
The distribution of the weight is very poor if your vehicle is unladen and the trail-
er is laden. Maintain a particularly low speed if you cannot avoid driving with this
combination.
Tyre pressure
Correct the tyre inflation pressure on your vehicle for a “full load” » page 173,
Service life of tyres .
Trailer load
The permissible trailer load must not be exceeded under any circumstan- ces » page 199 , Technical data .
The trailer loads specified apply only to altitudes up to 1 000 metres above mean
sea level.
The engine output falls as altitude increases, as does the ability to climb. There-
fore, for every additional 1000 m in height (or part), the maximum permissible
towed weight must be reduced by 10 %.
The towed weight comprises the actual weights of the (loaded) towing vehicleand the (loaded) trailer.
The trailer and drawbar load information on the type plate of the towing equip-
ment are merely test data for the towing equipment. The vehicle-specific values
are detailed 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 –
there is the risk of an accident and serious injury.■
Slipping loads can significantly affect the stability and safety of the vehicle/
trailer combination – there is the risk of an accident and serious injury.
Towing a trailer
First read and observe the introductory information and safety warn-
ings
on page 120.
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 can be lifted when a trailer is being towed and the head- lights can dazzle other road users.
Adjust the headlight setting on the headlight range control » page 42, Headlight
beam adjustment .
Driving speed
For safety reasons, do not drive faster than 80 km/h when towing 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
The speed must be reduced immediately if the needle for the coolant tempera-
ture gauge moves into the right-hand area or the red area of the scale.
Stop and switch off the engine if the warning light
in the instrument cluster
starts to flash. Wait a few minutes and check the level of coolant » page 166,
Checking the coolant level .
The following guidelines must be observed » page 22,
Coolant .
The coolant temperature can be reduced by switching on the heating.WARNING■ Adapt your speed to the conditions of the road surface and to the traffic sit-
uation.■
Improper or incorrectly connected electric cables can energise the trailer and
cause functional faults to the vehicle's entire electrical system as well as acci-
dents and severe injuries.
■
Work on the electrical system must only be carried out by specialist garages.
■
Never directly connect the trailer's electrical system with the electrical con-
nections for the tail lights or other current sources.
121Towing a trailer

WARNING (Continued)■Replace a frozen vehicle battery.■Never jump-start vehicle batteries with insufficient acid levels – risk of ex-
plosion and chemical burns.WARNING■ When you charge a battery, hydrogen is released, and a highly explosive gas
mixture is also produced. An explosion can be caused through sparkling over during unclamping or loosening of the cable plug while the ignition is on.■
Creating a bridge between the poles on the battery (e.g. with a metal object
or cable) creates a short circuit - risk of melting the lead bars, and risk of ex-
plosion, battery fire and acid splashes.
■
Avoid creating sparks when working with cables and electrical devices.
Strong sparking represents a risk of injury.
■
Before carrying out any work on the electrical system, switch off the engine,
the ignition and all electrical consumers and disconnect the negative termi-
nal ( ) of the battery.
CAUTION
Improper handling of the battery can lead to damage. We recommend having all
work on the vehicle battery carried out by a specialist garage.
CAUTION
■ The vehicle battery must only be disconnected if the ignition is switched off,
otherwise the vehicle's electrical system (electronic components) can be dam-
aged. When disconnecting the battery from the vehicle's electrical system, first
disconnect the negative terminal ( ), then the positive terminal ( ).■
When connecting the battery to the vehicle's electrical system first connect the
positive terminal ( ), and only then the negative terminal ( ) of the battery. Un-
der no circumstances must the battery cables be connected incorrectly – risk of a
cable fire.
■
Ensure that battery acid does not come into contact with the bodywork – risk of
damage to the paintwork.
■
Do not place the battery in direct daylight in order to protect the vehicle battery
housing from the effects of ultra-violet light.
■ If the vehicle has not been driven for more than 3 to 4 weeks, the battery will
discharge. This is because certain electrical components consume electricity (e. g.
control units) also in idle state. Battery discharge can be prevented by discon- necting the negative terminal ( ) of the battery or by continuously charging the
battery charged with very low charging current.■
If the vehicle is frequently used for making short trips, the vehicle battery will
not have time to charge up sufficiently and may discharge.
For the sake of the environment
A vehicle battery that has been removed is a special type of hazardous waste.
These must be disposed of in accordance with national legal regulations.
Note
You should replace batteries older than 5 years.
Open cover
Fig. 133
Vehicle battery: Open up the
cover
First read and observe the introductory information and safety warn-
ings on page 168.
The battery is located in the engine compartment below a plastic box.
›
Open the cover in the direction of the arrow » Fig. 133.
›
The installation of the battery cover on the positive terminal side takes place in
the reverse order.
169Inspecting and replenishing

Checking the electrolyte levelFig. 134
Vehicle battery: Electrolyte level
indicator
First read and observe the introductory information and safety warn-
ings on page 168.
We recommend that you have the acid level checked regularly by a specialist ga-
rage, especially in the following cases.
› High outside temperatures.
› Long daily drives
› After each charge
» page 170.
On vehicles with a vehicle battery fitted with a colour indicator, known as the
magic eye » Fig. 134, the electrolyte level can be determined by looking at the
change in colour.
Air bubbles can influence the colour of the indicator. For this reason carefully
knock on the indicator before carrying out the check.
› Black colour - electrolyte level is correct.
› Colourless or light yellow colour - electrolyte level too low, the battery must be
replaced.
Note
■ The battery acid level is also checked regularly by a specialist garage as part of
the inspection service.■
For technical reasons, on vehicles with the description “AGM”, the electrolyte
level cannot be checked.
■
Vehicles with a START-STOP system are fitted with a battery control unit for
checking the energy level for the recurring engine start.
Operation in winter
First read and observe the introductory information and safety warn-
ings
on page 168.
The vehicle battery only has some of its starting power at low temperatures. A
discharged vehicle battery may freeze at temperatures just below 0 °C .
We therefore recommend that you have the battery checked and, if necessary, re-
charged by a specialist garage before the start of the winter.
Charging
First read and observe the introductory information and safety warn-ings
on page 168.
A properly charged vehicle battery is essential for reliably starting the engine.
›
Switch off the ignition and all of the electrical components.
›
Disconnect both battery cables (“negative” first, then “positive”) only when
“rapid charging” the battery.
›
Attach the terminal clamps of the charger to the battery terminals (red = “posi-
tive”, black = “negative”).
›
Plug the mains cable of the charger into the power socket and switch thecharger on.
›
Once charging is complete: Switch off the charger and remove the mains cable
from the power socket.
›
Only then disconnect the charger's terminal clamps.
›
Reconnect the cables to the battery (first “positive”, then “negative”).
It is not necessary to disconnect the battery cables if you are recharging the vehi-
cle battery using low amperages (for example from a mini-charger). Refer to the
charger manufacturer's instructions .
A charging current of 0.1 multiple of the total vehicle battery capacity (or lower)
must be used until full charging is achieved.
Both cables must be disconnected before charging the battery with high amper-
ages, known as “ rapid charging”.
The vent plugs of the vehicle battery should not be opened for charging.
170General Maintenance

WARNING (Continued)■The non-insulated parts of the terminal clamps must never touch each other
– there is a risk of short circuit.■
The jump-start cable connected to the positive terminal of the battery must
not come into contact with electrically conducting parts of the vehicle – there
is a risk of short circuit.
■
Do not clamp the jump-start cable to the negative terminal of the dis-
charged battery. There is the risk of detonating gas seeping out the battery
being ignited by the strong spark which results from the engine being started.
■
Route the jump-start cables so that they cannot be caught by any rotating
parts in the engine compartment.
■
Do not bend over the battery – there is a risk of caustic burns.
■
The vent screws of the battery cells must be tightened firmly.
■
Keep any sources of ignition (naked flame, lit cigarettes, etc.) away from the
battery – there is a risk of explosion.
■
Never jump-start vehicle batteries with insufficient acid levels – risk of ex-
plosion and chemical burns.
CAUTION
■ There must not be any contact between the two vehicles otherwise current
may flow as soon as the negative terminals are connected.■
The discharged battery must be properly connected to the system of the vehi-
cle.
■
We recommend you buy jump-start cables from a car battery specialist.
Jump-starting using the battery from another vehicle
Fig. 149
Jump-starting: A – flat battery, B
– battery providing current
First read and observe the introductory information and safety warn-
ings on page 186.
The battery of another vehicle can be used to jump-start your vehicle if the en-
gine will not start because the battery is flat. Jump-start cables are required for
this purpose.
The jump-start cables must be attached in the following sequence.
›
Attach clamp
1
to the positive terminal of the discharged battery
A
» Fig. 149 .
›
Attach clamp
2
to the positive terminal of the battery supplying power
B
.
›
Attach clamp
3
to the negative terminal of the battery supplying power
B
.
›
Attach clamp
4
to a solid metal component firmly connected to the engine
block or to the engine block itself.
Starting engine
›
Start the engine on the vehicle providing the power and allow it to idle.
›
Start the engine of the vehicle with the discharged battery.
›
If the engine does not start, halt the attempt to start the engine after 10 sec- onds and wait for 30 seconds before repeating the process.
›
Disconnect the cables in exactly the reverse order to the one described above.
Both batteries must have a rated voltage of 12 V. The capacity (Ah) of the battery
supplying the power must not be significantly less than the capacity of the dis-
charged battery in your vehicle.
Jump-start cables
Only use jump-start cables which have an adequately large cross-section and in-
sulated terminal clamps. Obey the instructions of the jump start cable manufac-
turer.
Positive cable - colour coding in the majority of cases is red.
Negative cable - colour coding in the majority of cases is black.
187Emergency equipment and self-help