Thank you
 

Thank you.

Welcome to the forum

Your post is hard to read, and its doubled up, lol

SJB(smart junction box) is what is pictured, its the Body Computer, first used in 2004 Rangers and up
Yes, there were issues with it, most common was corrosion inside the larger wire connectors

There are TWO relays in side the OMRON part, Interior light relay and Battery saver relay, assuming that's the correct relay, I don't know
As far as I know there is no Ford Published schematic for the SJB

Yes, Board level repairs on these are not normally done, new or used are swapped in
That relay was not a common issue so used is not a big gamble, well any more of a gamble than any used electronics, lol

And that relay may not be the issue, its controlled by the "computer"(low current board), so that could be the issue

Interior light circuit diagram below

If you wanted you could rewire the door switches to your own added relay, take the SJB out of the picture
The Door switch GROUNDS its wire out, and wires are accessible behind each sides kick panel OR at the SJB
Same for the OUT to Dome light wire at the SJB
You just need a fused full time 12v source to your added relay and activated by any door opening