I'm new here, but had a similar issue with my 99 PSD truck. I ended up realizing that the airbag dash light was flashing in a particular sequence to reveal a trouble code when I first started the truck. I forget what code number was being flashed or how I even determined the number, but a google search on that number suggested that the light bulb in that "key switch mechanism" on the dash that turns on/off the passenger airbag was burnt out. Sure enough, the little bulb inside was burnt out because I always leave the passenger airbag turned off due to little kids being in the front seat (which causes that light to come on as a warning that the passenger airbag is inactivated). I took the assembly apart and desolderd the bulb and replaced it with a similar 12V bulb I found at Radio Shack. Problem solved!!! I think I read where some people replaced the bulb with a clear 12 volt LED and had success (should last nearly forever, also).
Anyways I don't know if this is your problem, but I think it is a very common cause for the "airbag" warning light to be illuminated on the dash. Post back with your findings. Best of luck and be safe.
Last edited by sluhbmet; 05-04-2011 at 04:02 PM.