I want to wire some bed lights on 2015 250 6.7L so they are on the interior lights and come on when I open door, etc. Recommendations on what tire to tap into on drivers side sill?

 

I would just use the running board courtesy light wire that is attached under the truck to each side of your frame. That wire will supply 12v when the doors are open or the dome light comes on. I believe you can purchase a Metra connector 72-5600 that will plug right into this capped plug on your truck. This is actually what I am planning to do in the spring when I wire my bed lights.

 

Can you elaborate on where this plug is please?

 

It is attached to the outer frame rail towards the rear doors / back of the cab. If I had my truck with me, I'd go out and snap a pic for you. If nobody else comes along with a pic, I'll post one up tonight when I get home.

 

Here ya go, I found the post with pictures:
https://www.ford-trucks.com/forums/1...l#post12318595