I am laying out my harness as described in aaron cake's walk through. However he makes no mention of which output a gm iac would use, just a stock bac valve. I know it is not a pwm device, its a stepper motor so what i am looking to verify is that i run a "stepper out" to the iac instead of the pwm/idle control wire.

 

You'd have to follow the manual for building up a 4 wire stepper IAC. What ECU are you using? I've always used the 2-wired Mazda PWM valve and it works well for cold start, but I've had some experience tuning the GM valves and they are nicer for sure.

 

The ms3 is farly easy, I think the other are more work. The MS3X/V3.0 or V3.57 Hardware Manual has the wire diagrams for the 4 wire IAC and the main board of the MS3.

 

Thanks, ill look back through the manual. Its a ms3pro setup

 

GM stepper IACs are in the MS3-Pro manual so you can follow the connection diagram there. The wires are the blue and green wires on the gray connector.

 

I would use the stock valve or a 3-wire pwm valve. They work better.