Hello, yes, the middle Yellow/Black wire is the 12v feed. The other 2 wires are the PCM control wires, to close or open the valve more or less. I'll post the wiring diagrams for you and code criteria.
The first quick test you can do is to measure the resistance between IAC pins 1 and 2, and then 2 and 3, it should read 16 to 18 Ohms for each coil inside the IAC. If not replace the IAC,
There is also a flow chart for the code, to verify wire integrity to the PCM. Just remember to have the key Off before disconnecting any PCM connectors. I think what you're going to find is an open in one of the coils inside the IAC, because at key on engine off, the PCM shouldn't be commanding the IAC to any particular position. The PCM would need to ground either side of the outside pins to move the valve open or closed.
The valve is pulse width modulated by the PCM, so hopefully one of the internal IAC coils did not short out. You should follow the flow chart, but I would do the resistance check first, each side of the IAC is controlled by a transistor inside the PCM and when components short out sometimes the excessive current flow can burn out the PCM driver. Service info doesn't state if the IAC control is intentionally shutdown if a fault occurs. But I will post any other additional service info that is relevant.
Since these valves have coolant running through them, verify the hoses aren't clogged as well when replacing the valve.
One other thing, when testing you had 12v on the orange wire as well, was this back probing the IAC connector while plugged in, or was this unplugged key on?
https://www.2carpros.com/articles/idle-air-control-valve-service
https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac
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Jul 22, 2023 at 6:22 PM
