My IAC was wired per a schematic provided by someone on this or Crossfire forum. It is a GM 7.4L TBI unit from a 1995-1996 truck used on my 1984 Corvette. IAC is 4 wire.

I have come to realize that either my buddy wired it wrong or it is defective. I honestly dont think it ever worked as I always had a low RPM on cold start that wasnt a big deal as car started and seldom died.

Is it possible it could be damaged with incorrect wiring sceme? if wired in reverse would the IAC function in reverse? Can I test it by providing 12V current or is it 5V? I will verify voltage to the sensor. I know the feed to ECU is 5V and is functional.

does anyone know the wire schematic?

if you are uncertain of the wiring can you explain what the 3 wires do as far as its function. i assume one extends-one retracts. the third? wire 4 is ground.

EDIT: this is a 4 wire square type used on later model. not the 4 inline.

 

ttt

 

If you want to do some reading this page should give you your answer. It explains the operation as well as which wire is 'usually' which.

http://www.megamanual.com/ms2/IAC.htm#stepper

 

Thanks much !