The LS460's fog lights from factory only comes on with the low beams on. With the high beams on the fog lights turn off. Wanted the flexibility of being able to turn on my fog lights, independent of the headlights. Want to thank Shibumi1 for documenting his version of the mod, I just modified it to do what I wanted. I did not want the fog lights on all the time nor did I want to put in another switch. I just wanted my fog lights on when the park lights come on and also full functionality of the factory fog light switch. The wiring diagram below is how I wired everything up.
The baby blue wire below is the ground signal for the fog light switch. It is located under the steering column, just remove the plastics of the steering wheel column and the picture below is what you see with the bottom plastic piece removed.
(picture courtesy of daniel1235)
For the harness I planned on mounting all the relays etc up front behind the bumper support so ran the fog light ground signal wire from under the steering column through the firewall into the engine bay to the front behind the bumper support. Soldered all the wires, heat shrunk every connection and made a nice harness with some techflex wire loom. The below shows the harness but with some extra wires etc I wanted to run that ties in to the front I plan on doing later. Also the harness has a fused power wire to run the HID's for the fog lights.
The relays mounted behind the bumper support.
For the fog lights to come on with the park lights, I tapped into the yellow wire on the harness that is connected to the headlights. Picture below shows the orange wire I used in my harness and tapped into the yellow wire.
The JDM fog lights that were modified slightly.