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Thread: TPS in a 4L80E...

  1. #1
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    TPS in a 4L80E...

    I have been researching my problem with my tranny in my truck and I think I have it narrowed down to a faulty TPS or an Imput Speed Sensor. I have a 99 Chevy Suburban 2500 454 4X4 with a 4L80E. HARD shift from first to second. I know the TPS is located next to the Valve Body and the Imput Speed Sensor is on the outside of the tranny about 8 in from the bellhousing. Can anyone help me with locating them and how to replace them? Thanks!

  2. #2
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    bradrhale's Avatar
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    check the TPS before changing it out. they are a bit pricey.

    1996 5.7 vortec/auto transmission jerky shift

    a faulty TPS will cause hard shifts but they are also delayed shifts. instead of the next shift in the 1000-1200 range, they are held out past 1500 and above. this will also affect mileage of the vehicle.

  3. #3
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    I called and Autozone carries the TPS and it is about 35 bucks, not too bad, sure beats replacing the whole Tranny! We will be taking care of it soon. Where is the TPS located do you know?

  4. #4
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    I just looked at the link you showed. The connection is a little loose, but not bad. I will try replacing that. If not do you know where the Imput Speed Sensor is? I just can't believe that something that far from the tranny would make it act up that way!

  5. #5
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    remember that you have an electronically controlled trans. everything that it does is controlled by the PCM. the PCM gets all of its readings from all over your truck. i would test the part out before replacing it. 35 might not seem much but it stacks up when you still dont fix the problem. usually a TPS problem will register a Service Engine Soon light. as for the input speed sensor, it should be located sonewhere close to the bellhousing like you mentioned earlier. the output shaft speed sensor will be located towards the back end on the output shaft. the PCM takes reading on both input and output shaft speed of the tranny and that too, controls certain things.

  6. #6
    Full Member Bigg G's Avatar
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    I have the same issue with my 95 Silvy but I changed the Coolant Temp. Sensor and T.P.S. and that seemed to have helped to make my 1st - 2nd shifts firmer sometimes but not always.
    Last edited by Bigg G; 03-15-2010 at 05:41 PM.
    1995 Silverado ECSB body work/new paint in April
    1996 Monte Carlo Z-34
    2003 Chevy Astro ----SOLD 2/2010
    2008 Suzuki Boulevard M109R

  7. #7
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    Well I replaced the TPS today and nada... Dang it! What next? We just passed Emissions this last weekend, if the PCM was bad that should have shown up at emissions. I am just at a stand still. Any other suggestions?

  8. #8
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    Just wanted to note the linked thread on this issue:
    4L80E Trans problom

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