Where do ABS sensors install on 1988 560SEL?
 

I recognize the rubbing feel when I brake as my ABS sensors acting up. Where are these installed on the 1988 560 SEL, at the wheels? I don't have a shop manual for this car.

The fronts are inside the wheel. You'll see an electrical line coming down to the inner side of each front wheel. The connection is somewhat L-shaped. A 5mm allen head loosens it. I found it helps to spray the area first with brake parts cleaner. I also found that getting them out is like pulling teeth. After cleaning, I sprayed some WD-40 around them, twisting them CC/clockwise to help loosen. Eventually they came out. My left front was filthy. I also sprayed it with brake parts cleaner; did the same for the right.

One pro who used to post here said he never had any luck with just cleaning them. In my case, the ABS light came on because of a loose wheel bearing. The sensor had pulled away from the wheel just enough for the magnetic field to weaken and trip the light on the dash, so cleaning dirty sensors didn't help. I did the cleaning first; then took it to a tech when the ABS light didn't go out.