PASSIVE SAFETY SYSTEM

1.2 8v, 1.3 Multijet, 1.4 16v

PASSIVE SAFETY SYSTEM

The vehicle is equipped with an electronic control system that governs the acivation of specific containment devices in the event of frontal or side impact.

The frontal protection system includes:

• dual activation stage driver''s front Air Bag;
• dual activation stage passenger front Air Bag;
• driver''s kneebag (optional);
• front seat belts with dual pretensioner and load limiter;
• additional front impact detection sensor.

The side protection system comprises:

• two Side Bags housed in the front seats (optional);
• two drop-down headbags housed in the under-roof rails (optional);
• two impact detection sensors located in the central pillars.

The dual stage driver''s front air bags, driver and passenger, are both capable of automatically adapting the activation parameters depending on the seriousness of the impact:

• when the impact is of moderate severity, the electronic control unit controls the first air bag activation stage so that the energy discharged onto the occupant is not harmful;
• for very severe crashes, the control unit activates the first and second stage with a very slight delay in order to absorb the occupant''s greater kinetic energy before he strikes the steering wheel or dashboard.
• for medium severity impacts the second stage is also activated after a preset time to ensure the charge is used fully.
• an ECS early crash sensor, located on the front crossmeber near the bonnet lock, helps the electronic control unit to anticipate the intervention of all the front air bags.

The airbag system components are designed to work on a specific vehicle. They therefore CANNOT be tampered with, adapted or installed on other types of vehicle.

For safety reasons, NO continuity checks can be carried out on the wiring.

The electrical connection between the airbag system components is via dedicated wiring built into the dashboard cable loom and the rear cable loom.

The control unit is connected to the system via two connectors, one for the dashboard lead and the other for the rear lead.

The control unit is connected to the vehicle CAN network through which it exchanges information with the other nodes, turns on the instrument panel warning lights and carries out diagnostic operations.

Because the control unit is a node in the CAN, the airbag system is connected:

• to the standard diagnostic socket via the CAN
• to the instrument panel, again via the CAN, to control the airbag system failure, seat belt unfastened and passenger airbag deactivated warning lights in addition to the belt unfastened buzzer.
• to the Body Computer for potential end of line customisation (Proxy) with a consequent reduction in the number of spare parts.

GRAVE DANGER! The front air bag module MUST be deactivated if a child seat is fitted to the front passenger seat.

THIS MAY BE DISABLED BY MEANS OF THE CONTROL PANEL SETUP FUNCTION AND NOT BY USING THE KEY.

When it is deactivated the warning light in the instrument panel comes on.

If the vehicle is equipped with side bags, deactivation of the front passenger side air bag module also disables the side bag.

Composition

The system consists of the following devices:

• An electronic control unit;
• driver and passenger front air bags with dual-stage activation;
• driver''s kneebag with single stage activation;
• a supplementary impact detection sensor, the ECS (Early Crash Sensor);
• two Side Bags on the front seats;
• two window bag modules for the side protection of occupants;
• two side impact sensors in the side pillars;
• four electronic pretensinoers on the front seat belts (two for each belt).

1. Electronic control unit;

2. Driver''s knee bag

3. Driver''s front air bag

4. ECS early crash sensor

5. Window Bag

6. Passenger front air bag

7. Pretensioners

8. Side impact sensor

The following indicate the status of the system:

• system fault warning light (red) in the instrument panel:
• passenger side airbag disabled warning light (amber) on the instrument panel;
• front seat belt unfastened warning light on the instrument panel;
• connection via the B-CAN with the diagnostic socket - for function checks using an EXAMINER.

1. Air Bag failure warning light

2. Passenger air bag warning light off

Electronic control unit

The following diagram shows the control unit.

1. Electronic control unit

2. Indication showing direction of motion

The control unit is the central occupant protection processing unit and is fastened rigidly to the vehicle floor pan near the central tunnel. It manages all the containment system detection and activation devices by processing signals from the various sensors distributed throughout the vehicle and internal sensors.

The control unit should always be fitted with the arrow, stamped on the adhesive plate, facing the direction of travel of the vehicle.

Always check that there are no foreign bodies between the control unit and the bodyshell and tighten the fixing bolts to the recommended torque

If the control unit falls to the ground or is subject to abnormal knocks during handling, it MUST be replaced.

Composition

The control unit has an electronic deceleration sensor which, with the assistance of front and side satellite sensors and, via a dedicated calculation algorithm, manages the activation of the front and side modules and the pretensioners.

Operation

Frontal impact:

When the impact is of moderate severity, the electronic control unit controls the first air bag activation stage for the driver''s and passenger air bag so that the energy discharged onto the occupant is not harmful.

Conversely, in the case of very severe impact, the control unit activates both stages almost simultaneously to absorb most of the kinetic energy from the occupant''s body before it strikes the steering wheel or dashboard.

Side impact:

Similarly, when side impact occurs, the control unit is able to recognise direction and intensity and thus activate both air bags and the pretensioners present on the side affected by impact. To provide total cover against side impacts, two satellite sensors located in the centre pillars are used.

When there is a side impact, the satellite sensors detect the deceleration due to the impact and notify the control unit which, by means of a dedicated calculation algorithm, manages the activation of the side modules and the pretensioners.

The side Air Bags (Window Bags and Side Bags) are activated simultaneously and independently of the front safety devices.

After each activation of one of the controlled systems (pretensioners, front airbags, sidebags), the control unit stores the activation in its permanent memory and controls activation of the fault warning light on the instrument panel.

Before it is replaced, the control unit guarantees individual device activation for a maximum number of:

• 3 impacts with activation of the seat belt pretensioners alone;
• 3 impacts in total (right or left) with side bag activation;
• 1 impact with activation of the pretensioners and front airbags;
• any combination of the above cases up to the maximum number.

If one of the limits described is not reached, it will be possible to reuse the control unit after carrying out the RESET procedure using the EXAMINER once system operating conditions have been restored. The final activation, corresponding to the maximum number for the limits indicated above, will prevent further reset procedures.

Control unit pin out

Self-diagnosis

The control unit carries out continuous self-diagnosis of system operation. More specifically:

• it detects and stores faults;
• it diagnoses connnections to system components and any type of fault that has occurred;
• it indicates the source of these faults by turning on a warning light in the instrument panel.

Faults stored in the control unit may be deleted only after the fault has been repaired using the EXAMINER diagnostic equipment.

If the fault is due to an error inside the control unit it should be replaced.

Driver''s air bag module

Specifications

The driver''s air bag is a passive safety device. It takes the form of a bag that inflates automatically in the case of frontal impact to interpose itself between the driver''s body and front passenger compartment structures. The Air Bag module is installed in the middle of the steering wheel. The module cover also acts as a horn control.

Composition

The module comprises:

• a plastic cover that tears at preset points when activated to allow the bag to expand correctly.
• a 60 litre bag, made out of nylon thread woven to minimise skin abrasions in the case of contact and folded in such a way as to ensure that inflation is gradual and not directed toward the driver;
• a pyrotechnic type gas generator;
• a plastic housing;
• the control device from the horns.

1. Cover

2. Cushion

3. Gas generator

4. Plastic housing

5. Horn control

Operation

Bag inflation is determined by a gas generator that offers two intervention stages that can be activated separately according to impact severity.

The gas generator is activated by two electrical resistances that burn propellant inside the generator to allow the bag to expand.

When fully inflated, the bag is in an optimal position to protect the occupant.

Bag deflation is immediate, due to two holes present in the lower part of the bag. These holes also soften contact between passenger and bag to avoid the risk of abrasions.

Clock spring

The following figure shows the clock spring.

1. Electrical connection for connecting air bag first stage

2. Electrical connection for connecting air bag second stage

3. Steering wheel electric functions connection (horns and radio controls)

4. Clock spring

Specifications

The clock spring transfers the electrical signal to controls on the steering wheel (horn and other optional controls) and connects the airbag module without risk of breakage.

The device consists of two plates and is secured to the steering wheel interface via its lower plate. It is built into the steering wheel by means of fasteners on the upper plate. Inside the two plates, the leads connecting the module and horn buttons are wound in a coil so that they can follow steering wheel movements.

Composition

The clock spring is fitted with three leads on the steering wheel side. Two of these are used to connect the air bag module (first and second stage) and one to connect the steering wheel electrical functions (horn, radio controls).

A ring on the lower plate, steering wheel side, automatically prevents both plate from turning in relation to one another when the device is disconnected from the steering wheel. The new clock spring is equipped with a safety key for transport, which must be removed after installation.

Operation

Inside the two plates, the leads connecting the air bag module and the various electrical functions are wound into a spiral with sufficient coils to follow the steering wheel rotations.

The upper plate is turned by fasteners on the inside of the retaining ring that fit into the seat on the steering wheel hub. In a working position, the steering wheel presses on the ring to release it from its fasteners and thus allow both plates to turn freely.

When the steering wheel is removed, the spring-loaded ring locks rotation between both plates. This function prevents the upper plate, now no longer secured to the steering wheel, from turning freely and unwinding or winding the coil inside the device and possibly causing it to break.

The following must be observed during operations that require removal of the steering wheel and device.

• always work with the car''s wheels aligned straight ahead.
• secure both plates with a band for safety before removing the device from the steering wheel stalk unit.

If the clock spring is being reused, it is advisable to secure the two shims with a band to prevent accidental rotation.

If the upper plate should turn in relation to the lower plate for any reason so that the exact starting position is no longer certain, the clock spring MUST be replaced.

For more details see:

See descriptions 5550A STALK UNIT

Passenger air bag module

Specifications

The passenger air bag module is a passive safety device that protects the front passenger in the event of front impact by means of a bag that interposes itself between the occupant and the vehicle dashboard.

Composition

The module comprises:

• a plastic housing;
• a 120 litre bag in nylon, a fabric that minimises skin abrasions in the event of contact. The bag is folded so that it does not inflate directly towards the occupant.
• a pyrotechnic type gas generator.

1. Cover and bag

2. Deflector

3. Housing

4. Gas generator

5. Fastening brackets

Operation

Bag inflation is determined by a gas generator that offers two intervention stages that can be activated separately according to impact severity.

The gas generator is activated by two electrical resistances that burn propellant inside the generator to allow the bag to expand.

Bag inflation opens the flap in the dashboard along predefined cut lines. When fully inflated, the bag is in an optimal position to protect the occupant.

The braids inside the airbag unfold in such a way as to allow inflation to the maximum specified dimensions to prevent collateral damaging effects on passengers.

Disabling of passenger front air bag and side bag protction (chest/pelvis) (where present)

The user can deactivate the passenger bag in order to install a child seat without any risk. When fitted in the front, it should be installed facing away from the direction of motion.

This instrument panel function allows the passenger air bag to be activated/deactivated.

Proceed as follows:

• press the MENU ESC button and, after the display shows the message (Passenger bag: Off) (for deactivation) or the message (Passenger bag: On) (for activation) by pressing the + and - buttons, press the MENU ESC button again;
• the confirmation message will appear on the display;
• by pressing the + or - buttons select (Yes) (to confirm the activation/deactivation) or (No) (to renounce);
• press the MENU ESC button briefly, a message confirming the selection will be displayed and you will return to the menu screen or pressing the button for longer you will return to the standard screen with memorizing.

When the function is on, the instrument panel warning light stays on.

1. Passenger air bag warning light off

Knee air bag module

Specifications

An optional airbag module is also supplied as an option. This is fitted in the lower part of the facia in front of the driver''s knees. This module, in addition to protecting the lower limbs, increases protection for the driver, particularly by preventing them from sliding forward, which is a possible cause of injury to the legs and chest.

Composition

The knee bag module consists of:

• a metal container;
• a gas generator;
• a nylon bag with a volume of around 16 litres;
• a plastic cover.

The container is secured to a mounting plate and a safety plate that secures it rigidly to the lower part of the dashboard.

The plastic cover tears at preset points when activated to allow the bag to expand correctly.

1. Housing

2. Cushion

3. Gas generator

4. Cover

Operation

The gas generator is electrically activated by means of a signal from the electronic control module. Following this signal, a pyrotechnic activation is triggered that causes the gas in the generator to expand. The expanding gases emerge through openings to inflate the bag. When the bag is inflated, the bag is in an optimum position to perform its role of protecting the occupant.

Side bag module

Specifications

The front seats contain two side bag modules to increase the protection offered by the body in the event of side impact.

This device ensures the airbag is always in an optimum position in relation to the occupant, regardless of the angle of the seat or the size of the occupant.

The side bag protects the chest and pelvis areas and also - together with the door panels - protects critical areas of the body such as the ribs and abdomen.

Its position on the seat always ensures maximum efficacy irrespective of seat position, even if the seat occupant is not seated correctly, because bag opening dynamics minimise the risk of body damage due to impact against the body.

Do not cover the front seat backrests with extra covers.

Do not wash the seat backrest with water or steam under pressure

Composition

The side bag module consists of:

• a metal container;
• a gas generator;
• a nylon bag with a volume of around 12 litres.

If the side bag is activated, the backrest cover fabric tears at preset points when activated to allow the bag to expand correctly.

The module is connected to the electrical system by means of two leads with yellow sheaths. These are contained, together with the seat earth connection lead, in a protective fabric-lined duct secured to the seat structure.

Operation

The gas generator is electrically activated by means of a signal from the electronic control module. Following this signal, a pyrotechnic activation is triggered that causes the gas in the generator to expand. The gases expand and emerge through openings to inflate the bag. Bag inflation causes the weak seams in the backrest trim to yield and allow the bag to emerge.

When fully inflated, the bag is in an optimal position to protect the occupant.

Window bag module

Specifications

The window bags are activated together with the sidebags and interpose themselves between the occupant and the vehicle to prevent the head coming into contact with highly intrusive objects such as glass, pillars etc.

Because the window bags extend from the front pillar to the luggage compartment, they protect front and rear passengers. The window bag system offers the best performance due to the broad area covered and their ability to be self-supporting even without a backing.

Composition

The window bag module consists of:

• a gas generator secured by two brackets to the rear pillar;
• a metal connecting pipe between the gas generator and the bag;
• a bag with a volume of about 22 litres made from a permeable nylon fabric folded inside a container. The bag is designed to ensure, once fully inflated, correct absorption of impact energy while maintaining the occupants'' heads at a proper distance from the impact area. Once fully inflated, the gas leaves the bag immediately through the porous tissue.
• plastic clips that secure the bag to the ceiling side rail;
• plastic references to secure the bag onto the vehicle;
• a retaining strap secured to the front pillar that holds the bag in position once inflated;

1. Gas generator

2. Clips fastening the bag to the ceiling side rail

3. Bag

4. Retaining strap

Operation

The gas generator is electrically activated by means of a signal from the electronic control module. Following this signal, a pyrotechnic activation is triggered that causes the gas in the generator to expand.

On expanding the gases escape via special openings and are evenly distributed along the entire bag.

The increase in bag volume causes the sleeve seams to yield and the trim to open. Everything is arranged so that the bag emerges correctly downward.

The bag is made to inflate correctly by a retaining strap on the front end of the bag.

When fully inflated, the bag is in an optimal position to protect the occupant.

The bag deflates immediately after being inflated by the gas because the fabric is permeable.

Side impact satellite sensors

The sensors are located in the two centre pillars above the pretensioners.

A. Link connection

B. Centering pin

Pin 1: satellite sensor signal

Pin 2: satellite sensor earth

Specifications

The side protection system consists of the air bags and also an electronic control circuit that ensures the system operates correctly. Two satellite sensors containing an accelerometer are installed inside the side pillars to measure accelerations resulting from side impact.

Composition

The satellite side impact sensor consists of a case containing the acceleration sensor. A pin on the rear part of the case is used to position the sensor correctly in its seat. The case also contains a connection point for connectoin to the electrical system.

Operation

If the acceleration level detected by the relevant sensor causes a given threshold to be exceeded, the information is compared with a measurement obtained by a safety sensor in the air bag system electronic control unit. If the measured values are consistent, the control unit controls activation of the side bags on the side affected by impact

in the case of a side impact the pretensioner affected by the impact should be replaced.

Front impact satellite sensor

A supplementary ECS “Early Crash Sensor” on the front beam near the bonnet lock also helps the electronic control unit to operate more quickly than a conventional system so that the airbag activation stage is comleted before the occupant''s body begins to move towards the steering wheel or dashboard.

Seat belt pretensioners

Specifications

The pretensioners are pyrotechnic devices that are activated electrically by means of a signal from the electronic control unit. They are built into the reel of the front and rear seat belts.

Activation of the seat belt pretensioners is controlled by the same strategy as the air bags.

The pretensioners are designed to take up slack in the seat belt to ensure it holds the occupant against the backrest from the first moments of impact, thus reducing movement inside the passenger compartment.

The seat belts are also fitted with load limiters which decrease the force transmitted by the belts to the chest: the force level at which the limiters act is sufficient to considerably reduce the risk of fracturing shoulder blades and ribs, even in people with brittle bones (e.g. the elderly).

Operation

The pretensioners on the reel are illustrated in detail below.

1. Gas generator

2. Electrical connector

3. Band

4. Reel

The pretensioners on the third point are illustrated in detail below.

1. Gas generator

2. Electrical connector

3. Third point rod

When the car decelerates to a sufficient extent, as measured by system accelerometers, the electronic sensor in the electronic control unit sends a signal to trigger the gas generator pyrotechnic charges.

The combustion of the propellant produces a chemical reaction creating inert gas whose pressure produces a force that thrusts a piston upwards, changing the rotary movement of the reel into the opposite direction of the seat belt, rewinding it by a few centimetres. The combined action of the two devices allows the even distribution of the length of belt to be recovered and, as a result, a more even distribution of the retaining action on the occupant.

Once the pretensioners have been activated, the belts are locked and must be replaced.

AIR BAG SYSTEM WARNING LIGHTS

The two warning lights for the air bag system are illustrated in the diagram below.

1. Air Bag system fault warning light

2. Passenger Air Bag disabled warning light

3. Seat belt not fastened warning light

Air bag system fault warning light

At key on, the fault warning light (red) comes on for about four seconds (initial self-diagnosis stage) and then goes off.

If no system faults are detected at key on and no fault conditions are present in the fault memory, the warning light goes off after four seconds of self-diagnosis. Otherwise it stays on.

The warning light stays or comes on during normal car operation in the following cases:

• the control unit detects a fault in the air bag system;
• the control unit detects a crash with system activation.

As a consequence of a crash when the pretensioners or sidebags alone are activated, the warning light stays on until system operating conditions are restored (replacement of affected part or control unit repair using an EXAMINER)

If the crash causes the front airbag modules to activate, the warning light stays on permanently because the control unit cannot reset (in this case the control unit must be replaced).

If internal operating errors occur during the operational lifetime of the control unit that cannot be repaired by means of the EXAMINER, these are indicated by permanent activation of the warning light.

Passenger air bag disabled warning light

With the front passenger air bag on, at the key on, the yellow passenger side air bag disabled warning light comes on for about four seconds (initial self-diagnosis stage) and flashes for the next 4 seconds after which it goes out.

The passgner Air Bag warning light flashes if the control unit detects a fault in the Air Bag system failure warning light.

Seat belt reminder

"Initial warning cycle": signalling via warning light

The "seat belts" warning light signals that the seat belt is not fastened (driver''s or passenger side) coming on constantly from the Key ON.

"warning cycle": indication via warning light and buzzer

The warning light starts to flash and the buzzer sounds continuously for 6 secs and then intermittently for 90 secs if one of the following conditions is verified:

• Time elapsed 50 secs and vehicle speed above 10 km/h
• Vehicle speed above 20 km/h
• Distance travelled more than 400 m

If the seat belts are fastened during the cycle, the warning cycle is automatically interrupted and is only repeated if the seat belt not fastened condition is detected once again. The cycle is also interrupted when reverse gear is engaged (the warning light only remains on constantly) and is only repeated when the seat belt not fastened condition is detected once again and the vehicle speed exceeds 10 km/h.

Warning cycle exclusion mode

The user can deactivate the warning cycle permanently only with the aid of the Fiat Dealer Network.

The deactivation procedure must be performed using a diagnostic instrument (Examiner) in communication with the control panel.

Noone can deactivate the signal issued by the warning light on the dashboard. This is always present (fixed light) if the seat belt is unfastened.

Warning cycle reactivation method

The driver can reactivate the warning cycle (if it is permanently deactivated) through intervention from the Fiat Dealer Network or through a special item in the set up menu. This item disappears once the warning cycle is reactivated.

Fuel cut off function

There is no inertia switch on this vehicle; the fuel cut off function is managed by the air bag control unit, the Body Computer node and by the engine management node as described in

See descriptions 5505 INSTRUMENT/GAUGE ELECTRICAL CIRCUITS