Driving and operating131Drive systems
All-wheel drive The All-Wheel Drive (AWD) system
enhances driving characteristics and stability, and helps to achieve the best possible driveability regardless of
ground surface. The system is always
active and cannot be deactivated.
The torque is distributed steplessly
between the wheels of the front and rear axle, depending on the driving
conditions. Additionally the torque
between the rear wheels is distributed
depending on the surface.
For optimum system performance,
the vehicle's tyres should not have
varying degrees of wear.
When using a temporary spare
wheel, the AWD system is
automatically disabled.
The AWD system will also be
temporarily disabled to protect the
system from overheating if there is
excessive wheel spin. When the
system cools down, AWD will be
restored.The deactivation of the AWD system
will be indicated by a message on the
Driver Information Centre.
If a service message or warning
code S73 is displayed on the Driver Information Centre, there is a
malfunction in the AWD system. Seek the assistance of a workshop.
Vehicle messages 3 95, Towing the
vehicle 3 191.Brakes
The brake system comprises two
independent brake circuits.
If a brake circuit fails, the vehicle can
still be braked using the other brake
circuit. However, braking effect is
achieved only when the brake pedal
is depressed firmly. Considerably
more force is needed for this. The
braking distance is extended. Seek the assistance of a workshop before
continuing your journey.
When the engine is not running, the
support of the brake servo unit
disappears once the brake pedal has been depressed once or twice.
Braking effect is not reduced, but
braking requires significantly greater
force. It is especially important to bear this in mind when being towed.
Control indicator R 3 85.
Antilock brake system Antilock brake system (ABS)
prevents the wheels from locking.
186Vehicle care
■ Never crawl under a jacked-upvehicle.
■ Do not start the vehicle when it is raised on the jack.
■ Clean wheel nuts and thread with a
clean cloth before mounting the
wheel.9 Warning
Do not grease wheel bolt, wheel
nut and wheel nut cone.
1. Disengage wheel nut caps with a screwdriver and remove. Pull off
the wheel cover.
2. Fold out the wheel wrench and install ensuring that it locates
securely and loosen each wheel
nut by half a turn.
3. Ensure the jack is correctly positioned under the relevant
vehicle jacking point.
Depending on the equipment, first
remove the covers from the
jacking points.
4. Set the jack to the necessary height. Position it directly below
the jacking point in a manner that
prevents it from slipping.
Attach wheel wrench and with the jack correctly aligned rotate wheelwrench until wheel is clear of the
ground.
5. Unscrew the wheel nuts.
6. Change the wheel. Spare wheel 3 187.
7. Screw on the wheel nuts.
8. Lower the vehicle and remove jack.
9. Install the wheel wrench ensuring that it locates securely and tighten
each nut in a crosswise
sequence. Tightening torque is
140 Nm.
Vehicle care187
10. Align the valve hole in the wheelcover with the tyre valve before
installing.
Install wheel nut caps.
Install centre cap on alloy wheels.
11. Install vehicle jacking point cover on versions with sill panelling.
12. Stow the replaced wheel 3 187
and the vehicle tools 3 175.
13. Check the tyre pressure of the installed tyre and the wheel nut
torque as soon as possible.
Have the defective tyre renewed or repaired as soon as possible.Jacking position for lifting
platform
Rear arm position of the lifting
platform centrically under the recess
of the sill.
Front arm position of the lifting
platform at the underbody.
Spare wheel Some vehicles are equipped with a
tyre repair kit instead of a spare
wheel.
If mounting a spare wheel, which is
different from the other wheels, this
wheel might be classified as a
temporary spare wheel and the
corresponding speed limits apply,
even though no label indicates this.
Seek the assistance of a workshop to
check the applicable speed limit.
