mine was doing this, i removed mine and tapped it somewhat - no its fine again - weird
Self-activating flashers. An owner of a 1993 BMW may complain that the emergency flashers come on by themselves and can't be shut off with the flasher switch. BMW says this may be caused by a bum transistor in the crash control module, which you need to remove. It's a tall brown case stamped with the words "Crash-Alarm-Geber." Check the manufacturing date stamped on the side in white. The first digit of the code indicates the year ("3" means 1993). The second and third digits indicate the week of manufacture (for example, "08" means eighth week). If the unit was built before the eighth week of 1993, replace it. Use Part No. 61 35 1 384 761 for 318i, 318iS, 325i and 325iS models. Use Part No. 61 35 1 384 732 for the 525i, 530i, 540i, 740i, 740iL, 750iL, 840Ci, 850Ci and 850CSi.
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from http://www.motor.com/
Just got this message from an1991 E31 850i owner: after shogun gave me a link to the wiring diagrams i was able to see terminal #7 on the crash relay was grounded so that led me to the hazards switch. i pulled apart the switch and found corrosion on the pc board that was shorting out. i just cleaned off the corrosion and put the switch back together (man that was tough because i have big fingers and there are tiny parts in there lol). it fixed the problem