I'm posting this simply to correct some erroneous information in an earlier post. I have a '92 or '93 Aerostar that had, when I got it, a constantly blinking airbag light. It was blinking out a code 45.
Earlier posters correctly indicated that this means that a crash sensor is not functioning properly. They have misidentified the location of the affected sensor. The sensor that this code refers to is mounted not behind the kick panel, but on the front radiator support. Being outside, of course, means it is exposed to the elements. What happens is that it develops corrosion (rust) between it and the component it is mounted to, which severs its ground connection, causing the fault that triggers the light. It is easy to reach: it is accessible through the grille.
The solution is equally simple: unbolt it, sand off the rust on the sensor (a small black box retained by only one bolt, if I recall correctly) and off its mount, apply some dielectric grease (to inhibit further corrosion in the future), and reassemble. Voila! The light's now off when you turn on the ignition, and airbag functionality has been restored.
Apparently the previous owner of my van found the same posts I did: scrape damage to the headliner and windshield indicates that he had removed the inside panel to access the crash sensor located by the driver's foot. What a pain!
It may be years overdue, but I know there are others out there with
1992 / 1993 (and other years) Ford Aerostars with flashing airbag lights. Put away your black electrical tape and break out the 1/4 inch drive ratchets!