IAC - Grafting a 6 wire Stepper to 3 wire System

[MBofMB]

This may be a tough one but any direction would be greatly appreciated.

Replaced the '98 original 2.5L with a JDM 2.5L. Actual year etc. is very difficult to nail down. From the parts on it => '02 Outback, '97-99,'01 Impreza,...

The JDM has a 6 wire IAC (A33-660 R00) stepper motor. The original '98 has a 3 wire (A22-667 R00) PWM Valve?
Solenoid (6 wire Male End):
White Red Blue/Black
Red/Black Red Blue/Black


I would really like to wire the stepper instead of changing the intake to accommodate the original wiring to the 3 wire PWM Valve.


The is a real head scratcher. Thank you for reading this request and thinking of a possible solution.

[86bratman]

sounds like you have a phase 2 ej25 you're going to put in the car. From the swaps I've read, there is no easy answer because the original ecu doesn't know how to control the newer iacv.

[r3v_v3ng3]

My friend and I swapped in an 01 2.5RS motor on his 96 legacy and we ran into this problem.
We tried out the 99 2.2 legacy/impreza california manifold which have the same 3 pin plug as the original phase 1 IACV. We left the map plugged in but it still idled really high. I didn't try depinning it though and switching the wires to see if it idles better.


You can get the car to idle around 1k rpm on the 6 pin iacv by opening it up and pulling on spring to plug the hole that make the car idle. You'll still get the code though but my friend drove his car around for awhile with both set up. Hope it made sense lol

Your only other option that I know of to make it run like it should is to get the bulkhead harness and ecu from a 99 legacy 2.2 california model. You'll know when you see a 3 pin iacv on top of the throttle body. I mostly see them on a auto but once in a while theres some 5 spd version of it.