Air Bag and Safety Belt Pretensioner (SRS) Componants
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The Supplemental Restraint System (SRS) has been specifically designed to help protect the driver and passenger from sustaining severe facial and upper body injuries in the event of a serious impact. Optimum protection can only be achieved when used in conjunction with a conventional three-point safety belt. The safety belts form an integral part of the SRS.
The SRS utilizes an Alternating Current (AC) firing strategy.
The driver, wearing the safety belt provided, should position the seat as far back as is practical, so the steering wheel can be reached with arms slightly angled, thereby leaving a gap between the steering wheel and the driver.
The front passenger, wearing the safety belt provided, should not position himself or herself so that the air bag cover is in direct contact with the occupants' body.
The front air bags and safety belt buckle pretensioners will deploy, in the event of an impact that exceeds the deployment threshold, either by a direct front impact or when the impact angle is up to 30 degrees from the left or right of the vehicle center line.
The air bags, driver safety belt retractor pretensioner and the front passenger safety belt buckle pretensioners will deploy only once. In a collision in which they deployed at the first impact, the air bag(s) and safety belt pretensioners will not reduce the risk of injury in a subsequent impact.
In the event of a side impact, in which the side air bags (if equipped) deploy, the front air bags will still deploy in a subsequent front impact, provided that the front impact exceeds the triggering threshold.
Under certain circumstances, although the damage sustained by the vehicle may look extensive, the impact may remain below the triggering threshold of the SRS and the air bags will not deploy. In such circumstances the safety belts would provide sufficient protection for the occupants.
The visible VIN plate, which shows the air bag symbol and either X1, X2 or X4 dependent on the number of air bags fitted, is attached to the windshield edge of the instrument panel.
Vehicles equipped with side air bags can be identified by an embossed AIRBAG logo on the seat fabric adjacent to the air bag module. A label is attached to the B-pillar adjacent to the seat.
WARNING: ALL VEHICLES FITTED WITH THE FRONT PASSENGER AIR BAG FROM THE FACTORY HAVE A WARNING STICKER ATTACHED TO THE INSTRUMENT PANEL, PROHIBITING THE USE OF REAR FACING CHILD OR BABY SEATS.
It is not possible under any circumstances to disable the front passenger air bag while maintaining the integrity of the whole SRS.
The SRS consists of the following components:
^ Air bag control module
^ Front two stage air bag modules
^ Side air bag modules
^ Front passenger safety belt buckle and pretensioner (includes a safety belt buckle switch)
^ Driver safety belt retractor and pretensioner
^ Clockspring
^ Crash sensor
^ Side impact sensors (vehicle equipped with side air bags)
^ Driver seat position sensor
^ Air bag warning indicator
Air Bag Control Module
The air bag control module, located under the floor console, governs the operation of the whole system and performs continual system diagnostics. Information on the severity of an impact is received from the crash sensor and, in the event of a side impact, the corresponding side impact sensor.
In the event of a frontal impact, in excess of a predetermined limit, the air bag control module will evaluate the signal received from the crash sensor and deploy the front air bag modules, driver safety belt retractor pretensioner and the front passenger safety belt buckle pretensioner dependent on the detected crash severity. However, the safety belt buckle pretensioners will only deploy if the safety belt buckle is fastened.
In the event of a side impact, in excess of a predetermined limit, the air bag control module will evaluate the signal received from the side impact sensors and deploy the corresponding side air bag module dependent on the detected crash type.
In the event of a failure in the vehicle power supply during an accident the air bag control module provides an auxiliary power supply sufficient to deploy the air bag(s) for a minimum of 150 mS. The vehicle battery supply maintains the air bag control module auxiliary supply and supports all other SRS functions when the ignition is in the 'RUN' position. In the event of a fault being detected by the air bag control module the air bag warning indicator is illuminated. The behavior of the warning indicator depends on the type of fault present.
A new air bag control module must be installed following a collision in which the safety belt pretensioners or air bag(s) are deployed.
The driver air bag module is fitted to the steering wheel, the cover forming the outer surface of the steering wheel boss. The cover has invisible 'split lines' moulded in its surface allowing the air bag to easily exit through the cover when the system deploys.
A new driver air bag module and wiring harness with the air bag module electrical connectors must be installed following deployment.
The front passenger air bag module is located above the glove compartment and is secured to the cross-vehicle beam and the instrument panel. The front passenger air bag has a visible air bag door to allow the front passenger air bag to easily exit when the system deploys.
A new instrument panel, front passenger air bag module and wiring harness with the air bag module electrical connectors must be installed following deployment.
Both the driver and front passenger air bag modules contain two inflators.
Front Two Stage Air Bag Modules:
In the event of a frontal impact, in excess of a predetermined limit, the air bag control module will deploy the driver air bag module first stage inflator. The second stage deployment is determined by the incident severity and the seat position sensor. From the evaluation of these conditions the second stage is either deployed between 10 mS and 30 mS or 100 mS following the first stage deployment.
The air bag control module will also deploy the front passenger air bag module first stage inflator. The second stage deployment is determined by the incident severity and occurs between 20 mS and 30 mS or 100 mS following the first stage deployment.
Deployment at 100 mS has negligible effect on the air bag inflation but is used as a "disposal" function to eliminate the risk of subsequent deployments.
Side Air Bag Modules
The side air bag, if equipped, will deploy on the same side that the air bag control module received the signal from the side impact sensor. The side air bag modules are integrated into the front seat backrests providing an unobtrusive appearance. The unique seat cover has been designed to accommodate air bag deployment. When the side air bag is deployed the stitched seam of the seat cover adjacent to the side air bag module splits, allowing the air bag to exit the seat backrest unobstructed.
A new seat must be installed following a side air bag deployment.
When the air bag(s) deploy, they remain fully inflated for only a fraction of a second and start to deflate immediately, cushioning the occupant. The high speed of inflation, along with the surrounding events and noise from the impact, can give the impression that the air bag(s) did not deploy to their full extent.
The air bag(s) are a one-piece woven item with a silicon coating to provide flame and heat protection in the vicinity of the inflator. The shape of the front passenger and side air bags (if equipped) are tailored to the vehicles proportions. In order to prevent the folds of the air bag from sticking together in its tightly stowed position, the fabric may be treated with talcum powder. When the air bag(s) deploy, some of the fine powder is blown into the vehicle. This powder is visible as a dust cloud and also has a characteristic odor. The particles soon settle and do not represent a health risk. The dust cloud is not a sign of external combustion outside the air bag inflator cartridge.
In certain circumstances slight grazing or minor friction burns can result from an air bag deployment.
There are two processes which are involved:
^ Friction can occur between the fabric of the air bag and unprotected areas of the skin, either during its very rapid deployment or when the occupant contacts the air bag.
^ Hot gases from the charge used to inflate the air bag vent as it starts to deflate. Depending on the position of the drivers hands, or how close the occupant is to the air bag, it is not always possible to exclude the possibility of these gases contacting the areas of skin unprotected by clothing.
Front passenger Safety Belt Buckle and Pretensioner
The front passenger safety belt buckle and pretensioner is seat mounted and incorporate a safety belt buckle switch. In the event of a front impact the air bag control module will deploy the pretensioner provided the safety belt buckle is fastened. The front passenger safety belt buckle pretensioner has a lower deployment threshold than that required by the air bags. Hence it is possible during a minor collision, which exceeds the deployment threshold, that only the safety belt pretensioner will deploy. The air bag control module receives information on the status of the safety belt buckle from a switch contained in the buckle.
A new front passenger safety belt buckle and pretensioner must be installed following deployment.
Driver Safety Belt Retractor and Pretensioner
In the event of a front impact the air bag control module will deploy the pretensioner provided the safety belt buckle is fastened. The driver safety belt retractor pretensioner has a lower deployment threshold than that required by the air bags. Hence it is possible during a minor collision, which exceeds the deployment threshold, that only the safety belt pretensioner will deploy. The air bag control module receives information on the status of the safety belt buckle from a switch contained in the buckle.
A new driver safety belt retractor and pretensioner must be installed following deployment.
Clockspring
The clockspring is designed to carry signals between the air bag control module and the driver air bag module. The clockspring is fitted to the steering column and consists of fixed and moving parts connected by a coiled Mylar tape with integral conducting tracks. The Mylar tape is able to 'wind up' and 'unwind' as the steering wheel (to which the moving part is attached) is turned, maintaining electrical contact at all times between the air bag control module and the driver air bag module.
A new clockspring must be installed following a driver air bag deployment.
Crash Sensor
The front crash sensor is located under the radiator grille opening panel to facilitate impact sensing along the longitudinal axis. The air bag control module processes the crash data sent by the front crash sensor and deploys the front air bag(s).
Install new components following a frontal impact:
^ if the safety belt pretensioners and front air bag(s) do not deploy, install a new radiator grille opening panel if it is damaged.
^ if either the safety belt pretensioners or front air bag(s) deploy, a new crash sensor and a new radiator grille opening panel must be installed.
Side Impact Sensor
The side impact sensors (if equipped) are located on the floor panel under the front seats to facilitate lateral impact sensing. In the event of a side impact the air bag control module processes the crash data sent by the side impact sensor. The air bag control module will deploy the side air bag, in the event of an impact which exceeds the deployment threshold, on the side the deployment request was initiated.
A new side impact sensor must be installed following a side impact in which a side air bag deploys.
Seat Position Sensor:
The seat position sensor is located on the driver seat track. The seat position sensor determines the position of the driver seat, which is then communicated to the air bag control module. If the driver seat is in the forward position and the safety belt buckles are not fastened, the driver air bag second stage will deploy at 100 mS following the first stage deployment.
Air Bag Warning Indicator:
The air bag warning indicator is located in the instrument cluster. In the event of a fault being detected by the air bag control module the warning indicator flashes a corresponding flash code five times and then remains illuminated.