hrm, my loom might be a freak.

There's two wires there alright, but they are red/white and green/blue - also they have round plugs not the flat spade connectors of the tacho. multimeter time I thinks... edit: they aren't plugged together either - I believe the ones I'm looking for should be plugged together?

Also a couple of the wires in the round plug are different too but I think they might just be discoloured as other than that they are in the right spots.