Rear Emergency flashers not working

I can only speculate what your issue might be but when I wire a new build.... I run a jumper wire between the Left and Right wires coming out of the signal switch, add a toggle switch to that jumper wire:  To operate flip the toggle on and move the signal switch to with the Left or Right position...  this powers all four signal lights.

Thanks for that info. I will have to try to implement that and get back to you all.

Thanks again

Ed

e-mail me a picture of your turn signal unit, or post it here.  Is it the more modern 3 arm black plastic version?  If so, then the connections are all made by the switch itself and use the same wires, the flasher lever just connects all together so it is most likely a bad connection inside the turn signal unit itself.  The "trailer box" isn also a culprit, but you've changed that already and ti doesn't know the difference from turn and hazard so if rear turns work and hazards do not, then you know the box is good and that leads back to the switch.

It's been a few years since I had dinner with Carey at Carlisle.

I had forgotten what a fantastic source of Speedster/Spyder/Coupe/general Car trivia he is.  Kinda miss the "Caddie Shack" dinners, too!