G.M. I.A.C. operation

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  #1  
Old 07-07-03, 10:43 PM
spooge031
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Question G.M. I.A.C. operation

does anybody out there know the PROPER way to diag. an unresponsive IAC on a 1989 GMC G2500 van equipped w/ a 350 and T.B.I.??? Vehicle has NO idle flair on start-up and the pcm won't try to force the idle down even if I use my IAC tester to give an excessive idle, my tester came with a noid lite and they only lite up green with no action at all (when i plug them into the tester they flash green/red indicating the tester is giving out the proper signal, I suspect a faulty pcm as the wiring checks out OK and the IAC works with my tester BUT I want to be sure I am not missing a bad ground or something stupid, normally I work on Chrysler/Jeep and have all the necessary info at my disposal BUT I have no good GM info available to me. note I opened up the computer and nothing looked burnt or smelled burnt.
 
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  #2  
Old 07-08-03, 03:31 AM
Joe_F
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Did you have a look in autolibrary below?
 
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Old 07-08-03, 07:51 AM
spooge031
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yes the info is VERY basic and only tells how the IAC operates, with no diag. tree
 
  #4  
Old 07-08-03, 07:54 AM
Joe_F
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If I have a chance later I'll look in Alldata. No guarantees though
 
  #5  
Old 07-08-03, 11:30 AM
Joe_F
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Yes, I have the proper procedure from Alldata.

You can e-mail me or post a fax # and I will send it to you.
 
  #6  
Old 07-08-03, 06:07 PM
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if the vehicle is idling high and may also be throwing a code 35 you might check for a leaking throttle body base gasket common gm tbi problem.
 
  #7  
Old 07-08-03, 10:03 PM
spooge031
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Cool thanks

thanks for your help i did a little searching of my own and found a company that had an original GM service manual,so I bought it, I also picked up a new IAC just for grins although the old one seems to work I have run into slow ones on Mopars before, if all else fails I think we will shoot the thing and put it out of our misery
 
  #8  
Old 07-09-03, 12:28 AM
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hey spooge, i see your credentials include jeep(another four letter word to me) a couple days ago someone posted a question about a grand cherokee with a clogged up a/c drain, all i know is it drains into the frame when it's working, the one i had was pouring water out of the rear vent under the passenger's seat and the customer took his car when we told him we have to take the box out.

is there any other way to clear the drain other than taking the box out?

(did you also get your gold bulova watch for last year)
 
  #9  
Old 07-09-03, 05:42 AM
Joe_F
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Original poster:

I have the Alldata printout here at work if you want it. But, it sounds like you have the best information out there...the factory manual.

Kudos to you on doing the right thing--way to go!
 
  #10  
Old 07-09-03, 04:56 PM
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mike if you have access to all data or shopkey and look under technical service bulletins you will find one on unclogging the a/c drain without pulling the box. basicly involves drilling a small hole into box and running a wire through the drain passage and plugging the hole you just made.
 
  #11  
Old 07-09-03, 06:15 PM
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that slap sound you just heard was me hitting my head, what was i thinking?? i have access to the factory bulletins, sure enough, there it was, major brain fade on that one. TSB#24-06-96 and it pays all of .2 hours it's so easy, thanks bejay!
 
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