Every time you start your car, the air bag system goes through a self test. It it doesn't pass the test for any reason, the computer will put the light on, store a trouble code to identify what area the problem is in and disable the system. When you disconnect the battery, you are simply erasing all the diagnostics that the computer just did for you. It comes right back on for the next key cycle when it fails the test again. What you have to do is have the ABS computer scanned to retreive the stored trouble codes and they will point you in the right direction.
78 Corvette Pace Car For Sale-18k mi orig-Florida