Jeep Strokers

I finally have my stroker up and running but im having trouble finding good directions on wiring my tachometer (1990 YJ 4.2) to the OBD2 setup. Ive seen some people say that my tach wont work and ill need to get a different one and Ive seen some say you just need to splice the green signal wire into the gray coming off the coil which i have tried and it didnt work. Not sure where to go from here

Thanks in advance.

OBD2 pin 31 on the ECM connector. You will have to look up whether it's C1,2 or 3. Don't recall off the top of my head

C1 is blk/tan ground
C2 is VT/OR 5v supply
C3 is empty.

Gray C1

C31 circuit G21 GY/LB Tach Signal per FSM XJ Shop Manual