I have a very fast idle all of a sudden, and I suspect it is the idle control valve. Do I need to unplug the electrical connection, and connect a wire with 12 volts to ICV? Is there a certain technique or method to do this correctly?

THE TEST:

The car should always rev the engine up slightly higher than the set idle when starting. The settle back to the set idle. If you listen for it when starting, you know the motor hasn't failed.


Ater cleaning you should be able to quickly twist the whole thing and get the valve to flop open and closed. The wire check will confirm it powers up.

I you think it needs lube only use a splash of silicone spray. You don't want anything that will collect gunk.


If it does that now, but stays high I would look for either a leaky hose or sticking dirty throttle valve plate. They can go hand in hand with the smut (oil vapors) that get around from that great flame trap invention. Got to keep it serviced for less problems. Of course you know where that is. In that neglecting land down under!

As Herb said, take it off the car so you can see it and apply 12V to the connector..doesn't matter what side is ground. You should see the 'butterfly close quick through the side hole.
If this butterfly is sticky, I use my fingers to open and close it as I spray some Carb cleaner in it. The car my idle high after install because of the fumes of the carb cleaner.
Also check the Bellows from the AMM to the throttle body for cracks. That will screw up the air/fuel mixture
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.no.net/ebrox/Tony's%20cars.htm

Do check the IAC, but my money is on a vacuum leak and/or and AMM.

-Ryan
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Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars

Take it out, and power it up by applying 12V across the two pins-- it should open completely with little delay. When you remove the voltage it should close quickly too. While it is powered open you can clean it out well with carb cleaner and Q-tips.

I have made a tool for cleaning these valves using a piece of the wiring harness of a junker with the appropriate connector and a length of wire with alligator clips to attach to the car battery. That way I can clean the valve very thoroughly.

Good luck!