It sounds more like a switch failure, but as I have stated on this forum too many times, "I could be wrong". I would drop the covers on the steering column and pull the switch to see what is going on. Good idea to disconnect the battery (neg first, then pos) and wait a few minutes for the airbag system to discharge. If it is the switch, you should be able to remove the tumbler assembly and put it in the new switch so you won't need to change keys. Keep us posted. I am interested to see what you find out. Thanks.