For those who may encounter the same problem I'll go through the fix then get to the question..
This weekend I finally got around to taking on my no turn signal problem. Bottom line was the turn signal switch did nothing.. Hazard lights happily blinked away so I know the wiring to the lights was good. I had tried 2 other flasher units known to be good but that didn't work either.
The car is an 87 converted from 2.3 auto to 5.0 5 speed. So as you can guess it's been torn apart but put together again.. Odd issues are expected..
in hand I started checking with the multimeter.
I starred by testing fuse #5.. I found 12v there and the fuse is good. Move on to the flasher can.. 12v on the purple orange wire coming from the fuse. Flasher output is a blue wire. Moving on to the hazard switch I still see 12v on the blue wire coming from the flasher unit. 12v on the orange/yellow line out of the hazard switch going to the multi function switch.. Hazard witch cuts power to the orange/yellow to the turn signal switch as it should when engaged.
At this point I was starting to think I had a bad multi function switch but I was wrong.. When I disconnected the turn signal plug block from the MF switch I noticed the orange/yellow power feed wire was not fully seated.. closer inspection showed that the pin retaining tab was broken letting the wire push back out of the block when it was plugged in.. I thought I could swap in another block from a 2nd dash harness I have but the exact same pin was broken on that one too. How odd..
I settled for holding the pin in with some silicone. Now with the pin seated the turn signals are working. Easy fix but rather difficult to find.
The question is are broken pin tabs on the plug blocks a common issue?
Hope this helps someone with the same problem.