Rev Counter Failure

[Barry]

Just got back from the Goodwood Breakfast Sunday. Rev counter ok on the way there, but when I started the engine to leave, it didn't work. My car has Luminition ignition, and since I bought it, when you turn over the engine, the rev counter went round to 5500, until the engine started. Do I need to have the gauge re furbished, or what else could it be. Thanks in advance!!!

[ChrisC]

Do you use the generator on the back of the camshaft?

Not sure what series your car is...

[Barry]

It is a late 1970 Series 2 FHC. (Last but 5 RHD chassis no) not sure about the camshaft generator!

[christopher storey]

On an S2 your tacho will be the electronic type which on an original car is actuated by picking up pulses from the main lead from ignition switch to the distributor . This is a white wire which goes 2 or 3 times ( wound in a circle ) through a little coil amplifier on the tacho . It is also powered by a green wire which provides electrical power for the tacho. If it was working before , then you may have no voltage on the green wire . I can't remember if the green wire is fused or not . However, electronic ignition systems are notorious for causing problems with these tachos, more commonly just not producing a reading at all . First thing to do I would suggest is to check that green wire and/or any fuse associated with it . Since the car is still running , I doubt that there is a problem with the white wire since if anything happens to that , it normally cuts the ignition supply altogether

[Barry]

Just tried the white wire next to the coil. Not connected, but doesn't do anything. Tacho still not working. I suppose I need to take the dash top off to take out the tacho.