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Thread: 6l80 p0974 intermittent no first

  1. #1
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    6l80 p0974 intermittent no first

    Just put the 6l80 back together for my first rebuild. The Torque Converter filled the trans up with small sparkly metal pieces and gouged out the pump and bell housing along with 4-5-6 clutch pack being burned to the extent of no friction material left. All other frictions were good. The only changes from stock was Sonnax 4-5-6 apply upgrade, Raybestos frictions, changed from the 7 balls to 8 balls with newer separator plate, billet TCC stock stall. Disabled DOD(AFM) with TCC lockup only in 4th 5th.

    I used HPT to do the clear, reset, fast learn etc.

    OK problem is I'm getting a "P0974 - Shift Solenoid A Control Circuit High (Pending, Current, Permanent) Controller Type ID By OS: 60".

    It may drive fine for a while then push the code and loose first gear going into 2nd. All other gears change fine. When I clear the code it will sometimes clear and drive ok and sometimes go right back into 2nd gear.

    Now question is, will HPT read the Shift Solenoids 1 and 2? I have been searching and I can not seem to ask the right search question to find out.

    Should I try a new TEHCM?

    Thanks for any guidance.
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  2. #2
    Tuning Addict blindsquirrel's Avatar
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    Why not connect the scanner and search in the available channels, instead of searching in the forum?

    But, P0974 is indicating an open circuit, and the only way to pin down whether it's wiring or the TECHM is to prove beyond doubt that it's not a wiring problem.


    Conditions for Setting the DTC
    The control solenoid (w/body and TCM) valve assembly detects an internal high voltage electrical malfunction of the SS 1 control circuit when the SS 1 is commanded ON for 300 milliseconds.
    In English, the driver grounds the solenoid winding but the voltage doesn't go low like it's expecting (that's what they mean by 'high voltage', it just means 'not ground when it should be').

  3. #3
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    Just happened to watch a ScannerDanner video during lunch today where he troubleshot a P0974 on a 2010 Cobalt that turned out to be a short in the transmission, either in the solenoid or wiring internal to the transmission. It would try and engage the solenoid, amps would shoot up in a few milliseconds and the ECM would release it. It was interesting to see on the scope how quickly amps would shoot up and off. Couldn't see any sign of it on a test light.

    https://www.youtube.com/watch?v=Sr7woeza8to&t=410s

    He start of assuming it's likely a bad driver in the TCM or open wiring.

  4. #4
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    Quote Originally Posted by blindsquirrel View Post
    Why not connect the scanner and search in the available channels, instead of searching in the forum?

    But, P0974 is indicating an open circuit, and the only way to pin down whether it's wiring or the TECHM is to prove beyond doubt that it's not a wiring problem.




    In English, the driver grounds the solenoid winding but the voltage doesn't go low like it's expecting (that's what they mean by 'high voltage', it just means 'not ground when it should be').
    Thanks blindsquirrel,

    Yes I did look through all the channels for the transmission. After not finding it I came to the forum. Could it be called something besides SS1?
    I did find something under the HPT editor called driver hi side 1 and 2 but have no idea what that does, yet. I have the PCS 1-5 in the channel along with shift times. With me being a team of one player on a vast empty field I was hoping to be able to pulse the solenoid with HPT so I could get under the vehicle with my Oscope and trace out the signal flow. As scannerdanner was able to do because his wiring was on the outside of the trans he was checking. All of these signals come out of the TCM to those darn spot welded on solenoids that I would not trust to solder back on due to heat and vibration. (not my lack of soldering skills)

    When I look at SS1 with my AUTEL scanner it shows it going in and out of fault. Like a loose connection.


    I am a little confused on the high voltage alarm. If the TCM is dropping a ground on the solenoid (sinking it), is it measuring the voltage drop across the semiconductor switch?
    If the solenoid or wire is open to the positive battery voltage there would be a lack of any voltage into the TCM. If the semiconductor switch failed to an open state I could see how it would be a hi voltage across it if the wiring and solenoid was good. I would really like to find a diagram for the solenoids.

  5. #5
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    ECM takes a high resistance voltage reading “upstream” of the ground switch. If the internal switch grounds, the high resistance means that the current goes to ground not to the voltage reading, so with the switch closed to ground, it should see basically 0 volts where it measures.

    Edit: I’m trying to learn this stuff and I might have gotten this backwards with a powered switch circuit instead of a grounded switch one. Maybe BS will set me straight if I’m wrong.
    Last edited by gtstorey; 06-02-2023 at 07:41 PM.

  6. #6
    Senior Tuner TheMechanic's Avatar
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    Personally I would use my Tech2Win and command on shift sol A with the engine off in a quite place. Should be able to hear it click. Even with my crap hearing I can hear them click.

  7. #7
    Tuning Addict blindsquirrel's Avatar
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    screenshot.02-06-2023 21.55.17.png

    There's more going on than shown in this stupid pic; for it to be able to set ckt hi/ckt lo codes there has to be some monitoring in there. Older diagrams show the voltage taps, this one does not.

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    Quote Originally Posted by blindsquirrel View Post
    screenshot.02-06-2023 21.55.17.png

    There's more going on than shown in this stupid pic; for it to be able to set ckt hi/ckt lo codes there has to be some monitoring in there. Older diagrams show the voltage taps, this one does not.
    Thanks again blindsquirrel,

    I forgot that the ATSG book had a sche in it. It shows the solenoids as being switched to ground as the pic you sent. I would like to try and pulse SS1 like TheMechanic (I loved the Karma in that movie) suggested but as of now I don't have access to one. I was just hoping that HPT had that feature and I was just not finding it. It would be a sweet feature to have a little AI built into HPT that would do as the adaptive learning procedure does (yes I know the TCM itself does the procedure, HPT just starts and monitors it) but have you select the gears and it would look at that data stream connection to see if the switches, proper solenoids on and pressures were within the expected range and if not have it show a discrepancy table.

    I think I'll drop the pan, take out the TEHCM and do another look over on it. It just doesn't seem that it is an electrical problem the way it almost works, but.....

  9. #9
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    Definitely could be an electrical problem. I would check out the circuit on the ground side of the solenoid.

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  11. #11
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    Quote Originally Posted by TheMechanic View Post
    Thanks TheMechanic, diagrams are perfect, I can now see how the controller monitors the solenoids.

    I ordered a TCM a few days ago. I dropped the pan and TEHCM today and found a broken spot weld on the Shift Solenoid One solenoid. It was randomly making mechanical contact thus not a hard fail.

    I now need to decide if I want to make a good mechanical connection and solder then reinstall or put in the new TCM and deal with reprogramming. The Forum says I can reload the file I downloaded from the TCM with HPT and all will work if I do a TCM only with an all write.

  12. #12
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    Quote Originally Posted by cgcallebs View Post
    Thanks TheMechanic, diagrams are perfect, I can now see how the controller monitors the solenoids.

    I ordered a TCM a few days ago. I dropped the pan and TEHCM today and found a broken spot weld on the Shift Solenoid One solenoid. It was randomly making mechanical contact thus not a hard fail.

    I now need to decide if I want to make a good mechanical connection and solder then reinstall or put in the new TCM and deal with reprogramming. The Forum says I can reload the file I downloaded from the TCM with HPT and all will work if I do a TCM only with an all write.


    OK just to keep this from being a ?well what happened? ending, I changed the TEHCM I ordered new from GM, did a ?flash write all? on the TCM only, with the file I pulled from the vehicle when I first got HPT(my first read all).

    It took about five minutes to download and all went well. I reloaded the tune I had with no DoD, no slip, and no TCC lockup in 1234. It took it and I did a ?clean? and fast relearn with no problems.

    GM dealer wanted me to tow it in after I replaced the TEHCM so they could charge me 1.5 Hr labor(around 170.00$plus taxes). With the tow price added to it, the HPT MPVI3 has paid for itself in this one Flash.