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Transmission Downshifting

Discussion in '1st Gen Tundras (2000-2006)' started by Olds69442w30, Apr 30, 2018.

  1. Apr 30, 2018 at 3:58 PM
    #1
    Olds69442w30

    Olds69442w30 [OP] New Member

    Joined:
    Apr 30, 2018
    Member:
    #14920
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    Gender:
    Male
    Vehicle:
    2002 Tundra
    2002 Tundra SR5
    4.7L, 2WD
    252,000 miles

    Hello,
    I am experiencing shifting issues. The transmission has been shifting through all the gears flawlessly as its done from day 1. However, I have recently noticed that the transmission will downshift from 4th to 3rd gear when driving on level roads without acceleration.

    I'm not sure what is causing this but my thoughts are that whatever controls the shifting may be receiving bad data. This is where I could use some help. I am wondering how the computer controls the shift points. I would guess that that is where my issue lies.

    Any Help is Appreciated
    Thank You
     
  2. Apr 30, 2018 at 5:07 PM
    #2
    Casper421

    Casper421 Adventure in a 1st gen

    Joined:
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    #8530
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    Chris
    N. Cal
    Vehicle:
    06 DC
    Are you hitting the brakes at all before it downshifts?

    First thing I would do is disconnect the negative battery terminal for at least 30 mins. This will “reset” all shift points. Over time these ecu’s will learn and adapt to the way a person drives.
     
  3. Apr 30, 2018 at 6:59 PM
    #3
    koditten

    koditten New Member

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    I'd check the trailer light plug. If it's corroded, you could get stray voltage accross the pins, thus causing OD to be kicked off via back feed to the ECU.
     
  4. Apr 30, 2018 at 8:15 PM
    #4
    Olds69442w30

    Olds69442w30 [OP] New Member

    Joined:
    Apr 30, 2018
    Member:
    #14920
    Messages:
    2
    Gender:
    Male
    Vehicle:
    2002 Tundra
    Hello,
    No corrosion on the trailer plug and no, I'm not hitting the brakes. This issue just started about a month ago. I noticed it on a roadtrip.

    I was thinking that it I could have a vacuum leak. But I just don't know what controls the shifting on this truck.

    Thank you for the advise.
    I do appreciate it.
     
    Last edited: Apr 30, 2018

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