This is on 2002 F150 4.2L V6, trying to track down possible short that keeps blowing starter relay fuse. While looking around underneath saw this connection to back left side of engine driver side that looks covered in I assume is oil/trans? Any idea what this connection or sensor is?

 

It look like you might be looking at the crankshaft position sensor or a similar connector. If it's covered in oil or transmission fluid, it could be a sign of a leak or a bad seal.