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700r4 lock-up

Discussion in 'Automatic Transmission' started by BJedi76, May 11, 2021.

  1. Ricko1966

    Ricko1966 Full Access Member

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    Well Damnit for some reason I thought you had an 85 I found a schematic for an 85. Is you're truck a carbureted 49 state car? If so I'd use this as schematic as a reference anyway.

    Screenshot_2021-05-17_230141.jpg
     
  2. BJedi76

    BJedi76 Full Access Member

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    Sooo…

    is this an ECM or a TCC?

    knowing this will help decide how I have to approach this. 36F62C9B-27A6-4FE1-9753-501970AB0F16.jpeg 9397D9E5-4B49-4F48-9DDD-466430D81A66.jpeg 4F33137F-1F3B-4178-A947-55B67EDBB98A.jpeg
     
  3. BJedi76

    BJedi76 Full Access Member

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    I followed instructions to bypass an ESC.

    The wire colors matched, so I didn’t even think about it. I’m guessing I was wrong and it’s an ECM.

    it starts and runs fine. It even revs. It has no issue in first gear, But after it shifts I can’t drive the truck at more than 10% throttle or it loses all power.

    as soon as I back off to about 10% throttle I get all the power back and the truck continues to drive, without issues.

    If I keep it at less than 10% throttle, Eventually I can get up to 55-ish, but at any point if I push the throttle further than about 10%, all power goes away & as soon as i back off the throttle, all power comes back.
     
    Last edited: May 18, 2021
  4. Ricko1966

    Ricko1966 Full Access Member

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  5. BJedi76

    BJedi76 Full Access Member

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    Sorry…

    I meant ESC, not TCC.
     
  6. BJedi76

    BJedi76 Full Access Member

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    So does that mean I do not have an ECM?

    this box is mounted up under my dash behind the glove box.

    If I do not have an ECM, why does my truck lose all power upon shifting.
     
  7. BJedi76

    BJedi76 Full Access Member

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    If I do not have an ECM, does the ESC have “ANYTHING” to do with shifting?
     
  8. Ricko1966

    Ricko1966 Full Access Member

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    This is 100 percent gut feeling and just a guess, but humor me. Make a mark on the manifold and distributor base so you can put things back if you have too.Now loosen the distributor hold down and twist the distributor body itself 1/2 inch counter clockwise, lock the distributor down and take a test drive. Is it better ? Twist it a little more, post your results. I'm theorizing you have your initial timing wayyy to low when it shifts, and you lose all the centrifugal and you step into the throttle and lose all your vacuum advance your timing is so slow it won't run.
     
    Last edited: May 19, 2021
  9. AuroraGirl

    AuroraGirl Full Access Member

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    Are you sure it’s not an ecm.. I have a 1990 ecm in my scrap pile that looks just like that... OP can I see your computer side ways to see the terminal? If you open the screws on one side do you open up to reveal a narrow chip with a blue cover that is pushed into the contacts?
     
  10. AuroraGirl

    AuroraGirl Full Access Member

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    Gm transmissions didn’t use electronic controls until the early 90s but they definitely could have electronic components such as something that interacts with a vacuum switch for lockup on a tcc
     
  11. BJedi76

    BJedi76 Full Access Member

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    B4E0D259-D2A7-43A1-B0B9-76857CDE869E.jpeg 5C98F1BB-B4B8-486A-80A8-004027AA6AA1.jpeg F75B2154-442C-4116-8FF3-CFD69EA8180C.jpeg 1B33DF81-AF28-4CC1-825D-6DCE2955B074.jpeg
     
  12. AuroraGirl

    AuroraGirl Full Access Member

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    Nvm that’s a lot smaller than I thought same general shape as what I thought. Ur good esc.
     
  13. BJedi76

    BJedi76 Full Access Member

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    I ordered the Painless 700r4 kit. 9EAC66E5-3CA0-4A21-99F9-FAF6144F94C7.png
     
  14. BJedi76

    BJedi76 Full Access Member

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    There were other, less expensive, kits, but they seemed to be more about bypassing than replacing.

    … and several of the other kits had a manual switch, which I don’t want.

    for some reason, I couldn’t buy direct from Painless and had to go through Summit.
     
  15. BJedi76

    BJedi76 Full Access Member

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    Why does this kit come with an external pressure switch?

    Can I not get the internal pressure switch(es). I haven’t even looked, yet.

    I assume that’s with the little silver canister that screws into the transmission, is for.

    what is the point of bypassing things that are already there?

    Did I buy the wrong kit?
    I (apparently wrongly) assumed that this kit was simply, modern replacement parts.

    everything in the kit seems to simply replace things that I already have, except that little silver pressure canister.

    Anyone care to explain this to my dumb ass..?
     

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