On our 1988 PSC 34 the nav light breakers are labeled "Running Lights" and "Bowlight". "Running Light" gets the red/green lamp at the bow pulpit, the white lamp at the stern pushpit (a red wire for both), and the compass light (a purple wire). "Bowlight" has a green wire that runs into the mast, passes thru a connector there, and goes on as a green wire to the steaming light.
We had ours fail coming off the Matanilla Shoal in the Bahamas headed for the Gulf Stream and the U.S. in 2014. It is in my wife's blog entry for June 27, 2014.
Irish Eyes to the Bahamas
"While Bill was still sleeping, I noticed the red and green sidelights were not working. Not too good. I was keeping track of several ships by eye and radar. They were miles away, but we still needed our lights shining so they could see us. I hated to do it, but I woke Bill. He is not only the Captain but also the fix-it man. Hanging over the bow in the dark and getting a little wet, he found that the wires to the lamp had corroded away. He rigged up some temporary wiring and got the lights working again."
By the way, I got soaked.
The repair story is in this thread on this group.
1988 PSC 34