Lost Luggage

I added a digital rev limiter now digital dash(my 1989)rpm tachometer is not working correctly and is misreading where it should be at like 2200rpm it's reading about 3500rpm and jumpy.. I followed the instructions exactly for the rev limiter and the limiter works great! I know there is a tach output for the limiter that I didn't use since I don't have a stand alone tach I'm not sure if I need to feed the dash tach somehow with that tach output from the limiter to make it work properly..

Any help would be appreciated
Thanks!