2008 MERCEDES-BENZ S550 4MATIC brake

69 Safety and Security
Driving safety systems
BAS Plus*
The Brake Assist System Plus (BAS Plus)
operates in emergency braking situations
and uses radar sensors* to assess the traf-
fic situation. BAS Plus assists you in brak-
ing at speeds above approximately 20 mph
(30 km/h).
When travelling in Canada in a vehicle not
registered in Canada, you must switch off
the radar sensor system* (
page 282).
Canadian law does not permit the use of
the radar sensor system* (
page 282) for
vehicles from outside of Canada. When you
switch off the radar sensor system*, the
following functions are deactivated:

BAS Plus

DISTRONIC Plus* (page 424)

Park Assist* (page 448)

PRE-SAFE® Brake* (page 76)BAS Plus detects obstacles that are in your
driving path for a sufficient period of time
to permit the system to recognize these
obstacles. If you approach the detected
obstacle quickly, BAS Plus calculates the
level of brake power boost appropriate for
the circumstance to supply when the driv-
er applies the brakes.
iUSA only:
This device has been approved by the FCC as a
“Vehicular Radar System”. The radar sensor is
intended for use in an automotive radar system
only. Removal, tampering, or altering of the de-
vice will void any warranties, and is not permitted
by the FCC. Do not tamper with, alter, or use in
any non-approved way.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
iCanada only:
This device complies with RSS-210 of Industry
Canada. Operation is subject to the following
two conditions:
(1) This device may not cause interference, and
(2) this device must accept any interference re-
ceived, including interference that may
cause undesired operation of the device.
Removal, tampering, or altering of the device will
void any warranties, and is not permitted. Do not
tamper with, alter, or use in any non-approved
way.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
Warning!G
BAS Plus is a convenience system designed
to assist the driver during vehicle operation.
The responsibility for the vehicle speed and
the distance to the vehicle ahead, including
most importantly brake operation to assure
safe stopping distance, always remains with
the driver.
Always pay attention to traffic conditions
even while BAS Plus is switched on. Other-
wise, you may not be able to recognize
dangerous situations until it is too late and
could cause an accident resulting in person-
al or fatal injury to you or others.

70 Safety and Security
Driving safety systems
When you step quickly on the brake pedal
in an emergency braking situation,
BAS Plus automatically regulates the
brake power boost to a level that is suit-
able for the traffic situation.
If BAS Plus requires a particularly high
brake power boost, PRE-SAFE
® is activat-
ed at the same time.
Keep constant pressure on the brake
pedal until the emergency braking situ-
ation is over.
During this process, ABS prevents the
wheels from locking up.
The brakes will resume normal operation
after

the brake pedal is released

no obstacles are detected in your path

the system no longer senses a risk of a
collision
BAS Plus is deactivated.BAS Plus can react to stationary obstacles
such as standing or parked vehicles at
road speeds of up to approximately
40 mph (70 km/h).
BAS Plus can only assist you when the
radar sensors are switched on and func-
tional. You can check whether the sensors
are active by switching on DISTRONIC
Plus* (
page 424) or using the “Radar
sensor” menu (
page 282) in the instru-
ment cluster control system.
After a hard collision or damage to the
front of the vehicle from an accident, have
the adjustment and operation of the radar
sensors checked by an authorized
Mercedes-Benz Center.
If BAS Plus is not available due to a radar
sensor malfunction, the braking system
will continue to function normally with full
brake boost and full standard BAS
function.
Warning!G
BAS Plus will only respond with brake assis-
tance if it has clearly detected an object. De-
tection can be impeded by

dirty or covered sensors

snowfall or heavy rain

disturbance from other radar sources

strong radar reflection such as in park-
ing garages
BAS Plus uses radar signals that are not re-
flected well by narrow objects and absorp-
tive materials. For this reason BAS Plus will
not react to

persons and animals

approaching traffic or cross-traffic
BAS Plus may not detect narrow vehicles
driving in front of you, such as motorcycles
and vehicles driving offset from your vehicle
center.

71 Safety and Security
Driving safety systems
EBP
The Electronic Brake Proportioning (EBP)
enhances braking effectiveness by allow-
ing the rear brakes to supply a greater pro-
portion of the braking effort in straight line
braking without a loss of vehicle stability.ESP®
The Electronic Stability Program (ESP®) is
operational as soon as the engine is run-
ning and monitors the vehicle’s traction
(force of adhesive friction between the
tires and the road surface) and handling.
The ESP
® recognizes when a wheel is spin-
ning or if the vehicle starts to skid. By ap-
plying brakes to the appropriate wheel and
by limiting the engine output, the ESP
®
works to stabilize the vehicle. The ESP® is
especially useful while driving off and on
wet or slippery road surfaces. The ESP
®
also stabilizes the vehicle during braking
and steering maneuvers.
The ESP
® warning lamp v in the instru-
ment cluster flashes when the ESP® is en-
gaged.
The ESP
® warning lamp v in the instru-
ment cluster comes on when you switch on
the ignition (
page 344). It goes out when
the engine is running.
Warning!G
When the EBP is malfunctioning, the ABS,
BAS, BAS Plus* and ESP® are also switched
off.
If the EBP is malfunctioning, the brake sys-
tem will still function with full brake boost.
However, the rear wheels could lock up dur-
ing emergency braking situations, for exam-
ple. You could lose control of the vehicle and
cause an accident. Adapt your driving style
to the changed driving characteristics.
Warning!G
Never switch off the ESP® when you see the
ESP® warning lamp v flashing in the in-
strument cluster. In this case proceed as fol-
lows:

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 ESP
® cannot prevent accidents result-
ing from excessive speed.

72 Safety and Security
Driving safety systems
For more information, see “Practical hints”
section (
page 604) and (page 612).Electronic traction system
The electronic traction system is a compo-
nent of ESP
®.
The electronic traction system improves
the vehicle’s ability to utilize available trac-
tion, especially under slippery road condi-
tions by applying the brakes to a spinning
wheel.
When you switch off the ESP
®, the elec-
tronic traction system is still enabled.
Warning!G
The ESP® cannot prevent the natural laws of
physics from acting on the vehicle, nor can
it increase the traction afforded. The ESP
®
cannot prevent accidents, including those
resulting from excessive speed in turns, or
hydroplaning. Only a safe, attentive, and
skillful driver can prevent accidents. The ca-
pabilities of an ESP
® equipped vehicle must
never be exploited in a reckless or danger-
ous manner which could jeopardize the us-
er’s safety or the safety of others.
iDISTRONIC Plus* and cruise control are
switched off when the ESP® engages.
iThe ESP® will only function properly if you
use wheels of the recommended tire size
(
page 718).
!Vehicles without 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 position0 or1) when

the electronic parking brake is being tested
on a brake test dynamometer

the vehicle is being towed with the
front/rear axle raised
Active braking action through the ESP
® may oth-
erwise seriously damage the brake system.
For information on vehicles with 4MATIC, see
“Four wheel electronic traction system (4MATIC)
with the ESP
®” (page 75).
Warning!G
If you are driving too fast, the electronic
traction system cannot reduce the risk of an
accident.
The electronic traction system cannot pre-
vent the natural laws of physics from acting
on the vehicle.

73 Safety and Security
Driving safety systems
Switching off the ESP®
(except S 63 AMG)
To improve the vehicle’s traction, turn off
the ESP
® in driving situations where it
would be advantageous to have the drive
wheels spin and thus cut into surfaces for
better grip such as:

when driving with snow chains

in deep snow

in sand or gravelWhen you switch off the ESP
®

the ESP® does not stabilize the vehicle

the engine output is not limited, which
allows the drive wheels to spin and
thus cut into surfaces for better grip

the electronic traction system will still
apply the brakes to a spinning wheel

the ESP® continues to operate when
you are braking

you cannot activate the cruise control
or the DISTRONIC Plus* 1ESP
® off/on
Press ESP® switch1 until the ESP®
warning lampv in the instrument
cluster comes on.
The ESP
® is switched off.
Warning!G
The ESP® should not be switched off during
normal driving other than in the circum-
stances described below. Disabling of the
system will reduce vehicle stability in stan-
dard driving maneuvers.
Warning!G
Switch on the ESP® immediately if the afore-
mentioned circumstances do not apply any-
more. Otherwise the ESP
® will not stabilize
the vehicle when it is starting to skid or a
wheel is spinning.
iWhen the ESP® is switched off and one or
more drive wheels are spinning, the ESP® warn-
ing lampv in the instrument cluster flashes.
However, the ESP
® will then not stabilize the
vehicle.

74 Safety and Security
Driving safety systems
Switching off the ESP® (S 63 AMG only)When you switch off the ESP®

the ESP® does not stabilize the vehicle

the engine output is not limited, which
allows the drive wheels to spin and
thus cut into surfaces for better grip

the traction control will still apply the
brakes to a spinning wheel

the ESP® operates while you are
braking

you cannot activate the cruise control
or the Distronic*

the cruise control or Distronic* switch
off if currently activated
Warning!G
When the ESP® warning lampv is illumi-
nated continuously, the ESP® is switched
off.
Adapt your speed and driving to the prevail-
ing road conditions and to the non-operating
status of the ESP
®.
!Avoid spinning of a drive wheel for an ex-
tended period with the ESP® switched off. This
may cause serious damage to the drivetrain
which is not covered by the Mercedes-Benz Lim-
ited Warranty.
Warning!G
The ESP® should not be switched off during
normal driving. Disabling of the system will
result in the following:

no restriction to engine torque

loss of system supported traction
control
“ESP
® OFF” is designed for driving on closed
tracks when the natural oversteer and un-
dersteer characteristics are desired and re-
quires a highly skilled and experienced
driver able to handle these critical driving
situations.
You could lose control of your vehicle and
cause an accident.
Please be aware of these limits when you
switch off the ESP
®.
Do not switch off the ESP
® when a spare
wheel is mounted.

76 Safety and Security
Driving safety systems
PRE-SAFE® Brake* (vehicles with
DISTRONIC Plus* only)
PRE-SAFE
® Brake* can assist you in mini-
mizing the risk of a rear-end collision with
a vehicle in front of you and in reducing the
severity of an accident. At speeds over ap-
prox 20 mph (30 km/h), it will

warn you of a possible collision

automatically begin to brake the vehi-
cle lightly in a speed range of up to
112 mph (180 km/h)

activate preventative occupant safety
measures (PRE-SAFE®) (page 56)
Warning!G
If you see the ESP® warning lampv
flashing in the speedometer, proceed as fol-
lows:

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 ESP
® cannot prevent accidents result-
ing from excessive speed.
!Do not tow with one axle raised.
Otherwise the transfer case can be damaged,
which is not covered by the Mercedes-Benz Lim-
ited Warranty.
!Performance testing must only be conduct-
ed on a two-axle dynamometer.
Otherwise the transfer case can be damaged,
which is not covered by the Mercedes-Benz Lim-
ited Warranty.
!Because the ESP® operates automatically,
the engine and the ignition must be shut off
(SmartKey in starter switch position0 or1 or
KEYLESS-GO start/stop button* in position0
or1) when the parking brake is being tested on a
brake test dynamometer.
Active braking action through ESP
® may other-
wise seriously damage the front or rear axle
brake system.
Operational tests with the engine running can
only be conducted on a two-axle dynamometer.
Warning!G
PRE-SAFE® Brake is a convenience system
designed to assist the driver during vehicle
operation. The responsibility for the vehicle
speed and the distance to the vehicle ahead,
including most importantly brake operation
to assure safe stopping distance, always re-
mains with the driver.

77 Safety and Security
Driving safety systems
PRE-SAFE® Brake will only assist you by
automatically initiating braking if the driver
and front passenger have their seat belts
fastened.
Using the radar sensors, PRE-SAFE
® Brake
detects obstacles that are in your driving
path for a sufficient period of time for the
system to recognize it. If you approach a
vehicle and PRE-SAFE
® Brake has estab-
lished that the distance to the vehicle
ahead at your current speed is so close
that PRE-SAFE
® Brake will not be capable
of slowing the vehicle sufficiently, the sys-
tem will initially warn you visually and
acoustically.When travelling in Canada in a vehicle not
registered in Canada, you must switch off
the radar sensor system* (
page 282).
Canadian law does not permit the use of
the radar sensor system* (
page 282) for
vehicles from outside of Canada. When you
switch off the radar sensor system*, the
following functions are deactivated:

BAS Plus* (page 69)

DISTRONIC Plus* (page 424)

Park Assist* (page 448)

PRE-SAFE® Brake
Always pay attention to traffic conditions
even while PRE-SAFE® Brake is switched on.
Otherwise, you may not be able to recognize
dangerous situations until it is too late and
could cause an accident resulting in person-
al or fatal injury to you or others.
iUSA only:
This device has been approved by the FCC as a
“Vehicular Radar System”. The radar sensor is
intended for use in an automotive radar system
only. Removal, tampering, or altering of the de-
vice will void any warranties, and is not permitted
by the FCC. Do not tamper with, alter, or use in
any non-approved way.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.
iCanada only:
This device complies with RSS-210 of Industry
Canada. Operation is subject to the following
two conditions:
(1) This device may not cause interference, and
(2) this device must accept any interference re-
ceived, including interference that may
cause undesired operation of the device.
Removal, tampering, or altering of the device will
void any warranties, and is not permitted. Do not
tamper with, alter, or use in any non-approved
way.
Any unauthorized modification to this device
could void the user’s authority to operate the
equipment.