Thank you for your reply. Basically, the issue is that the ABS system seems to kick in when not needed. That is, the brakes pulsate as though ABS is activated even during normal stopping. I am not sure whether that is dangerous, but I agree that it's not something to mess with.

My mechanic, an indy Volvo mechanic I trust completely, indicated that the simple solution was to disengage the ABS. He tried this by removing the fuse for the ABS, which means the car drives with no ABS. That would be fine (though the "brake failure" light would remain on, which is a little unnerving). However, removing this fuse also disengaged/disable the odometer, so we need another solution.

I asked what the alternative was, but this was at the end of the day Friday, when he was trying to wrap up his work for the holiday, and before we knew that the odometer wasn't working. The context of the question was basically "what if my wife would rather fix the ABS than drive a car without it?" His response that it would be about $800 to repair, but he did not specify why, as we both believed at that moment that we would not be interested in fixing it for that price.

The car has some rusting that makes this the last year the mechanic will allow it to pass inspection. Again, it runs well and is reliable, but the fact that it can't be inspected again makes us wish to avoid further expenses to the degree we can. If it is unsafe to drive, I imagine we would spend the money to fix it, as it would get us a year of use.