Howdy,
Always check your grounds first! The dark green wire is your right rear turn and brake light. Double check the dark green wire all the way back to the connector on the right side of the fire wall. From there, dark green and yellow, (left turn/brake,) go to the turn signal assembly.
The fuse box feeds brake light switch (orange wire) and from there a black wire goes to the turn signal assembly to feed the green and yellow.
What I'd look at is 1. corrosion and grounds between to lamp and the firewall. Don't overlook the socket. 2. Wires from the turn signal assembly to the firewall and the assembly itself. 3. fuse box to brake light switch to turn signal assembly.
Make sure all connections are good and there is no corrosion.
Your problem pretty much can't be anywhere else!
best wishes,
Les
