New transmission, now getting P1870

Discussion in 'Engine & Drivetrain' started by xjsc16x, May 12, 2018.

  1. xjsc16x

    xjsc16x Member

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    02 Tahoe LT with 209k miles. Transmission let go earlier this year, was off the road for a while and put a new one in that was rebuilt with some upgraded parts by a guy off Craigslist. For $500 I figured it was worth the shot.

    Transmission is in, started driving it last week drives and shifts great only problem is every once in a while the 1-2 shift is really hard. I have not tried adjusting anything only been driving it since Monday and now I pulled a P1870 code this morning.

    Does this sound like the typical loose TCC apply? Is there anything else I could look for?

    And what does everyone recommend to fix it if that is the problem? Would a transgo shift kit address this? I could consider getting it installed if it would. I'd rather not mess with valve bodies myself.

    Thanks,
    Justin
     
  2. Mechanic421

    Mechanic421 Full Access Member

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    Take it to a professional for diagnostics and then go from there. Could be a number issues line pressure, tcc solenoid , tcc valve or maybe pressure control solenoid.
     
    Last edited: May 12, 2018
  3. Scottydoggs

    Scottydoggs Full Access Member

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  4. Rocket Man

    Rocket Man Sometimes A Dumbass Supporting Member

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    That's an awesome video. I love it when they're detailed like that. Unfortunately like @Mechanic421 said it could be any number of components. All the code tells you is the input and output speeds are far enough off to set a code. Something is slipping.
     
  5. xjsc16x

    xjsc16x Member

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    Definitely going to have to. One thing I know better than go messing around in is a valve body. I hope it's something as simple as a solenoid because my wallet's not exactly feeling very heavy lol.

    -Justin
     
  6. Mechanic421

    Mechanic421 Full Access Member

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    If you google 4l60e harsh 1-2 shift and code p1870 there are some websites with some good information.
     
  7. xjsc16x

    xjsc16x Member

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    I've done some, seems that the TCC apply being loose is a fairly common cause which is why I asked about that. Guess the only way to find out is when the tranny guy tells me
     
  8. Mechanic421

    Mechanic421 Full Access Member

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    A
    And replacing the valve body is not all that hard but they are not cheap. You just can’t put the long bolts in the wrong place it will lockup the gear train!
     
  9. Mechanic421

    Mechanic421 Full Access Member

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    Good luck
     
  10. Mechanic421

    Mechanic421 Full Access Member

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    Were do you live I work at a transmission shop in ft Pierce fl
     

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