I recently purchased a 1966 Convertible. The signal lights were not working at all. I replaced the control unit with an replacement electronic module. Signal lights now work and sequence properly, but the opposite side blicks at the same time, but not sequentially. I have had the control unit rechecked, it is OK. Turn signal switch continuity seems to be correct. Any thoughts on the cause of this problem?

I suspect it is the "Turn Signal Relay". There is a diagram of the circuit on this website.

Don,
I had a chance to look at the circuit. There is also a "stoplight relay" in the circuit. Try unplugging that relay and see what happens. If the problem goes away I would suspect the stoplight relay. If it still persists it is probably the turn signal relay. You could try cleaning the contacts in the turn signal relay if you can get it open. Let us know what you find out.

Thanks for the info. However, the replacement electronic module replaces both the turn signal relay and the stop light relay. It also replaces the trun signal flasher and motor. I sent it back to the supplier after I had installed it and discovered the problem thinking the new unit might be defective,but all components checked OK.

Do you still have the original bag? If so did you ever open it to see where the problem was. I have 65's and someone had changed to the electronic module and I had all sorts of trouble with it(similar to what you describe) anyhow I put an original set up back in it and had to change the brakelight relay(I think 66 is a diffrent plug than 65) and have been cured for the past 2 years. I still have some extra pieces if you try that route (we have 14 Birds and 8 are licensed so I keep everything) Also Pat Wilson Thunderbirds will rebuild your bag and test it