air bag?

I have a 91 mustang lx (2.3L). recently, A beep[ing sound has suddenly started to sound everytime i start my car. it is a sequence of 5 sets of 5 beeps. i figure it is my air bag because my airbag light used to flash on and off, and when the beeping started the air bag light never came on again. again idea on what the problem is?