It amazes me that there isn't a post and/or nobody gave a definitive answer about this subject. The most I saw was, "check with a multimeter". One thread did mention wire colors, but not much else that I could remember. When one wants their Toyota-like button/switch or want their aftermarket button/switch backlight to ALSO turn on, these are the wires you are looking for:

so then, without much further adieu, look for the following wires, behind the button/switch of course:

Green: (+) 12V
White/Black Stripe : (-)

These wires can be found behind any switch (these were my DAC and heated seat switch). From consensus (and common sense), you can splice into these to light another Toyota-like switch that lights up when turning the outside lights on. DO NOT splice into these for something that needs a lot of amperage (wire to an radio amp, LED light bar, GPS equipment, etc). Do that and watch your truck's electrical system go down the toilet (ECU) . Be mindful that the negative is what dims the light.

Note (and surprise b/c i never noticed), the backlight wires are on opposite ends


Viola!


That is all, hope this helps anyone searching.

As always, use your multimeter JUST to be sure. If you don't know how to use one, maybe you shouldn't be fiddling with your wires