Driving safety systems
Overview of driving safety systems
In this section, you will find information about the following driving safety systems:
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ABS (Anti-lock Braking System)
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BAS (Brake Assist System)
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BAS PLUS* (Brake Assist System Plus*)
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Adaptive brake lamps
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ESP® (Electronic Stability Program)
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EBV (electronic brake-power distribution)
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ADAPTIVE BRAKE
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Distance warning function* (vehicles with Distronic*)
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PRE-SAFE Brake* (vehicles with Distronic Plus*)
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In wintry road conditions, always use winter tyres (M+S tyres) and, where necessary, snow chains. Only in this way will the driving safety systems described in this section work as effectively as possible.
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The risk of an accident is significantly increased by driving too fast. This is particularly the case when cornering on wet and slippery roads and when driving too close to the vehicle in front.
The driving safety systems described in this section cannot reduce this risk nor override the laws of physics.
For this reason, always adapt your driving style to suit prevailing road and weather conditions. Maintain sufficient distance from other road users and objects on the road.
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ABS (Anti-lock Braking System)
ABS regulates brake pressure in such a way that the wheels do not lock when you brake. This allows you to continue steering the vehicle when braking.
ABS works from a speed of about 8 km/h upwards, regardless of road surface conditions. ABS works on slippery surfaces, even when you only brake gently.
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Do not depress the brake pedal several times in quick succession (pumping). Depress the brake firmly and evenly. Pumping the brake pedal reduces the braking effect.
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Braking
If ABS intervenes when braking, you will feel a pulsing in the brake pedal.
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If ABS intervenes: continue to depress the brake pedal with force until the braking situation is over.
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To make a full brake application: depress the brake pedal with full force.
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If ABS is faulty, the wheels could lock when braking. This limits the steerability of the vehicle when braking and the braking distance may increase.
If ABS is deactivated due to a malfunction, then BAS, BAS PLUS* and ESP® are also deactivated. There is an increased risk of your vehicle skidding in certain situations.
You should always adapt your driving style to suit the prevailing road and weather conditions.
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BAS (Brake Assist)
BAS operates in emergency braking situations. If you depress the brake pedal quickly, BAS automatically boosts the braking force, thus shortening the stopping distance.
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Keep the brake pedal firmly depressed until the emergency braking situation is over.
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ABS prevents the wheels from locking.
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The brakes will function as usual once you release the brake pedal. BAS is deactivated.
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If BAS has malfunctioned, the braking system remains available with full brake boosting effect. However, braking force is not automatically increased in emergency braking situations and the stopping distance may increase.
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BAS PLUS* (Brake Assist Plus)
BAS PLUS provides braking assistance in hazardous situations and uses radar sensor technology to assess the traffic situation.
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BAS PLUS is only an aid to assist you when driving. You are responsible for maintaining a safe distance from other vehicles, for the vehicle's speed and for braking in good time. Always pay attention to the traffic conditions. You may otherwise recognise dangers too late, cause an accident and injure yourself and others.
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BAS PLUS detects obstacles that are in the path of your vehicle for an extended period of time. Should you approach a detected obstacle quickly, BAS PLUS calculates the braking pressure necessary to avoid a rear-end collision. Should you additionally apply the brakes, BAS PLUS will automatically increase the braking pressure to a level suitable for the traffic conditions.
If BAS PLUS demands particularly high braking pressure, PRE-SAFE® is activated simultaneously.
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Keep the brake pedal depressed until the emergency braking situation is over.
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ABS prevents the wheels from locking.
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The brakes will work normally again when:
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you release the brake pedal
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no obstacle is detected in front of your vehicle
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there is no longer any danger of a rear-end collision
BAS PLUS is then deactivated.
At speeds up to approximately 70 km/h, BAS PLUS can also detect stationary obstacles, for example, stopped or parked vehicles.
Vehicles with COMAND and navigation system*: the radar sensor system is switched off automatically in the vicinity of radio telescope facilities more.
For BAS PLUS to assist you when driving, the radar sensor system must be switched on and operational. You can check this by activating Distronic Plus* more or via the "Radar sensor" menu in the on-board computer more.
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Only clearly identified obstacles will initiate braking assistance by BAS PLUS. In particular, the detection of obstacles can be restricted if there is:
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dirt on the sensors or the sensors are covered
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snow or heavy rain
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interference by other radar sources
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strong radar reflections, for example in multi-storey garages
BAS PLUS does not react to people or animals, oncoming vehicles and crossing traffic.
BAS PLUS may not detect narrow vehicles such as motorcycles and vehicles driving on a different line.
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Following a collision or crash-related damage to the front end of the vehicle, have the configuration and operation of the radar sensors checked at a Mercedes-Benz Service Centre.
If BAS PLUS is not available due to a malfunction in the radar sensor system, the braking system remains available with full brake boosting effect and BAS.
Adaptive brake lamps
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Adaptive brake lamps are only available in certain countries.
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If you brake sharply from a speed of more than 50 km/h or if braking is assisted by BAS or BAS PLUS*, the brake lamps flash rapidly. In this way, traffic travelling behind you is warned in an even more noticeable manner.
If you brake sharply from a speed of more than 70 km/h to a standstill, the hazard warning lamps are activated automatically. If the brakes are applied again, the brake lamps light up continuously. The hazard warning lamps switch off automatically if you drive faster than 10 km/h again. You can also switch off the hazard warning lamps using the hazard warning switch button more.
ESP® (Electronic Stability Program)
ESP® monitors driving stability and traction, i.e. power transmission between the tyres and the road surface.
If ESP® detects that the vehicle is deviating from the direction desired by the driver, one or more wheels are braked to stabilise the vehicle. The engine output is also modified, if necessary, to keep the vehicle on the desired course within physical limits. ESP® assists the driver when pulling away on wet or slippery roads. ESP® can also stabilise the vehicle during braking.
When ESP® intervenes, the 
warning lamp flashes in the instrument cluster.
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If the
warning lamp in the instrument cluster flashes, proceed as follows:
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Do not deactivate ESP® under any circumstances.
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Only depress the accelerator pedal as far as necessary when pulling away.
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Adapt your driving style to suit the prevailing road and weather conditions.
The vehicle could otherwise go into a skid.
ESP® cannot reduce the risk of an accident if you drive too fast. ESP® cannot override the laws of physics.
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If the vehicle is to be towed with the front or rear axle raised, the ignition must be switched off (key in position
0 or
1 in the ignition lock). Application of the brakes by ESP® could otherwise destroy the brake system on the front or rear axle.
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Vehicles with 4MATIC* may not be towed with the front or rear axle raised.
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Only use wheels with the recommended tyre sizes. Only then will ESP® function properly.
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ESP® trailer stabilisation
If your trailer begins to lurch, you can only stabilise the vehicle/trailer combination by depressing the brake firmly.
In this situation, ESP® assists you and detects if the trailer begins to lurch. ESP® slows the vehicle down by braking and limiting the engine output until the vehicle/trailer combination has stabilised.
Trailer stabilising is active from about 65 km/h.
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If the road and weather conditions are bad, trailer stabilising will not be able to prevent the trailer from lurching and thereby reduce the risk of accident. Trailers with a high centre of gravity can tip over before ESP® can detect this.
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Trailer stabilising does not work if ESP® is deactivated or disabled because of a malfunction.
ETS (Electronic Traction Support)
Traction control is part of ESP®.
Traction control brakes the drive wheels individually if they spin. This enables you to pull away and accelerate on slippery surfaces, for example if the road surface is slippery on one side.
Traction control remains active when you deactivate ESP®.
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Traction control cannot reduce the risk of an accident if you drive too fast. Traction control cannot override the laws of physics.
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Deactivating/activating ESP®
ESP® is activated automatically when the engine is running.
It may be best to deactivate ESP® in the following situations:
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when using snow chains
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in deep snow
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on sand or gravel
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Activate ESP® as soon as the situations described above no longer apply. ESP® will otherwise not be able to stabilise the vehicle if the vehicle starts to skid or a wheel starts to spin.
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If you deactivate ESP®:
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ESP® no longer improves driving stability.
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engine torque is not limited and the drive wheels are able to spin. The spinning wheels produce a cutting effect for better traction.
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traction control is still activated.
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ESP® still provides support when you brake.
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If ESP® is deactivated and one or more wheels start to spin, the warning lamp in the instrument cluster flashes. In such situations ESP® will not stabilise the vehicle.
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 | Deactivating/activating ESP® |
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To deactivate: press button .
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The warning lamp in the instrument cluster lights up.
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If the warning lamp in the instrument cluster is continuously lit when the engine is running, ESP® is deactivated or not available due to a malfunction. There is an increased risk of your vehicle skidding in certain situations.
You should always adapt your driving style to suit the prevailing road and weather conditions.
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To activate: press button .
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The warning lamp in the instrument cluster goes out.
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EBV (electronic brake-power distribution)
EBV monitors and controls the brake pressure on the rear wheels to improve driving stability under braking.
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If EBV is malfunctioning, the brake system is still available with full brake boosting effect. However, the rear wheels can still lock, e.g. under full braking. This could cause you to lose control of your vehicle and cause an accident. You should therefore adapt your driving style to the different handling characteristics.
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ADAPTIVE BRAKE
Due to its higher level of braking safety, ADAPTIVE BRAKE offers exceptional braking comfort. In addition to the braking function, ADAPTIVE BRAKE also features the convenience function HOLD more. For further information, see Driving tips more.
Distance warning function (vehicles with Distronic*)
This function will issue a warning at speeds of around 30 km/h or more if:
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for a period of several seconds, the distance to the vehicle in front is too short for the speed at which you are travelling. The distance warning lamp 
in the instrument cluster will then light up.
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you are approaching the vehicle in front too rapidly. An intermittent warning tone will then sound and the distance warning lamp will light up in the instrument cluster.
In order to maintain the appropriate distance to the vehicle in front and thus prevent a crash, you must apply the brakes yourself.
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Pay particular attention to the traffic conditions if the distance warning lamp in the instrument cluster lights up or an intermittent warning tone sounds.
If necessary, brake or swerve to avoid an obstacle.
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To activate/deactivate: activate or deactivate the distance warning system in the on-board computer more.
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After activation, the  symbol is displayed in the left-hand section of the multi-function display.
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For more information on the distance warning system, see the Distronic* section more.
PRE-SAFE® Brake (vehicles with Distronic Plus*)
PRE-SAFE® brake can help you to minimise the risk of a
frontal collision with a vehicle ahead or reduce the results of an
accident.
This function will issue a
warning at speeds of around 30 km/h or more if:
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for a period of
several seconds, the distance to the vehicle in front is too short for the
speed at which you are travelling. The distance warning lamp
in the
instrument cluster will then light up.
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you are approaching
the vehicle in front too rapidly. An intermittent warning tone will then sound
and the distance warning lamp
will light up
in the instrument cluster.
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Pay particular attention to the traffic conditions if the distance warning lamp in the instrument cluster lights up or an intermittent warning tone sounds. If necessary, brake or swerve to avoid an obstacle.
In addition, at speeds of around 30 km/h or more, PRE-SAFE® brake can:
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PRE-SAFE® Brake is only an aid to assist you when driving. You are responsible for maintaining a safe distance from other vehicles, the vehicle's speed and for braking in good time. Always pay attention to the traffic conditions. You may otherwise recognise dangers too late, cause an accident and injure yourself and others.
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With the help of
the radar sensor system, PRE-SAFE® Brake detects obstacles that are in
front of your vehicle for an extended period of time. If you approach an
obstacle and PRE-SAFE® Brake detects a risk of a collision, the system will
initially alert you both visually and acoustically. If you yourself do not
brake or steer, the vehicle will automatically brake slightly. In cases of
increased risk of a collision, PRE-SAFE® is activated
more.
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Only clearly identified obstacles will trigger a warning and initiate braking assistance by PRE-SAFE® Brake.
In particular, the detection of obstacles can be restricted if there is:
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dirt on the sensors or the sensors are covered
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snow or heavy rain
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interference by other radar sources
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strong radar reflections, for example in multi-storey garages
PRE-SAFE® Brake does not react to persons, animals, oncoming vehicles and crossing traffic.
PRE-SAFE® Brake may not detect narrow vehicles such as motorcycles and vehicles driving on a different line.
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| Risk of accident |
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Depending on the
vehicle's speed, PRE-SAFE® Brake will brake your vehicle up to maximum of
4 m/s2. This is equivalent to approximately 40% of
the maximum braking power of the vehicle. You must also apply the brakes
yourself to avoid a collision.
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In order to
maintain the appropriate distance to the vehicle in front and thus prevent a
crash, you must apply the brakes yourself.
At speeds up to
approximately 70 km/h, the PRE-SAFE® Brake can also detect
stationary obstacles, for example stopped or parked vehicles.
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If, in a critical driving situation, you do not receive a visual and acoustic warning:
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PRE-SAFE® Brake did not detect the risk of a collision
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PRE-SAFE® Brake is switched off
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PRE-SAFE® Brake has failed
You must then brake to avoid a collision.
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To
activate/deactivate: activate or deactivate PRE-SAFE® Brake in the
on-board computer
more.
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After activation,
the symbol is
displayed on the left in the driver display.
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Vehicles with
COMAND and navigation system*: the radar sensor system is
switched off automatically in the vicinity of radio telescope facilities
more.
For PRE-SAFE®
Brake to assist you when driving, the radar sensor system must be switched on
and operational.
PRE-SAFE® Brake does not
always detect complex traffic situations properly. You can terminate the
braking action of PRE-SAFE® Brake in a non-critical driving situation at
any time if:
To do this you can either depress the accelerator pedal further,
activate kickdown or release the brake pedal.
The braking action of
PRE-SAFE® Brake is ended automatically if:
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you swerve to avoid
the obstacle
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you drive slower
than 15 km/h
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there is no longer
an obstacle detected in front of your vehicle
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there is no longer
any danger of a collision
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While Distronic
Plus is activated, PRE-SAFE® Brake remains passive.
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Following a
collision or crash-related damage to the front end of the vehicle, have the
configuration and operation of the radar sensors checked. Choose a qualified
specialist workshop for this which has the necessary specialist knowledge and
tools for the work required. Mercedes-Benz recommends that you use a
Mercedes-Benz Service Centre for this purpose.
