Idle air control valve not working

There probably won't be. There's four coils of wire inside it that are pulsed with varying voltages and polarities when the Engine Computer wants to adjust it.

This assembly is a "stepper" motor with a pintle valve on the end. That valve opens or blocks an air passage around the throttle blade. The armature of the motor doesn't spin like it does in a motor with brushes. This one can be pulsed to 256 positions, or "steps". As the number of steps increases, the armature turns a threaded rod to retract the valve and let more air into the engine. The computer increases or reduces the amount of time the injectors are pulsed on at the same time to adjust the amount of fuel going in to match the amount of air.

You didn't list any symptoms, so to tell if the idle speed motor is working, you only have to observe if idle speed is changing. Most importantly, you'll see a nice "idle flare-up" to 1500 rpm at engine start-up, then it will come down to normal within a few seconds.

If you want to try to measure one of the voltages going to that motor, you have to do it when you turn the ignition switch off. That is when GM typically retracts the valve a little so it's ready for when you start the engine next time. Chrysler uses the same idle speed motor, but they do it differently. They do retract it when you turn the ignition switch on. You can tell the difference because you can hear that motor operating when the computer is setting it to the desired position. You'll hear it on GM trucks if you're under the hood when a helper turns the engine off.

Even if you want to check for voltages, they won't mean anything. The armature is just a magnet, so to make it rotate, the electromagnetic fields around it have to be rotating. That means the four electromagnetic coils have to be pulsed with voltages at different times, for different lengths of time. Digital voltmeters don't respond fast enough to catch what's happening, and reading a pulsing voltage on the DC Volts scales will result in the reading jumping around all over the place. You can't read it on the AC Volts scale either. Those are only accurate when reading a 60 Hz sine wave, as in house voltage. There's no way to make sense of whatever reading might show up on the meter.

I've never heard of a driver circuit inside the Engine Computer causing a problem with the idle speed system. If the computer is causing a problem, it is going to be due to it improperly interpreting sensor data, or calculating an incorrect desired engine speed. More problems will occur from a cut wire, corroded connector terminal, or the air bypass passage is plugged with carbon.

With a cut wire or corroded connector terminal, the computer will see the resulting lack of current flow. It will immediately set a diagnostic fault code to that effect, but since the inability to adjust idle speed may not adversely affect emissions, it may not turn on the Check Engine light. To say that a better way, don't assume there's no fault code set just because the Check Engine light isn't on.

Carbon blockage in the air passage used to be real common on some engines, but not on others. That seems to be a thing of the past since there are improved additives in gas today. There's no way for the computer to monitor that, but it might detect the results of that blockage. Specifically, it increases the length of time the injectors are pulsed on, so there will be more fuel, but the matching extra air will be missing. That will result in a rich exhaust condition, but only at times of idle. Many tests aren't run by the computer during idle, so the only symptom might be idle speed is too low.