Airbag system (SIR)
Airbag system (SIR) is a safety device used in conjunction with seat belts. The airbag does not replace the seat belt. The driver and passengers must always wear properly adjusted seat belts.
The airbag system is designed to protect the driver and front seat passenger in the event of a severe frontal vehicle collision. The airbags deploy when the applied force is within 30 degrees of the vehicle's centerline.
The airbag system consists of the following components:
- Driver Airbag Module
- Driver side airbag module
- Driver curtain airbag module
- Passenger Airbag Module
- Passenger side airbag module
- Passenger curtain airbag module.
- Driver and passenger seat belt pretensioners (some models also have a load limiter).
- Sensor and diagnostic module (SDM)
- Clock spring.
- Wiring harness and connectors.
- AIRBAG indicator on the dashboard.
- Side airbag sensor
Airbag modules
Driver Airbag Module
Attention! Opening the driver's airbag module could result in injury due to unexpected deployment. Therefore, the driver's airbag module must not be disassembled.
The driver's airbag module is located under the center steering wheel trim. The driver's airbag module contains an initiating charge and a gas generator to inflate the folded airbag.
Passenger Airbag Module
Attention! Opening the passenger airbag module could result in injury from unexpected deployment. Therefore, the passenger airbag module must not be disassembled. The passenger airbag module is located on the dashboard on the passenger side. The passenger airbag module contains an initiating charge and a gas generator to inflate the folded airbag.
The passenger airbag module is located on the dashboard on the passenger side. The passenger airbag module contains an initiating charge and a gas generator to inflate the folded airbag.
Side airbag module
Attention! Opening the side airbag module could result in injury due to unexpected deployment. Therefore, the driver's airbag module must not be disassembled.
Side airbag modules are located in the driver and passenger seats. The side airbag module contains an initiating charge and a gas generator to inflate the folded airbag.
Curtain airbag module
Attention! Opening the curtain airbag module could result in injury from unexpected deployment. Therefore, the curtain airbag module must not be disassembled.
The curtain airbag modules are located in the roof rail from the A-pillar to the C-pillar. Curtain airbag modules contain an initiating charge and a gas generator to inflate the folded airbag.
Front seat belt tensioners
Attention! Opening the belt tensioner could result in injury due to unexpected operation. Therefore, the driver's airbag module must not be disassembled.
Belt tensioners (with load limiter in some vehicles) installed on all front seat belt buckles to retract the seat belt buckle if a frontal collision is registered. Seat belt pretensioners are controlled by the sensing and diagnostic module (SDM). The seat belt pretensioner contains an initiating charge and a gas generator for retracting the seat belt buckle. After an accident that triggered the seat belt pretensioner, the pretensioner must be replaced.
Sensor and diagnostic module (SDM)
Attention! During maintenance, handle the sensing and diagnostics module (SDM) very careful. Do not hit or shake the SDM. Never connect power to the airbag system (SIR), if the SDM is not hardwired to the vehicle. All SDM mounting bolts and ground nuts must be fully tightened. Failure to observe these precautions may result in operation and injury.
Sensor and diagnostic module (SDM) located on the floor under the floor console assembly. Sensor and diagnostic module (SDM) performs the following functions:
- Monitors the condition of the electrical components of the airbag system (SIR) and generates a diagnostic trouble code (DTC) in the event of a malfunction.
- Records data on all detected problems.
- Displays diagnostic trouble codes for the airbag system when a scan tool is connected (SIR) and system status information.
- Turns on the airbag warning light to alert the driver of a problem.
- Provides a backup power source to deploy the airbags and seat belt pretensioners if normal power is interrupted as a result.
- Controls vehicle speed by detecting frontal collisions that require the airbags to deploy.
- Passes an electrical current through the airbag modules and seat belt pretensioners, actuating them if a frontal collision of sufficient severity is detected.
Sensor and diagnostic module (SDM) does not contain repairable parts.
Airbag warning lamp
There is an airbag warning indicator in the instrument cluster related to the sensing and diagnostic module (SDM). The SDM performs an initial check when the ignition is turned to the ON position.
The SDM turns the airbag warning light on and off seven times by connecting and disconnecting ground on the warning lamp circuit. If no problems are found, the airbag indicator will turn off after flashing seven times.
If the sensing and diagnostic module (SDM) detects faults in internal or external electrical circuits that could adversely affect the operation of the airbag system (SIR), the airbag warning light stays on. Some faults may cause them not to trip when needed, or to trip under conditions when they are not normally required.
If the sensing and diagnostic module (SDM) not properly connected to its connector, the airbag circuit is shorted to ground because there is a shorting link in the SDM electrical connector. This jumper opens when the connector is properly connected, however, if the connection is poor, the SDM connector connects ground to the airbag indicator bypassing the SDM, causing the airbag warning light to stay on.
Clock spring
Attention! Disassembly of the clock spring may result in injury or damage to the clock spring.
Attention! Over-twisting the clock spring (more than 3 and a quarter turns in one direction) without the steering wheel installed, the clock spring may be damaged and the driver's airbag inoperative.
The steering column has a spiral element, which is called a clock spring for its external resemblance to the spring of a mechanical watch. It is forbidden to disassemble the clock spring; It has nothing to do with measuring time. The clock spring contains two or three conductive helical elements. One of the coils provides a permanent connection to the driver's airbag deployment circuit, regardless of steering wheel rotation. The clockspring also contains helical elements that maintain constant contact with the horn and remote control circuitry.
When the steering wheel is turned in one direction, the spiral is twisted, in the other it is weakened. Do not turn the clock spring when the steering wheel is not installed. For correct installation of the clock spring, see chapter «clock spring» in this section.
The clock spring also includes wiring and connectors for the horn circuit and the driver's airbag circuit. The clock spring wiring connects to the yellow reversible connector on the bottom of the steering column.
Wiring Harness Connectors
If the sensing and diagnostic module electrical connector (SDM) badly connected, the built-in shorting jumper connects the wire from the airbag warning lamp to the ground wire of the SDM module. At the same time, the airbag warning lamp comes on.
The shorting bar is only an additional safety device. Always disable the airbag system before starting any service procedures (SIR).
Passenger seat belt alarm sensor (SBR)
The seat belt warning device sensor detects the presence of a seated passenger and enables the sensing and diagnostic module (SDM) Operate the warning indicator or chime of the passenger's seat belt not fastened.
The SBR sensor monitors the passenger seat pressure profile and sends it to the SDM. If the occupant's weight is higher than the specified value, the SBR sensor detects the presence of a passenger.
If occupant presence is detected but the passenger's seat belt is not fastened, the SDM will illuminate the passenger warning indicator.
If no occupant is detected, the occupant warning indicator will turn off, regardless of whether the seat belt is fastened or not.
For information on the alarm status of the seat belt warning device, refer to "general description" V Section 8A, Seat Belts.
The SBR sensor is not a repairable unit and therefore must be replaced with the passenger seat cushion assembly.