OPERATION
The multistage Driver AirBag (DAB) is deployed by electrical signals generated by the Occupant Restraint Controller (ORC) through the DAB squib 1 and squib 2 circuits to the two initiators in the airbag inflator. By using two initiators, the airbag can be deployed at multiple levels of force. The force level is controlled by the ORC to suit the monitored impact conditions by providing one of several delay intervals between the electrical signals provided to the two initiators. The longer the delay between these signals, the less forcefully the airbag will deploy.
When the ORC sends the proper electrical signals to each 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 DAB 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 DAB trim cover will split at predetermined breakout lines, then fold back out of the way. Following a deployment, the airbag cushion quickly deflates by venting the inert gas towards the instrument panel through vent holes within the fabric used to construct the back (steering wheel side) panel of the 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, both initiators are used and all potentially hazardous chemicals are burned during an airbag deployment event. However, it is possible for only one initiator to be used during a deployment due to a Supplemental Restraint System (SRS) fault; therefore, it is necessary to always confirm that both initiators have been used in order to avoid the improper disposal of potentially live pyrotechnic or hazardous materials. Refer to STANDARD PROCEDURE .
The inert gas that is produced when the chemicals are burned during a deployment 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.
The ORC monitors the condition of the DAB through circuit resistance, and will illuminate the airbag indicator in the instrument cluster and store a Diagnostic Trouble Code (DTC) for any fault that is detected. Proper diagnosis of the DAB inflator and squib circuits requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.
The multistage Passenger AirBag (PAB) is deployed by electrical signals generated by the Occupant Restraint Controller (ORC) through the PAB squib 1 and squib 2 circuits to the two initiators in the airbag inflator. By using two initiators, the PAB can be deployed at multiple levels of force. The force level is controlled by the ORC to suit the monitored impact conditions by providing one of several delay intervals between the electrical signals provided to the two initiators. The longer the delay between these signals, the less forcefully the airbag will deploy.
When the ORC sends the proper electrical signals to each 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 airbag cushion 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 PAB door will split at predetermined tear seam lines concealed on the inside surface of the door, then the door will pivot up over the top of the instrument panel and out of the way. Following an airbag deployment, the airbag cushion quickly deflates by venting the inert gas through a vent hole in each fabric side panel of the airbag cushion.
Typically, both initiators are used during a PAB deployment event. However, it is possible for only one initiator to be used during a deployment due to an airbag system fault; therefore, it is necessary to always confirm that both initiators have been used in order to avoid the improper disposal of potentially live pyrotechnic materials. Refer to STANDARD PROCEDURE .
The ORC monitors the condition of the PAB through circuit resistance, and will illuminate the airbag indicator in the instrument cluster and store a Diagnostic Trouble Code (DTC) for any fault that is detected. Proper diagnosis of the PAB inflator and squib circuits requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.
Each Seat AirBag (SAB) (also known as a pelvic and thoracic airbag) is deployed individually by an electrical signal generated by the Occupant Restraint Controller (ORC) to which it is connected through left or right SAB line 1 and line 2 (or squib) circuits. The hybrid-type inflator assembly for each SAB contains a small canister of highly compressed inert gas. When the ORC sends the proper electrical signal to the SAB 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 so that all of the released gas is directed into the folded SAB cushion, causing the cushion to inflate. As the cushion inflates it will split the retainer wrap, the sewn pouch (intensifier) and the outboard side of the seat back trim cover and expand into the area between the outboard side of the front seat and the front door to form a cushion to protect the front seat occupant during a side impact collision or a vehicle rollover incident.
Following the SAB deployment, the SAB cushion slowly deflates by venting the inert gas through the loose weave of the cushion fabric, and the deflated cushion hangs down loosely from the outboard side of the front seat back.
The ORC monitors the condition of the SAB through circuit resistance, and will illuminate the airbag indicator in the instrument cluster and store a Diagnostic Trouble Code (DTC) for any fault that is detected. Proper diagnosis of the SAB inflator and squib circuits requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.
DESCRIPTION
Side curtain airbags (also known as Side AirBag Inflatable Curtains/SABIC) are available equipment in this vehicle 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 or a vehicle rollover incident.
Scheme 1
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 fabric wrap and extruded plastic channels that extend along the roof rail from the A-pillar at the front of the vehicle to just forward of the D-pillar at the rear of the vehicle.
A long tether (3) extends down the A-pillar from the front of the airbag cushion. The end of the tether is secured to a slot in the sheet metal with a metal clip, while two additional plastic fasteners secure the tether to the inside of the A-pillar. A short tether (4) extends down the D-pillar from the rear of the airbag cushion and is also secured with a metal clip.
The hybrid-type inflator (1) for each airbag is secured to the roof rail near the rear of the airbag unit between the C-pillar and the D-pillar, and is connected to the airbag cushion by a long tubular manifold (2). The inflator bracket and the extruded airbag cushion channel are secured with both plastic push-in fasteners and screws to U-nuts installed in the roof rail.
The initiator (5) of the airbag inflator is connected to the vehicle electrical system through a dedicated take out and connector of the body wire harness near the top of the D-pillar. The body wire harness connects the airbag unit to the Occupant Restraint Controller (ORC).
The side curtain airbag unit cannot be adjusted or repaired and must be replaced if deployed, ineffective, 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 (also know as Side AirBag Inflatable Curtain/SABIC) is deployed individually by an electrical signal generated by the Occupant Restraint Controller (ORC) 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 ORC 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 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 or a vehicle rollover incident.
The front and rear tethers keep the side curtain bag taut to the side of the vehicle, thus ensuring that the bag will deploy in the proper position. Following the airbag deployment, the airbag cushion slowly 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.
The ORC monitors the condition of the side curtain airbags through circuit resistance, and will illuminate the airbag indicator in the instrument cluster and store a Diagnostic Trouble Code (DTC) for any fault that is detected. Proper diagnosis of the side curtain airbag inflator and squib circuits requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.
All vehicles manufactured for sale in the United States and Canada are required to be equipped with a Lower Anchors and Tether for CHildren, or LATCH child restraint anchorage system. The second row seats in this vehicle have two pairs of anchor provisions for installing a LATCH-compatible child seat. A single seat may be mounted in the center seating position, or one in each outboard seating position.
With LATCH, child seats are secured by direct attachment to the vehicle seat structure, rather than by the seat belts. With LATCH-compatible child seats, lower anchors attach to the seat structure through heavy-gauge wire loops located at the intersection between the seat cushion and the seat back surfaces.
Three upper tether anchors are integral to the second row seat back frames to secure the top tether strap of child seats equipped with this feature. These upper tether anchors work with both LATCH-compatible and other child seats equipped with a top tether strap.
The owner's information packet in the vehicle glove box contains details and suggestions on the proper use of all of the factory-installed child restraint anchors.
The clockspring is a mechanical electrical circuit component that is used to provide continuous electrical continuity between the fixed instrument panel wire harness and certain electrical components mounted on or in the rotating steering wheel. On this vehicle the rotating electrical components include the Driver AirBag (DAB), the horn switch, the speed control switch, and the remote radio switches, if the vehicle is so equipped. The clockspring is positioned and secured near the top of the steering column. The fixed connector receptacles on the back of the fixed clockspring case connect the clockspring to the vehicle electrical system through three take outs with connectors from the instrument panel wire harness.
The turn signal cancel cam is integral to the rim of the clockspring rotor hub within the clockspring case so it also moves with the rotation of the steering wheel. Two short, black-sleeved pigtail wires on the upper surface of the clockspring rotor connect the clockspring to the DAB, while a steering wheel wire harness connected to the connector receptacle on the upper surface of the clockspring rotor complete circuits to the horn switch, the speed control switch and, if the vehicle is so equipped, to the optional remote radio switches on the steering wheel. The third connector receptacle is dedicated to the inputs and outputs of the Steering Angle Sensor (SAS) internal to the clockspring case.
Like the clockspring in a timepiece, the clockspring tape has travel limits and can be damaged by being wound too tightly during full stop-to-stop steering wheel rotation. To prevent this from occurring, the clockspring is centered when it is installed on the steering column. Centering the clockspring indexes the clockspring tape to the movable steering components so that the tape can operate within its designed travel limits. However, if the steering wheel is removed from the steering column, if the clockspring is removed from the steering column, or if the steering shaft is disconnected from the steering gear, the clockspring spool can change position relative to the other steering components. The clockspring must be re-centered following completion of this service or the tape may be damaged.
Service replacement clocksprings are shipped pre-centered and with a plastic locking pin installed. This locking pin should not be removed until the steering wheel has been installed on the steering column. If the locking pin is removed before the steering wheel is installed on a steering column, the clockspring centering procedure must be performed. Refer to CLOCKSPRING, STANDARD PROCEDURE . Proper clockspring installation may be confirmed by viewing the SAS data using a diagnostic scan tool.
The hard wired clockspring circuits as well as the hard wired inputs and outputs of the SAS may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the SAS or the electronic controls and communication between other modules and devices that provide features of the Electronic Stability Program (ESP) or Supplemental Restraint System (SRS). The most reliable, efficient and accurate means to diagnose the SAS or the electronic controls and communication related to ESP or SRS operation requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.
The microcontroller within the Occupant Restraint Controller (ORC) contains the supplemental restraint system logic circuits and controls all of the Supplemental Restraint System (SRS) components. The ORC uses On-Board Diagnostics (OBD) and can communicate with other electronic modules in the vehicle as well as with the diagnostic scan tool using the Controller Area Network (CAN) data bus. This method of communication is used for control of the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) and for SRS diagnosis and testing through the 16-way data link connector located on the driver side lower edge of the instrument panel.
The ORC microcontroller continuously monitors all of the SRS electrical circuits to determine the system readiness. If the ORC detects a monitored system fault, it sets an active and stored Diagnostic Trouble Code (DTC) and sends electronic messages to the EMIC over the CAN data bus to turn ON the airbag indicator. An active fault only remains for the duration of the fault, or in some cases for the duration of the current ignition switch cycle, while a stored fault causes a DTC to be stored in memory by the ORC. For some DTCs, if a fault does not recur for a number of ignition cycles, the ORC will automatically erase the stored DTC. For other internal faults, the stored DTC is latched forever.
The ORC receives battery current through two circuits; a fused ignition switch output (run) circuit through a fuse in the Totally Integrated Power Module (TIPM), and a fused ignition switch output (run-start) circuit through a second fuse in the TIPM. The ORC receives ground through a ground circuit and take out of the instrument panel wire harness. These connections allow the ORC to be operational whenever the ignition switch is in the START or ON positions. Refer to the appropriate wiring information for additional details.
The ORC also contains an energy-storage capacitor. When the ignition switch is in the START or ON positions, this capacitor is continually being charged with enough electrical energy to deploy the SRS components for up to one second following a battery disconnect or failure. The purpose of the capacitor is to provide backup SRS protection in case there is a loss of battery current supply to the ORC during an impact.
Two sensors are contained within the ORC, an electronic impact sensor and a safing sensor. The ORC also monitors inputs from two remote front impact sensors located on the back of the right and left vertical members of the radiator support near the front of the vehicle. The electronic impact sensors are accelerometers that sense the rate of vehicle deceleration, which provides verification of the direction and severity of an impact. On vehicles equipped with optional side curtain airbags or seat airbags, the ORC also monitors inputs from an internal rollover sensor and four additional remote impact sensors located on the left and right inner B-pillars and C-pillars to control deployment of the side curtain airbag and seat airbag units.
The safing sensor is an electronic accelerometer sensor within the ORC that provides an additional logic input to the ORC microcontroller. The safing sensor is used to verify the need for a SRS component deployment by detecting impact energy of a lesser magnitude than that of the primary electronic impact sensors, and must exceed a safing threshold in order for the airbags to deploy. Vehicles equipped with optional side curtain airbags or seat airbags feature a second safing sensor within the ORC to provide confirmation to the ORC microcontroller of side impact forces. This second safing sensor is a bi-directional unit that detects impact forces from either side of the vehicle.
Pre-programmed decision algorithms in the ORC microcontroller determine when the deceleration rate as signaled by the impact sensors and the safing sensors indicate an impact that is severe enough to require SRS protection and, based upon the severity of the monitored impact, determines the level of front airbag deployment force required for each front seating position. When the programmed conditions are met, the ORC sends the proper electrical signals to deploy the dual multistage front airbags at the programmed force levels, the front seat belt tensioners and, if the vehicle is so equipped, either side curtain and seat airbag unit.
The hard wired inputs and outputs for the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the ORC or the electronic controls and communication between other modules and devices that provide some features of the SRS. The most reliable, efficient and accurate means to diagnose the ORC or the electronic controls and communication related to SRS operation requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information.
The Active Head Restraint (AHR) units are deployed by a signal generated by the Occupant Restraint Controller (ORC) through the first row right and left solenoid and ground signal circuits. The ORC logic monitors inputs from the front impact sensors as well as electronic message inputs received over the Controller Area Network (CAN) data bus to determine when the appropriate conditions exist to send a deployment signal to both AHR units. When the ORC detects an impact pulse of sufficient magnitude originating from the rear of the vehicle, while any transmission gear is selected except Reverse ( R ), the ORC sends the deployment signals.
When the ORC sends the proper electrical deployment signal to the solenoid of the AHR unit, the solenoid releases the AHR latch. When the AHR latch is released, the tension of the spring-loaded linkage within the AHR mechanically drives the AHR pad through a short, slightly forward and upward arc to the final deployed position. Deployment of the AHR reduces the space between the back of the head of the seat occupant and the head restraint pad. Closing this space supports the head of the seat occupant during a low speed rear impact collision event and is important in reducing or eliminating potentially debilitating cervical (also known as whiplash) injuries.
The ORC monitors the condition of the AHR unit circuits, and will illuminate the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) and store a Diagnostic Trouble Code (DTC) for any fault that is detected.
The hard wired circuits between the AHR units and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the AHR units or the electronic controls and communication between other modules and devices that provide some features of the Supplemental Restraint System (SRS). The most reliable, efficient and accurate means to diagnose the AHR units or the electronic controls and communication related to AHR unit operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
Scheme 2
If the Active Head Restraint (AHR) units have been deployed, both the driver and passenger side units must be reset. You can recognize that an AHR has been deployed by the forward position of the head restraint cushion and the large spacing between the cushion and the AHR rear trim cover.
Note. Before attempting to reset, and after each unsuccessful attempt to reset an AHR, inspect the latch mechanism within the AHR rear trim cover (1) to be certain the latch is unlatched. This can be confirmed by placing a finger on the latch catches (4) and gently rocking them rearward and forward. The catches should move freely. If the catches do not move freely, they are in the latched position and the latch must be opened using the diagnostic scan tool. Follow the steps outlined for AHR - Activate Driver And Passenger Head Restraint under System Test for the Occupant Restraint Controller/ORC menu item. Each time this routine is performed, both the driver and passenger side AHR unit latches may be opened and both AHR units may have to be reset.
Scheme 3
Scheme 4
- Be certain to pull the center of AHR tether strap (2) located between the rear trim cover and the cushion (3) upward as far as possible to prevent it from becoming trapped between the latch striker and the latch catches, which could interfere with successful latching of the striker.
- Reaching from behind the seat and below the AHR, position both hands on the top of the AHR cushion as illustrated and brace your forearms or your upper torso against the upper seat back as needed for leverage.
- Three separate and distinct physical actions must each be completed in their entirety to successfully reset and latch an AHR. It may help to memorize these actions before attempting the reset as: DOWN , BACK and DOWN . A short explanation of each action follows: DOWN : Pull the cushion downward (arrow a) far enough to allow the AHR linkage to drop out of its locked, deployed position to its neutral position. The cushion cannot be compressed against the rear trim cover until after the AHR linkage has been moved to its neutral position. BACK : Pull the cushion rearward (arrow b) firmly and evenly against the pressure of the deployment springs until it is flush against the rear trim cover. DOWN : Finally, while still holding the cushion tightly against the rear trim cover, pull the cushion downward (arrow c) once again far enough to fully engage the latch striker with the AHR latch mechanism. Listen for an audible click as the latch catches engage the striker.
- If the tether remains hanging out between the top of the cushion and the rear trim cover, simply use a finger to tuck it out of sight between the top of the rear trim cover and the cushion.
- To confirm a successful reset, there should be no visually obvious space between the cushion and the rear trim cover; although, there may be enough space to physically insert your fingertips between them. Also, operation of the comfort tilt adjustment feature should be restored.
The seat belt retractors used in all seating positions include an inertia-type, emergency locking mechanism as standard equipment. However, the retractor locking mechanisms for all seating positions except for the driver side front are mechanically switchable from an emergency locking retractor to an automatic locking retractor. The primary function of this feature is to securely accommodate a child seat in any of these seating positions of the vehicle without the need for a self-cinching seat belt tip half latch plate unit or another supplemental device that would be required to prevent the seat belt webbing from unwinding freely from the retractor spool of an inertia-type emergency locking retractor mechanism.
The automatic locking mechanism is integral to the seat belt and retractor unit and is concealed beneath a molded plastic cover located on one side of the retractor spool. The automatic locking mechanism cannot be adjusted or repaired and, if ineffective or damaged, the entire seat belt and retractor unit must be replaced.
The locked mode of the automatic locking retractor is engaged and the retractor is switched from operating as a standard inertia-type emergency locking retractor by first buckling the combination lap and shoulder belt buckle. Then grasp the shoulder belt and pull all of the webbing out of the retractor. Once all of the belt webbing is extracted from the spool, the retractor will automatically become engaged in the pre-locked automatic locking mode and will make a light, audible clicking or ratchet-like sound as the shoulder belt is allowed to retract to confirm that the automatic locking mode is now engaged. Once the automatic locking mode is engaged, the retractor will remain locked and the belt will remain tight around whatever it is restraining.
The retractor is returned to standard emergency locking (inertia) mode by unbuckling the combination lap and shoulder belt buckle and allowing the belt webbing to be almost fully retracted onto the retractor spool. The emergency locking mode is confirmed by the absence of the light, audible clicking or ratchet-like sound as the belt webbing retracts. This mode will allow the belt to unwind from and wind onto the retractor spool freely unless and until a predetermined inertia load is sensed, or until the retractor is again switched to the automatic locking mode.
The Occupant Detection Sensor (ODS) acts as a simple switch to detect loads placed upon the passenger side front seat cushion. The sensor circuits are connected to and monitored by the Occupant Restraint Controller (ORC) whenever the ignition switch is in the ON position. The ORC uses an algorithm logic in monitoring the changing states of the sensor input to determine whether the seat cushion load is static or dynamic.
The ORC microcontroller continuously monitors all of the Supplemental Restraint System (SRS) electrical circuits to determine the system status and readiness. If the ORC detects a monitored system fault, it sets a Diagnostic Trouble Code (DTC). However, because the ODS input is only used for control of the passenger belt alert feature, which has no effect on SRS component features or functions, the airbag indicator is NOT illuminated in response to a detected ODS circuit fault.
The ODS receives source current and a clean ground through dedicated sensor plus and minus circuits from the ORC. The ORC then sends the appropriate sensor status information to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN), which uses this information as an additional logic input used for control of the passenger belt alert feature.
The hard wired circuits between the ODS and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the ODS or the electronic controls and communication between other modules and devices that provide some features of the passenger belt alert feature. The most reliable, efficient and accurate means to diagnose the ODS or the electronic controls and communication related to the passenger belt alert feature operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The Seat Track Position Sensor (STPS) is designed to provide a seat position data input to the Occupant Restraint Controller (ORC) indicating whether the driver or passenger front seat is in a full forward or a not full forward position. The ORC uses this data as an additional logic input for use in determining the appropriate deployment force to be used when deploying the multistage Driver AirBag (DAB).
The STPS receives a nominal five volt supply from the ORC. The STPS communicates the seat position by modulating the voltage returned to the ORC on a sensor data circuit. The ORC also monitors the condition of the STPS circuits and will store a Diagnostic Trouble Code (DTC) for any fault that is detected. The ORC then sends messages over the CAN data bus to control the illumination of the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN).
The hard wired circuits between the STPS and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the STPS or the electronic controls and communication between other modules and devices that provide features of the Supplemental Restraint System (SRS). The most reliable, efficient and accurate means to diagnose the STPS or the electronic controls and communication related to STPS operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The driver side seat belt switch is designed to control a path to ground for the seat belt switch sense input of the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN). The passenger side seat belt switch is designed to control a sense input to the Occupant Restraint Controller (ORC). 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. Conversely, when the seat belt tip-half webbing is wound onto the retractor spool the switch plunger is depressed, opening the sense circuit.
The EMIC monitors the driver side seat belt switch status through the hard wired input, then controls the illumination of the seat belt indicator and the generation of audible electronic chime tones based upon that input. The ORC monitors the passenger side seat belt switch and Occupant Detection Sensor (ODS) input status through hard wired inputs. If the ORC logic determines that the seat belt is not buckled while the seat is occupied, it sends an electronic message to the EMIC over the Controller Area Network (CAN) data bus requesting seat belt indicator illumination.
The driver side seat belt switch receives ground through its 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. The driver side seat belt switch is connected in series between ground and the driver side seat belt switch sense input of the EMIC. The passenger side seat belt switch receives a clean ground from the ORC and is connected in series between the clean ground and the passenger side seat belt switch input of the ORC.
The hard wired circuits between the seat belt switches and the EMIC (driver side) or ORC (passenger side) may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the switches or the electronic controls and communication between other modules and devices that provide features of the Supplemental Restraint System (SRS). The most reliable, efficient and accurate means to diagnose the seat belt switches or the electronic controls and communication related to seat belt switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The seat belt tensioners are deployed in conjunction with the dual front airbags by a signal generated by the Occupant Restraint Controller (ORC) through the driver or passenger seat belt tensioner line 1 and line 2 (or squib) circuits. When the ORC sends the proper electrical signal to the tensioners, 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 injuries that the occupant might experience in these situations as a result of harmful contact with the steering wheel, steering column, instrument panel or windshield. 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.
The ORC monitors the condition of the seat belt tensioners through circuit resistance, and will illuminate the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) and store a Diagnostic Trouble Code (DTC) for any fault that is detected. Proper diagnosis of the seat belt tensioner gas generator and the seat belt tensioner squib circuits requires the use of a diagnostic scan tool and may also require the use of the SRS Load Tool special tool along with the appropriate Load Tool Jumpers and Adapters. Refer to the appropriate diagnostic information. Refer to the appropriate diagnostic information.