AIRBAG SYSTEM

FUNCTION OF MAIN COMPONENTS

The main components in the airbag system have the following functions:

Components	Outline
Airbag ECU Assembly	The airbag ECU assembly receives signals from the deceleration sensor and safing sensor built into the airbag ECU assembly and one of the front airbag sensors, determines whether the horn button assembly, instrument panel passenger without door airbag assembly, LWR No. 1 instrument panel airbag assembly, front seat airbag assembly, curtain shield airbag assembly and front seat belt pretensioner should be activated, and diagnoses system malfunctions. The airbag ECU assembly receives signals from the deceleration sensor and the safing sensor built into the airbag ECU assembly, door side airbag sensor, rear side airbag sensor, No. 2 rear side airbag sensor and front floor side airbag sensor, determines whether the curtain shield airbag assembly, front seat airbag assembly and front seat belt pretensioner should be activated, and diagnoses system malfunctions. The airbag ECU assembly sends the airbag deployment signal to the ECM through the Controller Area Network (CAN) to operate the fuel pump control.
Horn Button Assembly	These consist of an inflator, a bag, and so on. The inflator deploys gas in accordance with an expansion signal from the airbag ECU assembly and deploys the bag.
Instrument Panel Passenger without Door Airbag Assembly
LWR No. 1 Instrument Panel Airbag Assembly
Curtain Shield Airbag Assembly
Front Seat Airbag Assembly
Front Airbag Sensor	The front airbag sensor uses an electrical type deceleration sensor. Based on the deceleration of the vehicle during a frontal collision, a distortion is created in the sensor and converted into an electrical signal.
Door Side Airbag Sensor	Detects the deceleration of the vehicle during a collision, and transmits the signal to the airbag ECU assembly.
Rear Side Airbag Sensor
No. 2 Rear Side Airbag Sensor
Front Floor Side Airbag Sensor
Combination Meter Assembly - SRS Warning Light	The SRS warning light turns on to alert the driver when the airbag ECU assembly detects a malfunction in the SRS airbag system.

OPERATING CONDITION

If the impact of a collision is greater than the specified value, the SRS is activated automatically. The airbag ECU assembly includes the safing sensor and deceleration sensor. The safing sensor is designed to turn on at a lower deceleration rate than the deceleration sensor.
1. In case of a frontal collision, the airbag ECU assembly determines whether airbag deployment or pretensioner activation is necessary based on signals from the deceleration sensor and the front airbag sensor. If the safing sensor turns on simultaneously, current flows to the squibs to deploy the SRS components as shown in the illustration below. However, a deployment ignition signal may be output with the deceleration sensor on signal even without a signal from a front airbag sensor.
2. In case of a side collision, the airbag ECU assembly determines whether airbag deployment is necessary based on signals from the door side airbag sensor, No. 2 rear side airbag sensor^*and front floor side airbag sensor. If the safing sensor turns on simultaneously with either the door side airbag sensor and front floor side airbag sensor, current flows to the squibs to deploy the SRS as shown in the illustration below:
  - *: For front passenger side on models with long slide seat
3. In case of a rear side collision, the airbag ECU assembly determines whether airbag deployment is necessary based on signals from the rear side airbag sensor, No. 2 rear side airbag sensor^*and front floor side airbag sensor.
  - *: Except for front passenger side on models with long slide seat

SYSTEM CONTROL

Airbag for Front Collision
1. For front collisions, there are 7 airbags and 2 seat belt pretensioners: an SRS driver airbag (horn button assembly), SRS front passenger airbag (instrument panel passenger without door airbag assembly), SRS knee airbag (LWR No. 1 instrument panel airbag assembly), SRS front side airbag (front seat airbag assembly LH and RH), SRS curtain shield airbag (curtain shield airbag assembly LH and RH), front seat outer belt assembly LH and front seat outer belt assembly RH. The deployment of the airbags and the activation of the seat belt pretensioners occur simultaneously.
Airbags for Side or Side Rear Collision
1. For a side collision, if the door side airbag sensor, No. 2 rear side airbag sensor^*and front floor side airbag sensor detects an impact, it informs the airbag ECU assembly, and the airbag ECU assembly causes the SRS front side airbag (front seat airbag assembly) and SRS curtain shield airbag (curtain shield airbag assembly LH and RH) to be deployed and front seat outer belt assembly LH and RH to be activated and operated simultaneously.
  - *: For front passenger side on models with long slide seat
  Figure 1. Side Collision
2. For a side rear collision, if the rear side airbag sensor, No. 2 rear side airbag sensor^*and front floor side airbag sensor detects an impact, it informs the airbag ECU assembly and the airbag ECU assembly causes the SRS curtain shield airbag (curtain shield airbag assembly LH and RH) to be deployed.
  - *: Except for front passenger side on models with long slide seat
  Figure 2. Side Rear Collision

DIAGNOSIS

If the airbag ECU assembly detects a malfunction in the SRS airbag system, the center airbag sensor assembly stores the malfunction data in memory, in addition to illuminating the SRS warning light.
The 5-digit DTCs can be read after connecting a Global TechStream (GTS) to the DLC3.
If the SRS airbag deploys, the airbag ECU assembly turns on the SRS warning light. However, in contrast to the ordinary diagnosis function, a DTC is not stored. The SRS warning light cannot be turned off. It is necessary to replace the airbag ECU assembly with a new one.