W126 ABS light & wheel bearing clearance
 

Ever since I replaced the front pads, rotors, inner and outter wheel bearings and races, the ABS started to act up. I tightned the wheel bearings by hand without using a dial indicator just enough to have little play but tight. The ABS seems to activate during normal braking up until 30 mph then the light stays on until the next key cycle. I rechecked everything, the sensors which look ok, the tone rings which got some bearing grease on them but I cleaned it off completely with shop air and brake kleen. I repacked the bearings again still with the same results. Anyone ever have issues like this? I am thinking the bearings clearance are way off causing this to happen

The way to tighten wheel bearings is to tighten with a wrench tight, not standing on it but tight by hand, then backing off the nut with the wrench and take your thumb and a finger and snug it up, set the lock screw and done. I always do it this way, well for the last 55 years that I have been working on autos, and don't think it is necessary to use the dial indicator method. Some people will say things like your wheels will fall off etc but that has never happened to me on my 5 MBs or my BMW, Jag, 2 Corvettes, and other assorted autos.
Have you cleaned the teeth on the hub that the sensor is reading?

FYI
 

A single tire shifted belt can activate ABS.


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Before you take the hubs off again I would check the sensors.
Hook up a multimeter (AC low voltage setting) to the connector (round rubber coax connectors).
The right side connector is between the battery and the windscreen washer reservoir.
The left side connector is in front of the fuse box
With the wheel spinning they should give about 0,7V AC
Also check the resistance, it should be about 1400 ohm.

Last week I had a strange problem with my ABS.
A couple of weeks ago my Indy changed a wheel bearing.
After that the ABS acted up just before stopping.
He cleaned the ring (with brake cleaner an compressed air) and the ABS stopped completely.
We ended up swapping the hub with a used one and the ABS is working again.


Rob