brake light MERCEDES-BENZ R320 2008 W251 User Guide

281 Controls in detail
Driving systems
Permanent four-wheel drive (4MATIC)*
Your vehicle is equipped with permanent
four-wheel drive (4MATIC). Both, the front
and rear axles, are powered at all times
when the vehicle is being operated. The
4MATIC improves traction in conjunction
with the ESP
® (page 101) and the
Electronic Traction System (
page 103).
Parktronic* (Parking assist)
Warning!G
If a drive wheel is spinning due to insuffi-
cient traction:

While driving off, apply as little throttle
as possible.

While driving, ease up on the accelera-
tor.

Adapt your speed and driving style to
the prevailing road conditions.
Failure to observe these guidelines could
cause the vehicle to skid.
The 4MATIC cannot prevent accidents re-
sulting from excessive speed.
!Operational or performance test must only
be conducted on a two-axle dynamometer. If
such tests are necessary, contact an authorized
Mercedes-Benz Light Truck Center. You could
otherwise seriously damage the brake system or
the transfer case which is not covered by the
Mercedes-Benz Limited Warranty.
!Because the ESP® operates automatically,
the engine and ignition must be shut off
(SmartKey in starter switch position0 or1 or
KEYLESS-GO* start/stop button in
position0or1) when testing the parking brake
on a brake test dynamometer and such testing
should be no longer than 10 seconds.
Active braking action through the ESP
® may
otherwise seriously damage the brake system
which is not covered by the Mercedes-Benz
Limited Warranty.
iIn winter operation, the maximum effective-
ness of the 4MATIC is only achieved with winter
tires (
page 398) or snow chains as required.
Warning!G
Parktronic is a supplemental system. It is
not intended to, nor does it replace, the
need for extreme care. The responsibility
during parking and other critical maneuvers
always remains with the driver.
Special attention must be paid to objects
with smooth surfaces or low silhouettes
(e.g. trailer couplings, painted posts, or road
curbs). Such objects may not be detected by
the system and can damage the vehicle.
The operational function of the Parktronic
system can be affected by dirty sensors,
especially at times of snow and ice, see
“Cleaning the Parktronic* system sensors”
(
page 408).
Interference caused by other ultrasonic
signals (e.g. working jackhammers, car
wash, or the air brakes of trucks) can cause
the system to send erratic indications, and
should be taken into consideration.

285 Controls in detail
Driving systems
Switching on
Press Parktronic switch1 once more.
Indicator lamp2 goes out.
Parktronic system malfunction
If only the red distance segments illumi-
nate and an acoustic warning sounds,
there is a malfunction in the Parktronic
system. The Parktronic system will auto-
matically switch off after 20 seconds and
the indicator lamp in the Parktronic switch
comes on.
Have the Parktronic system checked
by an authorized Mercedes-Benz Light
Truck Center as soon as possible.If only the red distance segments illumi-
nate and no acoustic warning sounds, the
Parktronic system sensors are dirty (e.g.
slush, snow or ice) or there is an interfer-
ence from other radio or ultrasonic signals
(e.g. working jackhammers, car wash or
the air brakes of trucks). The Parktronic
system will automatically switch off after
20 seconds and the indicator lamp in the
Parktronic switch comes on.
Switch off the ignition (page 39).
Clean the Parktronic system sensors
(
page 408).
Switch on the ignition (page 39).
or
Check the Parktronic system operation
at another location to rule out interfer-
ence from outside radio or ultrasonic
signals.
Rear view camera*
iThe Parktronic system switches on
automatically when you switch on the ignition
(
page 39).
Warning!G
The rear view camera is only an aid and may
display obstacles from a distorted perspec-
tive or inaccurately, or may not display ob-
stacles at all. The rear view camera does not
relieve you of the responsibility to be cau-
tious, take care and pay careful attention.
The rear view camera may not show objects
which are

very close to the rear bumper

under the rear bumper

above the tailgate handle
You are responsible for safety at all times
and must continue to pay attention to the
immediate surroundings when parking and
maneuvering. This includes the area behind,
in front of and beside the vehicle. Otherwise
you could endanger yourself or others.

311 Controls in detail
Useful features
Cupholders in third-row side trim
Cupholders are located in the side trims of
the third-row seats.
1Cup holderAshtrays
Your vehicle is equipped with an ashtray
and a cigarette lighter (
page 313)
located in the front center console and an
ashtray located in front of the second-row
seats (
page 312).
Ashtray in the front center console
Opening the ashtray
1Cover
2Chrome label
Tab lightly on chrome label 2 of
cover1.
Cover 1 swings open.
Removing ashtray insert
Warning!G
Remove ashtray insert only with vehicle
standing still. Set the parking brake to
secure vehicle from movement. Set auto-
matic transmission toP. With the automatic
transmission set toP, turn off the engine.

339 Operation
Driving instructions
Driving instructions
Drive sensibly – save fuel
Fuel consumption, to a great extent,
depends on driving habits and operating
conditions.
To save fuel you should:

Keep tires at the recommended
inflation pressures.

Remove unnecessary loads.

Remove carriers when not in use.

Allow engine to warm up under low
load use.

Avoid frequent acceleration and
deceleration.

Have all maintenance work performed
at the intervals specified in the
Maintenance Booklet and as required
by the Maintenance System. Contact
an authorized Mercedes-Benz Light
Truck Center.
Fuel consumption is also increased by
driving in cold weather, in stop-and-go
traffic, on short trips and in hilly area.
Drinking and drivingPedals
Warning!G
Drinking and driving and/or taking drugs
and driving are a very dangerous combina-
tion. Even a small amount of alcohol or
drugs can affect your reflexes, perceptions
and judgment.
The possibility of a serious or even fatal
accident are greatly increased when you
drink or take drugs and drive.
Do not drink or take drugs and drive or allow
anyone to drive who has been drinking or
taking drugs.
Warning!G
Make sure that absolutely no objects are ob-
structing the pedal’s range of movement.
Keep the driver’s footwell clear of all obsta-
cles. If there are any floormats or carpets in
the footwell, make sure the pedals still have
sufficient clearance.
During sudden driving or braking maneu-
vers, the objects could get caught between
the pedals. You could then no longer brake
or accelerate. This could lead to accidents
and injury.

340 Operation
Driving instructions
Power assistanceBrakes
Warning!G
With the engine not running, there is no
power assistance for the brake and steering
systems. In this case, it is important to keep
in mind that a considerably higher degree of
effort is necessary to brake and steer the ve-
hicle.
Warning!G
After driving in heavy rain for some time
without applying the brakes or through wa-
ter deep enough to wet brake components,
the first braking action may be somewhat
reduced and increased pedal pressure may
be necessary to obtain expected braking
effect. Maintain a safe distance from
vehicles in front.
Resting your foot on the brake pedal will
cause excessive and premature wear of the
brake pads.
It can also result in the brakes overheating,
thereby significantly reducing their effec-
tiveness. It may not be possible to stop the
vehicle in sufficient time to avoid an
accident.
!Because the ESP® operates automatically,
the engine and ignition must be shut off
(SmartKey in starter switch position0 or1 or
KEYLESS-GO* start/stop button in
position0or1) when the vehicle is being towed
with one axle raised.
Active braking action through the ESP
® may
otherwise seriously damage the brake system
which is not covered by the Mercedes-Benz
Limited Warranty
!Vehicles with 4MATIC must not be towed
with one axle raised.
!Vehicles with 4MATIC:
Operational or performance test must only be
conducted on a two-axle dynamometer. If such
tests are necessary, contact an authorized
Mercedes-Benz Light Truck Center. You could
otherwise seriously damage the brake system or
the transfer case which is not covered by the
Mercedes-Benz Limited Warranty.

341 Operation
Driving instructions
To help prevent brake disk corrosion after
driving on wet road surfaces (particularly
salted roads), it is advisable to brake the
vehicle with considerable force prior to
parking. The heat generated serves to dry
the brakes.
If your brake system is normally only
subjected to moderate loads, you should
occasionally test the effectiveness of the
brakes by applying above-normal braking
pressure at higher speeds. This will also
enhance the grip of the brake pads.Refer to the description of the Brake Assist
System (BAS) (
page 101).
Brake pad wear or a leak in the system may
be the reason for low brake fluid level in
the reservoir.
The brake fluid level in the reservoir may
be too low if the brake warning lamp
in the instrument cluster comes on and an
acoustic warning sounds although the
parking brake is released (
page 415).
Observe additional messages in the multi-
function display that may appear
(
page 447).
Have the brake system inspected
immediately. Contact an authorized
Mercedes-Benz Light Truck Center.All checks and service work on the brake
system should be carried out by qualified
technicians only. Contact an authorized
Mercedes-Benz Light Truck Center.
Only install brake pads and brake fluid
recommended by Mercedes-Benz.
!Vehicles with 4MATIC:
Because the ESP® operates automatically, the
engine and ignition must be shut off (SmartKey
in starter switch position0 or1 or KEYLESS-GO*
start/stop button in position0or1) when test-
ing the parking brake on a brake test dynamom-
eter and such testing should be no longer than
10 seconds.
Active braking action through the ESP
® may
otherwise seriously damage the brake system
which is not covered by the Mercedes-Benz
Limited Warranty.
Warning!G
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.
Warning!G
If other than recommended brake pads are
installed, or other than recommended brake
fluid is used, the braking properties of the
vehicle can be degraded to an extent that
safe braking is substantially impaired. This
could result in an accident.

342 Operation
Driving instructions
After hard braking, it is advisable to drive
on for some time, rather than immediately
park, so that the air stream will cool down
the brakes faster.Parking brake
When driving on wet roads or dirt covered
surfaces, road salt and/or dirt can get into
the parking brake. To prevent corrosion
and a reduction in the braking power of the
parking brake, observe the following:
From time to time, lightly engage the
parking brake before driving off.
Drive a distance of approximately
110 yds (100 m) at a maximum speed
of 12 mph (20 km/h)
Driving off
Apply the brakes to test them briefly after
driving off. Perform this procedure only
when the road is clear of other traffic.
Warm up the engine smoothly. Do not
place full load on the engine until the oper-
ating temperature has been reached.!When driving down long and steep grades,
relieve the load on the brakes by shifting into a
lower gear to use the engine’s braking power.
This helps prevent overheating of the brakes and
reduces brake pad wear.
When using the engine’s braking power, a drive
wheel may not spin for an extended period of
time, e.g. on slippery road surfaces. This may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.
Warning!G
While performing this procedure, please as-
sure that the vehicle is stopped before ap-
plying the parking brake. Otherwise the rear
wheels could lock up. You could lose control
of the vehicle and cause an accident. In ad-
dition, the vehicle’s brake lights do not light
up when the parking brake is engaged.
Make sure not to endanger any other road
users when you engage the parking brake.
!When driving off on a slippery surface, do
not allow a drive wheel to spin for an extended
period with the ESP
® switched off. Doing so may
cause serious damage to the drivetrain which is
not covered by the Mercedes-Benz Limited
Warranty.
!Simultaneously depressing the accelerator
pedal and applying the brakes reduces engine
performance and causes premature brake and
drivetrain wear.

343 Operation
Driving instructions
ParkingTires
Warning!G
Do not park this vehicle in areas where com-
bustible materials such as grass, hay or
leaves can come into contact with the hot
exhaust system, as these materials could be
ignited and cause a vehicle fire.
To reduce the risk of personal injury or dam-
age to the vehicle drivetrain as a result of
vehicle movement, before turning off the en-
gine and leaving the vehicle always:

Keep right foot on brake pedal.

Firmly depress parking brake pedal.

Shift the automatic transmission to
positionP.

Slowly release brake pedal.

When parked on an incline, turn front
wheel towards the road curb.

Turn the SmartKey in the starter switch
to position0 and remove the SmartKey
from the starter switch, or press the
start/stop button (vehicles with
KEYLESS-GO*).

Take the SmartKey or the SmartKey with
KEYLESS-GO* and lock vehicle when
leaving.
Warning!G
If you feel a sudden significant vibration or
ride disturbance, or you suspect that possi-
ble damage to your vehicle has occurred,
you should turn on the hazard warning
flashers, carefully slow down, and drive with
caution to an area which is a safe distance
from the road.
Inspect the tires and the vehicle underbody
for possible damage. If the vehicle or tires
appear unsafe, have the vehicle towed to
the nearest Mercedes-Benz Light Truck
Center or tire dealer for repairs.

346 Operation
Driving instructions
Winter driving instructions
The most important rule for slippery or icy
roads is to drive sensibly and to avoid
abrupt acceleration, braking and steering
maneuvers. Do not use the cruise control
system under such conditions.
When the vehicle is in danger of skidding,
shift the automatic transmission to
positionN. Try to keep the vehicle under
control by corrective steering action.Road salts and chemicals can adversely af-
fect braking efficiency. Increased pedal
force may become necessary to produce
the normal brake effect.
Depressing the brake pedal periodically
when traveling at length on salt-strewn
roads can bring road-salt-impaired braking
efficiency back to normal.
If the vehicle is parked after being driven
on salt-treated roads, the braking
efficiency should be tested as soon as
possible after driving is resumed.
For more information, see “Winter driving”
(
page 398).
iFor information on driving with snow chains,
see “Snow chains” (
page 399).
Warning!G
On slippery road surfaces, never downshift
in order to obtain braking action. This could
result in drive wheel slip and reduced vehi-
cle control. Your vehicle’s ABS will not pre-
vent this type of control loss.
Warning!G
Make sure not to endanger any other road
users when carrying out these braking
maneuvers.
Warning!G
If the vehicle becomes stuck in snow, make
sure that snow is kept clear of the exhaust
pipe and from around the vehicle with the
engine running. Otherwise, deadly carbon
monoxide (CO) gases may enter vehicle
interior resulting in unconsciousness and
death.
To assure sufficient fresh air ventilation,
open a window slightly on the side of the
vehicle not facing the wind.
Warning!G
The outside temperature indicator is not
designed to serve as an ice-warning device
and is therefore unsuitable for that purpose.
Indicated temperatures just above the freez-
ing point do not guarantee that the road sur-
face is free of ice.

355 Operation
At the gas station
Engine oil level
For more information on engine oil, see
“Engine oil” (
page 358).
Coolant
For normal replenishing, use water (pota-
ble water quality). For more information,
see “Coolant level” (
page 360) and
“Fuels, coolants, lubricants, etc.”
(
page 536).
Brake fluidWindshield/rear window washer
system and headlamp cleaning
system*
For more information on refilling the wash-
er reservoir, see “Windshield/rear window
washer system and headlamp cleaning
system*” (
page 362).
Vehicle lighting
Check function and cleanliness. For infor-
mation on replacing light bulbs, see “Re-
placing bulbs” (
page 480).
For more information, see “Exterior lamp
switch” (
page 143).
Tire inflation pressure
For more information, see “Checking tire
inflation pressure” (
page 373).
!If you find that the brake fluid in the brake
fluid reservoir has fallen to the minimum mark or
below, have the brake system checked for brake
pad thickness and leaks immediately. Contact an
authorized Mercedes-Benz Light Truck Center
immediately. Do not add brake fluid as this will
not solve the problem. For more information, see
“Brake fluid” (
page 539).