Front Air Bag Sensor Control problems of the 1997 Plymouth Voyager

I purchased a vehicle in 1997 from a friend. All of a sudden my horn stopped working. I have replaed the fuses. I have checked all the wires. I have replaced the horn. Their is nothing wrong. I think the problem is where the airbag is behind the steering wheel. What do I do. I dont think that is my responsibility if their is a problem with the air bag is it?.

Vehicle was not started. However, gear lever will move on its own. Gears move without placing foot on the brake. Consumer adds, there is a problem w/airbag, because the light is constantly on which prohibits the horn from working. (she concerned because she has small children).