Iveco daily euro 4, Repair Manual

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ELECTRIC/ELECTRONIC SYSTEM D
AILY
E
URO
4
Base - March 2006 Print 603.93.651
AIR BAG
General
The air bag is a passive safety device comprising one or two cushions which, in the event of a head-on crash, inflate automatically
setting themselves between the body of the occupants and the front structures of the cab.
The system is always integrated by seat belts with pretensioner, which are controlled by the air bag control unit, in the event
of head-on crashes.
The system does not cut in for front crashes at low speed, side crash, overturning or crashes from behind.
Inflation of the bags without the restraint of the belts compromises the safety of the driver and passengers.
System components are connected to each other and to the rest of electrical system through a special wiring harness that can
be easily identified as it is provided with a yellow sheathe.
SYSTEM OPERATION
Device intervention sequence can be INDICATIVELY REPRESENTED as illustrated in following figure.
For convenience’s sake, drive side device only is shown: passenger side air bag operation is quite similar.
Represented diagrams are qualitative and are not concerning subject vehicle.
Diagram A : this diagram represents inflation pressure in cushion versus crash dynamics developing time.
Diagram B : this diagram represents body positions during a front crash with respect to steering wheel and air bag positions.
Below is events time sequence from the time of electrical pulse triggering off by electronic central unit.
Time “t1”
Time when inflation system is triggered off. Thereafter, inflation pressure starts rising in the cushion, which is still enclosed inside
module cover. The module is made up of a plastic layer located at steering wheel centre. Driver’s body is still in almost normal
position (Figure B, reference 1).
Time “t2”
Pressure inside still closed module rises until it reaches such a value that the cover is opened, cushion stuck out and inflation
started.
Driver’s body starts in this time period to move forwards and is placed between normal position taken during drive and the
position of the collision against the cushion (Figure B, reference 2).
At the time when the cushion is released from its shell, gas pressure slows rapidly down owing to the high inertia of the cushion.
At a certain time, pressure is drawn to take negative values.
Time “t3”
Cushion pressure takes back positive values because from this time the very inflation starts which will lead the cushion to
maximum expansion condition.
Time “t4”
Driver’s body impact against the cushion takes place (Figure B, reference 3).
Pressure inside the cushion rises because of pressure exerted on it by driver.
Time “t5”
Pressure in the cushion slows rapidly down owing to the presence of an air vent hole and the cushion deflates entirely to the
end of allowing driver high mobility (compatible with the rest of the vehicle).
The air bag is complementary to the use of the seat belts and not in replacement of them. NOTE