Garrett F

Hey guys, I have a 91, and it idles like crap. It was shrieking real bad and I found out it was the idle air control valve. I replaced it and it still doesn’t work. I am guessing it must have to do with the wiring going to the plug. It has four wires and I’m not sure where these go, if anyone has a wiring diagram for this or knows what each of those four wires are, information would be greatly appreciated. Here is a picture.

2011KLR

Your fun is only beginning.

stew86MCSS396

How did you determine that the IAC is bad???

Been told you don't want to have the IAC removed from the throttle body and apply power. With key on engine off, the IAC stepper motor will be commanded by the ECM to fully retracted ~145-160 steps. You can do this and while koeo, disconnect the IAC connector. Turn ignition off, remove IAC and observe if it is fully retracted.

Subsequently you can perform this same procedure only difference is short A-B on the aldl, wait 30 seconds, disconnect the IAC connector and upon removal of the IAC you should see that it is now fully extended.

You can check continuity to each wire back to the ECM residing under the hood...
Post #5

You can give this thread a read as well...
https://www.corvetteforum.com/forums...procedure.html