I am working on a turn signal issue also.
everything seems to work fine, blinkers, emergency flashers, etc with headlights off. BUT if I turn on the headlights, the pass side no longer blink, front or rear. did a little work pulling all the lenses and checking bulbs. have not gone farther yet.
I need to read through this thread carefully as the answer may be hiding in there some where.
wanted to take advantage of this thread for ideas.
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Bob Cox
78 930 clone project car.
87 924S resurrect at some point.
84 928S, Ruby Red linen/brown interior - sold
86 944 turbo my new DE/track car - sold