Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)

AIR BAG AND SAFETY BELT PRETENSIONER SUPPLEMENTAL RESTRAINT SYSTEM (SRS)

Air Bag And Safety Belt Pretensioner Supplemental Restraint System (SRS) Components (Part 1):

Air Bag And Safety Belt Pretensioner Supplemental Restraint System (SRS) Components (Part 2):

The air bag supplemental restraint system (SRS) is designed to provide increased collision protection for front seat and second row outboard occupants in addition to that provided by the 3-point safety belt system. Safety belt use is necessary to obtain the best occupant protection and to receive the full advantage of the SRS.

This vehicle line contains dual stage deployment (advanced restraint system) driver and front passenger air bag modules and is also equipped with seat side air bag modules in the front seats. These vehicles are also equipped with driver and front passenger safety belt buckle pretensioners and adaptive load limiting retractors. These vehicles can also be equipped with optional safety canopies that deploy from the A-pillar to the C-pillar upon a side impact or if a rollover condition is detected.

In addition to dual stage deployment (advanced restraint system) driver and front passenger air bag modules, this vehicle is equipped with a passenger air bag adaptive tether as well as driver and passenger air bag canister vents.

A unique restraints control module (RCM) is used on these vehicles which will detect a potential rollover condition. In addition, 2 front impact severity sensors are mounted to the lower radiator support, 2 first row side impact sensors (mounted in both front doors), a seat position sensor is mounted to the driver seat and a usage detection switch is added to the front driver and passenger outboard buckles. If equipped with optional safety canopies, there are also 2 second row impact sensors.

Vehicles are also equipped with an occupant classification sensor (OCS) system as part of the front passenger seat. The OCS system includes 2 OCS rails and an OCS module.

Clockspring
The clockspring:
- is mounted on the steering column, behind the steering wheel.
- continuously transfers electrical signals from the driver air bag module to the restraints control module (RCM).

Driver Air Bag Module
The driver air bag module:
- contains dual stage deployment (advanced restraint system).
- is equipped with canister vent.
- is installed new as an assembly.
- is mounted in the center of the steering wheel.

In addition to dual stage deployment (advanced restraint system) driver air bag module, this vehicle is equipped with a driver air bag canister vent. Canister venting is a deployable device integrated to the driver air bag module. Canister venting controls the inflation rate of the driver air bag, and the escape rate of gases from the vent.

Driver Seat Side Air Bag Module

NOTE:
- References to seat side air bag modules refer to the seat-mounted and not to the steering wheel or instrument panel mounted air bag components of the SRS.
- When servicing a seat equipped with a seat side air bag module, refer to Seats.

A seat side air bag module provides protection of the thorax area (between the neck and abdomen) of the body, working in conjunction with the head protection provided by a safety canopy module (if equipped). The driver seat side air bag module:
- will deploy upon receiving a flow of current from the RCM initiated by the driver side impact sensor and internal RCM circuitry.
- is installed as an assembly.
- is mounted in the driver seat back.
- is used in conjunction with a safety canopy module (if equipped).

Deployable Steering Column
This vehicle is equipped with a deployable steering column. The deployable steering column includes a deployable device that, once deployed, reduces the amount of force necessary to collapse the steering column during a crash event. The deployable device is activated by the restraints control module (RCM) depending on when the module detects a crash event force exceeding a programmed limit and the position of the driver seat. After deployment, a new steering column must be installed. Refer to Steering.

High Speed Controller Area Network (HS-CAN)
This vehicle utilizes a communication system called a high-speed controller area network (HS-CAN). The HS-CAN consists of a twisted pair of wires connected to the following:
- Anti-lock brake system (ABS) module
- Instrument cluster module
- Occupant classification sensor (OCS) system
- Powertrain control module (PCM)
- Transmission control module (TCM)
- Restraints control module (RCM)
- 4x4 module
- Data link connector (DLC)

The HS-CAN circuits use a bias voltage of approximately 2.5 volts, one is a positive 2.5 volts while the other is a negative 2.5 volts. The HS-CAN also uses 2 terminating resistors, one contained within the PCM, the other in the instrument cluster module. The terminating resistors are not serviced separately. The terminating resistors have a value of 120 ohms each, for a total normal operating system total of 60 ohms. The HS-CAN will operate with only one terminating resistor and has the capability to communicate some messages to some of the control modules with only one circuit functioning, but at a reduced rate of performance. Refer to Information Bus (Module Communications Network).

Occupant Classification Sensor System
The occupant classification sensor system is found only on the front passenger seat. The front passenger OCS system is comprised of 2 OCS rails (weight sensors) that are mounted to each side of the seat track and an OCS module (electronic control unit) which is mounted to the electrical bracket underneath the seat cushion pan. The weight of any occupant or object on the front passenger seat is The weight is then electronically communicated to the OCS module.

The OCS system is also used for operation of the passenger Belt Minder.

The components that make up the OCS system, OCS module, inboard OCS rail and outboard OCS rail are serviced separately.

When the front passenger seat is removed for service, the Zero Seat Weight Test must be carried out after the installation of the front passenger seat. When a OCS system component is installed new, the System Reset must be carried out after the installation of the front passenger seat. The Zero Seat Weight Test and/or System Reset must be carried out only as instructed to do so.

OCS System Module
Based on programmed limits, the OCS module will inform the restraints control module (RCM), via a High Speed Controller Area Network (HS-CAN), of the necessary information. The RCM uses this information in determining if the passenger air bag module or passenger seat side air bag module is to be deployed in the event of a deployable collision.

The OCS module monitors the OCS system for faults and communicates on-demand and continuous Diagnostic Trouble Codes (DTCs) via the data link connector (DLC) with the use of a diagnostic tool.

The components that make up the OCS system, OCS system module, inboard OCS rail and outboard OCS rail are serviced separately.

OCS Rails (Weight Sensors)







The components that make up the OCS system (OCS system module, inboard OCS rail and outboard OCS rail) are serviced separately.

Passenger Air Bag Module

Passenger Air Bag Module:

The passenger air bag module:
- contains dual stage deployment (advanced restraint system).
- is equipped with canister vent.
- is equipped with adaptive tether.
- is installed new as an assembly.
- is mounted in the passenger side of the instrument panel.

In addition to dual stage deployment (advanced restraint system) front passenger air bag module, this vehicle is equipped with a passenger air bag adaptive tether as well as a passenger air bag canister vent. Canister venting is a deployable device integrated to the passenger air bag module. Canister venting controls the inflation rate of the passenger air bag, and the escape rate of gases from the vent. Adaptive tether is a deployable device integrated to the passenger air bag module. Adaptive tether restricts the rearward movement of the passenger air bag.

Passenger Air Bag Deactivation (PAD) Indicator
The passenger air bag deactivation (PAD) indicator is a visual indicator used to inform the front seat occupants of the passenger air bag deactivation state. The PAD indicator is a stand-alone lamp installed into the vehicle instrument panel in a position visible to each front seat occupant.

The restraints control module (RCM) controls the state of the PAD indicator through a direct hardwire connection, based on information provided by the occupant classification sensor (OCS) system. The PAD indicator is lit to indicate the passenger air bag module is disabled. An exemption to this is when the front passenger seat is determined to be empty and passenger safety belt buckle unbuckled, and therefore indication of a deactivated passenger air bag module is not necessary. In all other cases, the PAD indicator is unlit when the passenger air bag module is enabled.

When the ignition switch is in the ON position, the PAD indicator prove-out period is initiated by the RCM. The RCM briefly activates the PAD indicator to prove-out the indicator function and verify to the front occupants correct functional operation of the PAD indicator.

The PAD indicator will be lit/unlit within 1.0 to 1.5 seconds of a change of state from the OCS system.

When an OCS system fault is present, the RCM defaults the passenger air bag module to the last valid state received from the OCS system until the ignition switch is turned OFF. If the OCS system fault is still present when the ignition switch is turned ON, the RCM defaults the passenger air bag module to enabled regardless of the size of occupant in the front passenger seat. The PAD indicator will be unlit.

Passenger Air Bag And PAD Indicator Status:

The table indicates the passenger air bag status and the PAD indicator status based the size of the front outboard passenger occupant.

Passenger Seat Side Air Bag Module

NOTE:
- References to seat side air bag modules refer to the seat-mounted and not to the steering wheel or instrument panel mounted air bag components of the SRS.
- When servicing a seat equipped with a seat side air bag module, refer to Seats.

A seat side air bag module provides protection of the thorax area (between the neck and abdomen) of the body, working in conjunction with the head protection provided by a safety canopy module (if equipped).

The passenger seat side air bag module:
- will deploy upon receiving a flow of current from the RCM initiated by the passenger side impact sensor and internal RCM circuitry.
- is installed as an assembly.
- is mounted in the passenger seat back.
- is used in conjunction with a safety canopy module (if equipped).

Restraints Control Module (RCM)

WARNING:
- Do not handle, move or change the original horizontal mounting position of the restraints control module (RCM) while the RCM is connected and the ignition switch is ON. Failure to follow these instructions may result in the inadvertent deployment of the safety canopy and risk of personal injury.
- The restraints control module (RCM) orientation is critical for correct system operation. If a vehicle equipped with an air bag supplemental restraint system (SRS) has been involved in a collision in which the center tunnel area has been damaged, inspect the mounting and bracket for deformation. If damaged, the RCM must be replaced whether or not the air bags have deployed. In addition, make sure the area of the RCM mounting is restored to its original condition.

NOTE: When installing a new RCM, always make sure the correct RCM is being installed. If an incorrect RCM is installed, erroneous DTCs will result.

The RCM carries out the following functions:
- deploys the air bag(s) in the event of a deployable crash.
- activates the safety belt buckle pretensioner and safety belt adaptive load limiting retractor to control tension on the safety belt.
- monitors the SRS for faults.
- requests the illumination of the air bag indicator if a fault is detected.
- communicates through the data link connector (DLC) the on-demand or continuous Diagnostic Trouble Codes (DTCs).

The RCM monitors the SRS for possible faults. If a fault is detected while the ignition switch is in the ON position, the RCM will request illumination of the air bag indicator located in the instrument cluster.

When the ignition is cycled (turned OFF and then ON), the air bag indicator will prove out by lighting for 6 seconds and then off. If a SRS fault exists, the air bag indicator will illuminate and remain illuminated for the rest of the key cycle. The RCM will also communicate the on-demand (current) and continuous (historical) DTCs through the DLC, to the diagnostic tool. If the RCM requests illumination of the air bag indicator and the air bag indicator does not function, the instrument cluster module will automatically activate an audible chime. The chime is a series of 5 sets of 5 tone bursts. If the chime is heard, the SRS and the air bag indicator require repair.

The RCM includes a backup power supply. This feature provides sufficient backup power to deploy the air bags in the event that the ignition circuit is lost or damaged during impact. The backup power supply will deplete its stored energy approximately one minute after the battery ground cable is disconnected.

Safety Belt Buckle Pretensioners
As part of the SRS, the safety belt buckles are equipped with pretensioners. The safety belt buckle pretensioners remove excess slack from the safety belt webbing. The pretensioners are activated by the RCM when the module detects a crash event force exceeding a programmed limit.

Adaptive Load Limiting Safety Belt Retractor
This vehicle is equipped with driver and passenger adaptive load limiting retractors. Adaptive load limiting retractors are pyrotechnic devices integrated to the driver and passenger safety belt retractor assemblies. Adaptive load limiting retractors work in conjunction with the safety belt buckle pretensioners and control the tension of the driver and passenger seat belts in the event of a deployable collision. The RCM monitors the readiness of the adaptive load limiting retractors. The RCM uses this information and all other information provided by the restraints system to determine what action is to be taken.

Safety Belt Buckle Switches
As part of the supplemental restraint system (SRS), the front safety belt buckles are equipped with safety belt buckle switches. The safety belt buckle switches are comprised of integrated circuits called Hall-effect sensors. The safety belt buckle switches (Hall-effect sensors) are located in the driver and front passenger safety belt buckles. The safety belt buckle switches indicate to the RCM whether the safety belts are buckled or unbuckled. The RCM uses this information in determining the deployment rate of the dual-stage driver and passenger air bag modules. The RCM also communicates the driver safety belt buckle switch status to the instrument cluster module, which monitors the information to control the safety belt warning indicator.

Safety Canopy Module

WARNING: Anytime the safety canopy has deployed, the headliner, and all A-, B-, C- and D-pillar upper trim panels and attaching hardware must be replaced along with any other damaged components and hardware. Failure to do so can result in personal injury in the event of a safety canopy deployment.

The safety canopy module:
- is installed as an assembly.
- is mounted above the headliner.
- attaches from the A-pillar frame to near the D-pillar frame.

Safety Canopy Bridge Resistor

CAUTION: Do not deactivate the driver safety canopy module circuit by removing the bridge resistor from the electrical connector.

If the safety canopy bridge resistor is removed, an open circuit fault will be generated by the restraints control module (RCM).

If a restraint system diagnostic tool is installed at the safety canopy electrical connector, a low resistance fault will be generated.

The safety canopy bridge resistor:
- is equipped on vehicles without safety canopy modules.
- must not be removed during deactivation.
- is located on the LH side C-pillar, behind the trim panel.

Seat Track Position Sensor
The seat track position sensor is a Hall-effect sensor located on the driver seat track. The seat track position sensor informs the restraints control module (RCM) of the driver seat position. Based on programmed limits, the seat track position sensor will inform the RCM of the driver seat position. The RCM uses this information in determining the deployment rate of the dual-stage driver air bag module.

Electrical System
The electrical system that supports the air bag SRS:
- is powered from the battery through the ignition circuit.
- provides the electrical path from the restraints control module (RCM) to the SRS components.
- provides the electrical path from the RCM to the data link connector (DLC).
- provides the electrical path (via HS-CAN) from the RCM to the instrument cluster module.

Sensors

WARNING:
- The restraints control module (RCM) orientation is critical for correct system operation. If a vehicle equipped with an air bag supplemental restraint system (SRS) has been involved in a collision in which the center tunnel area has been damaged, inspect the mounting and bracket for deformation. If damaged, the RCM must be replaced whether or not the air bags have deployed. In addition, make sure the area of the RCM mounting is restored to its original condition.
- Vehicle sensor orientation is critical for correct restraint system operation. If a vehicle equipped with an SRS is involved in a collision, inspect the sensor mounting bracket and wiring pigtail for deformation. Replace and correctly position the sensor or any other damaged SRS components whether or not the air bag is deployed.

For these vehicles, the SRS uses up to 6 satellite sensors in addition to the RCM. The RCM is mounted to the center tunnel beneath the console. All vehicles will have 2 front impact severity sensors located in the front-center area of the vehicle, behind the grille mounted on the lower radiator support. The first row impact sensors are located in each of the front doors behind the trim panel. If the vehicle is equipped with safety canopies, there are 2 additional side impact sensors. The 2 additional sensors are located on each C-pillar. Mounting orientation and torque is critical for correct operation of all impact and rollover sensors.