Yahweh is the second person of the Trinity

Yahweh is, in fact, the second person of the Trinity, who became incarnate. As such, he is self-existent, as are the Father and the Spirit. Because God is self-existent, each person of the Godhead is.

 

Scott Oliphint (2011-11-02). God with Us: Divine Condescension and the Attributes of God (Kindle Locations 5323-5325). Crossway.