Operation
During the first stage of a collision, the restraint
system control unit evaluates important physi-
cal data relating to vehicle deceleration or accel-
eration, such as:
R
duration
R
direction
R
intensity
Based on the evaluation of this data, the
restraint system control unit triggers the seat
belt tensioners in the event of a head-on or rear
collision.
A seat belt tensioner can only be triggered if:
R
the ignition is switched on
R
the components of the restraint system are
operational. You can find further information
under: "Restraint system warning lamp"
(
Y
page 38)
R
the belt tongue has engaged in the belt buckle
of the respective front seat
The seat belt tensioners in the rear compart-
ment are triggered independently of the lock
status of the seat belts.
If the restraint system control unit detects a high
severity accident, in certain head-on collisions,
additional components of the restraint system
are deployed independently of each other:
R
front airbags and driver's kneebag
R
headbag, if the system determines that
deployment can offer additional protection to
that provided by the seat belt
Depending on the person in the front-passenger
seat, the front-passenger front airbag is either
disabled or enabled. The front-passenger front
airbag can only be deployed in an accident if the
PASSENGER AIR BAG OFF indicator lamp is off.
Observe the information on the PASSENGER AIR
BAG OFF indicator lamp (
Y
page 38).
Your vehicle has two-stage front airbags. In the
first deployment stage, the front airbag is filled
with propellant gas to reduce the risk of injuries.
The front airbag is fully deployed if the second
deployment stage is activated within a few mil-
liseconds.
The activation threshold for the seat belt ten-
sioners and airbags is determined based on the
evaluation of the vehicle's rate of deceleration
or acceleration at various points in the vehicle.
This process is pre-emptive in nature. The trig-
gering/deployment process should take place
in good time at the start of the collision.
The rate of vehicle deceleration or acceleration
and the direction of the force are essentially
determined by:
R
the distribution of forces during the collision
R
the collision angle
R
the deformation characteristics of the vehicle
R
the characteristics of the object with which
the vehicle has collided
Factors which can only be seen and measured
after a collision has occurred do not play a deci-
sive role in the deployment of an airbag, nor do
they provide an indication of airbag deployment.
The vehicle may be deformed significantly with-
out an airbag being deployed. This is the case if
only parts which are relatively easily deformed
are affected and the rate of deceleration is not
high. Conversely, an airbag may be deployed
even though the vehicle suffers only minor
deformation. This is the case if, for example,
very rigid vehicle parts such as longitudinal body
members are hit, and sufficient deceleration
occurs as a result.
If the restraint system control unit detects a side
impact or if the vehicle overturns, the applicable
components of the restraint system are activa-
ted independently of each other depending on
the apparent type of accident.
R
Sidebags and pelvisbag on the side on which
an impact occurs, independent from the seat
belt tensioner and seat belt usage
Vehicles with the automatic child seat recog-
nition on the front-passenger seat: the side-
bag and pelvisbag on the front-passenger side
(front) deploy under the following conditions:
-
an occupant is detected on the front-
passenger seat or
-
the belt tongue is engaged in the belt
buckle of the front-passenger seat
R
Headbag on the side on which an impact
occurs, independent of seat belt usage and
regardless of whether the front-passenger
seat is occupied
R
Seat belt tensioners, if the system determines
that deployment can offer additional protec-
tion for the vehicle occupants in this situation
R
Headbags on the driver's and front-passenger
side in certain situations if the vehicle over-
turns and if the system determines that
deployment can offer additional protection to
that provided by the seat belt
46
Occupant safety
Safet
y
