90 air bag
the 90 airbag is an ongoing problem. I have spent a considerable amount of time on this as well. My research has centered around what is called by some the "clock spring" in the bag. That goes bad, and sends off a bad code. This small part is not made anymore. I have hit most of the part suppliers and recyclers around the country, and you can't get 'em. The closest you get is to replace the whole steering column. That's cost prohibitive.
Here's what I've done. There's a specific air bag place, you can find it on the web. The lady who answered the phone has a '90 and she told me her's went off as well. Her boyfriend bought a "tool" from Eckler's. I knew about it, but she was the first one I heard who used it. It's about $19. you plug it in to the computer lead under the dash, above the gas pedal. The directions are simple and in about 30 second, the lights gone. In eckler's, it's called a INFL RST correction tool, or something like that. It's specifically set up for the '90 which has this problem.
I went ahead and ordered one, after spending tons of time, etc., and money messing with this. On her's, she said her light has not come back on for over a year. Mine only lasted about a month, then came back on. But I just hit it again.
This does appear to be an ongoing problem with that model only. The steering wheel airbag changed in '91 it appears, so it's just one of those things about that year. I know other folks with a '90, and they just pulled the bulb so they'd stop looking at it.
The practical problem is, other than cleaning sensors, etc. (which is suggested by the INFL RST tool from Ecklker's) it does appear that this "clock spring" is the problem, but no one makes a replacement. I even check around the country with GM dealerships. They just don't have 'em any more.
Hope that helps.
Just got tired of fixing it. 
