Air Bag and Safety Belt Pretensioner SRS

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

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

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

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

The SRS deployable components are shown in the illustration.

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

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

The SRS sensor components are shown in the illustration.

Driver Air Bag Module
The driver air bag module:
- is steering wheel mounted.
- is a dual-stage air bag, deploying at one of two different rates depending upon impact severity, safety belt usage, and driver seat position.
- will deploy upon receiving a signal from the restraints control module (RCM).
- has no subassemblies.

Clockspring
The clockspring:
- is mounted on the steering column, behind the steering wheel.
- provides a continuous electrical path from the driver air bag module to the restraints control module (RCM).

Driver Seat Side Air Bag Module

NOTE:
- References to side air bag modules refer to the seat-mounted and not to the steering wheel or instrument panel mounted air bag components of the supplemental restraint system (SRS).
- When installing a new driver seat side air bag module after deployment, refer to Seats.

The driver seat side air bag module:
- will deploy upon receiving a signal from the restraints control module (RCM) initiated by the driver side impact sensor.
- is installed as an assembly.
- is mounted in the driver seat back.

Passenger Air Bag Module

NOTE: References to the passenger air bag module must not be confused with the passenger seat side air bag components of the air bag components of the supplemental restraint system (SRS).

The passenger air bag module:
- is a dual-stage air bag, deploying at one of two different rates depending upon impact severity, safety belt usage, and passenger seat occupant classification (if equipped with a passenger seat occupant sensor).
- is installed as an assembly.
- is mounted in the passenger side of the instrument panel.

Passenger Seat Side Air Bag Module

NOTE:
- References to side air bag modules refer to the seat-mounted and not to the steering wheel or instrument panel mounted air bag components of the supplemental restraint system (SRS).
- When installing a new passenger seat side air bag module after deployment, refer to Seats.

The passenger seat side air bag module:
- will deploy upon receiving a signal from the restraints control module (RCM) initiated by the passenger side impact sensor.
- is installed as an assembly.
- is mounted in the passenger seat back.

Safety Belt Pretensioners
The front outboard safety belt retractors use a safety belt pretensioner system. This works in conjunction with the front air bag system mounted in the steering wheel and instrument panel. The pretensioner is a pyrotechnic device that removes excess webbing slack from the safety belt. When the front air bags are deployed, the pretensioners deploy in the front safety belt retractors, removing excess slack from the lap and shoulder safety belt. The pretensioners are activated by the restraints control module (RCM) when the module detects a frontal impact force exceeding a programmed limit. If the vehicle is involved in a collision that results in deployment of the front air bags and safety belt pretensioners, a new driver and passenger seat belt system (including safety belt buckle and pretensioners or safety belt retractor and pretensioners, safety belt retractors, safety belts, buckles and height adjusters), must be installed.

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 passenger safety belt buckles. Safety belt buckle switches are used to indicate to the restraints control module (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.

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

Occupant Classification Sensor

CAUTION:
- If installing only the front passenger seat cushion trim cover, the seat occupant classification sensor (OCS) must be rezeroed.
- The following precautions must be taken before rezeroing of the OCS system.
- Make sure the OCS system components are connected and no faults are present.
- Make sure the vehicle has not been exposed to temperatures below 6°C (42°F) or above 36°C (97°F) within four hours prior to the rezeroing process. If the vehicle has been exposed to temperatures outside the temperature limits (6-36°C ), the vehicle must be exposed to and kept at a temperature within the limits for minimum of four hours.
- Make sure nothing is present on the passenger seat before rezeroing and nothing is placed on the seat during the rezeroing process.
- Make sure a minimum five second time period has passed after cycling the ignition switch ON before the rezeroing process.

NOTE:
- It is necessary to rezero the OCS system when a front passenger seat cushion is disassembled, a new trim cover installed, or an OCS service kit is installed. A scan tool is used to trigger the active command to carry out rezeroing of the OCS system.
- When using a New Generation STAR (NGS) tester, the OCS system rezero function is on the Ford Service Function (red) card. To rezero the OCS system:
- select "SERVICE BAY FUNCTIONS"
- select "RCM"
- select "SYSTEM RESET"
- select the vehicle from the menu
- view the on-screen information then press "TRIGGER"

The NGS screen will then display "OCS RESET: REZERO." Press "DONE" (button 8) to rezero the OCS system. The NGS will return to the vehicle menu once rezeroing of the OCS system is complete.

- To rezero the OCS system using the Worldwide Diagnostic System (WDS):
- select the "Toolbox" icon
- select "Body" from the menu
- select "Restraints" from the menu
- select "Seat Weight Sensor ReZero"

After selecting "Seat Weight Sensor ReZero", follow the on-screen prompts to carry out rezeroing of the OCS system.

- If the first attempt to rezero the OCS system is unsuccessful, a second attempt must be made.

The seat occupant classification sensor system is found only on the front passenger seat. The front passenger seat occupant classification sensor (OCS) system is comprised of a silicone gel-filled bladder mounted in the seat cushion, a pressure sensor that is mounted to the seat frame and an electronic control unit which is also mounted to the seat frame. Pressure is applied to the OCS bladder when weight of any occupant or object in the front passenger seat is present. The pressure is then transferred through a tube, is sensed by the OCS pressure sensor, then electronically communicated to the OCS electronic control unit. Based on programed limits, the OCS electronic control unit will inform the restraints control module (RCM), via a High Speed Controller Area Network (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 system components (seat cushion foam pad, bladder with pressure sensor and electronic control unit) are calibrated to each other and are serviced as an assembly. OCS system components are not to be installed separately. If installing a new OCS system, OCS system component or seat cushion foam pad, a new OCS system service kit (seat cushion foam pad, bladder with pressure sensor and electronic control unit) must be installed as an assembly.

Restraints Control Module (RCM)

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.

The restraints control module (RCM) is mounted on the center tunnel under the instrument panel. The RCM performs the following functions:
- signals the inflators to deploy the air bags in the event of a deployable crash.
- activates the safety belt retractor pretensioners to remove slack from the safety belt.
- monitors the air bag supplemental restraint system (SRS) for faults.
- illuminates the air bag indicator if a fault is detected.
- receives information from the front and side impact sensors.
- sends safety belt buckle status to the instrument cluster for safety belt lamp and belt-minder.
- flashes the air bag indicator to indicate the Lamp Fault Code (LFC) detected.
- communicates through the Data Link Connector (DLC) the current or historical Diagnostic Trouble Codes (DTCs).
- signals the instrument cluster to activate a chime if the air bag indicator is not available and another SRS fault exists.
- contains an internal safing sensor which is not serviced separately.

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 illuminate the air bag indicator located in the instrument cluster.

When the ignition is cycled (turned off and then on), the air bag indicator will remain lit for six seconds and then go out. If an SRS fault exists, the air bag indicator will then flash the two-digit LFC. The air bag indicator will flash the LFC five times, then it will remain illuminated for the rest of the key cycle. The RCM will also communicate the current and historical DTCs through the data link connector (DLC), using the scan tool. If the air bag indicator does not function, and the system detects a fault condition, the RCM will signal the instrument cluster to activate an audible chime. The chime is a series of five sets of five tone bursts. If the chime is heard, the SRS and the air bag indicator require repair.

LFCs are prioritized. If two or more faults occur at the same time, the fault having the highest priority will be displayed first. After that fault has been corrected, the next highest priority fault will be displayed.

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 damaged in a collision before air bag deployment is activated. The backup power supply will deplete its stored energy approximately one minute after the power is removed from the RCM.

Electrical System
The electrical system that supports the air bag supplemental restraint system (SRS):
- is powered by 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 air bag indicator.
- provides the electrical path from the RCM to the data link connector (DLC).
- provides the electrical path from the RCM to the instrument cluster.

Impact Sensors

WARNING: Vehicle sensor orientation is critical for correct system operation. If a vehicle equipped with an air bag supplemental restraint system (SRS) is involved in a collision, inspect the sensor mounting and bracket for deformation. Replace and correctly position the sensors or any other damaged supplemental restraint system (SRS) components whether or not the air bag is deployed.

Vehicle With Side Air Bags
For these vehicles, the SRS employs four impact sensors. One of the sensors is integral to the RCM and is not separately serviceable. The RCM is mounted on the center tunnel under the instrument panel. A front impact severity sensor is located in the front-center of the vehicle, behind the grille. In addition, there are two side impact sensors located underneath the front driver and passenger seats. Mounting orientation is critical for correct operation of all impact sensors.

Vehicles Without Side Air Bags
For these vehicles, the SRS employs two impact sensors. One of the sensors is integral to the RCM and is not separately serviceable. The RCM is mounted on the center tunnel under the instrument panel. A front impact severity sensor is located in the front-center of the vehicle, behind the grille. Mounting orientation is critical for correct operation of all impact sensors.