ok here is what we got...

i have a 96 civic ex
engine - is a jdm dohc f20b vtec ( obd2b engine )
running a obd2a to obd1 jumper harness on a p28 with a h22 map

now my problem is that everything works great other than i am not getting a tach reading, question is how do i wire this to get the tach to work?

obd2a engine harness
obd2b enigine & dizzy
obd1 ecu

i have looked and cant seem to find how to do this

any help please, thanks