ABS light came on a few weeks back (1987 190e). I know it was related to the ABS, as it would only illuminate after the car was moving. Trying the simple things first, both front wheeel sensors are relatively new, I removed the battery and unplugged the ABS computer. I also cleaned the battery terminals which had a tiny bit of corrosion. No more ABS light.

For some reason, the older this car gets, the more attention it needs to grounds and connectors. Not the first problem that has been this simple to fix.........and definitely not the last.

Hope this helps someone.

Tinker