It's a common problem, and from what I hear can happen any time after about 60,000 miles. It's not just a volvo problem - a mechanic told me many makes have this issue (the controller is currently failing on my 1999 Saab 9-5). Victor's site has a lot of information and you can find additional information on just about any volvo discussion forum. You can search here on Brickboard and find tons of postings about it.

Victor provides general information at:

http://home.earthlink.net/~vicrocha/Volvo_Parts/Volvo_V70_ABS.htm

Like many "modern" electronic parts, the solder joints crack or components fry from the heat. Several posters over on volvospeed have succesfully repaired their own ABS controller. The problem with that is if you are not successful, most rebuilders are no likely to repair a unit that has already been openned up. I am not very good at soldering but have repaired the headlight relay and the information display on my Saab and the AC conrtol unit circuit board on a 92 940 I used to own. I had Victor repair my ABS controlers since it's such a high cost to replace if I screw it up.

Discussion on repairing yourself:

http://volvospeed.com/vs_forum/index.php?showtopic=2022

It's located on the driver's side of the engine bay. See Victor's removal instructions with pictures:

http://home.earthlink.net/~vicrocha/Volvo_Parts/Volvo_ABS_removal.htm

Good luck!