Thanks guys for imput the problem is solved(buy quality) GREG.

check out if it is to be connected to the negative or positive side of the coil. it can make a lot of difference

i used to have a VDO tacho that showed 4000 RPM when you were doing 3000 RPM.It was a wrong connection inside the tacho. Didn't find this til i took it to a VDO dealer, who tested it & found the fault. Could be the same problem.

Finally i got the new Autometre tacho and fitted it the same as the other two and a miracle it works accurately. (Pays to buy quality)

I have the stock 120y tach and it agrees with my handheld tach at higher revs, but shows 6-700 revs higher at idle.

my tacho instructions say:

black to ground
red to ignition switch
white to dash lghts (for light)
green to neg terminal of coil

it says connect green to the transistorised or capacitor discharge systems in accordance with ignition systems manufacturers instructions.


it is a $50 cheapy from supercrap but is fairly accurate.

i think gino120y has same one no problems there either.

The tacho was off EBAY(shit),whent to Autobarn got another brand $120, wired it up and the same thing took it back and ordered a $290 Autometer tacho,wil try it next week hope it works. I herd that some tachos dont work on early Dattos.
The ign system is STD,just modified the mechanicle advance

also depends on if there is a switch on the back of the tacho that selects 4 6 or 8 cyls.

What sort of ignition do you run? Coil pack or regular distributor?

the tacho itself must be faulty , cause i got one of ebay brand new and it flickers and jumps but it is hooked up 100% correct. (cheap crapy brand)