Description And Operation
In the European version, the airbag system comprises the following components:
- 1 - Driver AirBag (DAB) (Dual Stage)
- 2 - Passenger AirBag (PAB)
- 3 - Seat belts with dual tensioners
- 4 - Occupant Restraint Controller (ORC) module
- 5 - Front impact sensors.
In markets where provided, the following components are also present:
- Driver side Knee AirBag (KAB)
- Side airbags (inside the door panel)
- Side impact sensors (on carbon monocoque and doors)
- Seat Track Position Sensors (STPS) (driver and passenger)
The ORC module must comply with the following requirements:
- Communicate with the front impact sensors (and side impact sensors for NAFTA market)
- Carry out the diagnosis on all its peripheral units (sensors and actuators)
- Controller Area Network (CAN) interface, in order to:
- Signal errors and faults.
- Signal the driver side seat belt status.
- Signal the passenger side seat belt status (NAFTA market only).
- Communicate with the diagnosis equipment.
- Detect frontal, side and rear impacts.
- Provide control signals to the initiators.
- Provide fuel cutoff signals (Fire Prevention System/FPS function).
- Interface for the driver buckle switch.
- Interface for the passenger buckle switch.
- Provide energy reserve (in the case of lack of power supply) to activate the front initiators and write the diagnosis data.
The ORC module, along with the impact sensors, must be able to activate the front and side (in markets where provided) protection systems after a crash, according to the times and modes defined in the technical specifications of the vehicle restraint system.
The ORC module must ensure, without the need of replacement, that the single devices are activated within the following limits:
- 3 impacts with activation of the tensioners only
- 3 total impacts (right and left side) with activation of the side airbags (in markets where provided)
- 1 impact with activation of the front airbags and tensioners
- Any other combination of the above cases, until one of the limits is reached.
If one of the limits above has not been reached yet, after restoring the system, the same ORC module can be reused by resetting with the RESET procedure of the diagnostic scan tool.
In the case of an impact with activation of the airbags, the ORC module sends the Fuel Cutoff (FPS) control on CAN. With this control the Powertrain Control Module (PCM) cuts off the fuel tank submerged electric pump.
To reactivate the electric fuel pump, the procedure using the steering column stalk direction indicator lever must be carried out. The procedure comprises two complete right and left direction indicator engagement cycles. Each cycle comprises:
- Lever at OFF
- Lever upwards (right direction indicator)
- Lever at OFF
- Lever downwards (left direction indicator)
- Lever at OFF
The vehicle is equipped with an electronic control system that governs the activation of specific containment devices in the event of frontal or side impact. An electronic control unit manages the entire system.
The front protection system includes:
- driver side front airbag with double stage of activation (Driver AirBag / DAB)
- passenger side front airbag with triple stage of activation (Passenger AirBag / PAB)
- driver side knee protection with single stage of activation (Knee AirBag / KAB)
- driver side and passenger side safety belts with load limiters and double-retaining-action tensioners
- two seat position sensors (Seat Track Position Sensor / STPS)
- two frontal impact sensors (Early Crash Sensor / ECS)
In the most complete configuration the side protection system comprises:
- chest protection side airbags (side airbags)
- side impact detection sensors in the doors and on center pillars
Supplementary ECSs, on the front crossmember, help the Occupant Restraint Controller (ORC) to anticipate airbag intervention so that the airbag activation stage is completed before the occupant's body begins to move towards the steering wheel or instrument panel.
The ORC is located under the center console and is securely fastened to the body. In this way, the deceleration sensors located inside the ORC are near the center of gravity and accurately detect the deceleration for the entire vehicle.
The STPSs are sensors with a Hall effect designed to provide data on the sliding of the seats (forward/back).
Depending on the signals received from the sensors, the ORC acquires the data on seat position and then on the occupants, and uses these as a factor to determine the appropriate explosive charge to be used in the event of activation of the multi-stage front airbags.
The Driver AirBag (DAB) is located in the middle of the steering wheel. It is mounted on a rocker plate that is also used to control the horns. The plate houses a metal container that contains the folded bag and the gas generation device that inflates the bag.
A clock spring allows the connecting cables for the DAB to follow the rotation of the steering wheel without danger of breaking.
The driver knee bag module is located in the lower part of the instrument panel on driver side, beneath the steering wheel. This single-stage activation module, in addition to protecting the lower limbs, increases protection for the driver, above all by preventing them from sliding forward, which is a possible cause of injury, also to the chest.
The passenger side airbag is located on the instrument panel, and is fixed directly to the vehicle crossmember by means of a special bracket.
The Side AirBags protect the chest area and also - together with the door panels - protect critical areas of the body such as the ribs and abdomen.
Activation of the seat belt tensioners is controlled by the same strategy as the airbags.
The driver and passenger tensioners with dual retaining action are integrated respectively in the seat belt retractor and in the third point mounting for the actual seat belts (pyrotechnic tensioners). Their simultaneous activation is designed to take up slack in the seat belt to ensure it holds the occupant against the backrest and cushion from the first moments of impact, thus reducing movement inside the passenger compartment.
The seat belts are also equipped with load limiters which make it possible to adjust the force acting on the chest and shoulders during the retaining action of the belts in the event of a frontal impact.
The vehicle is equipped with a system called Seat Belt Reminder system (SBR) which, by turning on the "seat belt not fastened" warning light on the instrument panel steady, warns the driver that the driver seat belt and that of the passenger are not fastened.
When the system detects that one of the belts is not fastened with the vehicle moving, a warning cycle activates with an intermittent acoustic signal and the flashing of the "seat belt not fastened" warning light.
The acoustic indication of the SBR system can be permanently deactivated by an Authorized Workshop, but it can be reactivated directly by the driver at any time by using the dedicated item in the instrument panel menu.
The control unit is equipped with a self-diagnosis function:
- it detects and memorizes any faults
- it recognizes the various components and the fault type
- it indicates the onset of faults by means of the special warning light
The activation of the system following a particularly serious impact is memorized by the control unit.
This vehicle has not been equipped with an inertia switch; instead it has a fuel cut off function, which is managed by the ORC. After detecting an impact, the ORC sends the Fire Prevention System (FPS) signal over the network which:
- interrupts the flow of fuel by the Powertrain Control Module (PCM)
- activates the hazard warning lights
- activates the courtesy lights for 15 minutes
- unlocks the doors
This condition is also signaled on the instrument panel via the general failure warning light and a dedicated message on the display.
When the system self-diagnosis function detects a fault or an impact is recorded, the control unit sends a signal, through the CAN, for the activation of the airbag fault warning light located in the instrument panel.
Likewise, it turns on the "seat belt not fastened" and "passenger airbag disabled" warning lights.
If a child restraint system is installed, the passenger side airbag (front and side airbag) must be deactivated using the specific item of the instrument panel Menu and pressing the buttons on the left control panel; after the deactivation the corresponding warning light turns on constantly.
The passenger airbag disabling function is activated only via the setup menu in the instrument panel and not by using the key!
The system control unit supply circuit is protected by a dedicated Body Control Module (BCM) fuse. When operations are carried out to the airbag system, the following safety recommendations must be closely followed. For more details. Refer to WARNING .
OPERATION
The ORC receives an ignition-operated supply (INT) from the circuit protected by a fuse in the BCM and is connected to dedicated ground.
The front ECSs detect even slight front impacts and signal them respectively to the ORC. The return circuits provide the sensors with a reference ground.
The STPSs on the driver side and passenger side receive a reference ground from the ORC and supply the respective signals to the ORC.
Depending on the control strategy and the data provided by the sensors built into the ORC and by the satellite ECSs, when a front impact is detected, the ORC sends control signals to trigger the front airbags. Specifically to:
- the DAB first stage of activation, via the clockspring
- the DAB second stage of activation, via the clockspring
- the KAB
- the PAB first stage of activation
- the PAB second stage of activation
- the PAB third stage of activation
- the front seat belt tensioners on the retractors
- the front seat belt tensioners on the seat belt anchors
The sensors for the DAB and PAB on the pillar and on the door are connected in parallel to the ORC.
When, on the basis of the control logic and of the information supplied by the sensors, a side impact of a certain severity is detected, the ORC sends control signals for the intervention of the driver and side airbags
The metal structures of all the containment systems are connected to the AirBag ground.
The driver side and passenger side seat belt switches receive a reference ground from the ORC and send the respective signal back to the ORC.
The ORC connects via CAN-B to the BCM, to the instrument panel and to the other network modules.
When the system self-diagnosis function detects a fault or an impact is recorded, the ORC sends a signal, via the CAN, to activate the airbag fault warning light; a specific message appears on the display of the instrument panel at the same time.
After having detected an impact, the ORC sends the FPS signal via the network. This condition is also signaled on the instrument panel by means of the "fuel cut-off system tripped" icon and by a specific message in the display.
If the driver or the passenger side seat belt is not fastened, the instrument panel will indicate this dangerous situation, through the "seat belt not fastened" warning light turning on continuously.
When the system detects that one of the front belts is not fastened with the vehicle moving, the instrument panel activates a warning cycle with the simultaneous flashing of the "seat belt not fastened" warning light and an intermittent acoustic signal from the internal buzzer.
The BCM supplies a reference ground to the passenger airbag ON/OFF switch.
Pressing the buttons located in the passenger airbag ON/OFF switch sends a single coded signal through a resistive divider to the instrument panel. Using the Setup menu in the instrument panel display, it is possible to deactivate the PAB and Side AirBag, thus causing the warning light to turn ON.