2008 MERCEDES-BENZ ML550 brake

250 Controls in detail
Driving systems
Switching the Downhill Speed
Regulation on/off
The switch is located on the upper part of
the center console.
1DSR on/off
2Indicator lampiWhenever DSR is switched on, DSR will use
the programmed default speed to regulate the
vehicle’s speed. The default speed programmed
at the factory is 4 mph (Canada: 6 km / h). The
default speed can be reprogrammed using the
control system (
page 178). The next time DSR
is switched on, DSR will use the newly pro-
grammed default speed to regulate the vehicle’s
speed.
Once DSR is switched on, you can adjust the set
speed using the cruise control lever
(
page 245). Keep in mind that adjusting the
set speed using the cruise control lever with DSR
switched on will not change the programmed
default speed. If DSR is switched off and then
switched on again, DSR will use the programmed
default speed.
Depending on the road surface and level of
downhill grade, the DSR may not be able to
maintain the set speed. To maintain the set
speed, apply the brakes if necessary.
Warning!G
If the accelerator pedal is depressed while
the Downhill Speed Regulation is activated,
the vehicle can drive faster than the pro-
grammed set speed. You should therefore
drive downhill with particular caution as it
could otherwise lead to an accident and/or
serious injury to you or others. Keep in mind
that as soon as you remove the foot from
the accelerator pedal with the DSR switched
on, the DSR will start regulating the vehicle’s
speed including use of brakes if required.
Depending on the programmed set speed,
actual vehicle speed and gradient, the DSR
can cause the vehicle to slow down rapidly.
Sudden and unexpected deceleration can
result in loss of vehicle control, causing an
accident and/or serious personal injury to
you and others.

260 Controls in detail
Driving systems
The Parktronic system is an electronic
parking aid and designed to assist the
driver during parking maneuvers. It visually
and audibly indicates the relative distance
between the vehicle and an obstacle.
The Parktronic system is automatically
activated when you

switch on the ignition or start the
engine
and

release the parking brake
and

set the automatic transmission to
positionD,R, orN
The Parktronic system deactivates at
vehicle speeds exceeding approximately
11 mph (18 km/h). At lower vehicle
speeds the Parktronic system turns on
again.The Parktronic system also deactivates
when you set the automatic transmission
to positionP or depress the parking brake
pedal.
The Parktronic system monitors the sur-
roundings of your vehicle with six sensors
in the front bumper and four sensors in the
rear bumper.
1Sensors in the front bumper
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 394).
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.
Warning!G
Make sure no persons or animals are in the
area in which you are maneuvering. You
could otherwise injure them.


261 Controls in detail
Driving systems
Range of the sensors
To function properly, the sensors must be
free of dirt, ice, snow and slush. Clean the
sensors regularly, being careful not to
scratch or damaging the sensors, see
“Cleaning the Parktronic* system sensors”
(
page 394).Front sensors
Rear sensors
Minimum distance
If the system detects an obstacle in this
range, all the distance warning segments
illuminate and you hear a warning signal. If
the obstacle is closer than the minimum
distance, the actual distance may no
longer be indicated by the system.
!During parking maneuvers, pay special
attention to objects located above or below the
height of the sensors (e.g. planters or trailer
hitches). The Parktronic system will not detect
such objects at close range and damage to your
vehicle or the object may result.
Ultrasonic signals from outside sources (e.g.
working jackhammers, car wash or the air brakes
of trucks) may impair the operation of the
Parktronic system.
Centerapprox. 40 in (100 cm)
Cornersapprox. 24 in (60 cm)
Centerapprox. 48 in (120 cm)
Cornersapprox. 32 in (80 cm)
Centerapprox. 8in (20cm)
Cornersapprox. 6in (15cm)

262 Controls in detail
Driving systems
Warning indicators
Visual signals indicate to the driver the rel-
ative distance between the sensors and an
obstacle. The warning indicator for the
front area is located above the center air
vents in the dashboard. The warning indi-
cator for the rear area is located in the rear
passenger compartment under the roof.
Front area warning indicator
1Left side of the vehicle
2Right side of the vehicle
3Readiness indicatorsEach warning indicator is divided into five
yellow and two red distance segments for
either side of the vehicle. The Parktronic
system is operational when the readiness
indicators3 are illuminated.
The current transmission position deter-
mines which warning indicator will be acti-
vated.As your vehicle approaches an object, one
or more distance segments will illuminate,
depending on the distance. When the red
distance segment illuminates, you have
reached the minimum distance.

Front area: An intermittent acoustic
warning lasting a maximum of
2 seconds will sound as the first red
distance segment illuminates and a
constant acoustic warning lasting a
maximum of 2 seconds will sound for
the second red distance segment. The
signal is canceled when the automatic
transmission is set to positionP, or the
parking brake is set.

Rear area: An intermittent acoustic
warning lasting a maximum of
2 seconds will sound as the first red
distance segment illuminates and a
constant acoustic warning lasting a
maximum of 2 seconds will sound for
the second red distance segment. The
signal is canceled when the automatic
transmission is set to positionD, P, or
the parking brake is set.
Transmission
positionWarning indicator
DFront area activated
R or NFront and rear area
activated
PNeither activated

263 Controls in detail
Driving systems
Switching the Parktronic system*
on/off
You can switch off the Parktronic system
manually.
The Parktronic switch is located in the
upper part of the center console.
1Parktronic switch
2Indicator lampSwitching off
Press Parktronic switch1.
Indicator lamp2 comes on.
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.iThe Parktronic system switches on
automatically when you switch on the ignition
(
page 40).
Vehicles with original equipment Mercedes-Benz
Trailer Hitch Kit:
The rear Parktronic sensor will automatically
disengage when towing a trailer.

285 Controls in detail
Useful features
Removing and reinstalling cup holder
The front cup holder can be removed for
cleaning purposes.
1Cup holder
2Bridge with card, ticket holder
Hold cup holder at its bridge2 and
pull out bridge in direction of arrow.
Pull cup holder1 out in direction of ar-
row.
First, insert the cup holder1 and then
insert bridge2.
Ashtrays
Depending on vehicle configuration, your
vehicle is equipped with an ashtray and a
cigarette lighter (
page 287) located in
the front center console and an ashtray lo-
cated in front of the rear seats
(
page 286).
Ashtray in the center console
1Ashtray insert
2Cover plateOpening the ashtray
Briefly touch cover plate2.
The ashtray opens automatically.
Removing ashtray insert
Grip the ashtray insert1 on the sides
and pull it out upwards.
Reinstalling ashtray insert
Install ashtray insert1.
Close ashtray cover plate2.
iIf your vehicle is not equipped with an ash-
tray, it has a storage compartment (
page 281)
with a power outlet (
page 288) instead.
Warning!G
Remove ashtray only with vehicle standing
still. Set the parking brake to secure vehicle
from movement. Set automatic transmis-
sion toP. With the automatic transmission
set toP, turn off the engine.

311 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 infla-
tion pressures.

Remove unnecessary loads.

Remove carriers* when not in use.

Allow engine to warm up under low
load use.

Avoid frequent acceleration and decel-
eration.

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 driv-
ing in cold weather, in stop-and-go traffic,
on short trips and in hilly areas.
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 that 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.

312 Operation
Driving instructions
Power assistance
BrakesTo 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 sub-
jected to moderate loads, you should occa-
sionally 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.
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 re-
duced and increased pedal pressure may be
necessary to obtain expected braking ef-
fect. 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 acci-
dent.
!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.