The SRS system is designed with a capacitor that is capable of firing the air bag even if the connection to the battery is lost. However, the capacitor is designed so that it will not hold a charge for a long time - only long enough to last during a collision - say a few seconds. Once the battery is disconnected, I believe you should wait about 30 seconds or so to make sure the capacitor has discharged. However, due to the explosive components, I would certainly check the official factory manual for the proper procedures before tackling this one. It is not worth the safety risk to work on it without the correct procedures, nor is it worth wasting the $$$ air bag assembly with a simple mistake.