92 F 150 with idle issues. I have 12v at the IAC on one pin and a Good ground on the other. I can take it off and move the valve back and forth a little. My question is, If I take the valve off and leave the harness connected and turn the key on the valve has no movement at all. Should it move when you turn the key on? I am trying to figure out if the solenoid is bad.

 

Best way to diagnose an IAC problem is to unplug it, with it attached to the TB, and start the truck. If it idles better with it unplugged than with it plugged in then you should replace it, if it is the same or worse just take it off, clean it up with some TB cleaner and plug it back in because it's functioning properly.

The valve only moves when it needs to regulate the amount of air during idle, without the truck on the valve won't move. With it not attached the TB will be getting plenty of air so it won't move.

 

Can't unplug it while it's running. It stalls too quickly. This is the original part mfr in oct 1991. I need to know how to test the soleniod

 

The previous test you should have started with the truck off, unplugged the IAC (while it's still mounted) then started the truck. Unplugging it while running does nothing as the computer has already made the transition from closed loop to open.

Here is what I think you're looking for though:

Use an ohm meter to check the solenoid by attaching the positive lead to the VPWR (vehicle power pin) and the negative lead to the IAC pin.

• Your resistance reading should be between 7.0 ohms and 13.0 ohms. If your reading is off, your IAC solenoid is bad.

 

That's what I'm looking for, Thanks.

 

Resolved! IAC was bad. Purrs like a kitten now.

 

Thanks for reporting back, glad you got it figured out.