DESCRIPTION
An occupant restraint system is standard factory-installed safety equipment on this vehicle. Available occupant restraints for this vehicle 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.
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.
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 cushion 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 cushion, causing the cushion to inflate. As the cushion inflates, the PAB door area of the instrument panel cover will split at predetermined tear seam lines concealed on the underside of the cover, then the door will pivot up over the top of the instrument panel and out of the way. Following a deployment, the airbag cushion quickly deflates by venting the inert gas through vent holes within the fabric used to construct the back (windshield side) of the 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 .
Proper diagnosis of the PAB inflator and squib circuits requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
Each Seat AirBag (SAB) 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 airbag contains a small canister of highly compressed inert gas. When the ORC sends the proper electrical signal to the 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 open the clamshell case, the sewn pouch 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 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.
Proper diagnosis of the SAB inflator and squib circuits requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
Each 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 the left or right SABIC 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 airbag cushion, causing the cushion to inflate. As the 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 cushion features large chambers that inflate adjacent to the head of each front and rear seat occupant.
The front and rear tethers keep the SABIC cushion taut to the side of the vehicle. In addition, ramps integral to the side trim of the interior and integral to the SABIC modules themselves guide the cushion into the proper deployment position. Following the deployment, the 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.
Proper diagnosis of the SABIC inflator and squib circuits requires the use of a diagnostic scan tool. 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 (also known as ISOFIX) 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. On vehicles equipped with an optional third row seat, an upper tether anchor is also integral to each of the two third row seat back frames. 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, the horn switch, the speed control switch, the remote radio switches, the hands-free communication switches and the Electronic Vehicle Information Center (EVIC) control switches, if the vehicle is so equipped.
The clockspring is integral to the Steering Column Control Module (SCCM) positioned and secured near the top of the steering column. Refer to MODULE, STEERING COLUMN, DESCRIPTION . The turn signal cancel cam is integral to the rim of the clockspring rotor hub spool within the clockspring case so it also moves with the rotation of the steering wheel. Two short, sleeved pigtail wires on the upper surface of the clockspring rotor connect the clockspring to the Driver AirBag (DAB), while a steering wheel wire harness connected to the connector receptacles on the upper surface of the clockspring rotor completes circuits for the various steering wheel-mounted switches and the heated steering wheel, if the vehicle is so equipped.
Like the clockspring in a timepiece, the clockspring tape and conductors have 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 shaft is disconnected from the steering gear the clockspring rotor spool can change position relative to other movable steering components. Clockspring centering must be confirmed by viewing the inspection window on the clockspring rotor. If the black squares of the clockspring tape are not visible in the inspection window, clockspring centering has been compromised and the entire SCCM must be replaced with a new unit. Refer to MODULE, STEERING COLUMN, INSTALLATION .
Service replacement clocksprings are shipped pre-centered within the SCCM and with a plastic locking tab installed. This locking tab should not be removed until the SCCM has been properly installed on the steering column. If the locking tab is removed before the SCCM is installed on a steering column, clockspring centering must be confirmed by viewing the inspection window on the clockspring rotor. If the black squares of the clockspring tape are not visible in the inspection window, the SCCM must be replaced with a new unit. Proper clockspring installation may also be confirmed by viewing the Steering Angle Sensor (SAS) data using a diagnostic scan tool.
The hard wired clockspring circuits to the SCCM 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 SCCM, the Steering Control Module (SCM) or the electronic controls or 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 electronic controls and communication related to SRS operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The microprocessor in the Occupant Restraint Controller (ORC) contains the Supplemental Restraint System (SRS) logic circuits and controls all of the 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 microprocessor 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 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 that is secured by a ground screw to the body sheet metal. These connections allow the ORC to be operational whenever the ignition switch is in the START or ON positions.
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.
Various sensors within the ORC are continuously monitored by the ORC logic. These internal sensors, along with several external impact sensor inputs allow the ORC to determine both the severity of an impact and to verify the necessity for deployment of any SRS components. Two remote front impact sensors are located on the back of the right and left ends of the Front End Module (FEM) carrier inboard of the headlamps 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.
The ORC also monitors inputs from an internal rollover sensor and six additional remote side impact sensors located on the left and right front door hardware module carriers, on the left and right inner B-pillars and C-pillars to control deployment of the side curtain airbag units and seat (thorax) airbags.
The impact sensors within the ORC are electronic accelerometer sensors that provide an additional logic input to the ORC microprocessor. These sensors are 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 SRS components to deploy. On vehicles equipped with side curtain airbags or seat airbags, a separate impact sensor within the ORC provides confirmation to the ORC microprocessor of side impact forces. This separate sensor is a bi-directional unit that detects impact forces from either side of the vehicle.
Pre-programmed decision algorithms in the ORC microprocessor determine when the deceleration rate as signaled by the impact 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, the Active Head Restraint (AHR) units and either side curtain or 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 or communication between other modules and devices that provide features of the SRS. The most reliable, efficient, and accurate means to diagnose the ORC or the electronic controls and communication related to ORC operation requires the use of a diagnostic scan tool. 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 or 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.
Both front seating position seat belts are equipped with a Constant Force Retractor (CFR), while the seat belt retractors used in all seating positions include an inertia-type, Emergency Locking Retractor (ELR) mechanism as standard equipment. However, the ELR for all seating positions except the driver side front are mechanically switchable from an ELR to an Automatic Locking Retractor (ALR).
The CFR, ELR and ALR features are all integral to the seat belt retractor unit mechanism that is concealed beneath a molded plastic cover located on one side of the retractor spool. The CFR, ELR and ALR features cannot be adjusted or repaired and, if ineffective or damaged, the entire seat belt and retractor must be replaced as a unit.
The Constant Force Retractors (CFR) used for both front seating positions provide a constant force load-limiting feature. This load-limiting feature helps to limit the maximum force on the belt webbing to help absorb the energy of the upper torso during an impact event. The CFR feature also helps to offset any extreme torso loading that might occur as the seat belt webbing is automatically retracted by deployment of the belt tensioners in conjunction with a front airbag deployment.
The primary function of the switchable Emergency Locking Retractor (ELR) to Automatic Locking Retractor (ALR) feature is to securely accommodate an infant or child booster seat in any seating position of the vehicle except the driver side front seat 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 ELR in situations where the minimum inertia locking threshold has not been achieved.
The locked mode of the ALR is engaged and the retractor is switched from operating as a standard inertia-type ELR by first buckling the combination lap and shoulder belt buckle. Then all of the shoulder belt webbing is pulled out from the retractor. Once all of the belt webbing is extracted from the retractor spool, the retractor will automatically become engaged in the pre-locked ALR mode and will make a light, audible clicking or ratcheting sound as the shoulder belt is allowed to retract onto the spool to provide an audible confirmation that the ALR mode is engaged. Once the ALR 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 ELR (inertia) mode by unbuckling the combination lap and shoulder belt buckle and allowing the belt webbing to be almost fully retracted back onto the retractor spool. The ELR mode is confirmed by the absence of the light, audible clicking or ratcheting 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 threshold is sensed, or until the retractor is again switched to the ALR mode.
Remote or satellite impact sensors are mounted in various strategic locations of the vehicle. These sensors are mounted remotely from the impact sensor that is internal to the Occupant Restraint Controller (ORC). Sensors at the front of the vehicle provide an additional logic input for use by the Occupant Restraint Controller (ORC) to control the Active Head Restraints (AHR), front airbags and the seat belt pretensioners. Sensors on each side of the vehicle provide an additional logic input for use by the ORC to control the side curtain airbags, seat airbags and the seat belt pretensioners. Two types of sensors are used in this vehicle. They are the acceleration-type and the pressure-type, which are described in further detail in the following paragraphs.
Scheme 1
Remote or satellite acceleration-type impact sensors (1) are mounted in various locations in the vehicle. These sensors are mounted remotely from the impact sensor that is internal to the Occupant Restraint Controller (ORC). Sensors at the front of the vehicle provide an additional logic input for use by the ORC to control the front airbags, the seat belt pretensioners and the Active Head Restraints (AHR). Sensors on each side of the vehicle provide an additional logic input for use by the ORC to control the side curtain airbags, the seat belt pretensioners and the seat (or thorax) airbags.
Although the front and side acceleration-type impact sensors are similar in appearance and construction, they are not interchangeable. The front impact sensors monitor acceleration forces on a different axis than those monitored by the side impact sensors. Each sensor is secured with a single screw to its mounting location. The front sensors are located on the outboard side of each vertical support member of the Front End Module (FEM) between the cooling module and the front lamp unit. A side sensor is located near the base of each inner B-pillar and C-pillar and concealed behind the interior trim.
Each sensor housing has an integral connector receptacle (3), an integral locator pin with two latch features (5), and an integral mounting hole with a metal sleeve (2) to provide crush protection. A cavity in the center of the molded plastic impact sensor housing contains the electronic circuitry of the sensor which includes an electronic communication chip and an electronic acceleration sensor. Potting material fills the cavity and a molded cover (4) is laser welded over the cavity to seal and protect the internal electronic circuitry and components.
The front impact sensors are each connected to the vehicle electrical system through dedicated take outs and connectors of the Front End Module (FEM) wire harness, while the side impact sensors are connected through dedicated take outs and connectors of the body wire harness.
The acceleration-type impact sensors cannot be repaired or adjusted and, if damaged or ineffective, they must be replaced.
Scheme 2
Two pressure-type front door side impact sensors (2) are used on this vehicle, one each for the left and right sides of the vehicle. These sensors are mounted remotely from the impact sensor that is internal to the Occupant Restraint Controller (ORC). Each side sensor is secured with two screws and is sealed by a resilient gasket (1) to the front door hardware module carrier on the front door inner panel. The sensors are concealed behind the front door trim panel within the passenger compartment.
The right and left front door side impact sensors are identical in construction and calibration. The impact sensor housing has an integral connector receptacle (3), two integral mounting tabs, and an integral hood-like water shield (4) that extends through a hole in the front door module carrier into the interior of the door cavity and protects the sensor orifice from contamination. A cavity in the center of the molded plastic impact sensor housing contains the electronic circuitry of the sensor, which includes an electronic communication chip and the pressure sensor.
The housing cavity is filled with a potting material to seal and protect the internal electronic circuitry and components. A label on the sensor has a directional arrow and the word down imprinted upon it to provide verification of the correct sensor orientation in the vehicle. The side impact sensors are each connected to the vehicle electrical system through a dedicated take out and connector of the front door wire harness.
These pressure-type front door side impact sensors cannot be repaired or adjusted and, if damaged or ineffective, they must be replaced.
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 microprocessor 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 seat belt indicator and 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 passenger belt alert feature operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The seat track position sensor is designed to provide a seat position data input to the Occupant Restraint Controller (ORC) indicating whether the driver side 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 side front airbag.
The seat track position sensor receives a nominal five volt supply from the ORC. The sensor 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 sensor circuits and will store a Diagnostic Trouble Code (DTC) for any fault that is detected. The ORC then sends messages over the Controller Area Network (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 seat track position sensor 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 seat track position sensor 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 track position sensor or the electronic controls and communication related to seat track position sensor operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The front seat belt switches are designed to control a hard wired sense input to the Occupant Restraint Controller (ORC). A spring-loaded slide with a small window-like opening is integral to the buckle latch mechanism. When a seat belt tip-half is inserted and latched into the seat belt buckle, the slide is pushed downward and the window of the slide exposes the Hall Effect Integrated Circuit (IC) chip within the buckle. The field of the permanent magnet induces a current within the chip. The chip provides this induced current as an output to the ORC. When the seat belt is unbuckled, the spring-loaded slide moves upward and shields the IC from the field of the permanent magnet, causing the output current from the seat belt switch to be reduced.
The seat belt switches receive a supply of current from the ORC, and the ORC senses the status of the front seat belt switches through its connection to the seat wire harness. The ORC provides electronic seat belt switch status messages to the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) over the Controller Area Network (CAN) data bus. The EMIC uses these messages as an additional logic input for control of the seat belt indicator. The ORC monitors the condition of the seat belt switch circuits and will store a Diagnostic Trouble Code (DTC) for any fault that is detected.
The hard wired circuits between the seat belt switches 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 switches or the electronic controls or communication between other modules and devices that provide some features of the seat belt reminder system. 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.
Scheme 3
Seat belt tensioners supplement the dual front airbags for this vehicle. The seat belt tensioners are integral to the front seat belt retractor units (1), which are secured to the lower inner B-pillar on the right and left sides of the vehicle. The retractor is concealed beneath the molded plastic lower inner B-pillar trim.
The seat belt tensioner consists primarily of a sprocket/pinion, a steel tube (2), a cast metal housing, numerous steel balls, a stamped metal ball trap, a torsion bar and a small pyrotechnically activated gas generator with a connector receptacle (3). 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 Occupant Restraint Controller (ORC) 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 ineffective or damaged, the entire front seat belt and retractor unit must be replaced. If the front airbags have been deployed, the seat belt tensioners have also been deployed. The seat belt tensioners are not intended for reuse and must be replaced following any front 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. Refer to RETRACTOR, SEAT BELT, REMOVAL .
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. Refer to the appropriate diagnostic information.