spare wire to alternator ?

[Niander]

black/red wire
got a new[to me] alternator from fleebay
eventualy [as i must of manually charged it about 20 times]..yep got sick of that.
:/
and it has an extra wire going to alternator black/red wire
whats it for?
i have the blue and main power red conected and its working

[koendd]

I have the same "problem"

installed a 1Y golf lump instead of the JX and I'm left with that one wire.
It's not connected ever since (15K km ago) and no problems.

So no idea what it's for

[billy739]

that will be the speed sensor wire (rpm)

used for the oil buzzer circuit and rev counter

should connect to the W terminal

on petrols its a green wire connected to the coil negative

[Niander]

ok thanks
is there a revcounter i could get to feed off it?