2007 GMC 1500 V6 With Transmission Error Codes

Discussion in 'Engine & Drivetrain' started by andy383, Oct 26, 2016.

  1. andy383

    andy383 New Member

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    Hello All,
    Thank you very much in advance for the help. Last week I purchased the vehicle from a junk yard after they purchased it at auction. It has 107,000 miles. The yard owner was very up front and said he thought there was a transmission problem base on his driving it about 4 months earlier. He hadn't driven it since until we test drove it. During our test drive it ran fine, no codes, no shifting issues, felt great.

    I then went to pick it up on Saturday and after a mile or so the check engine light came on. At low speeds it felt ok but lacked power when starting from stop. At higher speeds it felt not great. At 45mph when I took my foot off the gas the transmission seemed to disengage abruptly. And it was sort of hard going back in when I stepped on the gas. I'm new to this vehicle so it was hard to determine which gear I was in. On the highway I got up to 55mph and apart from the issue just described it seemed ok, tac was not abnormally high, I think around 2000-2500. No tranny noise and fluid was nice cranberry red.

    I brought to my mechanic who is generally good and whom I trust. He called today to report two error codes P0740 and P0758. He said he had a similar problem with a Blazer he owned and had to replace the tranny. Being ignorant but also after asking the basics questions like: can't you just replace the shift solenoid, I agreed to approve him to proceed with the transmission re-build at $2k.

    After doing some research on the two codes it would seem a lot more trouble shooting is needed before we replace the tranny. I am going first thing in the morning to find out what other troubleshooting he did. That being said, is it common for this vehicle to need a new transmission after 100k miles? How likely is the problem a transmission failure versus the numerous other electronic/wiring issues I've read about.

    Again, thank you very much for the help.
     
  2. Sparky

    Sparky Moderator

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    It is just a 4L60E so not vehicle specific, and for what it is worth I got 215k out of one (vehicle rotted out, trans was still fine), another has 170k and counting, the one in my 07 Silverado 5.3L has 147k and counting.

    Can they blow earlier? Yeah. Common? Not particularly.

    P0758 is electrical in nature, most likely, from what I'm seeing. Shift solenoid error. "A continuous open, short to ground or short to power in the 2-3 Shift Solenoid was detected." Could be a connection, or shorted solenoid.

    P0740 is also electrical for the TCC, with a similar description as the other.

    The fact that both are electrical codes, and the fact that it drove perfectly normally, then acted up, then was normal again when you got it before acting up again makes me really think you're only looking at electrical issues.

    Frankly, I'd be dropping the pan and checking all the electrical stuff first. Look for a common signal wire for those two solenoids, I cannot remember off the top of my head if they share a common wire or not.
     
  3. andy383

    andy383 New Member

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    Sparky, thanks a million!
     
  4. Mooseman

    Mooseman Moderator

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    Could also be a connection issue outside the transmission. Disconnect the connector and check for corrosion. Also check that the wires are not broken.
     
  5. Sparky

    Sparky Moderator

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    Yeah, good point, I probably jumped the gun there a bit.
     
  6. andy383

    andy383 New Member

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    Mooseman, thanks a ton. I asked the mechanic this morning what other diagnostics he did and his response was "everything". He said the torque converter was bad to which I responded that the error code was for torque converter control. Seems like red flags all around. Sad, because to date they have been great.
     

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