Tacho stopped working

[colinevans]

Evening all. My S2 came back from the trimmers (dash came out) with a few electrical gremlins which were easily fixed, but the tacho has stopped working. The car has elec ignition but always has had and nothing has changed there.
Car starts and runs fine so no ignition issue that I can see, and testing shows voltage at the green and whites. After reading other old posts I suspected an earth issue so hooked up an earth to the case body but no joy.
I have just pulled the tacho apart and I can’t see anything obvious. There is continuity from the green wire to the board and around the white loop. The small earth from the board to the metal body is also showing continuity.
My only thought is that screws that hold the board etc to the case aren’t providing a good enough earth so I can clean the connections up and add a ring connector to the outside of the case and run to a good earth if that might help. Otherwise I am scratching my head and at the end of my limited electrical skills, so any suggestions would be gratefully received. Can send pics if it helps.
Cheers, Colin.

[dlgis]

Hi Colin, this sounds a very familiar story, my tach was not working properly after mine came back from the trimmers, although mine’s an S1 with the tach driven off a rev generator. During the trimming process i had tidied up all the gauges - light cleaning, new bezels and gaskets. I recently took the tach back out as i’d tried all other options and removed the glass and bezel and flicked the needle around a bit to give it some encouragement. On refitting it looks like that has got it working! Just thought I’d mention it in case this helps you at all.

[colinevans]

Thanks for the tip Darryl. Sadly I have just put it back together with a new earth on the case screws and still nothing! Frustrating but not unusual!

[tim wood]

Are you sure that the white loop wires are the right way round ?
It’s a while since I had this system but I seem to recall that the little bracket with the wire loop and plastic holder inside it can be fitted the wrong way around and if so the tachometer doesn’t work.

Five minute job to undo the knurled nut and turn it around

Tim

[colinevans]

Hi Tim. The 3 way connector (2 whites and green) can only go one way, and the actual connections haven’t been touched, only the main block was disconnected then reconnected as far as I know. Thanks anyway though.

[tim wood]

Ahh,
You have the later block -I understand that. Do the white wires then go directly into the tach case?

[colinevans]

Yes, exactly right Tim

[colinevans]

As an update, borrowed another tacho this afternoon, plugged it in and it works fine, so at least I know what needs doing!

[colinevans]

Now gone off to Speedy Cables. I assume I can put a loop across the two white cables in the remaining part of the connector block and keep driving in the meantime?
Thanks all.