TH400

Discussion in 'Automatic Transmission' started by SqauredSon, Nov 8, 2018.

  1. SqauredSon

    SqauredSon Junior Member

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    Hey guys I recently put a new motor in my 85 Scottsdale. The transmission will shift 1-3 fine for a while, almost like clock work it will down shift into 2nd and won’t shift. I changed the vacuum modulator and put a new governor in. I don’t want to spend the money for a new tranny when it could be something simple.
     
  2. Charlie

    Charlie Full Access Member

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    :welcome:
     
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  3. Matt69olds

    Matt69olds Member

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    Are you saying once it gets hot it won’t shift out of 2nd gear, or it will downshift on it’s ouw and stay there?
     
  4. SqauredSon

    SqauredSon Junior Member

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    When it gets warm it will down shift into second and stays there. If I manually put it into N then back to drive it will be in third temporarily then downshift on it’s own back to second. I read a few things about a kickdown switch under the pedal, not sure if there’s any coralation.
     
  5. Matt69olds

    Matt69olds Member

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    Unplug the lockdown connector on the drivers side of the transmission. If that solves the issue (unlikely) you know the issue is with the lockdown switch or wiring. Next, pull the govenor back out, make sure the bore the govenor spins in isn’t chewed up. If so, you will either need to find another case or have that one torn down and a govenor sleeve repair installed. Next, remove the pan. Make sure all the valve body bolts are tight and the lockdown solenoid is tight. If you have another solenoid to try, maybe you will get lucky.

    Are you sure the vacuum hose is in good condition, no kinks, pinholes, etc?
     
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