In the area in question, some of the cars had a violet (purple) wire that was unused. It originated from fuse 8. Somewhere in the wire loom there are two green wires (factory) spliced into the violet wire. One green wire goes to the windshield wiper / washer switch, and the other green wire goes to the emergency flasher switch.
Fuse 8 is unswitched +12 volts.
John