You either have a bad ABS sensor at one of the wheels or the gears need to be ceaned at the wheels where the sensros are located. I don't know of a way to test the sensors, but my dad's 300E use to do that until a mechanic cleaned the teeth at the front wheels. There are 3 sensors I believe, one at each front wheel and one on the rear diff.
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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