Wiring for third brake bed light

Long time lurker, first time poster.

I've searched for info on the details and location of wiring for the third brake light bed light and its three position toggle...

Problem is, the results get flooded with wiring of the third brake light on a topper. Not what I'm looking for.

The goal is to wire a relay to power rocklights when that bed light kicks on in the "when door is open" position. This makes them courtesy lights when you open the door or unlock the truck.

Why not just pull from the dome on the A-pillar? Well they dim on and off and relays don't like that. I guess I could direct wire them but that feels... unprofessional. The third brake bed light does not fade so it must be different.

Anybody have a link to a thread with good detail on how that light functions and where the wires are? Maybe I'm over thinking and can just investigate that toggle with the multimeter to see what's going on, but your experience is better than my research.

 

3rd GEN Added Lamps to Cargo SW

 

Perfect, Cargo Lamp was phrase I was looking for! Thank you.