The service manual shows the power comes from the fuse box on the "accessories" fuse. It's a 20 amp fuse. You can check it with a test lamp or a volt meter, power when the key is on.
The light green wire at the switch (power) will be connected to an accessories plug under the dash that will be an orange coloured plug with 3 "bullet" connectors. The dark green wire from the switch then goes to the road lamp bulbs
I can look at my Cuda later today for the fuse exact location if you need it