the button under the fog light button, what does this button do? It doesn’t seem to do anything?

I have a 2017 XL STX. I also swapped out my third brake light with the Anso smoked third brake light.

 

It should turn on the exterior lights as if you opened a door, and keep them on longer after you close the door. On my XLT that is the puddle lights and the center high mount cargo lights.

 

I guess it’s working. Since the are smoked they just aren’t bright at all. I may need to look into some bed LEDs.

 

I've got the 302A package on my XLT. It comes with LEDs in the bed on either side of the tailgate. When I push that button, it turns on the LEDs. What I'm saying, is the chances may be you're already prewired for those lights, and could make for an easy power source.

 

I need to check this out. I can say the cutouts are there for where the lights would mount. They just need to be punched out.

 

Agree with above. On yours, without the bed side LED's, it will turn on the high mount bed lights on each side of your brake light. Could come in handy if your unloading cargo at night and need it on for several minutes.

As mentioned above, in the XLT 302A with bed side LED's, there's an additional button below the driver's side light. This turns on the bed side LED's and the high mount. Very handy. If you look into adding the LED's, I'd also explore the option of adding this button.