SAS UNIT CONSTRUCTION/OPERATION


BHE081057030T02

Front Air Bag System (2-Step Deployment Control)

1. During a frontal or frontal offset collision, the crash sensors in the crash zone sensor and the SAS unit detect the impact.

2. The degree of impact detected by the crash sensors in the crash zone sensor is converted to an electric signal and sent to the SAS unit.

3. Simultaneously, the SAS unit crash sensor converts the degree of impact detected to an electrical signal.

4. The SAS unit processes the calculations for the two electrical signals at the output control circuit and compares the value to a preset value.

5. The output control circuit determines the degree of impact to the vehicle by the value from the crash sensors, completes an inflator No.1 or inflator No.2 ignition circuit, and sends the deployment signal to the air bag modules.

No.

Degree of collision force

Air bag module deployment force

Inflator deployment pattern

1
Large
Large
Inflator No.1 and inflator No.2 deploy.
2
Small
Small
Inflator No.1 deploys.

6. The SAS unit completes an ignition circuit for the pre-tensioner seat belts that is synchronized to the deployment of the driver and passenger-side air bag modules, and an operation signal is sent to the pre-tensioner seat belts.

1
SAS unit
2
Crash zone sensor
3
Crash sensor
4
Signal amplification circuit
5
Output control circuit
6
Front air bag module (driver or passenger-side air bag module)
7
Inflator No.1
8
Inflator No.2
9
Pre-tensioner seat belt

Side air bag system

1. During a lateral collision to the vehicle, the crash sensors in the side air bag sensor and SAS unit detect the collision.

2. The degree of impact detected by the crash sensor in the side air bag sensor is converted to an electrical signal and sent to the SAS unit through the signal amplification circuit.

3. Simultaneously, the SAS unit crash sensor converts the degree of impact detected to an electrical signal.

4. The SAS unit processes the calculations for the two electrical signals at the output control circuit and compares the value to a preset value.

5. The output control circuit determines the degree of impact to the vehicle by the value from the crash sensors, completes a side air bag module and curtain air bag module ignition circuit, and sends the deployment signal to the air bag modules.

1
SAS unit
2
Side air bag sensor
3
Crash sensor
4
Signal amplification circuit
5
Output control circuit
6
Side air bag module
7
Curtain air bag module

Passenger Air Bag Deactivation (PAD) Switch Operation (Deployment) Control

• When the PAD switch is turned to the OFF position, the SAS unit inhibits operation (deployment) of the passenger-side air bag module, passenger-side side air bag module, and the passenger-side pre-tensioner seat belt even if the degree of impact from a collision is sufficient for normal air bag module operation (deployment). At the same time, the PAD indicator illuminates to alert the driver and passengers (passenger-side seat) of the inoperational (undeployable) condition of the air bag.

• When the PAD switch turned to the ON position, the passenger-side air bag module, passenger-side side air bag module, and the passenger-side pre-tensioner seat belt operate (deploy) normally during a collision and the PAD indicator goes out.

• When the ignition switch is turned to the ON position, the PAD indicator illuminates for approx. 6 s while the SAS unit inspects for malfunctions in the circuit. If a malfunction is detected in the circuit, a DTC is displayed.