I have a 93 EG so OBD1 and will be swapping in a B18C1 that has a OBD2 wire harness. Question is can I use this harness eventhough it has 4 plugs on pass side and my current one has 3 plugs? The extra plug has 3 wires. Any help appreciated before I spend more money.

 

You can use it but you'll still need to wire up VTEC, knock and IAB from the shock tower to the ECU. This is unless you have VTEC model already and then you'll only have to wire up knock and IAB's. Using this wiring harness will make it easier as the injectors, alternator, and distributor will be plug and play.

 

use the harness in the car and work form that u can not use that obd2 harness sell it for cash to someone that can use it without hacking it up. u have various other sensors on obd2 like the crank sensor a 3 wire plug.

 

You can very definitely use that harness and it will make life a lot easier to do so. So long as it is a USDM harness if it's a RHD harness forget it.

Observe:

 

I know that three of the plugs will connect but what are the 3 wires on the smallest plug for? Do they get repinned in the other plugs or are they something like IAB and not important. The harness Im using is for a GSR.

 

I believe they are for CKF sensor (you won't use this one on OBD1) and IAB on that connector but you'll wire up IAB independently anyways.

 

On the OBD1 GS-R harness there was an extra two wire plug at the shock tower for evap purge (for whatever reason Honda decieded to put the IAB wiring where the evap purge solenoid would normally go) not sure what it is on the OBD2 setup, but CKF wouldn't surprise me.

 

Sorry that's what I'm meant to say CKF and evap not IAB

 

So all i should have to do is change the alternator plug to the OBD1 type to retain my current one and I should be good? Trying to not rewire my current OBD1 LS harness.

 

Yes, or just use an OBD2 alternator.

 

Ill be doing the swap here soon once I get a clutch and tuneup the engine. Thanks for help.