I would like to test the IAC valve on a 1995 940, which unfortunately does not have a reliable diagnostic port I know how to use.

To test the valve itself, is it safe to disconnect its hoses while it is running and to visually check if it opens and closes appropriately? At what temperatures does it open or close? Alternatively, what kind of voltage do I have to run through the two pins to see if it opens and closes?

To test the harness to it, how can I use a mulitmeter to verify the harness is still good?

I am trying to diagnose a Check Engine light. I cleaned out the Throttle Body and the EGR valves, with new hoses, and am trying to diagnose the components one by one. Next test is if the Throttle Body is controllable with electricity.

 

I recently saw an excellent youtube video showing how to diagnose it on an older 240, it can be "shut off" and the results tell you whether it is functioning as designed. It also explained that the various years and models used specific IAC valves that don't interchange (naturally) so be careful of replacement parts.

 

He's talking about this:

 

Great. That was straight forward. I cleaned out my IAC, tubes and connectors. I ran 12 volts through the two connectors and saw the IAC valve open and close. I only have two terminals on it. I think I can be sure that works correctly. Next thing I will test is the Throttle Position Sensor, and the MAF sensor.