I bought myself a 1990 Celica St and the biggest issue Im having with it is the tach not working. Ive done what I can so far with checking fuses, swapped out the instrument cluster to see if it was just my tach not working, and Ive searched through what wiring manuals I can find but no luck. Hopefully since this is the only place Ive found with actual useful information someone here will know how to fix it or at least how tp figure out a way to fix it. For reference I have no rpm reading at idle but the needle kinda bounces when I give it some gas. This is the same on both tachs Ive tried.