ABS light

ABS light on my 560sl goes on while driving,but not all the time.what do I check first.

[Blitzen Bob]

The first step is to diagnose if the problem is in the ABS system,or if it's an electrical gremlin that is manifesting itself in the warning light.
When is the last time ALL the fuses were changed. This should be done every seven years. These little ceramic fuses can look good, but be bad. Change all the fuses, then disconnect the battery overnight. If the light still comes on, we'll go to the next step.

Blitzen

the light is still coming on,only after car warms up.

[Blitzen Bob]

Well, we eliminated an electrical gremlin so now we'll go on to diagnose for mechanical problems.


Next you'll want to check the sensors at the hubs. These sensors get gummed up with filings and brake dust. This is the biggest cause of intermittent ABS fault. Spray a couple of cans of brake cleaner into where the sensors mount, while spinning the rotor.

You'll also want to check the wires for corrosion or breaks. This will be done with an olm meter. Next, trace the ABS cable up into the engine compartment and make sure all the connectors are snug. If you want, you can remove and clean these connections to be sure.

Lastly (and worse case scenario) is a problem in the ABS controller module. These don't often go bad, but it is possible.
What happens is the solder cracks on the printed circuit connections. These can be resoldered if you're very careful.
You need skills in electronic soldering of printed circuits before
tackling this one as a DIY project.
It's much easier to get a recycled one from a salvage yard that specializes in Benz's. A used one should run about $140.

Hope this helps.
Blitzen