A/C Lighting Circuit - 3 Wires - Why?

[EnglishLes]

I have an Evinrude 15HP 1984 model that has an A/C lighting circuit. The original 3 pin connector has been cut off and the wires wrapped in tape.

I don't understand why there are 3 wires.

The manual says:

That all 3 should show infinite resistance with the engine earth.

The resistance between the yellow and yellow/grey tracer should be 0.81 to 0.91 ohm.

The resistance between the the yellow/blue tracer and yellow/grey tracer should be 1.19 to 1.23 ohm.

Is it OK to connect all 3 together and use this and the earth for lighting?

Thanks

[nik]

If you are taking readings from 3 wires to earth, than that would suggest that it is a low voltage 3 phase system, ie. the wires are coming directly from the alternator windings.
Normally these 3 live wires would connect to a rectifier/regulator to give a dc output.
You could use the raw output from an alternator, the trouble with that is that as the engine revs go up and down, so does the voltage and frequency.
If there is a voltage to earth on all 3 wires, then that would be a star configuration. If there is no voltage to earth, then it could be a delta configuration as in the diagram below.

[nik]

Just for clarity, if the windings are connected in star, then the neutral or earth would be where all 3 windings are connected together, or star point.