Does anyone know how to convert from 2-wire ( obd2 wiring) to a 3-wire IAC?
I have a JDM D15b in a 97 LX, and the Idle Air Control valve on the motor is a 3-wire sensor, where as my wiring harness only has a 2-wire plug.
Are there any kinda of re-wiring charts, or even wire adapters? ( i would imagine if one of the three wires were a ground, it wouldnt be all that hard)

 

You'll need a different ECU too.

Two wire IAC's are like the IAC's on the B series engines, it's the thing that bolts on the back of the intake manifold which the ECU controls through Pulse Width Modulation (PWM). The 3 wire IAC's like on the low end D motors use a stepper motor. You can't just change the wires to make it works. They're fundamentally different.

You'll need a 3 wire ECU and on the harness connector you need to move 2 wires and add the 3rd. It's all listed in the shop manual, the EX civics with SOHC vtec use 2 wire PWM and the CX/DX motors use a 3 wire stepper IAC.

I'm not 100% clear on whether the ECU you're currently using is a PWM or stepper motor one.

 

I switched from a 2 wire iac to a 3 wire iac and it worked fine with the same ECU. Take the wire from slot A12 and move it to A14. Then you'll need to add an extra wire into slot A13 . After you do that all you need to do is attach the wires to the 3 wire plug. I forget what colors i matched. It was just trial and error testing the wires with the plug. But it worked fine with the stock ecu. My buddy did the same thing and had no problems.

 

I was switching from D to B series so, maybe it's the B series ECU that can't run a stepper. Be convenient for him.