SRS System Description - Components
SRS Unit (Automatic Short-Circuit Mechanism of SRS Unit Connectors)
When the SRS unit connectors are disconnected from the SRS unit, the automatic short-circuit mechanism in the connectors creates short-circuits to prevent accidental deployment of airbags or tensioners. This automatic short-circuit mechanism is configured in such a way that the respective deployment side circuits (adjacent terminal) are short-circuited when the connector is disconnected.


SRS Unit (Electrical Terminal Fit Detection System)
The connectors connected to the SRS unit are equipped with a terminal that short-circuits the fit detection terminals with each other. If the connectors are properly connected, the fit detection terminals are short-circuited to each other and the SRS unit detects the fitting of the various connectors. When the vehicle is turned to the ON mode while a fitting is not detected, poor terminal fitting is judged and a DTC is stored.
SRS Unit (Rollover Detection)
A sensor integrated into the SRS unit performs rollover detection. The sensor detects the degree of vehicle roll and converts it to an electrical signal. If the SRS unit determines that a vehicle rollover is occurring, one or both side curtain airbags and seat belt tensioners will be deployed depending on the direction and number of rollover events.
Driver's and Front Passenger's Airbag
Airbag
The driver's airbag is located in the center of the steering wheel. The front passenger's airbag is located in the dashboard on the front passenger's side.

Dual Inflators
The airbag modules adopt dual inflators for the driver's and the front passenger's airbags. The dual inflators increase airbag effectiveness by properly adjusting the timing when the two inflators are to be ignited (together or sequentially) based on speed or impact.

Driver's Airbag (Continuous Capacity Change Type)
For the driver's airbag, the continuous capacity changing airbag that is spiral stitched coming with the exhaust air control valve helps lower the impact of airbag while protecting the occupants effectively. The spiral stitched airbag can get inflated in a shorter time at the suitable air-pressure with a small amount of inside-air; however it does not compromise the ability of protecting the occupants. The exhaust air control valve on the airbag adjusts the air-pressure properly, and tearing the spiral stitches on the airbag will increase its air-capacity inside the airbag so that the system can keep its proper air-pressure.

Safety Vent
The front passenger's airbag (A) is equipped with safety vents (B). When the airbag deployment occurs near the occupant, releasing gas from the safety vents reduces the possibility of injury to the occupant. When the airbag is fully deployed, the safety vents close and hold the internal pressure to ensure the occupant restraint and protection performance.

Side Airbag and Side Curtain Airbag
Side Airbag
The side airbags are located at the outside position of the seat-back of the driver's seat and the front passenger's seat. Being installed at the seat-back enables operation in optimal condition for the occupants regardless of the seat slide and recline position.

The side airbag assembly is configured with an inflator and an airbag. It is designed in a way that the airbag tears open the seam of the seat-back to enable efficient deployment. Objects adjacent to deployment or using a seat cover other than the one dedicated for the side airbag may prevent proper operation of the side airbag.

Side Curtain Airbag
A side curtain airbag inflates the full area of the window to protect your head from hitting the window or frame pillar in a side-impact collision. The side curtain airbags are located under the roof side panels. The side curtain airbags are deployed by triggering a gas inflator located near the B-pillar. Objects adjacent to deployment or attaching parts other than the ones dedicated for side curtain airbags is subject to prevent proper operation of the side curtain airbags.

Impact Sensor
The G-force sensor within the impact sensor detects the force upon a collision. If the impact exceeds a preset threshold value, it is converted into an electrical signal that is sent to the SRS unit.
Front impact sensor: The front impact sensors are installed at the right and left front side frame. They detect the frontal vehicle impacts.
Side impact sensor: The first and second side impact sensors are installed at the right and left floor near the center pilllars. They detect the lateral vehicle impacts.
Driver's Seat Position Sensor
The driver's seat position sensor is mounted to the driver's seat rail. When the driver's seat is moved to the full-forward position, a metal part of the seat track interrupts the sensor signal. This change in signal is then sent to the SRS unit for processing. If a frontal airbag deployment becomes necessary, the driver's airbag will deploy at the slowest rate, regardless of impact severity. With the seat moved further back, the SRS unit commands the appropriate deployment force based on impact severity.

Front Passenger's Weight Sensor
Overview
The front passenger's weight sensors for load detection are equipped inside the front passenger's seat. The SRS unit receives the load information from the weight sensors, performs an occupant judgment of the front passenger's seat, and adjusts the front passenger's airbag deployment and performance. In addition, there are two types of weight sensors, a two sensor type and a four sensor type. The HDS can determine which type is used.
Operation
The weight of the front passenger's seat is detected by the weight sensors and sent to the SRS unit. If the weight is above a threshold level, front passenger's airbag operation is allowed, and if the weight is below a threshold level, the system will automatically turn the front passenger's airbag off. Also, the front passenger's airbag cutoff indicator turns on to inform the occupant that the front passenger's airbag will not deploy.

NOTE: The front passenger's weight sensors measure only the weight that's actually on the seat cushion. They do not measure the weight of the front passenger's legs extending to the floor or arms resting on the armrests. A front seat passenger who weighs near the airbag's cutoff threshold may cause the airbag and indicator to turn on and off just by moving around in the seat and shifting the occupant weight. This may cause some occupants to believe there's something wrong with the airbag system when it is operating normally. Also, although the measured weight of the two sensor type differs by the seating state of the occupant, load detection by the weight sensors is performed accurately.

Seat Belt Tensioner
Overview
When the seat belt tensioner operates, it quickly tightens the seat belt, and improves the occupant's initial restraining effect (preventing the occupant's body from being moved forward). When the load exceeds the preset value, the load limiter keeps the restraining effect while sending out the seat belt to protect the chest of the passenger.

Operation of Seat Belt Tensioner
1.
When the SRS unit detects a collision signal at the time of an impact acting upon the vehicle, it sends the actuation signal to the seat belt tensioner and the internal gas generator to generate gas.

2.
The winding mechanism is rotated by the generated gas pressure and winds the seat belt.
Operation of Load Limiter
3.
After the seat belt tensioner actuation, or if the seat belt is rapidly pulled out, the ELR lock mechanism of the seat belt retractor is activated and locks the seat belt.

4.
When the load applied to the seat belt exceeds the specified load, the load limiter is actuated and releases a certain amount of the seat belt to reduce the extra load.
ELR (Emergency Locking Retractor) Lock Mechanism
If the seat belt is rapidly pulled out (occupant sliding forward during a collision), the ELR lock mechanism of the seat belt retractor is actuated and locks the seat belt to secure the occupant's body.
Seat Belt Outer Lap Tensioner
Overview
In the event of a collision, the seat belt outer lap tensioner coordinates with the seat belt tensioner and instantaneously retracts the seat belt. This ensures the seat belt's ability to restrain and protect the occupant at the chest and waist by firmly securing the occupant to the seat.
Operation
1.
When the SRS unit detects a collision signal at the time of an impact, it sends an actuation signal to the seat belt outer lap tensioner, and the internal gas generator generates gas.

2.
A piston in the cylinder moves by the generated gas pressure and pulls the wire and seat belt.

3.
After the retraction is complete, the seat belt outer lap tensioner locks the wire to prevent growth of the seat belt by the forward movement of the occupant.
Selectable Energy Absorption Device
When the seat belt tensioner operates, it instantly retracts the seat belt, enhancing its ability to immediately restrain the occupant. Also, a selectable energy absorption device is fitted within the front passenger's seat belt tensioner that reduces the burden on the occupant's chest while properly maintaining the restraining force of the seat belt. To ensure the seat belt's ability to protect the occupant, the seat belt adjusts to its optimum energy absorption characteristic for the occupant by using the occupant weight information which is detected by the front passenger's weight sensor.

Seat Belt Reminder
Driver's Seat Belt Reminder Function
The SRS unit turns on the seat belt reminder indicator in order to urge the driver to wear their seat belt if the system detects that the seat belt is not buckled.
Passenger's Seat Belt Reminder Function
The SRS unit turns on the seat belt reminder indicator in order to urge the passenger to wear their seat belt if the system detects that there is a passenger and their seat belt is not buckled.