1999 Lexus SC 300 Owners Manual - Page 148

COMFORT ADJUSTMENT The SRS airbag system is designed to activate in response to a severe frontal impact within the shaded area between the arrows in the illustration. There may be the case that the SRS airbags will not activate with such an impact in which the occupant wearing the seat belt correctly would not get serious injury. The SRS airbags will deploy if the severity of the impact is above the designed threshold level, comparable to an approximate 20 km/h (14 mph) collision when impacting straight into a fixed barrier that does not move or deform. If the severity of the impact is below the above threshold level, the SRS airbags may not deploy. However, this threshold velocity will be considerably higher if the vehicle strikes an object, such as a parked vehicle or sign pole, which can move or deform on impact, or if it is involved in an underride collision (a collision in which the nose of the vehicle "underrides", or goes under, the bed of a truck, etc.). 130 It is possible with collision severity at the marginal level of airbag sensor detection and activation that only one of your vehicle's two airbags will deploy. For the safety of all occupants, be sure to always wear seat belts.