The rpm signal im sure is the blue wire at the dizzy next to the yellow and black wire ont the dizzy side and goes all the way back to the dash I'm 99.99999999% sure
can confirm that vtec6000 is correct, the icm wire at the ecu is the rpm signal and so is the blue wire from the dizzy. recently wired vtec controller and used the icm.
If you look on dist plug (dist side) there is a large blue wire bottom back. This is the RPM sig for the pre face-lift, not used on the face-lift. I have had to connect this wire straight up to my rev counter to get it working.
I have a face-lift with a pre-facelift APEXi power FC. When i got the car the revcounter did not work. Just ran a wire and all worked.
Good luck Dunx