tachometer not working

[planes49]

My tacho has never worked, and I havn't really been bothered by it. However would now like to have a go at fixing it. I see there are 3 wires (plus lighting) fixed to top back of instrument. The black central is I believe the earth, the black/white goes to the coil, and I'm not sure about the green. Does it go to the ignition?
I did aquire a spare tacho and tried fitting that, with no luck, so it appears not to be the instument.

[planes49]

Thanks all. Have been out playing with the car this afternoon. The coil has a white wire either side at bottom, a black wire on top nearside, and black/white on top offside. The wires then disappear into a very complicated looking connector, before going into loom. Am thinking of running direct wire from the top offside connector on coil to back of tachometer?

[planes49]

I have finally got back to playing with my wiring/tachometer. R-tried my spare tacho, and hey presto, I now have a working tacho. Can't have wired it up properly when I checked it about 3 years ago. Now to investigate my recently misbehaving water temp gauge.
Incidentally, if anybody wants a white tacho with black figures for a rebuild etc, very happy to post it out if it can be of use.

[planes49]

Basically, it has stopped working. It used to run a bit hot and I did the paper clip thing with the otter switch. Have now put it back to normal. Took it for a run this afternoon, hot air from the heater, and the water pressure tank hot, so thermostat is working. I havn't had a look at the bible yet, but I suppose the water temp sensor may be faulty.

[planes49]

Many thanks with that. I am having great trouble locating the lower one. I think there is a green wire running from the loom on the top one down into the bowels, but am nor quite double jointed enought to get in the bay and find it. This is despite all the helpful photos on the site! repacing it on top one looks more straightforward. I guess if I can establish that the green wire is the feed, I could just cut that and use it.

[planes49]

No problem identifying the otter switch. Shall try harder to find the temp sensor.

[planes49]

Got it!! It is of course where it should be! In broad daylight and with a torch to help. It is underneath a wiring loom. Even managed to get the terminal off with a screwdriver. I suspect that if I could get down in there with some sandpaper that all would be well, but have just ordered a sensor up from Redline as recommended. Very helpful guy. I shall fit as recommmended in unused Rover port. Incidentally the green wire which runs down past the top sensor was the correct one. Many thanks for all the inputs everyone.