Question about 2005 Hummer H2

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Hummer h2 wont shift into gears,replaced the tranny with another one from another h2 which was working well,but still wont shift,what could the problem be

Replaced my gearbox after shifting problems,but the same problems persists it wont shift into gears .Hummer h2 automatic

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  • Hummer Master
  • 85,206 Answers

When you scan the transmission control module do you get any fault codes showing up?

Posted on Jul 18, 2016

  • 3 more comments 
  • Anonymous Jul 22, 2016


  • Marvin
    Marvin Jul 22, 2016

    P0751 refers to shift solenoid A stuck off, which according to the manual I have should be the 1-2 shift solenoid. If this one is stuck off, you should have 2nd and 3rd gears only. Both of the shift solenoids are identical. The 'A' solenoid is the one closest to the manual valve. The problem must be in the wiring harness or the connector, can't believe you replaced the entire transmission for a Code P0751. Mistake made learn from it. In any event you need to have a tool called a breakout box installed by the dealer, then they can watch live what is going on electrically in the harness and pin down the loss of control to shift solenoid "A". In short it is time for a GM dealer, a Chevy dealer can do this, it is a Chevy with a different body hung on it..

  • David Malatsi
    David Malatsi Aug 09, 2016

    thanx your comments are very good,but why is the same tranny that did not shift is shifting in the other Hummer H2.I have two hummer H2 and one H3.I actually swopped the trannys.

  • David Malatsi
    David Malatsi Aug 09, 2016

    The tranny that did not shift and had the P0751 code is shifting normally in my other hummer.The one that was shifting and was swopped is now no longer shifting.You are correct I can feel it is locked into 2nd and 3rd gear?

  • Marvin
    Marvin Aug 09, 2016

    I think (my opinion) your Hummer has an issue in the electrical harness to the transmission, most likely in the connector, swap the harness out from the other hummer you mentioned. If that cures the issue find a new or used harness for the tranny.



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P0751 obd code hummer h2

  • Shift Solenoid "A" Valve S1. the transmission is going to have to be pulled, opened up and that shift solenoid replaced, sorry.

  • If you have any comments please feel free to leave them here.
  • Hope this helps and thank you for using FixYa.

Regards, Tony

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