The cord that the umbilical connects to your TV with is the driver for the turn signals and the running lights.
The green wire controls the running lights on both sides. The brown wire connects to the right turn and stop.
So, a look at your umbilical system would seem to be in order.
Sometimes, just reversing the umbilical cord can fix things (flip the connectors end to end).
ps: some years (and I think `74 is one of them) use different connections to the umbilical plug. There`s a hint