Restraints and Safety Systems: Description and Operation
An occupant restraint system is standard factory-installed safety equipment on this model. Available occupant restraints for this model 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 for this model include:
- Front Seat Belts - Both outboard front seating positions are equipped with three-point seat belt systems employing a lower B-pillar mounted inertia latch-type emergency locking retractor, height-adjustable upper B-pillar mounted turning loops, a fixed lower seat belt anchor secured to the lower B-pillar (standard cab) or floor panel adjacent to the B-pillar (quad cab), and a traveling end-release seat belt buckle secured to the inboard seat track. The driver side retractor for standard cab models includes an electrically actuated seat belt tension reducer. Except for the driver side front seat, the retractors for all models are also switchable from an emergency locking retractor to an automatic locking retractor for compatibility with child seats. The front seat belt buckle for the driver side of all models includes an integral seat belt switch that detects whether its seat belt has been fastened. The center front seating position for standard cab models is also equipped with a three-point seat belt employing a floor panel mounted inertia latch-type retractor, a routing bracket and bezel near the top of the cab back panel, and two fixed end-release buckles secured to the center seat cushion frame. The center front seating position for quad cab and mega cab models is equipped with a fixed lap belt and an end-release buckle secured to the center seat cushion frame.
- Rear Seat Belts - On all vehicles equipped with rear seats, each rear seating position is equipped with a three-point seat belt system. The outboard seating position belts employ lower rear pillar mounted inertia latch-type emergency locking retractors, a fixed position upper C-pillar mounted turning loop (quad cab) or height adjustable upper C-pillar mounted turning loops (mega cab), and a fixed lower seat belt anchor secured to the lower C-pillar. The quad cab rear seat center seating position belt has a rear floor panel mounted inertia latchtype emergency locking retractor and a routing bracket and bezel on the top of the cab back panel, while the mega cab rear seat center position retractor and a routing bracket and bezel are mounted to the rear seat back panel. A fixed end-release buckle unit for the quad cab right outboard seating position is integral to the center retractor mounting bracket on the rear floor panel. The end-release buckle units for the quad cab center and left outboard seating positions are individually secured to the rear floor panel on vehicles with the standard equipment rear bench seat, or secured with the rear seat mounting hardware on vehicles with the optional 60/40 split rear bench seat. The rear seat retractors for all models are also switchable from an emergency locking retractor to an automatic locking retractor for compatibility with child seats.
- Child Restraint Anchors - All standard cab models are equipped with two, fixed-position, child seat upper tether anchors that are integral to the upper cab back panel reinforcement and concealed behind individual trim cover and bezel units that are integral to the cab back trim panel. All vehicles with rear seats are equipped with three child seat upper tether anchor straps that are secured to the upper cab back panel reinforcement, behind the upright rear seat back. Two lower anchors are also provided for the front outboard seating position of standard cab models, and for each rear outboard seating position on quad cab models. Mega cab models have lower anchors provided for all three rear seating positions. These lower anchors are accessed from the front of the seat where the seat back meets the seat cushion. The child seat tether and lower anchors for the front seat are deleted on quad cab and mega cab models.
The primary passenger restraints in this or any other vehicle are the standard equipment factory-installed 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.
PASSIVE RESTRAINTS
The passive restraints available for this model include the following:
- Dual Front Airbags - Multistage driver and front passenger airbags are used in 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 top of 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 Electromechanical Instrument Cluster (EMIC) for about six seconds as a bulb test each time the ignition switch is turned to the On position. A pyrotechnic-type seat belt tensioner is also integral to the front outboard seat belt retractors to work in conjunction with the dual front airbags.
- Side Curtain Airbags - Optional side 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.
The supplemental restraint system includes the following major components, which are described in further detail elsewhere:
- Airbag Indicator - The airbag indicator is integral to the Electromechanical Instrument Cluster (EMIC), which is located on the instrument panel in front of the driver.
- Clockspring - The clockspring is located near the top of the steering column, directly beneath the steering wheel.
- Driver Airbag (3) - The driver airbag is located in the center of the steering wheel, beneath the driver airbag trim cover.
- Driver Knee Blocker - The driver knee blocker is a structural unit secured to the instrument panel directly behind the instrument panel steering column opening cover.
- Front Impact Sensor (1) - Two front impact sensors are used on vehicles equipped with dual front airbags, one left side and one right side. One sensor is located on the back side of each end of the lower radiator support crossmember.
- Occupant Restraint Controller (4) - The Occupant Restraint Controller (ORC) is located on a mount on the floor panel transmission tunnel below the center section of the front seat, or under the center floor console, as the vehicle is equipped.
- Passenger Airbag (2) - The passenger airbag is located in the instrument panel, beneath the passenger airbag door on the top of the instrument panel above the glove box on the passenger side of the vehicle.
- Passenger Airbag On/Off Switch - Standard cab models with dual front airbags are equipped with a passenger airbag on/off switch, which is located in the lower right corner of the instrument panel center bezel.
- 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 (6) - The seat belt tensioner is integral to both front outboard seat belt retractor units on vehicles equipped with dual front airbags. The seat belt retractor and tensioner units are secured to the right and left inner B-pillars and concealed beneath the lower B-pillar trim.
- Seat Track Position Sensor (5) - Certain models may include a seat track position sensor that is located on the inboard side of the upper inboard seat adjuster track on the driver side front seat.
- Side Curtain Airbag (8) - In vehicles equipped with this option, a side curtain airbag is secured to each inside roof side rail above the headliner, and extends from the A-pillar to near the cab back panel.
- Side Impact Sensor (7) - Two side impact sensors are used on vehicles equipped with the optional side curtain airbags, one left side and one right side. One sensor is located behind the B-pillar trim within each B-pillar.
The ORC and the EMIC each contain a microprocessor and programming that allow them to communicate with each other using the Controller Area Network (CAN) data bus. This method of communication is used by the ORC for control of the airbag indicator in the EMIC.
Hard wired circuitry connects the supplemental restraint system components to each other through the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system, and to the supplemental restraint system components through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
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 factory-installed 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 six 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 airbags 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 outboard 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 right 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 right front seat passenger to the structure of the instrument panel. The seat belt tensioners remove the slack from the outboard front seat belts to provide further assurance that the driver and right front seat passenger are properly positioned and restrained for an airbag deployment.
Typically, the vehicle occupants recall more about the events preceding and following a collision than they do of an airbag deployment itself. This is because the airbag deployment and deflation occur very rapidly. In a typical 48 kilometer-per-hour (30 mile-per-hour) barrier impact, from the moment of impact until the airbags are fully inflated takes about 40 milliseconds. Within one to two seconds from the moment of impact, the airbags are almost entirely deflated. The times cited for these events are approximations, which apply only to a barrier impact at the given speed. Actual times will vary somewhat, depending upon the vehicle speed, impact angle, severity of the impact, and the type of collision.
When the ORC monitors a problem in any of the supplemental restraint system circuits or components, including the seat belt tensioners, it stores a fault code or Diagnostic Trouble Code (DTC) in its memory circuit and sends an electronic message to the EMIC to turn on the airbag indicator. Proper testing of the supplemental restraint system components, the Controller Area Network (CAN) 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 EMIC requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic trouble code charts.
See the vehicle glove box for more information on the features, use and operation of all of the factory-installed passive restraints.