the air bag warning light on the dash

we have a 2004 Toyota Corolla hatchback car which is causing concern with regard to the air bag warning light on the dash. The drivers airbag warning is lighting up sometimes when we put in the keys, it then may stay on whilst driving or may go out after a few seconds, it also sometimes comes on whilst driving along? We took it to our local Toyota garage who charged us one hours labour but could report no faults, since having the car returned to us we are still experiencing the same fault but are not sure whether to return the car for another check or if the fault is an intermittent fuse? How would we know or perhaps this is a known fault (although surely the Toyota garage would have known this? They have said the car is safe to drive but we are unsure what the problem is - if any? Kind regards, George

Airbag warning lights are exactly that...a warning that the airbag system is not operating properly. When they illuminate, the system is inactive. That means the airbags will not deploy if you are in an accident. When the warning light comes on, it is indicating a fault in the system and a scanner is usually required to diagnose the problem. The scanner for an airbag system is a different scanner than the one used to diagnose engine problem or reset the 'check engine' lights (although some scanners will do both). Vehicles have different computers for each system.
As the airbag systems are now covering more and more components, front airbags, side airbags, curtain, seat belt pretensioners, knee airbags (and coming) seat belt airbags, it is important to get the right answer before you start working to get the light out.