Cletis, thanks for the correction - I shoulda counted the number of wires required for turn signals for single filament park lamps and brake lights. Yes, needs more than four wires.
Here is one of the patents for the switch that uses single filament park lights. "... the 'stop' and parking lamps of a vehicle can be used as turn indicating signals. Thus, the need for extra signal lamps for turn indication, and their associated wiring is eliminated."
Can oldchevytrucks' signal switch for single filament park lights work with double filament park lights?
