Jonathan, Unfortunately the fitting instructions were somehwat limited. The issue could be caused by the warning lamp in Alans car being a LED integrated in the tacho. Exactly how the lamp is wired in is not described in the wiring diagram of an EU3 car, but for older cars it would be an ordinary bulb with a diode in series. Alan, I think I'd try to wire in a 12V/2W bulb that simply goes to IGN and see how it behaves. A bit like on page 52 - top image - of this file: https://www.denso.ua/media/815126/160747-denso_manual-starters-en-alternators_a4_web_locked.pdf Depending on the electronics inside the alternator you may need a diode in series. It should have the cathode pointing towards the alternator. It doesn't matter what ide of the bulb it's on as long as it's in series with the bulb. The diode could be a 1N4001-1N4007, that doesn't matter as the last figure simply identifies the maximum voltage. I think the non EU3 diagram in the K-series build manual from around 2001 has the diode the wrong way around, so don't be confused ;-)