1977 turn signal relay wiring

Ok I have a weird one. I think one of the wires has come off of my turn signal relay socket. Right now it only has two wires on it, a yellow and black that is 12V and a white and black that is grounded when the turn signal switch is on left or right. There is no third wire that goes to the relay signal terminal. All the diagrams I have seen seem to be for a couple of year newer 308 that seems to have different colors. Does anyone with 77 know what color wire should be on this terminal and where does it go? This would help me track down the missing wire. Btw my emergency flashers seem to work fine as do all dash indicators. Just no turn signals and thus I found the missing relay wire. Thanks!

 

Thanks! This is very interesting. My relay had been replaced with another three pin flasher relay at some point. So I wonder if the replacement relay isn’t happy with that pin not being used. I will look to see if I need to either ground that pin or just get a different flasher relay possibly. Thanks again!

 

Thank you both for your help! I was able to get the turn signals going. The previous owner had put in an aftermarket relay that required three wires to work. As My 77 did not have a ground wire, the relay wasn't right. I swapped for a two pin relay, and the flashers are going now. Thanks for all of the help!