Mystery wire - anyone what its supposed to connect to?

Hi all

There are four wires that come from the loom to the alternator. Brown, red and green go to the voltage regulator but the black one isn't connected to anything and looks like it should be. Any clues as to what its supposed to be for? Its the one in the foreground in this photo.

Cheers

 

I think that goes to the heater fan but not 100%

Does it come from the voltage regulator?

 

It was probably connected to the electric chokes, fuel cut-off valves etc. on the original carbs.

 

That would make sense. The bus runs fine without it. Is it a switched live then?

 

Test it and find out

 

good point!