Hi Woolie,
I don't know how true this is but I have heard that if there is no load on an alternator then the signal that drives the tacho can drop off.
Next time it does it, switch on the head lights and see if the tacho comes back.
Tony
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It has actually gotten worse since I refitted the plug on the wire attaching to the alternator. This makes me think it's either the wire itself, or the connection behind the plug on the alternator itself. As for working without a load, most of the time it has been playing up the A\C or the fan has been on so I doubt if that has any effect.
I hope to get som time to play with the wire next week, for now I've got to fix the rear drivers side door lock that doesn't unlock with the remote.:confused:
Locks fine, just won't unlock.