Mercedes-Benz CLA Operator's Manual page 43

Emergency Tensioning Devices for the
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front seat belts and the outer seat belts in
the rear
Seat belt force limiter for the front seat
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belts and the outer seat belts in the rear
SRS reduces the risk of vehicle occupants
coming into contact with parts of the vehi-
cle's interior in the event of an accident. It can
also reduce the forces to which vehicle occu-
pants are subjected during an accident.
SRS warning lamp
G WARNING
If SRS is malfunctioning, restraint system
components may be triggered unintentionally
or might not be triggered at all in the event of
an accident with a high rate of vehicle decel-
eration. There is an increased risk of injury,
possibly even fatal.
Have SRS checked and repaired immediately
at a qualified specialist workshop.
SRS functions are checked regularly when
you switch on the ignition and when the
engine is running. Therefore, malfunctions
can be detected in good time.
The 6 SRS warning lamp in the instrument
cluster lights up when the ignition is switched
on. It goes out no later than a few seconds
after the engine is started.
The SRS components are in operational read-
iness when the 6 SRS indicator lamp goes
out while the engine is running.
There is a malfunction if:
the 6 SRS warning lamp does not light
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up when the ignition is switched on
the engine is running and the 6 SRS
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warning lamp does not go out after a few
seconds
the engine is running and the 6 SRS
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warning lamp lights up again
Occupant safety
Triggering of Emergency Tensioning
Devices and air bags
During the first stage of a collision, the air bag
control unit evaluates important physical
data relating to vehicle deceleration or accel-
eration, such as:
duration
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direction
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magnitude
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Based on the evaluation of this data, the air
bag control unit pre-emptively triggers the
Emergency Tensioning Device in the first
stage.
If there is an even higher rate of vehicle decel-
eration or acceleration in a longitudinal direc-
tion, the front air bags are also deployed.
Your vehicle has adaptive, two-stage front air
bags. The air bag control unit evaluates vehi-
cle deceleration or acceleration in the event
of a collision. In the first deployment stage,
the front air bag is filled with enough propel-
lant gas to reduce the risk of injuries. The
front air bag is fully deployed if a second
deployment threshold is reached within a few
milliseconds.
The Emergency Tensioning Device and air bag
triggering thresholds are variable and are
adapted to the detected rate of deceleration
or acceleration of the vehicle. This process is
pre-emptive in nature. The triggering process
must take place in good time at the start of
the collision.
The rate of vehicle deceleration or accelera-
tion and the direction of the force are essen-
tially determined by:
the distribution of forces during the colli-
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sion
the collision angle
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the deformation characteristics of the vehi-
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cle
the characteristics of the object with which
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the vehicle has collided
Factors that can only be seen and measured
after a collision has occurred do not play a
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