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Throttle position sensor voltages

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by newyorkin, Jul 30, 2001.

  1. newyorkin

    newyorkin 1 ton status

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    Hey all. I keep getting a code 13 on highway acceleration. Going through the factory troubleshooting, I've reached the point where it says replace the TPS. The one on my TBI is kind of like a cone, narrower at top where harness connects. I happen to have one at home that I'd like to test with, but it's kind of a wrap-around one, from a car tbi I guess. It has the same bottom half as my sensor, except instead of pointing up, it kind of turns back and the harness plugs in on the side. Anybody know what I'm talking about and if I can interchange these two?

    I'm not going to make it to a parts place before they close until saturday, so I'm kind of stuck with what I have laying around in my junk, I mean, back yard. And, I don't even know if that will solve the problem.

    Edit: Does anybody know the exact voltages/limits that are supposed to be present for testing?


    Ratch
    <a target="_blank" href=http://k5.8m.com>k5.8m.com</a>
    **K5 - What more is there to life?**<P ID="edit"><FONT class="small">Edited by newyorkin on 07/30/01 02:52 PM.</FONT></P>
     
  2. BurbinOR

    BurbinOR 3/4 ton status

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    Re: Throttle position sensors

    I personally wouldn't mess with a non-standard TPS.........these are very sensitive instruments and I just don't think a bone/back-yard one that is not the same will be a good idea.

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.alloffroad.com>www.blazzinor.alloffroad.com</a>
     
  3. newyorkin

    newyorkin 1 ton status

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    Re: Throttle position sensors

    Deep down inside I'm afraid of that, but I figured since it is another GM product, just earlier model year or different model type, someone had experience with it. But I guess not. Oh well. I'll just have to deal with it until the weekend or I can get the exact voltage limit specs... hmmm, I feel an edit coming on...

    Ratch
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  4. dyeager535

    dyeager535 1 ton status Premium Member

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    I can't believe I don't have more of this info here somewhere, but all I could find, off the Q-jet CCC stuff, was

    "I can see the converter not liking it much, but when it returns to
    14.7:1, it should recover nicely. The 307 computer tends to run things
    a bit lean anyway. The converter does not work well if at all unless it
    is at 14.6 to 14.8:1. Hence the reason the CCC computer keeps the mix
    at 14.7 until 3.75v +/- .1v TPS voltage (like starting to tip in the secondaries)."

    Not much help I guess eh?



    Dorian
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  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: Throttle position sensors

    A bit more..again Q-jet, but I believe they should be the same:

    WOT = 4.5
    idle = ~.50

    Dorian


    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
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  6. K5 NUTT

    K5 NUTT 1/2 ton status

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    One wire is sensor ground...1 is the 5v reference signal...and the last one transmits the volts back to the ecm...the TPS units are not interchangeable....got a couple spares layin around and i allready tried that...lol. 91 up points straight up i beliefve where 91 down point owards the fender...and the older style uses a 3 pin weatherpack connector where as the late model uses a 3 pin metri pack connector. .50 a volt is normal at idle...iv'e tweaked mine to .75 volt but thats another story...what is probably wrong is there is a dead spot in the tps (pontentometer) that gives the ecm a bogus siganl under speed. So .5v at idle 4.5 to 5v at WOT....You can use a ohm meter to watch the resistance slowly as the throttle is opened to check this also.

    Azblazer

    1979 K5 350 TBI
    1976 K5 Chalet
    If it ain't got arizona pinstriping.....you ain't wheelin the pee outa her!
     
  7. jarheadk5

    jarheadk5 1/2 ton status

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    I've heard the trick to troubleshooting a TPS is to use an ANALOG voltmeter (you remember, the one with the pointy thing?? [​IMG][​IMG]) because it will show the (ideally) linear voltage increase far better than a digital, which jumps around quite a bit.

    If at first you don't succeed, failure may be your style...
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