2003 MERCEDES-BENZ ML350 brakes

149 Controls in detail
Driving systems
Parktronic system* (Parking assist)
The Parktronic system assists the driver
during parking maneuvers. It visually and
audibly indicates the distance between the
vehicle and an obstacle.
With the ignition on, Parktronic engages
automatically at speeds up to approxi-
mately 10 mph (15 km / h) and deactivates
during higher speeds.Parktronic monitors your vehicle’s environ-
ment by means of six sensors in the front
bumper and four sensors in the rear
bumper.
1Sensors located in front bumperWarning!
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 rests
always with the driver.
Make sure that no persons or animals are lo-
cated in the area in which your are maneu-
vering. They could otherwise be injured.
Special attention must be paid to objects
with smooth surfaces or low silhouettes
(e.g. trailer couplings, painted posts, or
street curbs). Such objects may not be de-
tected by the system and can damage the
vehicle.
The operational function of the Parktronic
can be affected by dirty sensors, especially
at times of snow and ice. For notes on clean-
ing the Parktronic system sensors
(page 220).
Interference caused by other ultrasonic sig-
nals (e.g. working jackhammers or the air
brakes of trucks) can cause the system to
send erratic indications, and should be tak-
en into consideration.

180 OperationDriving instructionsBrakes
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 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.If the parking brake is released and the
brake warning lamp in the instrument clus-
ter stays on and there is no audible warn-
ing (EBP), the brake fluid level in the
reservoir is too low.
Brake pad wear or a leak in the system may
be the reason for low brake fluid in the res-
ervoir.
Have the brake system inspected at an
authorized Mercedes-Benz Light Truck
Center immediately.
All checks and service work on the brake
system should be carried out by an autho-
rized Mercedes-Benz Light Truck Center.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 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.
!Be very careful not to endanger other
road users when you apply the brakes.
Refer to the description of the Brake
Assist System (BAS) (
page 73).

181 Operation
Driving instructions
Install only brake pads and brake fluid rec-
ommended by Mercedes-Benz.
After hard braking, it is advisable to drive
on for some time, rather than immediately
parking, so the air stream will cool down
the brakes faster.
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 starting off on a slippery surface, do
not allow one drive wheel to spin for an ex-
tended 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.
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.
!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.

183 Operation
Driving instructions
The tread wear indicator appears as a solid
band across the tread.
Specified tire pressures must be main-
tained. This applies particularly if the tires
are subjected to high loads (e.g. high
speeds, heavy loads, high ambient temper-
atures).
Hydroplaning
Depending on the depth of the water on
the road, hydroplaning may occur even at
low speeds and with new tires. Reduce ve-
hicle speed, avoid track grooves in the
road and apply brakes cautiously in the
rain.Tire traction
The safe speed on a wet, snow covered or
icy road is always lower than on a dry road.You should pay particular attention to the
condition of the road whenever the outside
temperatures are close to the freezing
point.
Mercedes-Benz recommends M+S rated
radial-ply tires for the winter season for all
four wheels to insure normal balanced
handling characteristics. On packed snow,
they can reduce your stopping distance as
compared with summer tires. Stopping
distance, however, is still considerably
greater than when the road is not covered
with snow or ice. Exercise appropriate cau-
tion.
Warning!
G
Do not allow your tires to wear down too far.
As tread depth approaches
1/16in
(1.5 mm), the adhesion properties on a wet
road are sharply reduced.
Depending upon the weather and/or road
surface (conditions), the tire traction varies
widely.
Warning!
G
Do not drive with a flat tire. A flat tire affects
the ability to steer or brake the vehicle. You
may lose control of the vehicle. Continued
driving with a flat tire or driving at high
speed with a flat tire will cause excessive
heat build-up and possibly a fire.
Warning!
G
If ice has formed on the road, tire traction
will be substantially reduced. Under such
weather conditions, drive, steer and brake
with extreme caution.

186 OperationDriving instructionsOff-road driving
Read this chapter carefully before you be-
gin off-road travel.
Familiarize yourself with the vehicle char-
acteristics and gear changing before you
attempt any difficult terrain off-road driv-
ing. We recommend that you start out with
easy off-road travel.Special driving features for off-road
driving
The following driving features are available
for specific kind of operation:


LOW RANGE mode (
page 118)


LOW RANGE – ABS (
page 72)


LOW RANGE – 4-ETS (
page 74)


LOW RANGE – ESP (
page 76)
Off-road driving rules
Engage the LOW RANGE mode before driv-
ing under off-road conditions
(
page 118).
Fasten items being carried as securely as
possible (
page 139).
Warning!
G
Drive slowly in unknown terrain. This will
make it easier to recognize unexpected ob-
stacles and avoid damage to the vehicle.
To help avoid the vehicle rolling over, never
turn it around on steep inclines. If the vehi-
cle cannot complete the attempted climb,
back it down in reverse gear.
Do not drive along the side of a slope (dan-
ger of vehicle rollover). The vehicle might
otherwise rollover. If in doing so the vehicle
begins to show a tendency to roll, immedi-
ately steer into a line of gravity (straight up
or downhill).
Never let the vehicle roll backwards in idle
or when the clutch is disengaged. You may
lose control of the vehicle if you use only the
service brake.
Warning!
G
Sand, dirt, mud and other material having
friction property can cause exceptional wear
and tear as well as brake failure.
Have the brakes checked for dirt build-up
and cleaned. There is otherwise a risk that
full braking power may not be available in an
emergency.
iWe recommend keeping doors, liftgate,
windows, and sliding/pop-up roof*
closed whenever driving in off-road
mode.

188 OperationDriving instructions

Switch to LOW RANGE mode before
starting to drive up or down steep in-
clines (
page 118).


Driving on embankments, slopes and
other steep inclines should only be
done straight up or downhill, i.e. in the
line of gravity. Maximum vehicle climb-
ing ability is a 60% grade.


Do not drive along the side of a slope
(danger of vehicle rollover). If in doing
so, the vehicle begins to show a ten-
dency to roll, immediately steer into a
line of gravity (straight up or downhill).


To help avoid the vehicle rolling over,
never turn it around on steep inclines.
If the vehicle cannot complete the at-
tempted climb, back it down in reverse
gear.


Utilize the engine’s braking power
when descending a slope, observe the
engine speed (do not overrev the en-
gine). Apply the service brake as need-
ed.


Check the brakes after a lengthy down-
grade drive.
Traction in steep terrain


Be easy on the accelerator and watch
for continuous wheel traction when
driving in steep terrain.
The 4-ETS helps greatly when starting
out on a steep incline when the front
wheels have then the tendency to slip
due to the weight shifting away the
front axle.
The 4-ETS recognizes the situation and
limits the torque for the front wheels by
braking them. Simultaneously the
torque for the rear wheels is increased.Driving across a hilltop


Decelerate just ahead of a hilltop (do
not select gear rangeN), to prevent the
vehicle from speeding up too much af-
ter climbing a hill.
Use the momentum of the vehicle to
drive across the hilltop.
Driving in this manner prevents the ve-
hicle from jumping across the hilltop
and thus loosing its forward momen-
tum.
iAvoid excessive engine speeds – drive
with moderate engine speeds
(max. 3000 RPM).
Select gear range2 or1 on the auto-
matic transmission (
page 114).

189 Operation
Driving instructions
Driving downhill

Select gear range1 on the automatic
transmission (
page 114).


Drive downhill observing the same
rules as driving uphill (
page 187).


The special LOW RANGE – ABS setting
allows for precise and brief (cyclical)
blocking of the front wheels, permitting
them to dig into loose ground.
Remember that the front wheels when
stopped, slide across a surface, thus
loose their ability to steer the vehicle.Driving through water
120 in (50 cm)


Before driving through water, deter-
mine its depth. It should not be deeper
than approximately 20 inches (50 cm).


Switch to LOW RANGE mode before
driving through water (
page 118).


Switch off the exterior lamps as well as
the climate control.


Enter the water only at a shallow spot.
Never take a running start.


Drive slowly, avoiding a bow wave.


Do not stop vehicle immersed in water,
and do not shut off the engine.


To dry the brakes, apply pressure to the
brake pedal several times after leaving
the water.

191 Operation
Driving instructions
Returning from off-road drivingOff-road driving increases strain on the ve-
hicle.
We recommend that you inspect the vehi-
cle for possible damage after each off-road
trip. Recognizing any damage and a subse-
quent timely repair reduces the chance of
a possible breakdown or accident later on.
Proceed as follows:


Switch off the LOW RANGE mode
(page 118).


Remove excessive dirt from tires,
wheels, wheel housings, and under-
body.
For instance, after driving in mud, clean
the radiator, chassis, engine, brakes,
and wheels from extreme dirt using a
strong jet of water.


Inspect frame, oil pan, brake hoses,
etc., as well as vehicle underbody for
possible damage.


Check tires for possible damage, clean
all exterior lamps, and conduct a brake
test.


Check for brush or branches caught in
the undercarriage.
They could increase the possibility of a
fire, as well as cut fuel and/or brake
lines, puncture rubber bellows of the
axles or drive shafts.


After continued operation in mud,
sand, water or other dirty conditions
clean the brake discs, wheels, brake
pads and check and clean axle joints.
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 flash-
ers, carefully slow down, and drive with cau-
tion to an area which is a safe distance from
the roadway.
Inspect the tires and under the vehicle for
possible damage. If the vehicle or tires ap-
pear unsafe, have it towed to the nearest
Mercedes-Benz Light Truck Center or tire
dealer for repairs.