99+ civic's got obd 2.1 wiring harnasses.

which do not combine at the strut tower. they run from the engine as one piece all the way to to the ecu.

if i'm thinking it through properly. a 99-00 si harnass would've been done you perfectly fine and then a jumper to go to the obd1 ecu.


but being an ls i'm not too sure. it's too pieced together of a swap to make it easy.
can be done to run, but just a pain in the ass.