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Advice needed hazard issue

Started by MichaelBrown, 15 November 2023, 12:58 PM


I am working on a 1978 280SE. Turn signals work as expected but the turn signal/flasher relay buzzes when the turn signals are not in operation.  The bussing stops if the hazard switch is removed.  The hazard lights are inop.

I have replaced both the hazard switch and flasher relay off a known working car with the same result. 

I have cleaned all the connections.

Any ideas?


Upon further examination it seems that the flasher relay is getting constant power with the hazard switch off and no power with the switch activated.

with the flasher plugged in, Pin 15 appears to be providing power and pin 49 and 31 both appear to be ground.  Pin 49 and 31 both go straight to the flasher.  I do not believe this to be correct.


Perhaps the wires in the socket have been inserted incorrectly?
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'21 E450 Cabrio