1990 convertible tach not working

[Dzire]

okay tach was working before I put in the new transmission so I put in the new transmission now the tach not working it does work for a second right when you start it up but then it stops any help on this is much appreciate

[Glass Machine]

Same thing was happening to my vert not to long a go, but it was cuz of the bad top and almost having full 1in of water on the passenger side floor board and that flooded the ECU. Got a new ECU and keeping a car cover on it and she has been doing fine. Sorry that dont help you much haha but hope you get it working soon

[rx4ur7]

Check to see that you have trailing fire.