How to test an IAC Valve?
'90 LS with the 2,400 RPM idle problem.
My Chilton's directed me toward the IAC valve and then doing a search here shows that it could also be the TPS.
Chilton's shows a simple ohmmeter test for the IAC, but a more complicated test for the TPS. So I have decided to test the IAC first. Problem is Chilton's has a warning that states:
"Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR pin and the negative lead on the ISC pin."
OK. Which is which? Don't want to damage the IAC if it is in fact good. Any idea which pin is which?
Also, before the high idle popped up this morning, last Thursday the car started occasionally doing a kind of bucking bronco thing when I had a load on the engine. Almost felt like it was rapidly downshifting & upshifting a few times before I could back off the gas. Only did it probably 12-15 different times before that problem went away. Now the high idle problem popped up. Any correlation ya think?
Thanks for any ideas or tips.
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but I can change,
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