Factory Foglights

A view of the wiring diagram would be useful. A lot of the wiring and switching takes place within the column mounted switch. Ideally, we would like to retain use of the rotating collar on-off switch. If that doesn't matter too much, then a new switch mounted in one of the blank positions with one end running to the foglight hot wires (which will be tied together at SOME point) and the other end picking up power from the parking/tail lights. Wattage might be an issue. Again, the wiring diagram would help clear up any such issues. Sadly, I have none.

EDIT: It is SO easy to find stuff on the Internet: Wire Diagram | PriusChat It appears that the foglights just pass through the stalk switch with all connections being made in the BODY ECU (right side of instrument panel) and also via fog light relay in the engine compartment. I will correct this entry when I read further, if editing remains an option.

 

(This is theory)

On page 162 of that schematic: pin 16 (light blue wire) in the steering wheel stalk is the power for the fogs (only active with low beams)
If you made that wire attach to pin 12 (Green wire) it would make fogs independent of headlights.

 

I looked at Jimbo's plan and it should work but would make the fog lights independent of the remainder of the lighting. If you attach light blue instead to yellow (#18), it would only turn on the fog lights when the tail lights were already on. Further more, they would extinguish with the tail lights. Incidentally, I believe that light blue is on pin 4 rather than 16. Light blue should be cut and the harness end (toward the car) taped off. Yellow should be spliced to and not cut. I'd verify both color and pin number before cutting.

This is theory too, but I'm willing to try it, when I finally open the dash to do the EV button mod. The OP's original letter has caused me to do the research and I'm very pleased to have located the seemingly complete set of color wiring diagrams. Loading should not be an issue since the fog lights, their dedicated relay, and dedicated fused circuit all remain unchanged.

 

Would you mind if the Fog lights were ON all the time the car was ON?

Check this out... Cheap Fog-DRL Mod

Really easy to do.