Restraints and Safety Systems: Description and Operation

This vehicle is equipped with a Frontal Impact Air bag System, which utilizes the driver/passenger air-bags, two front impact sensors, and seat belt tensioners located in the front seat belt buckles. This system is designed to protect occupants in the event of a front impact collision. These airbags are all serviceable parts. The tensioners are integral to the front seat belt buckles. If these pyrotechnics are deployed or defective, they must be replaced.

Vehicles equipped with the Side Impact Airbag System utilize a curtain airbag, three side impact sensors, and the Occupant Restraint Controller (ORC) to determine if the airbag should be deployed. Following a side impact event where the side airbag was deployed, the headliner as well as the curtain airbag must be replaced.

The occupant restraints include both active and passive types. Active restraints are those which require the vehicle occupants to take some action to employ, such as fastening a seat belt; while passive restraints require no action by the vehicle occupants to be employed.

ACTIVE RESTRAINTS
The active restraints include:
- Front Seat Belts - Both front seating positions are equipped with three-point seat belt systems employing a lower B-pillar mounted inertia latch-type retractor, height-adjustable upper B-pillar mounted turning loops, a fixed lower seat belt anchor secured to the lower B-pillar, and a traveling end-release buckle secured to the inboard side of the seat cushion frame. The driver side front seat belt buckle includes an integral Hall-effect seat belt switch that detects whether the driver side front seat belt has been fastened.
- Rear Seat Belts - Both outboard rear second and third seating positions are equipped with three point seat belt systems. The outboard seating position belts employ a lower C or D-pillar mounted inertia latch-type retractor, a fixed position upper C or D-pillar mounted turning loop, and a fixed lower seat belt anchor secured to the inboard side of the seat cushion frame.
- Child Restraint Anchors - Also equipped in this vehicle are two, fixed-position, child seat upper tether anchors located on the lower seat cushion, in the rear of the lower seat cushion. There is one anchor integral to the back of the third row seat back panel, one on each seat back panel. Two lower second row anchors are also provided for each rear outboard seating position. The lower anchors are integral to the seat cushion frame and are accessed from the front of the second row seat where the seat back meets the seat cushion.

The primary passenger restraints in this or any other vehicle are the seat belts and child restraint anchors. Seat belts and child restraint anchors are referred to as an active restraint because the vehicle occupants are required to physically fasten and properly adjust these restraints in order to benefit from them. See the owner's manual in the vehicle glove box for more information on the features, use and operation of all of the active restraints.

PASSIVE RESTRAINTS
The passive restraints available for this model include the following:
- Dual Front Airbags - Multistage driver. front passenger, and driver knee blocker airbags are available for this model. This airbag system is a passive, inflatable, Supplemental Restraint System (SRS) and vehicles with this equipment can be readily identified by the "SRS - AIRBAG" logo molded into the driver airbag trim cover in the center of the steering wheel and also into the passenger airbag door on the instrument panel above the glove box. Vehicles with the airbag system can also be identified by the airbag indicator, which will illuminate in the instrument cluster for about seven seconds as a bulb test each time the ignition switch is turned to the ON position. A pyrotechnic-type seat belt tensioner is integral to the driver and passenger front seat belt buckle of all models equipped with dual front airbags.

Pad Indicator:

- Occupant Classification System - These vehicles also include an Occupant Classification System (OCS) with components that are located on or in the passenger front seat cushion. These components include an Occupant Classification Module (OCM) and a seat weight bladder and pressure sensor assembly. In addition, this system includes a belt tension sensor integral to the lower anchor of the passenger side front seat belt. Vehicles equipped with the OCS can be readily identified by a Passenger Air-bag Disabled (PAD) indicator located in the center stack on the instrument panel above HVAC control head and radio.

SRS Logo:

- Curtain Airbags - Curtain airbags are available for this model when it is also equipped with dual front airbags. This airbag system is a passive, inflatable, Supplemental Restraint System (SRS) and vehicles with this equipment can be readily identified by a molded identification trim button with the "SRS - AIRBAG" logo located on the headliner above each B-pillar.

This vehicle is equipped with a Frontal Impact Air-bag System, which utilizes the driver/passenger air-bags, driver knee blocker airbag, and seat belt tensioners. This system is designed to protect occupants in the event of a front impact collision. These airbags and seat belt tensioners are all serviceable parts. If these pyrotechnics are deployed or defective, they must be replaced, as well as the Occupant Restraint Controller (ORC) must be diagnosed following procedures outlined in the diagnostic information.

The Driver and Passenger Airbag System was designed to reduce the likelihood of injury or death in frontal collisions. Each separate system is supplemental or Passive to the primary restraint device, which are the seat belts.
- Airbag Indicator - The airbag indicator is integral to the Instrument Cluster, which is located on the instrument panel in front of the driver.
- Belt Tension Sensor - Vehicles equipped with the Occupant Classification System (OCS) include a belt tension sensor. This sensor is integral to the passenger side front seat belt lower anchor which is secured to the floor, out board and rear of the front passenger seat. concealed beneath an access cover on the seat belt assembly.

Airbag Component Location Instrument Panel:

- Clockspring - The clockspring is located near the top of the steering column, directly beneath the steering wheel.
- Curtain Airbag - A side curtain airbag is located on each inside roof side rail above the headliner, and extends from the A-pillar to just beyond the D-pillar.
- Driver Airbag - The driver airbag is located in the center of the steering wheel, beneath the driver airbag trim cover.
- Front Impact Sensor - Two front impact sensors are used on vehicles equipped with dual front airbags, one left side and one right side. The sensors are located on the rail tips, rearward of the bumper attachments.
- Knee Blocker Airbag - The driver knee blocker airbag is secured to the instrument panel behind the steering column opening cover.
- Occupant Classification Module - Vehicles equipped with the Occupant Classification System (OCS) include an Occupant Classification Module (OCM) which is secured to a stamped steel mounting bracket on the underside of the passenger side front seat cushion frame. The OCM can be replaced separately from the seat weight bladder and sensor assembly. IF the seat weight bladder and sensor assembly are replaced, the module will be replaced as well in the service kit. There are tamper resistant connectors on the service kit to insure correct serviceability.
- Occupant Restraint Controller - The Occupant Restraint Controller (ORC) is also sometimes referred to as the Airbag Control Module (ACM). The ORC is located on a mount on the floor transmission tunnel just underneath the instrument panel center stack.
- Passenger Airbag - The passenger airbag is located on the instrument panel, beneath the instrument panel top pad and above the glove box on the passenger side of the vehicle.
- Passenger Airbag Disabled (PAD) Indicator - Vehicles equipped with the Occupant Classification System (OCS) include a passenger airbag disabled (PAD) indicator which is located in the instrument panel center stack.
- Passenger Knee Blocker - The passenger knee blocker is a structural reinforcement that is integral to and concealed within the glove box door.
- Seat Belt Tensioner - A seat belt tensioner is integral to both front seat belt buckles. The seat belt buckles are secured to the inner seat frame sides, beneath a cushion trim panel.
- Seat Weight Bladder and Pressure Sensor Assembly - Vehicles equipped with the Occupant Classification System (OCS) include a seat weight bladder that is sandwiched between an insulator pad on the top of the passenger side front seat pan and the seat cushion foam padding. A short hose connects the bladder to a pressure sensor which is secured to the Occupant Classification Module (OCM) mounting bracket on the underside of the passenger side front seat cushion frame. The seat weight bladder and pressure sensor can only be replaced as an assembly. This service kit includes the module. There are tamper resistant connectors on the service kit to insure correct serviceability. These components are not replaceable separately from the seat cushion foam. When replaced as an assembly, the complete service kit (seat cushion, bladder,/sensor, OCM, and new wiring harness) MUST be used.
- Side Impact Sensors - Six side impact sensors are used on vehicles equipped with the curtain air-bags, three left side and three right side. The first row side impact sensor is located in the B-pillar, just above the front seat belt retractor. The second row side impact sensor is located in the sliding side door track opening, just in front of the C-pillar. The third row side impact sensor is located behind the quarter trim panel, above the rear tire wheel well, between the C and D-pillars.

The ORC, the OCM, and the cluster each contain a microprocessor and programming that allow them to communicate with each other using the Programmable Communications Interface (PCI) data bus network. This method of communication is used by the ORC for control of the airbag indicators.

The passive restraints are referred to as a supplemental restraint system because they were designed and are intended to enhance the protection for the occupants of the vehicle ONLY when used in conjunction with the seat belts. They are referred to as passive restraints because the vehicle occupants are not required to do anything to make them operate; however, the vehicle occupants must be wearing their seat belts in order to obtain the maximum safety benefit from the supplemental restraint system.

The supplemental restraint system electrical circuits are continuously monitored and controlled by a microprocessor and software contained within the Occupant Restraint Controller (ORC). An airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) illuminates for about seven seconds as a bulb test each time the ignition switch is turned to the ON or START positions. Following the bulb test, the airbag indicator is turned ON or OFF by the ORC to indicate the status of the supplemental restraint system. If the airbag indicator comes ON at any time other than during the bulb test, it indicates that there is a problem in the supplemental restraint system electrical circuits. Such a problem may cause air-bags not to deploy when required, or to deploy when not required.

Deployment of the supplemental restraints depends upon the angle and severity of an impact. Deployment is not based upon vehicle speed; rather, deployment is based upon the rate of deceleration as measured by the forces of gravity (G force) upon the impact sensors. When an impact is severe enough, the microprocessor in the ORC signals the inflator of the appropriate airbag units to deploy their airbag cushions. The front seat belt tensioners are provided with a deployment signal by the ORC in conjunction with the front airbags. During a frontal vehicle impact, the knee blockers work in concert with properly fastened and adjusted seat belts to restrain both the driver and the front seat passenger in the proper position for an airbag deployment. The knee blockers also absorb and distribute the crash energy from the driver and the front seat passenger to the structure of the instrument panel. The seat belt tensioners remove the slack from the front seat belts to provide further assurance that the driver and front seat passenger are properly positioned and restrained for an airbag deployment.

When the ORC monitors a problem in any of the dual front airbag system circuits or components, including the seat belt tensioners, it stores a Diagnostic Trouble Code (DTC) in its memory and sends an electronic message to the EMIC to turn on the airbag indicator. Proper testing of the supplemental restraint system components, the Programmable Communications Interface (PCI) data bus, the electronic message inputs to and outputs from the EMIC or the ORC, as well as the retrieval or erasure of a DTC from the ORC or the EMIC requires the use of a scan tool. Refer to the appropriate diagnostic information.

OCCUPANT CLASSIFICATION SYSTEM
The Occupant Classification System (OCS) automatically suppresses or enables passenger airbag and seat belt tensioner operation based upon whether or not the passenger side front seat is occupied and, if the seat is occupied, classifies the size of the occupant and whether the seat is occupied by a child seat.

The OCS has an Occupant Classification Module (OCM) that monitors inputs from the seat weight bladder pressure sensor under the passenger front seat cushion and from the belt tension sensor on the passenger front seat belt lower anchor. Based upon those inputs the microprocessor within the OCM classifies the occupant of the passenger front seat. The OCM then sends electronic occupant classification messages to the ORC. The microprocessor and programming of the ORC uses these occupant classification messages to determine whether to enable or disable the deployment circuits for the passenger air-bag and seat belt tensioner. These components are not replaceable separately from the seat cushion foam. When replaced as an assembly, the complete service kit (seat cushion, bladder,/sensor, OCM, and new wiring harness) MUST be used.

The OCS electrical circuits and components are continuously monitored by the OCM, and the OCM is continuously monitored by the ORC. A passenger air-bag ON/OFF indicator is located in the instrument panel center stack area. This indicator receives battery current whenever the ignition switch is in the ON or START positions, and illuminates only when the ORC pulls the indicator control circuit to ground. The indicator illuminates for about seven seconds as a bulb test each time the ignition switch is turned to the ON or START positions. Following the bulb test, the indicator is turned ON or OFF by the ORC based upon the electronic occupant classification messages received from the OCM. This indicator is illuminated whenever the passenger airbag and seat belt tensioner operation has been suppressed, and is turned OFF whenever they are enabled or when the passenger seat is classified as empty.

When the OCM monitors a problem in any of the OCS circuits or components, it stores a fault code or DTC in its memory circuit and sends an electronic message to the ORC. The ORC then sends an electronic message to the EMIC to turn ON the airbag indicator. If for any reason the OCM is unable to classify the occupant it sends an electronic message to the ORC, and the ORC suppresses passenger air-bag and seat belt tensioner operation. Proper testing of the OCS components, the Programmable Communications Interface (PCI) data bus, the electronic message inputs to and outputs from the OCM, the EMIC or the ORC, as well as the retrieval or erasure of a DTC's, requires the use of a scan tool. Refer to the appropriate diagnostic information.