I am having the same problem with my 2000. My ABS light came on and stayed on. I took it to a brake shop and for $40 they diagnosed it as a bad ABS computer. I mention this in hopes of saving you going that route. They diagnosed it, but couldn't fix it........waste of $40.
Eventually, I made an appointment with Ford. They wouldn't look at the diagnosis from the brake shop. They rediagnosed it ($69) and determined (big surprise coming.....) that the ABS computer was bad. The service guy told me that it is fine to drive with the light on. You do loose ABS capability....but the brakes will work like normal old non ABS brakes.
I decided to have it fixed. It is covered by my warranty.
As of today my Expy has been in the Ford shop, 1 month 1 day. Part of the delay was that the computer was back ordered. About a week later...they told me that they had it in...then called me back to tell me that the ABS computer part had changed. If I have this right.... what used to be one Ford part is now 2 Ford parts..and that they never got a Ford bulletin about it. Maybe if this is your problem and you have it fixed you should mention it. Good luck.