Integrated Masthead Light Wiring Question

[TJSocal]

I've got a masthead light (old, incandescent, not sure brand) with an integrated strobe, anchor light and tricolor. Some previous owner cut all the nav light wires, apparently in prep for some project that never progressed, so I'm trying to figure out the wiring.

There are four wires going up to the masthead light. I've figured out which one is ground, and have identified the hot wire for the strobe.

The strobe turns off when the anchor light is on, which I assume is by design.

The problem I'm having is that both of the other wires seem to turn on the anchor light and neither seems to activate the tricolor.

Any ideas? Is there something I'm missing?

[AKA-None]

You said incandescent so maybe burned out bulbs?

[TJSocal]

Originally Posted by AKA-None

You said incandescent so maybe burned out bulbs?

It's possible, although I remember in an earlier easter-egging session I managed to get the tricolor to turn on (but not sure how...).

If the tricolor bulb is burned out would that light the anchor light when the tricolor is energized? That seems a little strange to me.

[alctel]

Could be one of those ones on a timed switch, if you turn them on they activate anchor, on and off within 3 seconds activates the tricolour

[SailingHarmonie]

Sounds like a job for a multimeter instead of randomly pushing power through wires.

[TJSocal]

Originally Posted by SailingHarmonie

Sounds like a job for a multimeter instead of randomly pushing power through wires.

Yeah, but where's the sport in that?

[gs41escapade]

Originally Posted by TJSocal

I've got a masthead light (old, incandescent, not sure brand) with an integrated strobe, anchor light and tricolor. Some previous owner cut all the nav light wires, apparently in prep for some project that never progressed, so I'm trying to figure out the wiring.

There are four wires going up to the masthead light. I've figured out which one is ground, and have identified the hot wire for the strobe.

The strobe turns off when the anchor light is on, which I assume is by design.

The problem I'm having is that both of the other wires seem to turn on the anchor light and neither seems to activate the tricolor.

Any ideas? Is there something I'm missing?

I assume you have independently tested all the bulbs.
In some modern devices, (we make one), reversing the voltage sense (i.e. plus to minus and minus to plus) on the line may activate the other light set. I.e. the ground wire may not be the return, but rather a pair of the other lines is supply and return. Switching might be done by diodes integrated into the light unit. You have to be careful testing this hypothesis as you don't want to burn out the unit if wrong, but that's what I would check. Sometimes you can just "brush" the test connection to get a quick flash and not cause damage. Another test approach might be to try with a 9V battery to see if you get response.