Just to let you all know that I have fitted a relay behind the rear light cluster so that I can run with 4 brakes lights, two reversing lamps and the LED brake light with my rear fog lamp OFF. (So standard, as per Jap spec car)
But when the fog lamp is turned ON the inner rear brake lights now act as Fog lamps (i.e. permenantly brightly lit) The outer remaining brake lights and the LED are for the brakes and I still have two reversing lamps.
This was all because
I like the look of the four brake lights and hated having two removed just to have a fog lamp which you hardly ever use.
Didn't want to loose the LED brake light.
I have smoked/tinted glass and couldn't get enough light from just one reversing lamp to see where I was reversing. Hence I couldn't practicaly use the reversing lamp as my fog lamp.
Again this is dead easy and you just need two 5pin 30A automotive relays, some wire, a pair of wire cutters and a soldering iron (or spade connectors). I prefer soldering and heat shrinking the joins. Much better, no corrosion or rust problems for the soldered connections.
Here is the simple wiring diagram. If you need any info then ask.
Fog Lamp Conversion
Now if you wish to re-use the brake light warning bulb as a fog lamp indicator then here's the wiring diagram kindly drawn by Mr John Morris who liked my first idea he expanded upon it. Thanks John.
Dashboard FogLamp Warning Light