General IAC Info & Ford PWM IAC Wiring

[S2H]

Yes, on a Ford, the IAC gets constant +12V (ignition key on) power, and the Ground is controlled by the ECU using a PWM− signal at 300 Hz.
The Holley can control it by PWM+ with a Ground tied to the engine block, or it can get a +12V power source and control it with a PWM− signal.

In my personal experience, the Ford IAC, because of how it operates, will be more stable & perform better, if you supply it with a constant +12V
signal and a PWM− from the Holley ECU. I do not know why it works better, I just know we have tried it both ways, and it has always worked
better using a PWM− signal to control it. Also, in my personal experience, if you can use a GM IAC, it always works better than the Ford IAC.

[jeff@califon]

In my personal experience, the Ford IAC, because of how it operates, will be more stable and perform better, if you supply it with a constant +12V signal and a PWM- from the Holley ECU. I do not know why it works better, I just know we have tried it both ways, and it has always worked better using a PWM- signal to control it.

Thanks, I will connect it as you suggested. I discovered which terminal was which by using the diagram, and verified that using a 9 volt battery.

[one5oh2nv]

Resurrecting this one. I'm going to use the Ford IAC PWM−, and was wondering if I can re-purpose the pins/open slots from the original IAC wiring, in the ECU, to make a different I/O.

[Danny Cabral]

I'm going to use the Ford IAC PWM−, and was wondering if I can re-purpose the pins/open slots from the original IAC wiring, in the ECU, to make a different I/O.

Yes, you can relocate one of the existing four wires (stepper IAC motor) to an available custom I/O position.
Installing, removing & relocating (pinning) the ECU connector terminals is easy. No special tools involved.
Push the single wide white tab to release the lock (on all terminals), and push the two narrow white tabs to re-secure.
http://forums.holley.com/showthread....neral-IAC-Info (IAC Information)

[Just Chuck]

FYI: If you are looking for the connector for '87-'93 Mustang IAC, here's an alternate source:
http://www.oreillyauto.com/site/c/de...1517&ppt=C0189 (BWD - Electrical Connector PT317)

[jeff@califon]

Yes, on a Ford, the IAC gets constant +12V (ignition key on) power, and the Ground is controlled by the ECU using a PWM− signal at 300 Hz.

The Holley can control it by PWM+ with a Ground tied to the engine block,
or it can get a +12V power source and control it with a PWM− signal.

In my personal experience, the Ford IAC, because of how it operates, will be more stable and perform better, if you supply it with a constant +12V signal and a PWM− from the Holley ECU. I do not know why it works better, I just know we have tried it both ways, and it has always worked better using a PWM− signal to control it.

Also, in my personal experience, if you can use a GM IAC, it always works better than the Ford IAC.

Finally getting to this point. The AAW Classic Update harness install took longer then I expected. I would appreciate some clarification. Does the +12V source need be provided by the Holley ECU or can I use a switched source from anywhere else? The AAW harness has a circuit that is switched, and remains on even while the starter is engaged, is it suitable?

[Danny Cabral]

Does the +12V source need be provided by the Holley ECU...

No, just the PWM− signal to control it.

...or can I use a switched source from anywhere else?

Yes.

The AAW harness has a circuit that is switched, and remains on even while the starter is engaged, is it suitable?

Yes.

[jeff@califon]

Thank you very much Danny.

[ultraspeed]

Does the Ford PWM− from ECU need to be used with relay? Or just the positive side? Any idea what the amp draw is on the negative side?

[Danny Cabral]

There's no relay involved with an IAC motor installation.

[ThePunisher2]

I have the Modular Mustang HP EFI harness. They have PIN B1, B2, B8 & B9 on the J1B harness plugged with white plugs as those are the IAC outputs for a GM. I've switched to a GM IAC Actuator. I need to wire into the J1B plug to those 4 pins, and run 4 wires to the GM IAC actuator. How do I wire them into that J1B plug? What parts do I need? I've seen you talk about Metri-Pack, looked like that was for the IAC connector and not the J1B. Thanks.

[Danny Cabral]

They have PIN B1, B2, B8 & B9 on the J1B harness plugged with white plugs as those are the IAC outputs for a GM.

Yes, remove those four white plugs.
Since you decided to use a 4-wire stepper type IAC motor, you'll have to install the four IAC wires to the P1B ECU connector.
http://forums.holley.com/showthread....neral-IAC-Info (Scroll down to "IAC Motor Harness Connector PIN-OUTS".)

I need to wire into the J1B plug to those 4 pins, and run 4 wires to the GM IAC actuator. How do I wire them into that J1B plug? What parts do I need?

http://forums.holley.com/showthread....als-Holley-EFI (ECU Connectors & Terminals)

I've seen you talk about Metri-Pack, looked like that was for the IAC connector and not the J1B. Thanks.

Correct, that's for the IAC motor itself, not the ECU connector.

[ThePunisher2]

GM IAC Wiring on a 2000 Mustang with the Modular Mustang Holley EFI Harness:
I bought a GM Flat 4-wire IAC Pigtail, a 22 AWG 4 conductor wire, and 4 TE 3-1447221-4 pins to put in the J1B ECU connector.

GM IAC Pigtail:
A: Purple/White "B LO" > White wire of 4 conductor > Pin B8 J1B.
B: Purple/Black "B HI" > Red wire of 4 conductor > Pin B9 J1B.
C: Purple/Blue "A LO" > Green wire of 4 conductor > Pin B1 J1B.
D: Purple/Yellow "A HI" > Black wire of 4 conductor > Pin B2 J1B.

The GM IAC Pigtail has the letters A, B, C, D on it if you look real close.
The J1B connector also has the numbers on it if you look real close, makes it easy to know what white plugs you need to pull out with pliers to put in the new pins.

I stripped the wires back enough for the top clamp on the pin to be able to crimp down on it with pliers, and the lower clamp to clamp down on the actual plastic of the wire. I then soldered above and below the top clamp.

Then unplug the J1B and press the long white rectangle to release it so you can shove the pins up in it.
It's hard to do with 22 AWG wire. I seen some guys running thicker wire, which would probably help push them in. I had to get a small pick and press on the pin and push it real hard until you hear it click. I also verified by shining a light up on the pins, and making sure they were even with the other ones. Either way, when you press the 2 white plastic things on the J1B plug to secure the wires, they won't go in if you don't have them seated properly.

[procharged67]

Typical IAC Control/Ramp Down parameter settings.
Advanced Idle Control: ......................... Slow (Usually the best control.)
IAC Type: ........................................... Stepper (4-wire), PWM (2-wire)
IAC Hold Position: ................................ 10%-30%
Ramp Decay Time: ............................... 1.0-3.0 sec
RPM Above Idle To Start Ramp: .............. 1000 RPM (Or higher.)
RPM Above Idle To Re-enable Idle Control: 50-200 RPM (This setting can be finicky.)

Going to try this on my car to try & clean up the idle problems I have, instead of the custom setting. I'll try the Slow setting. I notice the box that shows PID is gone.

[Rage]

RE: Parameters - Idle Spark
Description: Idle spark control will modulate the ignition timing at idle to assist with maintaining the target idle speed.

When the RPM at 0% TPS is above or below the Target Idle Speed specified per coolant temperature, how much IAC Idle Spark control spark advance/retard modulation does the Holley have available to use to control idle? I.E. override the Base Timing Table?