Clarifications and conclusions
After some digging with the wiring diagrams in the manual and poking around behind the panel, I've come to the following tentative conclusions:
- The PO changed the existing 2-bulb masthead light (Steam/Anchor) with an LED combination tri-color/Anchor light, and got rid of the steaming light altogether. I haven't found any combo lights that include Anchor/Steaming/Tri-color in one unit; I'm confident that the one on my mast probably isn't unique. Best guess is that the PO intended to use the anchor light for steaming (and display an extra white to stern). I know this is illegal, but I've seen it on quite a few boats around here.
- The circuit breaker for the nav lights is definitely bad. It wasn't connected to the masthead spaghetti in any way; even with the load wires disconnected, it will not stay in the on position. In fact, the switch stopped 'tripping' and is simply loose in its housing now (won't reset). I moved the load (lights) to the windlass breaker (a lower amperage breaker, and I don't have a windlass on the boat- there was nothing else connected to it). Bow and stern lights function as they should now, other than being mis-labeled at the panel.
- Carl's right about the labels being moved, but there's no label underneath the Steaming Light label- Just a hole for the backlight. Several breakers have been moved from their factory-installed positions on the panel (It's amazing what you discover when you RTFM).
- All of the breakers except the one labelled 'steaming' get their power from a common bus. When I first started looking, the steaming light's source side was connected to the anchor light's load side- so the steaming light breaker would not have power unless the anchor light was switched on. (I intend to source the power for the 'steaming' breaker from the running lights, once I get the masthead lighting/mystery switch sorted out.)
- Given the number of other electrical gremlins aboard (my AC outlets are only producing 84 volts, but I have 115 at the panel... My tach and fuel gauges don't work (but the hour meter does!)... the LED indicators on the breaker panel are hit-or-miss... the refrigeration unit doesn't seem to work...), I intend to ring out ALL of the onboard wiring. I suspect I'll be 'fixing' quite a bit more as time goes on. (Btw Rick, I think you're right- There's a grounding issue somewhere.)
Thanks again to all for your comments! As soon as I know what's what, I'll post a definitive answer.