1999 Subaru Impreza Owner's Manual - Page 100

The SRS AIRBAG can function only when the ignition switch is in the "ON" position. If the impact sensors in the airbag control module and the front sub sensors in both front fenders detect a certain predetermined amount of force during a frontal collision, the control module sends signals to the airbag modules instructing them to inflate the SRS AIRBAGs. Then both airbag modules produce gas, which instantly inflates driver's and passenger's SRS AIRBAGs. After the deployment, the SRS AIRBAGs immediately start to deflate so that the driver's vision is not obstructed. The time required from detecting impact to deflating of the SRS AIRBAGs after deployment is shorter than the blink of eye. Although it is highly unlikely that the SRS AIRBAG would activate in a non-accident situation, should it occur, the bag will deflate quickly, not obscuring vision and will not interfere with the driver's ability to maintain control of the vehicle. When the SRS AIRBAG deploys, a sudden, fairly loud inflation noise will be heard and some smoke will be released. These occurrences are a normal result of the chemical reaction in the airbag module. This smoke does not indicate a fire in the vehicle. SRS AIRBAG deployment depends on the level of force experienced in the passenger compartment during a collision. That level differs from one type of collision to another, and it may have no bearing on the visible damage done to the vehicle itself. 2-34