Good Evening everyone, well after some time i managed to get the parts i need to get the tachometer working

Diesel tach.
Tach amp
New pickup sensor cable.

wired it up and no go.

it sits on 0 rpm, until i rev the engine and the needle won't move until i think the engine is doing 2000 rpm or more :/

Does anyone know how to calibrate it ?
om617 turbo engine 4 spd manual