.
The sensor can distinguish objects by radiating and receiving electromagneticwaves.
155Assist systems
The sensor function may be impaired in the events of one of the following.
› The sensor is covered by mud, snow or debris, for example.
› The sensor or its immediate surroundings are covered by other objects, for ex-
ample, a sticker is attached.
› When visibility is poor, (e.g. fog, heavy rain, thick snowfall).
If the sensor is dirty or does not have “visibility” for any other reason, the follow-
ing message appears in the instrument cluster display.
Front Assist: no sensor view.
Stop the car, switch off the engine and clean the sensor or eliminate the obstacle
causing the lack of“visibility”. Should Front Assist still be unavailable after the en-
gine is restarted, consult a specialist garage for help.WARNING■ If you suspect that the sensor is damaged, deactivate Front Assist. Have the
sensor checked by a specialist garage.■
The sensor can become misaligned by collisions or by damage to the front of
the vehicle, the wheel arch or the underside of the vehicle. This can lead to
impaired function of the Front Assist function - risk of accidents! If this is the
case, have the sensor checked by a specialist garage.
■
Any improperly carried out work to the front of the vehicle may cause the
sensor to become misaligned. We therefore recommend only having these
modifications and technical alterations carried out by a specialist garage. Please also observed the instructions in » page 200, Service work, adjust-
ments and technical alterations .
■
The area in front of and around the sensor must not be covered with stick-
ers, additional lights or similar items. This can lead to impaired function of the
sensor - risk of accidents!
WARNINGThe sensor may not be able to distinguish all objects correctly under certain
circumstances. You should therefore not use Front Assist in the following ca-
ses - risk of accidents!■
When driving through places where metal objects (such as metal buildings,
railroad tracks, etc.) can be found.
■
When driving through very divided and enclosed spaces (such as large-ca-
pacity garages, car ferries and the like.)
CAUTIONRemove the snow with a brush and the ice with a solvent-free de-icer.
Operation
Fig. 142
Instrument cluster display: Note
(dangerous proximity) / advance
warning or intervention of the
city emergency braking function
First read and observe the introductory information and safety warn-
ings on page 154.
Front Assist assists the driver while driving in the following ways:
› Alerts you about a dangerous proximity to the vehicle ahead.
› Warns you of an impending collision.
› Prepares the brakes for emergency braking prior to a detected danger.
› Assists with a brake action triggered by the driver.
› If the driver fails to respond to a detected danger, an automatic brake action is
performed.
Front Assist can work only if the following basic conditions are met. Front Assist is enabled.
TCS is enabled » page 137, Brake assist systems .
The vehicle is traveling forwards at a speed of more than approx. 5 km/h.
proximity warning (dangerous proximity)
If a safe time interval to the vehicle ahead is exceeded, the display of the instru- ment cluster shows the symbol » Fig. 142 -
.
Immediately increase the proximity if the current traffic situation allows you to do so!
The proximity at which the warning is displayed depends on the current speed.
The warning may occur when driving between about 60 km/h and 210 km/h.
156Driving
Advance warning
If Front Assist detects a risk of collision with a vehicle ahead, a symbol appears in
the display of the instrument cluster and an acoustic signal is heard » Fig. 142 - .
At the same time, the braking system is prepared for possible emergency braking.
The advance warning may occur when driving between 30 km/h and 210 km/h.
Apply the brakes or avoid the obstacle!
Acute alert
If the driver does not react to the advance warning, Front Assist briefly applies
the brake automatically via an active brake intervention to draw attention to the
potential danger of a collision again.
Automatic Braking
If the driver fails to respond to the acute warning, Front Assist starts to apply the
brakes automatically with increasing stopping power in several stages.
Front Assist can help to mitigate the consequences of a potential accident by
means of a speed reduction.
Brake Support
If the driver does not brake sufficiently in case of an imminent collision, Front As-
sist can increase the braking power, thereby reducing the consequences of a po-
tential accident.
The brake support only occurs as long as the brake pedal is being firmly pressed
down.
CAUTION
The automatic braking interventions by Front Assist can be terminated by press-
ing the clutch or the accelerator, or by moving the steering wheel.
Note
If an automatic brake intervention is triggered by Front Assist, the pressure in the
brake system increases and the brake pedal cannot be operated with the normal
pedal stroke.
Activating/deactivating
First read and observe the introductory information and safety warn-ings
on page 154.
Front Assist is automatically activated each time the ignition is switched on.
Front Assist should only be disabled in exceptional cases.
Activate / deactivate front assist
Front Assist can be activated or deactivated in the Infotainment » Infotainment
manual , chapter Vehicle settings (CAR button) or in the MAXI-DOTDis-
play » page 32 , Menu item wizard .
By disabling the system, the proximity warning system and the advance warning are also deactivated.
Activate/deactivate proximity warning
The proximity warning indicator can be activated/deactivated in the Infotain-
ment » Infotainment manual , chapter Vehicle settings (CAR button) .
The set proximity warning remains active even after stopping and starting the ig-
nition.
Activate/deactivate advance warning
The advance warning can be activated/deactivated in the Infotainment » Info-
tainment manual , chapter Vehicle settings (CAR button) .
The set advance warning remains active even after stopping and starting the ig- nition.
“City”Emergency braking
First read and observe the introductory information and safety warn-ings
on page 154.
The “City”Emergency braking function (From here on referred to only as the emer-
gency brake function) is a component of the Front Assist system.
The emergency brake function assists the driver when driving as follows. › Prepares the brakes for emergency braking prior to a detected danger.
› If the driver fails to respond to a detected danger, an automatic brake action oc-
curs with stopping power that increases in several stages.
The emergency brake function intervenes when driving between about 5 km/h
and 34 km / h.
157Assist systems
The engine output falls as the height increases, as does the ability to climb.
Therefore, for every additional 1000 m in height (or part), the maximum permissi- ble towed weight must be reduced by 10%.
The towed weight is made up of the actual weights of the loaded towing vehicleand the loaded trailer.
The trailer and drawbar load information on the type plate of the towing device are merely test data for the towing device. The vehicle-specific values are de-
tailed in the vehicle documents.WARNING■ Do not exceed the maximum permissible axle and drawbar load and the
maximum permissible total or towed weight of the vehicle and the trailer –
risk of accident and serious injury.■
Slipping loads can significantly impair the stability and safety of the vehicle/
trailer combination – risk of accident and serious injury.
Driving with a trailer
Fig. 157
Swivel out the 13-pin power
socket
First read and observe the introductory information and safety warn- ings on page 172.
Before the journey
›
Grip the 13-pin socket at point
A
and swing out in the direction of ar-
row » Fig. 157 .
›
Lift off protective cap
5
» Fig. 152 on page 169 .
After the journey
›
Grip the 13-pin socket at point
A
and swing in the opposite direction to the ar-
row » Fig. 157 .
›Place the protective cover 5
» Fig. 152 on page 169 onto the tow bar.
Safety eye
The purpose of the safety eyelet B
» Fig. 157 is to attach the breakaway cable of
the trailer.
When attaching the breakaway cable to the safety eye, it must sag freely in all
trailer positions (sharp bends, in reverse, etc.).
Exterior mirrors
You have to have additional exterior mirrors fitted if you are not able to see the
traffic behind the trailer with the standard rear-view mirrors. The national legal requirements must be observed.
Headlights
The front of the vehicle may lift up when a trailer is being towed and the head-
lights may dazzle other road users.
Adjust the headlights using the headlight beam control » page 55, Side lights and
low beam .
Driving speed
For safety reasons, do not drive faster than 80 km/h when hitching a trailer.
Immediately reduce your speed as soon as even the slightest swaying of the trail- er is detected. Never attempt to stop the trailer from “swaying” by accelerating.
Brakes
Apply the brakes in good time! If the trailer is fitted with a trailer brake, apply the
brakes gently at first, then brake firmly. This will avoid brake jolts resulting from
the trailer wheels locking.
On downhill sections shift down a gear in good time to also use the engine as a
brake.
Engine overheating
If the needle for the coolant temperature gauge moves into the right-hand area
or the red area of the scale, the speed must be reduced immediately.
Stop and switch off the engine if the warning light
in the display » page 22 is
lit. Wait a few minutes and check the level of coolant » page 222.
The following guidelines must be observed » page 22,
Coolant .
The coolant temperature can be reduced by switching on the heating.
173Towing a trailer