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Home >> Alfa Romeo >> 2018 >> Stelvio Base >> Repair and Diagnosis >> Restraints >> Restraints Control Systems >> Restraints (Service Information) >> Description And Operation >> Description

Description And Operation: Description

IMPORTANT 

In the event of a collision, carefully check the vehicle for fuel leaks, for instance in the engine compartment, under the vehicle or near the tank area. Bring the ignition device to STOP to prevent the battery from running down. 

IMPORTANT 

MULTISTAGE AIRBAGS WITH MULTIPLE INITIATORS (SQUIBS) MUST BE CHECKED TO DETERMINE THAT ALL SQUIBS WERE USED DURING A DEPLOYMENT EVENT. REFER TO THE STANDARD PROCEDURES SUBSECTION OF THE RESTRAINTS SYSTEM SECTION IN THE SERVICE INFORMATION FOR MORE INFORMATION REGARDING THE SQUIB STATUS CHECK AND FOR CORRECT AIRBAG DISPOSAL PROCEDURES. Refer to  HANDLING NON-DEPLOYED SUPPLEMENTAL RESTRAINTS  . 

GC0195726Courtesy of CHRYSLER GROUP, LLC

The vehicle is equipped with six airbags (steering wheel airbag, passenger airbag, seat airbags, side curtain bags) and advanced retention systems on the seat belts to guarantee optimal protection to front occupants in case of accident. The Supplemental Restraint System (SRS) is equipped as follows:

Number of charges per airbag or tensioner:

The ORC system uses the various sensors to classify the type of impact that the vehicle undergoes: Number of sensors:

Occupant Restraint Controller (ORC) 

GC0196177Courtesy of CHRYSLER GROUP, LLC

The ORC, located on the central tunnel under the console, monitors the impact and occupant sensors and activates restraint system devices in the event of an impact. The ORC also contains impact sensors that are used to determine the level of deployment and to verify the information received from the remote sensors.

An arrow printed on the ORC label indicates the installation orientation. The arrow must point toward the front of the vehicle. The ORC must be installed correctly for proper restraint system operation.

NOTE:

The yaw or lateral acceleration sensor is installed inside the ORC module and is used for the correct operation of the vehicle dynamic stability functions.

The ORC module will set a specific DTC which cannot be deleted, not even using the diagnostic tool. This will happen when the following conditions are reached:

When one of the above mentioned limits is reached, the ORC module will have to be replaced.

Impact Sensors 

In order to function properly, the SRS has:

Front Impact Sensors 

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The front impact sensors (1) detect frontal impacts and support deployment of the driver/passenger airbags and tensioners. The front impact sensors (1) contain an accelerometer that measures the rate of vehicle deceleration in the event of an impact. The sensors are located on each side attached to the corresponding front fender supports (2). In head-on frontal collisions, the impact sensor in the ORC is used as primary sensor while the front sensors provide confirmation of the event. In angled or offset front impacts, the front sensors are used as primary sensor while the ORC sensor provides confirmation of the event.

Side Pressure Sensors 

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One pressure sensor is located in each of the front doors to protect front row passengers in the event of side crashes. The pressure sensors can detect a sudden change in air pressure within the door which is consistent with a direct impact to the door. The sensor signal alone cannot command the deployment of the airbag. The ORC or a second sensor must detect a simultaneous crash event to deploy the seat airbags.

B-pillar Side Impact Sensors 

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The airbag system of the vehicle is provided with two side collision sensors of the accelerometer type placed on each side of the vehicle to detect side collisions in order to activate the side curtain airbags, the seat airbags and the tensioners. The side impact sensors are located behind the B-pillar trim and specifically in the lower part.

Seat Belt Buckle Switch 

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The buckles of driver and front and rear passenger seat belts have a resistive sensor for monitoring their fastening.

Buckle technical details

Occupant Detection Sensor (ODS) 

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The ODS is a resistive pressure switch. The ODS closes when a pre-programmed load is placed on the seat. The ODS is used to trigger a seat belt reminder if a passenger is detected on the seat. The ODS does not affect the level of airbag deployment.

Driver AirBag (DAB) 

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The DAB has a multistage pyrotechnic charge (2) with a vent pyrotechnic charge (1) for quick deflation of the DAB after a deployment impact. The DAB module is anchored to the steering wheel by means of anchoring clips (there are no screws).

Passenger AirBag (PAB) 

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The PAB is integral to the top of the dashboard and bolts to the instrument panel carrier. The PAB contains a multistage pyrotechnic charge with a vent pyrotechnic charge for quick deflation of the PAB after a deployment impact.

Side Curtain Airbags 

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The side curtain airbags use a hybrid inflator. To deploy the airbag the ORC sends a current to the airbag inflator which ignites the chemical pellets. The gases produced by the combustion of the pellets produce a pressure sufficient to break the containment cap of a cylinder of inert gas. The gases are directed into the side curtain airbags causing them to inflate. The side curtain airbags stay inflated for a few seconds to protect passengers in the event of a roll-over. The deflation rate of the airbags is controlled by the tightness of the airbag fabric mesh.

Seat Airbags 

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The vehicle includes seat airbags integrated in the side of the front seats (outer side) to improve the safety of driver and passenger in case of side crashes.

Seat Belt Tensioners 

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The airbag system is provided with four tensioners. A tensioner is fitted on the seat belt anchoring on both sides (driver and passenger) and the other tensioner is present in the seat belt retractor. The tensioners are located in the seat belt retractors at the back. They are operated by the ORC jointly with the two front airbags. When the ORC sends the proper electrical signal to the tensioners, the electrical energy generates enough heat to initiate a small pyrotechnic gas generator.

On the retractor tensioner, a gas generator is installed in one end of a steel tube which contains numerous steel balls. As the gas expands, it pushes the steel balls through the tube into a cast metal housing, where a ball guide directs the balls into engagement with the teeth of a sprocket that is geared to one end of the retractor spool.

As the balls drive past the sprocket, the sprocket turns and drives the seat belt retractor spool causing the slack to be removed from the front seat belts. The ball trap captures the balls as they leave the sprocket and are expelled from the housing.

On the anchor tensioner, the gas generator is installed in one end of the tubular metal piston housing, which contains a piston secured to one end of a cable. The cable is routed around an integral guide to the buckle anchor, which is secured to the opposite end of the cable. As the gas expands, it pushes the piston and the cable through the tube and pulls the buckle anchor downward, removing the slack from the front seat belt.

Battery Pyrotechnic Fuse 

GC0196433Courtesy of CHRYSLER GROUP, LLC
NOTE:

In the event of a collision, carefully check the vehicle for fuel leaks, for instance in the engine compartment, under the vehicle or near the tank area. Bring the ignition device to STOP to prevent the battery from running down.

A pyrotechnic fuse is installed on the vehicle and specifically in the Battery Distribution Unit (BDU) installed on the positive battery terminal. In case of accident with deployment of the airbags, the ORC will cause this fuse to blow.

GC0197337Courtesy of CHRYSLER GROUP, LLC

When the fuse is blown, it will break the foil which allows battery voltage to reach the starter motor, generator and the various components which must be powered. Once this fuse has blown, the vehicle cannot be restarted until the blown fuse is replaced with a new one.

SEAT BELT REMINDER (SBR) SYSTEM 

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7 inch Electronic Vehicle Information Center (EVIC)

The SBR system warns the front and rear seat occupants if their seat belt is not fastened. The system signals unfastened seat belts with visual warnings (warning lights on in the instrument panel and icons on the display) and an acoustic signal.

The ORC will send the buckle condition messages to the IPC via the Controller Area Network (CAN) for the activation of the indications.