What's the blue wire on the alternator for?

[Deefadog]

As above

Just got a new alternator to soloniod made up and just wondered what the thin blue wire was for?

cheers

[Overseer]

IIRC its the one that is live when the alternator is charging.. as people run split-charge relay activation things off this

[Deefadog]

Cheers, can't hold much though, it's only about a 5amp cable?

[Judderi]

I think its used for the battery warning light on the dash. Un-plug it and the light should come on if the cars running. It has a spade connector near to the battery.

[tobz.]

Yep it is the charge-light signal cable.
You can't draw any current from it though, if you try to draw more than about 150mA the battery light on your dash will remain on when the engine is running. In the case of a split charging system the blue wire is used to switch a relay which supplies the charging current to the second battery.

[Deefadog]

Nice one guyz! Learning all the engine bits one by one

Now what's that big shiney metal thing in the middle? lol

[monzablue16v]

I think thats an expensive bit don't touch it!

[Deefadog]