Originally Posted by Andy

You have a '96 Civic, a GS-R harness will not work at all! '92-'95 Civic's (EG's) and '94-'01 Integra's (DC's) use a 2 piece harness. One is attached to the engine and has a series of plugs that connect to a second harness actually physically in the car (and remains there if the motor is removed). '96-'00 Civic's (EK's) are wired very differently. The plugs attaching to the engine are very similar, a few sensors are in different places and a few less wires for VTEC and the knock sensor (depending on how each car/engine is equiped) but the other side is completely different. EK Civic's do not have disconnects in the engine bay and an in-car harness, the entire harness just goes to the passanger side firewall, passes through it and goes right to the ECU. When the engine is removed, that whole thing comes out. You must use a '96+ Civic harness ('96-'98 harness are a little different than '99-'00 harness as well, sometimes called OBD IIa and OBD IIb) for your swap. The process of swaping the harnesses over isn't extremely complicated with both engines out of the car and a careful eye though.