Mk2 vr6 1 wire ?

[popleyruss]

Right then Ive just extended and tidied my loom up to hide and found 1 wire that is on plug a2 pin 1 blue wire single colour
It says it's the exciter wire for alternator do I need this ? 
I'm using mk3 wiring ce2 fuse box

[lemski]

isnt that for the revs on the clocks? or it is on a mk2 anyway, dont know bout the mk3s