Why is the speedometer not working in my 1998 Cadillac Concours Deville?
 

Last week my speedometer and tachometer quit working, also my Traction Control Light (abs light is not on) as well as my Check Engine light are illuminated, this all started at the same time. Can someone PLEASE give me some assistance on this. Also, I took it to AutoZone and they can't get any codes. Help I love my caddy and I can find no info on this!!

I got in my car after it had been sitting for a few days (at the airport) and when I started it, these things were not working, and the next day the alternator went out.