brakes MERCEDES-BENZ M-CLASS 2007 User Guide

254 Controls in detailDriving systemsIf Distronic calculates that there is a dan-
ger of collision:

The distance warning lampl in the
instrument cluster comes on
(page 27).


An intermittent warning sounds.

Immediately apply the brake to avoid a
collision.
Under no circumstances should the
driver await the intermittent warning
sound before braking. See the follow-
ing warning note.
The intermittent warning sound ceases
and the distance warning lampl
goes out when the necessary distance
to the vehicle ahead is again estab-
lished.
Warning!
G
An intermittent warning sounds and the
distance warning lampl in the instru-
ment cluster is illuminated if the Distronic
system calculates that the distance to the
vehicle ahead and your vehicle’s current
speed indicate that Distronic will not be ca-
pable of slowing the vehicle sufficiently to
maintain the preset following distance,
which creates a danger of a collision.
Immediately brake the vehicle to increase
your distance to the preceding vehicle. The
warning sound is intended as a final caution
in which you should intercede with your own
braking inputs to avoid a potentially danger-
ous situation. Do not wait for the operation
of the warning signal to intercede with your
own braking. This will result in potentially
dangerous emergency braking which will
not always result in an impact being avoid-
ed.
Tailgating increases the risk of an accident.
Warning!
G
Distronic brakes your vehicle with a maxi-
mum deceleration of 6.5 ft/s
2 (2 m/s
2). This
corresponds to about 20% of the maximum
deceleration of your vehicle.
Distronic brakes the vehicle in an effort to
restore the preset distance or to maintain
the set speed.
Keep driver’s foot area clear at all times, in-
cluding the area under the brake pedal. Ob-
jects stored in this area may impair pedal
movement which could interfere with the
braking ability of the Distronic system.
Do not place your foot under the brake pedal
– your foot could become caught.
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260 Controls in detailDriving systems
Setting the following distance in
Distronic
You can set the specified following
distance for Distronic by varying the time
setting between 1.0 and 2.0 seconds. Us-
ing this time setting and the current speed
of your vehicle, Distronic calculates and
sets the required following distance to the
preceding vehicle. The set distance will be
shown in the multifunction display
(page 255).
The distance setting switch for the time
setting is located on the cruise control le-
ver on the left-hand side of the steering
column.1Distance setting switch
2To decrease distance
3To increase distance
Increasing distance
Increasing the distance setting tells
Distronic to maintain a greater following
distance to the preceding vehicle.

Turn distance setting switch1 in
direction of arrow3.
Warning!
G
Distronic switches off and releases the
brakes when the vehicle decelerates below
the minimum speed of 20 mph (30 km/h)
by operation of the system. At that time the
driver must apply the brakes in order to
reduce vehicle speed further or bring it to a
stop.!
Setting the automatic transmission toN
while driving cancels the Distronic. 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).
i
Depressing the accelerator pedal does not
deactivate the Distronic. After a brief accelera-
tion (e.g. for passing), the Distronic will resume
the last set speed.
Warning!
G
It is up to the driver to exercise discretion to
select the appropriate setting given road
conditions, traffic, driver’s preferred driving
style and applicable laws and driving recom-
mendations for safe following distance.
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263 Controls in detail
Driving systems
Narrow vehicles
Because of their narrow profile, the vehi-
cles traveling near the outer edges of the
lane have not yet been detected by
Distronic. There will be insufficient
distance to the vehicles ahead.
Distance warning function*
When Distronic* is deactivated, this
function will continue to warn you when
recognizing a stationary obstacle or a
slower vehicle moving in your vehicle’s
path and the danger of a collision exists:

The distance warning lampl in the
instrument cluster comes on.


An intermittent warning will sound if
necessary.
If these warnings are issued, you must
brake manually to maintain a safe distance
and avoid a collision with the preceding
vehicle.
When pressing the brake pedal, the warn-
ing sound ceases. The warning sound will
also cease when the distance to the
preceding vehicle is sufficient again with-
out applying the brakes. In this case, the
distance warning lamp will also go out.

Switch on the distance warning
function in the control system
(page 179).
Warning!
G
If the distance warning lampl in the in-
strument cluster comes on while driving
and/or an intermittent warning sounds,
immediate attention on the part of the driver
is required. As required by the traffic
situation, apply the brakes and navigate
around a possible obstacle. However, do not
drive by relying on the distance warning
function, as this will result in an emergency
braking application. This will not always
enable you to avoid a collision, especially
when traveling on varying road surface
conditions and with varying driver reaction.
Complex driving situations are not always
fully recognized by the distance warning
function. This could result in wrong or miss-
ing distance warnings.
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264 Controls in detailDriving systemsDownhill Speed Regulation (DSR)For more information, see “Off-road driv-
ing” (
page 333).
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 179). 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
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 179), 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.
i
In addition, make use of the engine’s braking
effect by shifting the automatic transmission
into a lower gear.
i
Whenever 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 179). 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 255). 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.
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265 Controls in detail
Driving systems
Switching the Downhill Speed
Regulation on/off
The switch is located in the lower part of
the center console.
1DSR on/off
2Indicator lampSwitching Downhill Speed Regulation on

Press DSR switch1 (
page 265).
The indicator lamp2 comes on.
The message
DSR
and the set speed ap-
pear in the multifunction display.
For information on how to program the set
speed while driving, see “Adjusting Down-
hill Speed Regulation speed with DSR
switched on” (
page 266).
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.
i
The DSR can only be switched on if the vehi-
cle speed is below 18 mph (Canada: 30 km/h).
i
If the DSR is switched on at a speed above
18 mph (Canada: 30 km/h), the message
DSR
Max. speed 18 mph
(Canada:
30 km/h
) ap-
pears in the multifunction display.
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274 Controls in detailDriving systemsWhen the highway level is reached, indica-
tor lamp2 (
page 271) goes out. and
the following message appears in the mul-
tifunction display for 5 seconds:
Parktronic system*
i
The message can be cleared by pressing
theèÿk or buttonj on the
multifunction steering wheel.
i
The vehicle is lowered automatically to the
highway level if:


the vehicle speed is above 55 mph
(88 km/h)


the speed stays between 40 mph (64 km/h)
and 55 mph (88 km/h) for approximately
20 seconds
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 rests 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.
Warning!
G
Make sure no persons or animals are in the
area in which you are maneuvering. You
could otherwise injure them.

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275 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 bumperRange 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 408).
!
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.
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278 Controls in detailDriving systemsSwitching 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.

Switch off the ignition (
page 40).

Clean the Parktronic system sensors
(page 408).

Switch on the ignition (
page 40).
or

Check the Parktronic system operation
at another location to rule out interfer-
ence from outside radio or ultrasonic
signals.
i
The 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.
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326 OperationDriving instructionsPower assistance
Brakes
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 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 dynanometer. 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 brakes 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.
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327 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 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.
Refer to the description of the Brake Assist
System (BAS) (
page 97).Brake pad wear or a leak in the system may
be the reason for low brake fluid 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 449).
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.
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.
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.!
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.
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