
Intelligent Technology
106
•
Changes to vehicle (e.g. on engine, on the brakes, on chassis or another combi-
nation of tyres and wheels) can influence the function of the ESP page 146,
“Accessories, changing and replacing parts”.
Electronic Differential Lock (EDL)*
The electronic differential lock prevents an individual wheel from
slipping.Models fitted with ESP are equipped with electronic differential lock (EDL).
General
The EDL makes it much easier, and sometimes at all possible, to start off, accelerate
and climb a steep hill when the conditions of the road surface are unfavourable.
Operating principle
The EDL is activated automatically, that is without any action on the part of the
driver. It monitors the speeds of the driven wheels with the aid of the ABS sensors.
Should only one drive wheel begin spinning on a slippery surface there will be an
appreciable difference in the speed of the driven wheels. The EDL function brakes
the slipping wheel and the differential transmits a greater driving force to the other
driven wheel. This control process is also accompanied by noises.
Overheating of the brakes
The EDL switches off automatically if unusually severe stresses exist in order to
avoid excessive heat genera tion in the disc brake on the wheel which is 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.
WARNING
•
Carefully depress the accelerator when accelerating on uniformly slippery
road surfaces, such as ice and snow. The driven wheels might still spin despite
the EDL and affect the stability of the vehicle - risk of an accident!
•
You should always adapt your style of dr iving to the condition of road surface
and to the traffic situation even when your vehicle is fitted with EDL. The
increased safety offered must not temp t you to take greater risks than other-
wise - risk of an accident!
Note
•
If the ABS or ESP warning light comes on, this may also indicate a fault in the
EDL. Please have the vehicle inspected as soon as possible by a specialist garage.
•
Changes to vehicle (e.g. on engine, on the brakes, on chassis or another combi-
nation of tyres and wheels) can in fluence the function of the EDL page 146,
“Accessories, changing and replacing parts”.
Traction control system (TCS)
The traction control system prevents the driven wheels from spin-
ning when accelerating.General
The TCS makes it much easier, and sometimes at all possible, to start off, accelerate
and climb a steep hill when the conditions of the road surface are unfavourable.
Operating principle
The TCS switches on automatically when the engine is started and then conducts a
self-test. The system monitors the speeds of the driven wheels with the aid of the
ABS sensors. If the wheels are spinning, th e force transmitted to the road surface is
automatically adapted by reducing the engi ne speed. The system operates at all
speeds.
The TCS operates in combination with the ABS page 108, “Antilock brake system
(ABS)”. The TCS will not function if a fault exists in the ABS system.
The TCS warning light lights up in the instrument cluster when there is a fault on
the TCS
page 25.
During an intervention of th e system, the TCS warning light
flashes in the instru-
ment cluster page 25.
Fig. 112 TCS switch
s2lk.2.book Page 106 Monday, April 18, 2011 7:41 AM

Intelligent Technology
108
Low brake fluid level
An insufficient level of brake fluid may result in problems in the brake system. The
level of the brake fluid is monitored electronically page 27, “Brake system ”.
WARNING
•
Only apply the brakes for the purpose of drying and cleaning the brake discs
if the traffic conditions permit this. Do not place any other road users in jeop-
ardy.
•
When retrospectively mounting a front spoiler, solid wheel hubs etc. one
must ensure that the air supply to the front wheel brakes is not reduced other-
wise the braking system could run too hot.
•
Allow for the fact that new brake pads do not achieve their full braking effi-
ciency until after the first 200 kilometres. New brake pads must be first “run in”
before they develop their optimal friction force. You can, however, compensate
for this slightly reduced braking force by increasing the pressure on the brake
pedal. This guideline also applies to an y new brake pads installed at a future
date.Caution
•
Never allow the brakes to rub by applying slight pressure if you do not wish to
brake the vehicle. This causes the brakes to overheat and can also result in a longer
braking distance and excessive wear.
•
Before negotiating a steep downhill section, reduce your speed, shift down into
the next lower gear. This enables you to ma ke full use of the braking power of the
vehicle and reduces the strain on the brakes. Any additional braking should be done
intermittently, no t continuously.Note
The brake light flashes automatically in ca se of an emergency braking at speeds
greater than 60 km/h or with the interven tion of the ABS, which lasts longer than
1.5 seconds. After the speed was reduced below 10 km/h or the vehicle was stopped,
the brake light stops flashing and the hazard warning light system switches on. The
hazard warning light system is switched off automatically after accelerating or
driving off again.Brake boosterThe brake booster boosts the pressure wh ich you generate with the brake pedal.
The necessary pressure is only generated when the engine is running.
WARNING
•
Never switch off the engine be fore the vehicle is stationary.
•
The brake booster only operates when the engine is running. Greater phys-
ical effort for braking is required when en gine is switched off. Because if you do
not stop as normal, this can caus e an accident and severe injuries.
Antilock brake system (ABS)ABS prevents the wheels locking when braking.General
The ABS contributes significantly to enhancing the active safety of your vehicle.
Compared to a vehicle not fitted with ABS, you are able to retain optimal steering
ability even during a full brake application on a slippe ry road surface because the
wheels do not lock up.
You must not expect, however, that the braking distance will be shorter under all
circumstances as a result of the ABS. The braking distance for example on gravel
and fresh snow, when you should anyway be driving slowly and cautiously, will be
longer.
Operating principle
The brake pressure will be reduced on a wheel which is rotating at a speed which is
too low for the speed of the vehicle and tending to lock. This control cycle is notice-
able from a pulsating movement of the brake pedal which is accompanied by
noises. This is consciously intended to pr ovide the driver with the information that
the wheels are tending to lock (ABS control range). You must always keep the brake
pedal depressed to enable the ABS to optimally control the brake application in this
braking range. Never interrupt the application of the brakes!
WARNING
•
The ABS can also not overcome the physical limits of your vehicle. Please do
not forget this, particularly when driving on icy or wet road surfaces. If the ABS
is operating within the control range, adapt your speed immediately to the
conditions of the road surface and the traffic situation. The increased safety
offered by the ABS must not tempt you to take greater risks than otherwise -
risk of an accident!
•
The normal braking system is still fully functional if there is an ABS fault.
Visit a specialist garage as quickly as poss ible and adjust your style of driving to
s2lk.2.book Page 108 Monday, April 18, 2011 7:41 AM

Towing a trailer119
Using the system
Safety
Driving Tips
General Maintenance
Breakdown assistance
Technical Data
Driving Tips
Particular caution is required when towing a trailer.– Do not, as far as possible, drive with your vehicle unladen and the trailer laden.
– Do not make full use of the legal maximum speeds. This applies in particular to downhill sections.
– Apply the brakes in good time.
– Keep a check on the coolant temperatur e gauge if the outside temperature is
high.
Distribution of weight
The distribution of the weight is very poor if your vehicle is unladen and the trailer
is laden. Maintain a particularly low speed if you cannot avoid driving with this
combination.
Driving speed
Do not drive faster than 80 km/hour for sa fety reasons. This also applies for coun-
tries in which higher speeds are allowed.
The fact that the driving stability of the vehicle + trailer combination reduces with
increasing speed means that the legally allowed speed should not be used when
there are unfavourable road, weather or wind conditions, particularly near accident
black spots.
You must always reduce your speed immedi ately as soon as you detect even just
the slightest swaying of the trailer. On no account attempt to stop the trailer from
“swaying” by accelerating.
Apply the brakes in good time! If the trailer is fitted with a trailer brake, apply the
brakes gently at first and then brake firmly . This will avoid brake jolts resulting from
the trailer wheels locking. Shift down gears in good time before negotiating a
downhill section to allow the engine to also act as a brake.
Engine overheating
Please keep a check on the coolant temper ature gauge if you have to negotiate a
lengthy slope in a low gear at a high engine speed when the outside temperature is
very high page 16, “Engine coolant temperature Display”.
If the needle of the coolant temperature gauge moves into the right-hand area or
even the red area of the scale, reduce yo ur speed immediately. Stop and switch off
the engine if the warning light
in the instrument cluster begins flashing. Wait a
few minutes and check the level of coolant in the coolant expansion bottle
page 134, “Inspecting the coolant level”. Please refer to the following guidelines
page 25, “Coolant temperature/coolant
level ”.
The coolant temperature can be reduced by switching on the heating.
Any increase in the cooling effect of the coolant fan through shifting down a gear
and increasing the engine speed is not possible since the fan speed is independent
of the engine speed. One should also not drop a gear for this reason when towing a
trailer as long as the engine can manage the slope without any drop in speed.
Detachable towing device*The ball head of the towing device is stow ed together with separate fitting instruc-
tions in the spare wheel well in the luggage compartment of the vehicle.
Inspect the ball head to ensure that it is properly locked each time before setting
off. The inspection is performed by turning the closed locking lever downwards. If
the locking lever can only be turned around a small angle (approx. 5°), the locking
mechanism is O.K. After the inspection pull the locking lever back again to its stop.
The towing device must not be used, if it does not wish to close or the locking lever
turns slightly in the closed position.
WARNING
Do not use any aids or tools for installing or removing the ball head. This might
result in damage to the locking mechanism to the extent that the safety of the
towing device is no longer assured - risk of an accident.
Note
•
Do not carry out any modifications or re pairs to the ball head or to any other
components on the towing device.
Fig. 118 Detachable ball head
s2lk.2.book Page 119 Monday, April 18, 2011 7:41 AM

Fuel129
Using the system
Safety
Driving Tips
General Maintenance
Breakdown assistance
Technical Data
Caution
•
Remove any fuel which has spilled onto the paintwork of your vehicle immedi-
ately - risk of paint damage!
•
Vehicles fitted with catalytic converter should never be allowed to let the fuel
tank to run completely empty. An irregular supply of fuel to the engine can result in
misfiring and unburnt fuel may get into the exhaust system, which may result in
overheating and damage to the catalytic converter.
•
Make sure that the valve is not pressed into the filler tube when inserting the
pump nozzle into the filler tube. Otherwis e you are unintentionally filling up the
volume, which in case of heat can cause an expansion of the fuel. This can lead to
an overflow of fuel or damage to parts of the fuel reservoir.
•
The fuel tank is full just as soon as the pump nozzle switches off for the first
time, provided the nozzle has been operated properly. Do not continue refuelling -
otherwise the expansion volume is filled up.
s2lk.2.book Page 129 Monday, April 18, 2011 7:41 AM