I am currently suffering with the drama of adding door sill plates to my 2005 V6. Imagine my shock when I removed the original scuff plates, only to notice that oh no! There is no plug to hook into. Not really a surprise, I have done extensive reworking on my Mustang since I got it bone stock off the lot two years ago. While furiously digging in the door frame, I found a lone plug lying in the door frame. Of course it didn't match the one I needed, but I was wondering if anyone can shed a little light on what this plug is.

In other words...HEEEEEELP!

 

Sill plates need a "plug" ..... what do they do to need a plug?

 

Not too sure. Possibly for the illuminated sill plates?

 

I thought the same thing AirForcePonyCar, but I notice that there isn't one on the passenger side...

 

Yes, they are illuminated sill plates. But the riddle is what this lone plug does...