Control Unit - Mercedes-Benz S 350 Owner's Manual

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Risk of injury
A malfunction has occurred if the =
warning lamp:
does not light up when you start the ig-
nition
does not go out a few seconds after the
engine has started
lights up again
Some systems could be triggered uninten-
tionally or might not be triggered at all in the
event of an accident with high deceleration.
Have the restraint systems checked and re-
paired immediately at a qualified specialist
workshop which has the necessary special-
ist knowledge and tools to carry out the
work required. Mercedes-Benz recommends
that you use a Mercedes-Benz Service Cen-
tre for this purpose. In particular, work rele-
vant to safety or on safety-related systems
must be carried out at a qualified specialist
workshop.
Triggering belt tensioners, belt force
limiters and airbags
In the event of a collision, the sensor in the
airbag control unit evaluates important
physical data such as duration, direction
and rate of vehicle deceleration or acceler-
ation. Based on the evaluation of this data
and depending on the vehicle's rate of lon-
gitudinal deceleration in a collision, at the
first level, the airbag control unit pre-emp-
tively triggers the belt tensioners.
The front airbags are only then deployed if
there is a higher degree of vehicle deceler-
ation in a longitudinal direction.
Since your vehicle is fitted with adaptive
dual-stage front airbags, the front airbag is
filled with enough gas to reduce the risk of
injuries at the first deployment threshold.
The front airbag is only fully inflated if a
second threshold is reached within a few
milliseconds due to the control unit having
detected further deceleration.
Occupant safety
i
The front-passenger front airbag is only de-
ployed if the front-passenger seat occupancy
recognition system recognises that the seat is
occupied.
The front belt tensioners can only be triggered if
the belt tongue is correctly engaged in the seat
belt buckle.
Activation of belt tensioners and airbags
In the first stages of a collision, the airbag
control unit evaluates physical data, such
as duration and direction of vehicle decel-
eration or acceleration in order to deter-
mine whether it is necessary to trigger the
belt tensioners or deploy the airbags.
The belt tensioner and airbag deployment
thresholds are variable and are adapted to
the degree of deceleration of the vehicle.
This process is pre-emptive in nature as
the airbag must be deployed during – and
not after – the collision.
Safety
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