I've recently completed electrical mods as per the Mike Drew article using (http://www.panteraplace.com/page109.htm). I didn't have a radiator fan dash light wired up so I added a suitable cable and now have an indicator when the fans are on. both my fans switch on at the same time (aftermarket adjustable temp switch) but still via the two factory relays. Anyway that is the background.
All works as it should but when the fans are off at speed the wind milling of the fan units generates enough power to light the dash warning light dimley - usually over about 50mph the light starts to glow.
Has anyone designed a circuit to cut the dash warning light connection when the voltage on it is say less than 9v ? (a guess) so that the dash light doesn't glow when wind milling but would when running voltage is turned on via the relays. I would think a zener diode driven circuit to disconnect the feed below 9v would be suitable.
Photo is when the fans are running showing the orange warning lamp, just because I have a photo of it. Can't take a photo of it dim when driving 
