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Discussion Starter #1
More 60's ingenuity biting me in the butt I think. First, it was the glove box light being reverse polarity (shell hot, pin ground) to make the switch simpler. This means the standard LED is reverse biased and will not turn on. Bulb now in that position. Now, the single turn signal indicator in the cluster only flashes the turn in one direction (right, IIRC) which leads me to believe the current flows the other way when the left TS is set. A bulb would not care. Still hear the blinker, just no indicator. Any bi-directional LEDs for this or am I going back to a bulb here too? Whenever I do a search for bidirectional LED I get the Bi-color LEDs. Not really what I'm looking for.
 

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@gtonavy here on the board sells a special LED that fits there. I'm sure if you dug around you could find someone else making them too. He calls it an isolator LED and it looks like he solved the problem by adding a separate ground (though there's probably more to it than that.)

It's halfway down the page of all his other brilliant LEDs here.
 

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I recently upgraded my 65 instrument cluster, interior, and all exterior lighting to LED. The Falcon style turn signal indicator lamp does require a special bulb for exterior LED lighthing. Part number is
MP-FAL-TRN. This might be part of the issue. Did you swap out the stock flasher module for one that is compatible for LEDs?

742212
 

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Discussion Starter #4
Thanks. That's what I thought the solution would entail when I first was considering it. I was then thinking I could design something with some N and P channel FETS to automatically determine voltage direction, but if I can solve this for ten bucks, I'm in.

I do have an electronic flasher that I have not installed, but I'm sure with the additional ground in the solution for the bulb that it's a current direction problem.
 

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Discussion Starter #5
I can probably junk box the dual LED in an old bayonet base. I actually did come up with the 'no additional GND' version this morning just for fun. Might junk box that too.
 

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Knowing Ford and their bean counters, it's no wonder that they designed the turn signal indicator that way, where the bulb is wired to use the opposite side's signal circuit as a ground path, the resistance in the bulb preventing the other side from flashing, instead of using a 3-prong flasher with a "pilot" terminal with one wire going to an indicator bulb. Of course, they didn't anticipate LED's back in the forties either. The "conversion bulb" is actually two separate bulbs and diodes to prevent back-flow and a dedicated ground... much the same if you snipped the wires at the indicator plug and installed 2 separate, grounded bulbs.
 
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