Part 2 of 2
DRIVER AIRBAGFig.12 Driver Airbag:
The black, injection molded, thermoplastic driver airbag protective trim cover is the most visible part of the driver airbag. The driver airbag is located in the center of the steering wheel, where it is secured with two screws to the armature of the four-spoke steering wheel. All models have a Dodge Ram logo embossed in the center of the trim cover. Concealed beneath the driver airbag trim cover are the horn switch, the folded airbag cushion, the airbag housing, the airbag inflator, and the retainers that secure the inflator to the airbag housing. The airbag cushion, housing, inflator, and horn switch unit is secured within an integral receptacle on the back of the trim cover. The four vertical walls of this receptacle have a total of twelve small windows with blocking tabs that are engaged by twelve hook formations around the perimeter of the airbag housing. Each hook is inserted through one of the windows, and an integral blocking tab in each window keeps each hook properly engaged with the trim cover, locking the cover securely into place.
Fig.11 Horn Switch:
The resistive membrane-type horn switch is secured within a plastic tray that is inserted in a pocket or pouch sewn onto the airbag cushion retainer strap, between the trim cover and the folded airbag cushion. One horn switch pigtail wire has an eyelet terminal connector that is captured beneath a nut and washer on the upper right inflator mounting stud. The other horn switch pigtail wire is routed between the upper left inflator mounting stud and the inflator, where it is captured by a small plastic retainer that is pushed onto the stud.
The airbag used in this model is a Next Generation-type that complies with revised federal airbag standards to deploy with less force than those used in some prior models. A 65 centimeter (25.5 inch) diameter, radial deploying fabric cushion with internal tethers is used. The airbag inflator is a conventional non-azide, pyrotechnic-type unit with a flange and four studs that also serves as the airbag cushion retainer and is secured to the stamped metal airbag housing with four nuts. A connector receptacle on the driver airbag inflator connects the inflator initiator to the vehicle electrical system through a yellow-jacketed, two-wire pigtail harness of the clockspring.
The driver airbag cannot be repaired, and must be replaced if deployed or in any way damaged. The driver airbag trim cover and the horn switch with tray may be disassembled from the driver airbag unit, and are available for separate service replacement.
The driver airbag is deployed by an electrical signal generated by the Airbag Control Module (ACM) through the driver airbag squib circuit to the initiator in the airbag inflator. When the ACM sends the proper electrical signal to the initiator, the electrical energy generates enough heat to initiate a small pyrotechnic charge which, in turn ignites chemical pellets within the inflator. Once ignited, these chemical pellets burn rapidly and produce a large quantity of inert gas. The inflator is sealed to the back of the airbag housing and a diffuser in the inflator directs all of the inert gas into the airbag cushion, causing the cushion to inflate. As the cushion inflates, the driver airbag trim cover will split at predetermined breakout lines, then fold back out of the way along with the horn switch and tray unit. Following an airbag deployment, the airbag cushion quickly deflates by venting the inert gas towards the instrument panel through the porous fabric material used to construct the back (steering wheel side) panel of the airbag cushion.
Some of the chemicals used to create the inert gas may be considered hazardous while in their solid state before they are burned, but they are securely sealed within the airbag inflator. Typically, all potentially hazardous chemicals are burned during an airbag deployment event. The inert gas that is produced when the chemicals are burned is harmless. However, a small amount of residue from the burned chemicals may cause some temporary discomfort if it contacts the skin, eyes, or breathing passages. If skin or eye irritation is noted, rinse the affected area with plenty of cool, clean water. If breathing passages are irritated, move to another area where there is plenty of clean, fresh air to breath. If the irritation is not alleviated by these actions, contact a physician.
PASSENGER AIRBAG
The rearward facing surface of the injection molded, thermoplastic passenger airbag is the most visible part of the passenger airbag. The passenger airbag door is located above the glove box opening in front of the front seat passenger seating position on the instrument panel. Return flanges near the top and bottom of the airbag door feature windows that are engaged on hook formations at the top and bottom of the airbag housing. Three tabs extend downward from the lower return flange and are secured with the same screws that secure the glove box module to the upper glove box opening reinforcement. Five molded snap features along the top of the airbag door above the upper return flange snap into receptacles located in the instrument panel base trim just below the instrument panel top cover. The molded plastic passenger airbag door has a predetermined horizontal breakout line near its center which is concealed beneath its decorative outer surface.
The passenger airbag unit used in this model is a Next Generation-type that complies with revised federal airbag standards to deploy with less force than those used in some prior models. Concealed beneath the passenger airbag door are the folded airbag cushion, the airbag cushion retainer, the airbag housing, and the airbag inflator. An approximately 55 centimeter (21.5 inch) wide by 65 centimeter (35.5 inch) high rectangular fabric cushion is used. The airbag inflator is a compressed gas, hybrid-type unit that is secured to and sealed within the airbag housing along with the folded airbag cushion. A yellow connector insulator on the end of a short, two-wire pigtail harness connects the passenger airbag inflator initiator to the vehicle electrical system through a dedicated take out and connector of the instrument panel wire harness. The airbag housing is constructed of a long U-shaped aluminum extrusion with two stamped steel end plates. Two tabs that extend from the bottom of the extrusion serve as the rear mounting brackets, while an angled foot on the bottom of each end plate serve as the front mounting brackets. The front brackets are secured with screws to the instrument panel armature above the glove box, while the rear brackets are secured with screws to the upper glove box opening reinforcement.
Following a passenger airbag deployment, the passenger airbag and airbag door unit must be replaced. The passenger airbag cannot be repaired, and must be replaced if faulty or in any way damaged. The passenger airbag door is serviced only as a unit with the passenger airbag.
The passenger airbag is deployed by an electrical signal generated by the Airbag Control Module (ACM) through the passenger airbag squib circuits to the initiator in the airbag inflator. The hybrid-type inflator assembly includes a small canister of highly compressed inert gas.
When the ACM sends the proper electrical signal to the airbag inflator, the initiator converts the electrical energy into chemical energy. this chemical energy ruptures a containment disk to allow the inert gas to flow into the airbag cushion. The inflator is sealed to the airbag cushion so that all of the released inert gas is directed into the airbag cushion, causing the cushion to inflate. As the cushion inflates, the passenger airbag door will split predetermined tear seam lines concealed on the inside surface of the door, then the two halves of the door will pivot out of the way Following an airbag deployment, the airbag cushion quickly deflates by venting the inert gas through vent holes within the fabric used to construct the back (instrument panel side) of the airbag cushion.
Some of the chemicals used to create the pressure to burst the inert gas containment disk are considered hazardous in their solid state, before they are burned, but they are securely sealed within the airbag inflator. However, the gas that is produced when the chemicals are burned is harmless. A small amount of residue from the burned chemicals may cause some temporary discomfort if it contacts the skin, eyes, or breathing passages. If skin or eye irritation is noticed, rinse the affected area with plenty of cool, clean water. If breathing passages are irritated, move to another area where there is plenty of clean, fresh air to breath. If the irritation is not alleviated by these actions, contact a physician immediately.
SEAT BELT SWITCH
The seat belt switch is a small, normally open, single pole, single throw, plunger actuated, momentary switch. Only one seat belt switch is installed in the vehicle, and it is integral to the driver seat belt retractor assembly. The seat belt switch is connected to the vehicle electrical system through a short pigtail wire to a dedicated take out and connector of the body wire harness.
The seat belt switch cannot be adjusted or repaired and, if faulty or damaged, the entire driver seat belt and retractor unit must be replaced.
The seat belt switch is designed to control a path to ground for the seat belt switch sense input of the Electro-Mechanical Instrument Cluster (EMIC). The seat belt switch plunger is actuated by the seat belt webbing wound onto the seat belt retractor spool. When the seat belt tip-half webbing is pulled out of the retractor far enough to engage the seat belt buckle-half, the switch plunger is extended and closes the seat belt switch sense circuit to ground; and, when the seat belt tip-half webbing is wound onto the retractor the switch plunger is depressed, opening the ground path. The EMIC monitors the seat belt switch status, then controls the seatbelt indicator and sends electronic chime request messages over the Programmable Communications Interface (PCI) data bus to the Central Timer Module (CTM) based upon that input.
The seat belt switch receives ground through its pigtail wire connection to the body wire harness from another take out of the body wire harness. An eyelet terminal connector on that ground take out is secured under a ground screw to the left lower B-pillar. The seat belt switch is connected in series between ground and the seat belt switch sense input of the EMIC.
SEAT BELT TENSIONER
Seat belt tensioners supplement the airbag system for this model. The seat belt tensioners are integral to the front seat belt retractors, which are secured within each B-pillar in the vehicle where they are concealed behind the B-pillar trim. The seat belt tensioner consists primarily of a sprocket/pin/on, a steel tube, a cast metal housing, numerous steel balls, a stamped metal ball trap, a torsion bar, a small pyrotechnically activated gas generator, and a short pigtail wire. All of these components are located on one side of the retractor spool on the outside of the retractor housing except for the torsion bar, which serves as the spindle upon which the retractor spool rides. The seat belt tensioners are controlled by the Airbag Control Module (ACM) and are connected to the vehicle electrical system through a dedicated take out of the body wire harness by a keyed and latching yellow molded plastic connector insulator to ensure a secure connection.
The seat belt tensioners cannot be repaired and, if faulty or damaged, the entire front seat belt, retractor, and tensioner unit must be replaced. The seat belt tensioners are not intended for reuse, and both tensioners must be replaced following any airbag deployment. A growling or grinding sound while attempting to operate the seat belt retractor is a sure indication that the seat belt tensioner has been deployed and requires replacement. For seat belt tensioner service procedures, (Refer to ELECTRICAL/RESTRAINTS/FRONT SEAT BELT & RETRACTOR - REMOVAL).
The seat belt tensioners are deployed in conjunction with the airbags by a signal generated by the Airbag Control Module (ACM) through the driver or passenger seat belt tensioner line 1 and line 2 (or squib) circuits. When the ACM sends the proper electrical signal to the tensioner, the electrical energy generates enough heat to initiate a small pyrotechnic gas generator. The gas generator is installed in one end of a steel tube that 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. Removing excess slack from the front seat belts not only keeps the occupants properly positioned for an airbag deployment following a frontal impact of the vehicle, but also helps to reduce the likelihood of a harmful contact with interior components. Also, the seat belt tensioner torsion bar that the retractor spool rides upon is designed to deform in order to control the loading being applied to the occupants by the seat belts during a frontal impact, further reducing the potential for occupant injuries. All damaged, faulty or non-deployed seat belt tensioners must be disposed of properly.(Refer to ELECTRICAL/RESTRAINTS - STANDARD PROCEDURE).
The ACM monitors the condition of the seat belt tensioners through circuit resistance, and will illuminate the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) and store a Diagnostic Trouble Code (DTC) for any fault that is detected. For proper diagnosis of the seat belt tensioners, a DRB III scan tool is required Refer to the appropriate diagnostic information.
SIDE CURTAIN AIRBAG
Fig.2 SRS Logo:
Optional side curtain airbags are available for this model when it is also equipped with dual front airbags. These airbags are passive, inflatable, Supplemental Restraint System (SRS) components, 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 system is designed to reduce injuries to the vehicle occupants in the event of a side impact collision.
Fig.30 Side Curtain Airbag:
Vehicles equipped with side curtain airbags have two individually controlled curtain airbag units. These airbag units are concealed and mounted above the headliner where they are each secured to one of the roof side rails. Each folded airbag cushion is contained within a long extruded plastic channel that extends along the roof rail from the A-pillar at the front of the vehicle to between the C and D-pillar at the rear of the vehicle. The channel is located with plastic push-in fasteners to the roof rail. A tether extends down the A-pillar from the front of the airbag cushion, where it is retained to the pillar with plastic push-in routing clips and it is secured to a slot at the base of the A-pillar near the belt line with a hook.
The hybrid-type inflator for each airbag is located with plastic push-in fasteners to the roof rail at the rear of the airbag unit near the D-pillar, and is connected to the airbag cushion by a long tubular manifold. The bracket holding the inflator and the other brackets holding the manifold and channel are secured with screws to U-nuts in the roof rail. A two-wire take out of the body wire harness with a keyed and latched connector insulator connects directly to an integral receptacle on the inflator initiator.
The side curtain airbag unit cannot be adjusted or repaired and must be replaced if deployed, faulty, or in any way damaged. Once a side curtain airbag has been deployed, the complete airbag unit, the headliner, the upper A, B, C and D-pillar trim, and all other visibly damaged components must be replaced.
Each side curtain airbag is deployed individually by an electrical signal generated by the left or right Side Impact Airbag Control Module (SIACM) to which it is connected through left or right curtain airbag line 1 and line 2 (or squib) circuits. The hybrid-type inflator assembly for each airbag contains a small canister of highly compressed inert gas. When the SIACM sends the proper electrical signal to the airbag inflator, the electrical energy creates enough heat to ignite chemical pellets within the inflator. Once ignited, these chemicals burn rapidly and produce the pressure necessary to rupture a containment disk in the inert gas canister. The inflator and inert gas canister are sealed and connected to a tubular manifold so that all of the released inert gas is directed into the folded curtain airbag cushion, causing the cushion to inflate.
As the airbag cushion inflates it will drop down from the roof rail between the edge of the headliner and the side glass/body pillars to form a curtain-like cushion to protect the vehicle occupants during a side impact collision. The front tether keeps the front portion of the bag taut, thus ensuring that the bag will deploy in the proper position. Following the airbag deployment, the airbag cushion quickly deflates by venting the inert gas through the loose weave of the cushion fabric, and the deflated cushion hangs down loosely from the roof rail.
Fig.32 Side Impact Airbag Control Module:
SIDE IMPACT AIRBAG CONTROL MODULE
On vehicles equipped with the optional side curtain airbags, a Side Impact Airbag Control Module (SIACM) and its mounting bracket are secured with four screws to the inside of each B-pillar above the front seat belt retractor, and concealed behind the B-pillar trim . Concealed within a hollow in the center of the die cast aluminum SIACM housing is the electronic circuitry of the SIACM which includes a microprocessor and an electronic impact sensor. The SIACM housing is secured to a stamped steel mounting bracket, which is unique for the right or left side application of this component. The SIACM should never be removed from its mounting bracket. The housing also receives a case ground through this mounting bracket when it is secured to the vehicle. A molded plastic electrical connector receptacle that exits the top of the SIACM housing connects the unit to the vehicle electrical system through a dedicated take out and connector of the body wire harness. Both the SIACM housing and its electrical connection are sealed to protect the internal electronic circuitry and components against moisture intrusion.
The impact sensor internal to the SIACM is calibrated for the specific vehicle, and is only serviced as a unit with the SIACM. The SIACM cannot be repaired or adjusted and, if damaged or faulty, it must be replaced.
The microprocessor in the Side Impact Airbag Control Module (SIACM) contains the side curtain airbag system logic circuits and controls all of the features of only the side curtain airbag mounted on the same side of the vehicle as the SIACM. The SIACM uses On-Board Diagnostics (OBD) and can communicate with other electronic modules in the vehicle as well as with the DRB III scan tool using the Programmable Communications Interface (PCI) data bus network. This method of communication is used by the SIACM to communicate with the Airbag Control Module (ACM) and for supplemental restraint system diagnosis and testing through the 16-way data link connector located on the driver side lower edge of the instrument panel. The ACM communicates with both the left and right SIACM over the PCI data bus.
The SIACM microprocessor continuously monitors all of the side curtain airbag electrical circuits to determine the system readiness. If the SIACM detects a monitored system fault, it sets an active and stored Diagnostic Trouble Code (DTC) and sends electronic messages to the ACM over the PCI data bus. The ACM will respond by sending an electronic message to the EMIC to turn ON the airbag indicator, and by storing a DTC that will indicate whether the left or the right SIACM has stored the DTC that initiated the airbag indicator illumination. An active fault only remains for the current ignition switch cycle, while a stored fault causes a DTC to be stored in memory by the SIACM. For some DTCs, if a fault does not recur for a number of ignition cycles, the SIACM will automatically erase the stored DTC. For other internal faults, the stored DTC is latched forever.
The SIACM receives battery current on a fused ignition switch output (run-start) circuit through a fuse in the Junction Block (JB). The SIACM has a case ground through its mounting bracket and also receives a power ground through a ground circuit and take out of the body wire harness. This take out has a single eyelet terminal connector that is secured by a ground screw to the body sheet metal. These connections allow the SIACM to be operational whenever the ignition switch is in the Start or ON positions. An electronic impact sensor is contained within the SIACM. The electronic impact sensor is an accelerometer that senses the rate of vehicle deceleration, which provides verification of the direction and severity of an impact. A pre-programmed decision algorithm in the SIACM microprocessor determines when the deceleration rate as signaled by the impact sensor indicates a side impact that is severe enough to require side curtain airbag protection. When the programmed conditions are met, the SIACM sends the proper electrical signals to deploy the side curtain airbag.
The hard wired inputs and outputs for the SIACM may be diagnosed and tested using conventional diagnostic tools and procedures. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the SIACM, the PCI data bus network, or the electronic message inputs to and outputs from the SIACM. The most reliable, efficient, and accurate means to diagnose the SIACM, the PCI data bus network, and the electronic message inputs to and outputs from the SIACM requires the use of a DRB III scan tool. Refer to the appropriate diagnostic information.