So I I have a 1998 Honda Civic hx and I recently bought a obd1 ecu, I have a jumper harness laying around but that’s for obd2b to obd1 the harness I need is for obd2a to obd1 the only difference I’ve noticed so far was that the obd2b harness doesn’t have a fuel pump pin or cable.
can I add my own pin from the jumper to the ecu and it’ll still work?
JUST WANTED TO SEE IF I CAN DO IT MYSELF BEFORE I ORDER THR RIGHT ONE bc if I can connect 1 thing there’s no need to order one

 

You can do it yourself, but it is a LOT more difficult that just one wire. I suggest you get the other jumper harness and not modify/damage the wiring in the car. Also, what OBD-1 ECU do you have ? You do understand that there really isn't a proper OBD-1 ECU that will operate the HX engine properly, right ?