I got this problem the first day the car came home. I took out the fuse upper tray to access the relays below and it was indeed a buzzing relay (can't remember which). I thought it was the relay and opened it up to inspect for broken solder joints. In the end turned out to be faulty fuse or fuse circuit.

Either way your problem may be somewhere in between.

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1992 124 E200 (Euro)