still have a tach problem

i've got a 90 240sx with an sr20 swap, i have a tach from a 180sx in it, well the tach doesn't work and just a couple of days ago i installed a hks type-0 turbo timer and it has the rpm gauge on it, i wired it all into the ECU and figured it would work, and the tach on the turbo timer doesn't work either....

would my tach problem be an engine lead? or maybe even ecu problem?

any info would be great, i would like to have a working tach