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
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.
Scheme 14
The clockspring (3) for this vehicle is secured near the top of the steering column below the steering wheel. The clockspring also includes an integral, internal turn signal cancel cam and a Steering Angle Sensor (SAS) that are both serviced as a unit with the clockspring. The clockspring also supports the left (lighting) multi-function switch (1), the Steering Control Module (SCM) internal to the left multi-function switch housing (2), and the right (wiper) multi-function switch (6). Each of these switches and the jumper wire harness (5) between the two multi-function switches can be separated from and are serviced individually from the clockspring.
The clockspring case includes integral tabs for mounting the unit with three screws to the steering column lock housing as well as integral provisions for mounting and supporting both multi-function switches. The multi-function switches are each secured to the clockspring with a single screw (7). The SAS within the clockspring includes an electronic circuit board and a microprocessor, which allows it to communicate with other electronic modules in the vehicle over the Controller Area Network (CAN) data bus. The SAS circuitry, the clockspring, and the turn signal cancel cam are all contained within a flat, molded plastic case.
The clockspring case includes three connector receptacles that face toward the instrument panel. Within the plastic case is a spool-like molded plastic rotor with a large exposed hub. The upper surface of the rotor hub has a large center hole, two short pigtail wires with connectors, and a connector receptacle that faces toward the steering wheel. The lower surface of the rotor has an integral dowel or drive pin that also faces toward the steering wheel. Wound around the rotor spool within the case is a long ribbon-like tape that consists of several thin copper wire leads sandwiched between two thin plastic membranes. The outer end of the tape terminates at two of the connector receptacles that face the instrument panel, while the inner end of the tape terminates at the pigtail wires and connector receptacle on the hub of the clockspring rotor that face the steering wheel. The outer surface of the rotor hub rim within the clockspring case also has the integral lobes of the turn signal cancel cam.
The service replacement clockspring is shipped pre-centered and with a molded plastic locking pin (4) installed. The locking pin secures the centered clockspring rotor to the clockspring case during shipment and handling, but must be removed after the clockspring is installed on the steering column and the steering wheel is installed. See STANDARD PROCEDURE .
The clockspring cannot be repaired. If the clockspring is ineffective, damaged, or if the driver airbag has been deployed, the clockspring/turn signal cancel cam/SAS unit must be replaced.
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 and the Electronic Vehicle Information Center (EVIC) control 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 driver airbag, 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 and EVIC control 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. See 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 SYSTEM WIRING DIAGRAMS . However, conventional diagnostic methods will not prove conclusive in the diagnosis of the SAS or the electronic controls or 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. Refer to the appropriate diagnostic information.
Each side curtain airbag 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 tether keeps the front portion of the 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.
Proper diagnosis of the side curtain airbag inflator and squib circuits requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The multistage driver airbag is deployed by electrical signals generated by the Occupant Restraint Controller (ORC) through the driver airbag 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 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. Following an airbag 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 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, 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 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 or hazardous materials. See STANDARD PROCEDURE .
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.
Proper diagnosis of the driver airbag inflator and squib circuits requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The microprocessor in the Occupant Classification Module (OCM) contains the Occupant Classification System (OCS) logic circuits. The OCM 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 also used for OCS diagnosis and testing through the 16-way data link connector located on the driver side lower edge of the instrument panel.
The OCM provides voltage to the four seat weight sensors located on the corners of the passenger side front seat. The OCM then monitors return inputs from each of the sensors on dedicated hard wired data communication circuits. The seat weight sensor inputs allow the OCM to determine whether the passenger side front seat is occupied and the relative size of the occupant by providing a weight-sensing reference to the load on the seat.
Pre-programmed decision algorithms and OCS calibration allow the OCM microprocessor to determine when passenger airbag protection is appropriate based upon the seat load as signaled by the seat weight sensors. When the programmed conditions are met, the OCM sends the proper electronic occupant classification messages over the CAN data bus to the Occupant Restraint Controller (ORC), and the ORC controls the deployment circuits for the passenger side front supplemental restraints. On vehicles so equipped, the ORC also provides a control output for the passenger airbag on/off indicator in the instrument panel based upon the electronic occupant classification messages it receives from the OCM.
The OCM microprocessor continuously monitors all of the OCS electrical circuits and components to determine the system readiness. If the OCM detects a monitored system fault, it sets an active and stored Diagnostic Trouble Code (DTC) and sends the appropriate electronic messages to the ORC over the CAN data bus. Then the ORC sets a DTC and sends messages to control the airbag indicator operation accordingly. 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 OCM and the ORC. For some DTCs, if a fault does not recur for a number of ignition cycles, the OCM will automatically erase the stored DTC. For other internal faults, the stored DTC is latched forever.
The OCM receives battery current on a fused B(+) circuit through a fuse in the Totally Integrated Power Module (TIPM) and receives electronic ignition switch status messages indicating the ignition switch position over the CAN data bus. The OCM receives ground through a ground circuit and take out of the body wire harness. These connections allow the OCM to be operational whenever the ignition switch is in the ON or START positions.
The hard wired inputs and outputs for the OCM may be diagnosed using conventional diagnostic tools and procedures. Refer to SYSTEM WIRING DIAGRAMS . However, conventional diagnostic methods will not prove conclusive in the diagnosis of the OCM or the electronic controls and communication between other modules and devices that provide features of the OCS. The most reliable, efficient, and accurate means to diagnose the OCM or the electronic controls and communication related to OCM 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. Refer to OPERATION .
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 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.
On vehicles so equipped, the ORC provides voltage to the seat track position sensors on the inboard passenger and driver side front seat upper seat tracks. The ORC then monitors return inputs from each of the sensors on dedicated hard wired data communication circuits. The seat track position sensors provide additional logic inputs to the ORC microprocessor that allow it to determine the position of the front seat passenger and the driver relative to the front airbags for determining the force level with which to deploy the multistage front airbags.
On vehicles equipped with the Occupant Classification System (OCS), the ORC communicates with the Occupant Classification Module (OCM) over the CAN data bus. The ORC will internally disable the passenger airbag and seat belt tensioner deployment circuits if the OCM detects that the passenger side front seat is unoccupied or that it is occupied by a load that is inappropriate for an airbag deployment. The ORC also provides a control output to the passenger airbag on/off indicator through the passenger airbag indicator driver circuit. The OCM notifies the ORC when it has detected a monitored system fault and stored a DTC in its memory for any ineffective OCS component or circuit, then the ORC sets a DTC and controls the airbag indicator operation accordingly.
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 SYSTEM WIRING DIAGRAMS 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 ends of the front end module 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 four additional remote impact sensors located on the left and right inner B and C-pillars to control deployment of the side curtain airbag units.
The safing sensor is an electronic accelerometer sensor within the ORC that provides an additional logic input to the ORC microprocessor. 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. A second safing sensor within the ORC provides confirmation to the ORC microprocessor 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 microprocessor 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 either side curtain airbag unit. For vehicles equipped with the OCS, the passenger side front airbag and seat belt tensioner will be deployed by the ORC only if enabled by the OCM messages (passenger airbag on/off indicator OFF) at the time of the impact.
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 supplemental restraint system. 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 multistage passenger airbag is deployed by electrical signals generated by the Occupant Restraint Controller (ORC) through the passenger airbag squib 1 and squib 2 circuits to the two initiators of the hybrid 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 produces the pressure necessary to rupture a containment disk in an inert gas canister. The inflator and inert gas canister are 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 passenger airbag door will split horizontally at predetermined tear seam lines concealed on the inside surface of the door. The upper half of the door pivots up and the lower half pivots down 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 an airbag 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. See STANDARD PROCEDURE .
Proper diagnosis of the passenger airbag inflator and the passenger airbag squib circuits requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
Vehicles equipped with the Occupant Classification System (OCS) include a passenger airbag on/off indicator (4), which is located just to the right of the hazard switch (3) in the center of the instrument panel switch pod (1) near the base of the instrument panel center bezel. The passenger airbag on/off indicator consists of a molded plastic housing and a rectangular dark translucent outer lens.
The opaque text PASS AIRBAG OFF and an opaque International Control and Display Symbol icon for Passenger Airbag Off or Not Available are imprinted on the back of the lens within the indicator. The dark outer lens prevents the indicator text and icon from being clearly visible when it is not illuminated. An amber Light Emitting Diode (LED) behind the lens causes the text and icon to appear silhouetted against an amber field through the translucent lens when the indicator is illuminated from behind by the LED.
The passenger airbag on/off indicator cannot be repaired or adjusted and, if ineffective or damaged, the switch pod unit must be replaced. Refer to REMOVAL .
In the Occupant Classification System (OCS) the passenger airbag on/off indicator gives an indication when the passenger airbag and seat belt tensioner deployment circuits are disabled by the Occupant Restraint Controller (ORC). This indicator is controlled by a transistor within the ORC through a hard wired output based upon ORC programming and electronic occupant classification messages received by the ORC over the Controller Area Network (CAN) data bus from the Occupant Classification Module (OCM).
The passenger airbag on/off indicator Light Emitting Diode (LED) is completely controlled by the ORC. The LED receives a battery current input on a fused ignition switch output (run) circuit. Therefore, the LED will always be OFF when the ignition switch is in any position except ON. The LED only illuminates when it is provided a path to ground by the ORC transistor. The ORC will turn ON the passenger airbag on/off indicator for the following reasons
- Bulb Test - Each time the ignition switch is turned to the ON position the passenger airbag on/off indicator is illuminated for about six seconds.
- Child Seat Detected (or Load Less Than Minimum Weight Threshold) Occupant Classification Message - Each time the ORC receives an electronic message from the OCM indicating a child seat has been detected in the passenger side front seat (or that the seat load is less than a minimum weight threshold) the passenger airbag and seat belt tensioner deployment circuits are deactivated and the passenger airbag on/off indicator will be illuminated. The indicator remains illuminated until the ORC receives an occupant classification message indicating that the passenger side front seat is empty, that the seat is occupied by a load equal to or greater than a minimum weight threshold, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Load Undetermined Occupant Classification Message - Each time the ORC receives an electronic message from the OCM indicating that a load cannot be determined in the passenger side front seat, the passenger airbag and seat belt tensioner deployment circuits are deactivated and the passenger airbag on/off indicator will be illuminated. The indicator remains illuminated until the ORC receives an occupant classification message indicating that the passenger side front seat is empty, that the seat is occupied by a load equal to or greater than a minimum weight threshold, or until the ignition switch is turned to the OFF position, whichever occurs first.
- Communication Error - If the ORC receives invalid occupant classification messages or no messages from the OCM, the passenger airbag on/off indicator is illuminated. The indicator remains illuminated until the ORC receives a valid message from the OCM indicating that the passenger side front seat is empty, that the seat is occupied by a load equal to or greater than a minimum weight threshold, or until the ignition switch is turned to the OFF position, whichever occurs first.
The ORC continually monitors the occupant classification messages from the OCM to decide whether the passenger airbag and seat belt tensioner deployment circuits should be activated or deactivated. Note that there may be several seconds of delay between changes in the detected occupant status and passenger airbag on/off indications. This is a programmed feature of the OCM used to prevent a flashing indicator condition resulting from the normal shifting of occupant weight on the passenger seat cushion. The ORC then provides the proper control output to turn the passenger airbag on/off indicator ON or OFF.
The ORC will store a Diagnostic Trouble Code (DTC) for any malfunction it detects. The hard wired circuits between the passenger airbag on/off indicator and the ORC may be diagnosed using conventional diagnostic tools and procedures. Refer to SYSTEM WIRING DIAGRAMS . However, conventional diagnostic methods will not prove conclusive in the diagnosis of the passenger airbag on/off indicator or the electronic controls and communication between other modules and devices that provide features of the OCS. The most reliable, efficient, and accurate means to diagnose the passenger airbag on/off indicator or the electronic controls and communication related to passenger airbag on/off indicator operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
Two different seat belt switches are used in the front seat buckles of this vehicle. The driver side uses a mechanical switch, while the passenger side is actually a Hall Effect-type sensor. The driver side switch is a small, normally open, single pole, single throw, leaf contact, momentary switch. The driver side seat belt switch is integral to the buckle of the driver side front seat belt buckle. The passenger side switch consists of a fixed-position, Hall Effect Integrated Circuit (IC) chip and a small permanent magnet that is integral to the passenger side front seat belt buckle. The front seat belt buckles (1) are located on a molded plastic scabbard and secured along with the seat belt buckle tensioner mechanism by a screw (2) near the back of the inboard front seat cushion frame.
The seat belt switches are connected to the vehicle electrical system through a two-lead pigtail wire (3) and a four-way connector shared with the buckle tensioner squib circuits on the front seat belt buckle-half, which is connected to a wire harness connector and take out of the seat wire harness routed beneath the front seat cushion. On the passenger side, a one kilohm diagnostic resistor is connected in parallel with the IC where the two pigtail wire leads connect to the IC pins.
The seat belt switches cannot be adjusted or repaired. If ineffective or damaged, the entire front seat belt buckle-half and tensioner unit must be replaced.
The driver side front seat belt incorporates dual tensioners: one integral to the retractor, and one integral to the buckle. In vehicles manufactured for domestic markets, the passenger side front seat belt uses a single tensioner integral to the retractor. In vehicles manufactured for export markets, the passenger side front seat belt incorporates dual tensioners: one integral to the retractor, and one integral to the buckle.
Scheme 15
Seat belt retractor tensioners supplement the dual front and side curtain airbag system for all versions of this vehicle. These tensioners are integral to the front seat belt and retractor units (1), which are secured to the B-pillars on the right and left sides of the vehicle. The retractors are concealed beneath the molded plastic B-pillar trim. The seat belt tensioner consists primarily of a molded plastic tensioner housing (2), a tubular metal piston housing (3), a piston, a short rack gear, a set of pinion gears, a pyrotechnically activated gas generator (5), and a short pigtail wire (4).
All of these components are located on one side of the retractor spool on the outside of the retractor housing. The seat belt tensioners are controlled by the Occupant Restraint Controller (ORC) and are connected to the vehicle electrical system through dedicated take outs of the body wire harness by keyed and latching molded plastic connector insulators to ensure a secure connection.
The retractor tensioners cannot be repaired and, if ineffective or damaged, the entire front seat belt and retractor unit must be replaced. The retractor tensioners are not intended for reuse and must be replaced following any front airbag deployment. A locked retractor that will not allow the seat belt webbing to be retracted or extracted is a sure indication that the seat belt tensioner has been deployed and requires replacement. See REMOVAL .
Scheme 16
A driver side seat belt buckle tensioner supplements the dual front and side curtain airbags for all versions of this vehicle. In vehicles manufactured for export markets, a passenger side seat belt buckle tensioner also supplements the dual front and side curtain airbags. This tensioner is integral to the front seat belt buckle unit, which is secured by a large screw to the outside of the inboard seat cushion frame of the front seat. The buckle tensioner consists primarily of a buckle (2), a molded plastic scabbard (1), a cable and piston, a cable guide and bracket (5), a steel cylinder tube (4), and a small pyrotechnically activated gas generator.
The buckle tensioner is controlled by the Occupant Restraint Controller (ORC) and is connected to the vehicle electrical system through a dedicated take out of the seat wire harness by a keyed and latching yellow molded plastic connector insulator to ensure a secure connection. The buckle tensioner connector is shared by two pigtail harnesses (3): one two-wire squib pigtail and a second two-wire pigtail for the integral seat belt switch.
The buckle tensioner cannot be repaired and, if ineffective or damaged, the entire front seat belt buckle unit must be replaced. If the front airbags have been deployed, the buckle tensioners have also been deployed. The buckle tensioners are not intended for reuse and must be replaced following any front airbag deployment. See REMOVAL .
The seat belt retractor and buckle tensioners are deployed 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.
On the retractor tensioner, the gas generator is installed in one end of the tubular metal piston housing, which contains a piston and a small rack gear. As the gas expands, it pushes the piston and the rack gear through the tube. The rack gear engages a pinion gear that drives a gear set in the tensioner housing, which rotates the seat belt retractor spool causing the slack to be removed from the front seat belts.
On the buckle tensioner, the gas generator is installed in one end of the tubular metal piston housing, which contains a piston secured to one end of a cable. The cable is routed around an integral guide to the buckle, which is secured to the opposite end of the cable. As the gas expands, it pushes the piston and the cable through the tube and pulls the buckle downward, causing the slack to be removed from the driver side front seat belt.
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 occupants of the front seat might experience in these situations as a result of a harmful contact with the steering wheel, steering column, instrument panel or windshield. Also, the seat belt retractor has a torsion bar mechanism that 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) and store a Diagnostic Trouble Code (DTC) for any fault that is detected. Proper diagnosis of the seat belt tensioner gas generator and squib circuits requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
The seat weight sensor units are designed to sense the relative weight of a load applied to the passenger side front seat, which provides a logic input to the microprocessor of the Occupant Classification Module (OCM). When any load is applied to the seat the load is transmitted through the sensor mounting stud to the sensor body (strain gauge) of each sensor, causing a change of electrical resistance through the strain gauge. These changes in resistance within the internal sensor circuitry change the sensor output voltage.
Each weight sensor receives a nominal five volts and a ground through parallel hard wired circuits from the OCM. The OCM then monitors the output voltage of each sensor on dedicated hard wired data communication circuits. The OCM also monitors the condition of the sensor circuits and will store a Diagnostic Trouble Code (DTC) for any fault that is detected, then send messages to the Occupant Restraint Controller (ORC) to illuminate the airbag indicator in the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN).
The hard wired circuits between the seat weight sensor and the OCM may be diagnosed using conventional diagnostic tools and procedures. Refer to SYSTEM WIRING DIAGRAMS . However, conventional diagnostic methods will not prove conclusive in the diagnosis of the seat weight sensors or the electronic controls and communication between other modules and devices that provide features of the Occupant Classification System (OCS). The most reliable, efficient, and accurate means to diagnose the seat weight sensors or the electronic controls and communication related to seat weight sensor operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.