2008 MERCEDES-BENZ ML550 brake

191 Controls in detail
Automatic transmission
Rocking the vehicle
Rocking the vehicle by shifting between
drive positionD and reverse gearR can
help free a vehicle stuck in mud or snow.
The engine control system of this vehicle
electronically limits shifting between
drive positionD and reverse gearR to
very low speeds, i.e. approximately
5 mph (9 km/h). To shift between drive
positionD and reverse gearR, move the
gear selector lever past the resistance
point up or down.
Working on the vehicleHill start assist system
On uphill grades with a gradient angle of
more than 5°, the hill start assist system
maintains the pressure in the brake sys-
tem for approximately 1 second after you
have released the brake pedal. Therefore,
you can start off smoothly without the
vehicle moving immediately after releasing
the brake pedal.The hill start assist system is inactive

when starting off on a level road or
downhill grades

with the transmission in neutral
positionN

with the parking brake set

if the ESP® has switched off due to a
malfunction
Towing a trailer
If you tow a trailer, note the following
points:

Manually shift to a lower gear range
(
page 192) if the transmission hunts
between gears on inclines.
A lower gear range and reduction of
speed reduces the chance to overload
or overheat the engine.
For more information on trailer towing, see
the “Operation” section (
page 328).
Warning!G
When working on the vehicle, set the
parking brake and shift to park positionP.
Otherwise the vehicle could roll away.
Warning!G
The hill start assist system is not designed
to function as a parking brake and does not
prevent the vehicle from moving when
parked on an incline.
Always set the parking brake in addition to
shifting to park positionP.

196 Controls in detail
Automatic transmission
Upshifting
Briefly press right shift button2
(
page 193).
The transmission shifts to the next
higher gear.
If you have selected the AMG menu in the
control system and you are driving in the
manual program modeM, upshift
indicator2 in the multifunction display
advises you to upshift before the engine
reaches the overspeed range. Thus you
can drive at the maximum engine speed for
each gear without overrevving the engine.1Gear indicator
2Upshift indicator
Shift to the next higher gear.
The fuel supply will otherwise be inter-
rupted to prevent the engine from over-
revving.
Downshifting
Briefly press left shift button1
(
page 193).
The transmission shifts to the next
lower gear.
Kickdown
Using the kickdown when driving in the
manual program modeM is not possible.
Deactivating manual shift program
Press the program mode selector
switch (
page 194) repeatedly until
CorS appears in the multifunction
display.
or
Restart the engine.
The transmission will go to the
automatic program mode (C orS).
The manual program modeM is not
stored.
!In the manual program modeM, the trans-
mission will not upshift, even if the engine has
reached its overrewing range. Shift up to the
next gear before the engine has reached its over-
rewing range. Make absolutely certain that the
engine speed does not reach the red marking on
the tachometer (
page 28). Otherwise the en-
gine could be damaged which is not covered by
the Mercedes-Benz Limited Warranty.
Warning!G
On slippery road surfaces, never downshift
in order to obtain braking action. This could
result in drive wheel slip and reduced
vehicle control. Your vehicle’s ABS will not
prevent this type of loss of control.
iWhen you brake or stop, the transmission
shifts down to a gear from which you can easily
accelerate or drive off.

198 Controls in detail
Transfer case
!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.
iThe vehicle is equipped with permanent
four-wheel drive. Both the front and rear axles
are powered at all times when the vehicle is
being operated.

245 Controls in detail
Driving systems
1Setting current or higher speed
Adjustment in 1 mph increments (to
the resistance point) or 5 mph
increments (past the resistance point)
(Canada: 1 km/h or 10 km/h)
2Setting current or lower speed
Adjustment in 1 mph increments (to
the resistance point) or 5 mph
increments (past the resistance point)
(Canada: 1 km/h or 10 km/h)
3Canceling cruise control
4Resume to last set speed
Warning!G
The cruise control is a convenience system
designed to assist the driver during vehicle
operation. The driver is and must always
remain responsible for the vehicle’s speed
and for safe brake operation.
Only use the cruise control if the road, traffic
and weather conditions make it advisable to
travel at a constant speed.

The use of the cruise control can be
dangerous on winding roads or in heavy
traffic because conditions do not allow
safe driving at a constant speed.

The use of the cruise control can be
dangerous on slippery roads. Rapid
changes in tire traction can result in
wheel spin and loss of control.

Deactivate the cruise control when
driving in fog.
The “Resume” function should only be
operated if the driver is fully aware of the
previously set speed and wishes to resume
this particular preset speed.
Warning!G
The cruise control brakes automatically so
that the set speed is not exceeded. The
brake pedal depresses when the cruise con-
trol engages the brakes.
Keep driver’s foot area clear at all times,
including the area under the brake pedal.
Objects stored in this area may impair pedal
movement which could interfere with the
braking ability of the cruise control system.
Do not place your foot under the brake pedal
– your foot could become caught.
Keep in mind that the cruise control is a
convenience system designed to assist the
driver during vehicle operation. The driver is
and must always remain responsible for the
vehicle’s speed and for safe brake
operation.

246 Controls in detail
Driving systems
Activating cruise control
You can activate the cruise control when
the vehicle speed is above
20 mph (30 km/h).
In the following cases you cannot activate
the cruise control:

when you brake

when you have set the parking brake

when the automatic transmission is set
to positionP, R, or N

if the ESP® is switched off

if the ESP® has switched off due to a
malfunctionSetting current speed
Accelerate or decelerate to the desired
speed.
Briefly lift the cruise control lever in
direction of arrow1 or depress in
direction of arrow2.
The current speed is set.
Remove your foot from the accelerator
pedal.
The cruise control is activated.
The currently set speed appears in the
status indicator of the multifunction
display:

USA only:
Cruise XXX Miles

Canada only:
Ñ
XXX km/h
Canceling cruise control
There are several ways to cancel the cruise
control:
Step on the brake pedal.
The cruise control is canceled. The last
speed set is stored for later use.
or
Briefly push the cruise control lever in
direction of arrow3 (
page 245).
The cruise control is canceled. The last
speed set is stored for later use.
iThe vehicle speed displayed in the speedom-
eter can briefly vary from the speed setting for
the cruise control system.
iOn uphill grades, the cruise control may not
be able to maintain the set speed. Once the
grade eases, the set speed will be resumed.
On downhill grades, the cruise control maintains
the set speed by braking with the vehicle’s
braking system. In addition, on longer downhill
grades the automatic transmission will down-
shift automatically.
iThe last stored set speed is canceled when
the engine is turned off.

247 Controls in detail
Driving systems
Setting a higher speed
You can increase the speed in two ways.Adjustment in 1 mph (Canada: 1 km/h)
increments
Briefly lift the cruise control lever up to
the resistance point in direction of
arrow1 (
page 245).
Release the cruise control lever.
The vehicle speed increases in incre-
ments of 1 mph (Canada: 1km/h).
Adjustment in 5 mph
(Canada: 10 km/h) increments
iThe cruise control switches off
automatically when

you step on the brake pedal

you depress the parking brake pedal
The cruise control switches off automatically and
an acoustic warning will sound when

the vehicle speed is below 20 mph
(30 km/h)

the ESP® is in operation

the ESP® is switched off with the ESP®
switch (
page 102)

the ESP® has switched off due to a
malfunction (
page 405)

you set the automatic transmission toN
while driving
Observe additional messages in the
multifunction display that may appear.
!Setting the automatic transmission toN
while driving cancels the cruise control.
However, the automatic transmission should not
be set toN while driving except to coast when
the vehicle is in danger of skidding (e.g. on icy
roads).
iDepressing the accelerator pedal does not
deactivate the cruise control. After a brief accel-
eration (e.g. for passing), the cruise control will
resume the last set speed.
Warning!G
If you increase the set vehicle speed, keep in
mind that it may take a brief moment until
the vehicle has reached the set speed.
Increase the set vehicle speed to a value
that the prevailing road conditions and legal
speed limits permit. Otherwise, sudden and
unexpected acceleration of the vehicle
could cause an accident and/or serious in-
jury to you and others.
iThe set value is increased in 1 mph
(Canada: 1 km/h) increments each time you lift
the cruise control lever up to the resistance
point.
iThe set value is increased in
5 mph (Canada: 10 km/h) increments each time
you lift the cruise control lever past the
resistance point.

248 Controls in detail
Driving systems
Briefly lift the cruise control lever up
past the resistance point in direction of
arrow1 (
page 245).
Release the cruise control lever.
The vehicle speed increases in incre-
ments of 5 mph (Canada: 10 km/h).
Setting a lower speedYou can reduce the speed in two ways.
Adjustment in 1 mph (Canada: 1 km/h)
increments
Briefly press the cruise control lever
down to the resistance point in direc-
tion of arrow2 (
page 245).
Release the cruise control lever.
The vehicle speed decreases in incre-
ments of 1 mph (Canada: 1 km/h).Adjustment in 5 mph
(Canada: 10 km/h) increments
Briefly press the cruise control lever
down past the resistance point in direc-
tion of arrow2 (
page 245).
Release the cruise control lever.
The vehicle speed decreases in incre-
ments of 5 mph (Canada: 10 km/h).
iThe new speed is set and the vehicle will
accelerate. Keep in mind that it may take a brief
moment until the vehicle has reached the set
speed.
Warning!G
If you decrease the set vehicle speed, keep
in mind that it may take a brief moment until
the vehicle has reached the set speed.
Decelerate the set vehicle speed to a value
that the prevailing road conditions and legal
speed limits permit. Otherwise, sudden and
unexpected deceleration of the vehicle
could cause an accident and/or serious in-
jury to you and others.
iWhen you use the cruise control lever to
decelerate, the brake system will automatically
brake the vehicle if the engine’s braking power
does not brake the vehicle sufficiently.
iThe set value is decreased in 1 mph
(Canada: 1 km/h) increments each time you
press the cruise control lever down to the resis-
tance point.
iThe set value is decreased in 5 mph
(Canada: 10 km/h) increments each time you
press the cruise control lever down past the
resistance point.
iThe new speed is set and the vehicle will
decelerate. Keep in mind that it may take a brief
moment until the vehicle has reached the set
speed.

249 Controls in detail
Driving systems
Setting to last stored speed
(“Resume” function)
Briefly pull the cruise control lever in di-
rection of arrow4 (
page 245).
The cruise control resumes to the last
set speed, or if no speed is stored, it
will set and store the current speed.
Remove your foot from the accelerator
pedal.
The last set speed appears in the multi-
function display for approximately
5seconds.
Downhill Speed Regulation (DSR)For more information, see “Off-road driv-
ing” (
page 319).
The DSR is an aid for driving downhill. DSR
regulates your vehicle’s speed when driv-
ing downhill to the value set in the control
system (
page 178). The steeper the
downhill gradient is, the greater the brake
application. On flat road surfaces, DSR
brakes only slightly or not at all.
DSR regulates the vehicle’s speed in auto-
matic transmission positionsD, orR.
You can drive slower or faster than the set
speed at any time by braking the vehicle or
depressing the accelerator pedal.
Warning!G
The set speed stored in memory should only
be set again if prevailing road conditions
permit. Possible acceleration or decelera-
tion differences arising from returning to the
preset speed could cause an accident
and/or serious injury to you and others.
Warning!G
Downhill Speed Regulation is a convenience
system designed to assist the driver during
vehicle operation. The system must be set
to be appropriate for the topographical and
weather conditions encountered which can
change quickly. The driver is and must
remain at all times responsible for the vehi-
cle speed and for safe brake operation.
Depending on the programmed speed
(
page 178), actual vehicle speed and gra-
dient, switching on the DSR while driving
can cause the vehicle to slow down rapidly
and you may hear a sound which is caused
by the activation of the vehicle’s brake sys-
tem through the DSR. Sudden and unex-
pected deceleration can result in loss of
vehicle control, causing an accident and/or
serious personal injury to you and others.
Do not switch on the DSR in a circumstance
where rapid deceleration could result in a
loss of vehicle control.
iIn addition, make use of the engine’s braking
effect by shifting the automatic transmission
into a lower gear.