1. Turn the ignition key to the "ON" position but do not start the car.
2. Press and hold the TRIP button on the instrument panel.
3. While continuing to hold the TRIP button, turn the ignition key to the "OFF" position.
4. Release the TRIP button.
5. Turn the ignition key back to the "ON" position.
The air bag light should now be reset.
Please note that this procedure may not apply to all 1999 Infiniti i30 vehicles. If the light does not reset, consult the vehicle's owner manual or contact a certified mechanic for further assistance.