Why is my airbag light coming on when engine idles? on 1990 Mercedes-Benz 190E

My 190E has always had problems but not like this one! While my car was in idle, the Airbag light came on for no reason at all. I looked in the manual and it says nothing about it. Can you help? Thanks!

Asked by for the 1990 Mercedes-Benz 190E
abs fault likely