I had this problem once in my W126; if it's the same, remove the carpet from the passenger side and unscrew the cover for these relays in the footwell.

Should be a big black one making a ticking noise; unplug it. The problem with mine was that moisture got in there (long story) and was shorting something. I left the windows down and it didn't reoccur when I hooked it back up.


Hope this helps!


-Carlen

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1987 560SEL (210,000 miles)