Got your PM.

Replying to your thread for the benefit of all.

Here is the wiring diagram for your car:
http://www.startekinfo.com/StarTek/outside/12265/disc_2/program/ETM/80_300.pdf

The flashing controller is inside the button. Not separate like it is in later 123s.

Now if you lost your ground at the flasher connector that would explain why you can jump out the connector and get the lights to come on, but two different flasher relays won't work. The flashing controller needs ground to function.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech