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idle air control valve?

Discussion in 'Chevy Trucks' started by bassfishn1, Aug 5, 2010.

  1. bassfishn1

    bassfishn1 Member
    from ct.
    Messages: 30

    hey all, back after moving to sunny fla., (actually, it sux out loud, but......), on to my problem, my 94 k-3500, 5.7 quit on me yesterday, just died, checked the codes, threw a 35, changed out the idle air control valve, did'nt cure it, changed out the ecm, still nothing, i have fuel, and no new codes, anything else this code 35 is for?, thanx
    i also checked the 4 pin connector and it has a couple of pins where the hard plastic around it has broken off of it, exposing the pin, is there a good chance this is crossfiring, or shorting out? thanx again
     
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Have GOOD spark at the plugs? Have fuel from the injectors while cranking?


    Not sure which 4 pin plug your referring to....there's several.
     
  3. bassfishn1

    bassfishn1 Member
    from ct.
    Messages: 30

    yes, have good fuel, and good spark, changed out the cap and rotor, changed the 4-pin connector on the IAC, changed the ECM, started right up after i changed the cap and rotor,(needed changing anyways), went out this morning, started right up, and then when it reached operating temp., it shut right down, no codes. i am now thinking maybe ECT?
     
  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Not likely an ECT issue, it will make it run rich as it comes up to temp but not die...even if you disconnected it completely. More like an ignition or FP issue so definitely recheck your work as it only requires fuel and spark to run and I suspect it's losing one or the other.
     
  5. bassfishn1

    bassfishn1 Member
    from ct.
    Messages: 30

    yes, definately need one or the other, so i got it fixed today, it turned out that the ignition module was the culprit, the one that i had tested, and tested to be ok, twice!!! so much for those drive in testing facilities, now i am just curious as to why it failed, it's not too old, or maybe just one of those things that happen, anyways, thanx for the help B+B
     
  6. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Good to hear you're fixed up. :drinkup:

    When you encounter a vehicle that likes to "eat" ignition modules it's only caused by four things....

    1) As always a defective/cheap module to begin with. As with anything you do get what you pay for.

    2) It's overheating due to lack of heat conduction grease between the module and dist body.

    3) Poor ground between the battery, alternator, engine.

    4) But the one that's most overlooked and/or unknown is a defective diode set in the alternator. When the diodes get weak they allow too much AC current to escape from the alternator (which is what they produce) thus it's introduced into the system which of course is intended to be run on DC current. Too much AC current flowing through and being received by the more sensitive electrical components (ignition moduels being one of many) will greatly shorten their life. Easy enough to check though, simply connect a DVOM on the charging stud on the alternator set to the AC scale and with the engine running. If you find more than .5 ACV there's an issue with the diodes and it should be addressed before it causes damage to other electrical components...such as an ignition module.
     
  7. bassfishn1

    bassfishn1 Member
    from ct.
    Messages: 30

    that is good information to have, thanks
    and it did seem not to have alot of that conduction grease as you said, and it seemed very cakey, liked it has been cooked, so it probably got fried, definately gonna check that alternator, even though it is fairly new, but like you said, you get what you pay for
    thanks again b+b, you have been a great help
     
  8. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Should the heat conducting paste be uses on all electronic/ignition components? Is this the stuff I get at Radio Shack for computer chips?
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    No real advantage since the only place it's effective (or needed) for transferring heat is under a module.

    But you can try it out in your radiator and report back with the temp reduction results. :D