Where does that wire head to? It kind of looks like it’s headed toward your electric fans which makes me think it could be some kind of aftermarket fan controller?

On closer look, that looks like a temp probe wire headed toward your radiator, and other wires head into the wiring bundle that has the wiring for the factory fan relays. Which just adds to the assumption it’s a fan control of some kind. Most likely a previous owners effort to get the fans to kick on at a lower temp.