What is this ground plug for

[honda34dad]

Connects to ground wire off the battery and is pig tailed on, right at the frame. Has Essex m-10354 on it and in tiny print has d4ab-14a459-fb. Anyone know what this is for? It is from a 1986 bronco 2. Wire looks to be a light orange color. The plug/connector has a small flat piece of metal coming out “male” and is in an “oval” plastic receptacle. Any help is appreciated!