This might sound like a dumb ass question, but i wanna know if if an aftermarket tacho works the same as a factory one. The reason i ask is i'm doin a dash conversion and i can't get the factory tacho workin, so i was wondering if i could run a power wire, earth wire, and a wire to the neg. side of the coil. and hook it up to the rear of the tacho were i can tap it in?? Any suggestions??
Thanks

you should be able to do that provided that it is an electrical tacho not a mechanical one...

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you are not a beautifull and unique snowflake...

What car are we talking about?? 510?

I know that the 1200 B110 tacho is totally different to normal tachos.
There's at least 3 different tacho->engine connection standards( Not including a different tacho type for 4cyl,6cyl,8cyl,12cyl,rotary).

Maybe your factory tacho is broken?

Normal tachos (Aftermarket ones) have a mode switch for 4cyl..6cyl etc. It then has a black and a red wire for the tacho light, which is wired into your headlight circuit. Then the tacho signal wire is routed to the coil (I think which terminal, depends on tacho type).

Depending on what a car..and what the back of tacho looks like, we can suggest ways to get it working.There is no simple answer without knowing these details.

Cheers,
Chris