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Thread: Transmissin Hot displayed

  1. #1
    Join Date
    Mar 2003
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    Transmissin Hot displayed

    There aren't any issues that can get by us when troublehshooting an issue at the shop, but this one we just can't resolve.

    Transmission Hot is displayed on the cluster.

    2006 Silverado SS, 2wd. 80e conversion.

    Here's what we've done. Some of the easier things were done first, then as time passes, you start thinking of anything remotely possible that could be causing this.

    Steps are not in order, just typing them as I remember.

    - replaced the internal transmission harness and temperature sensor
    - replace the transmission terminals on the main harness transmission connector
    - replaced the two wires associated with the temp sensor
    - replaced both pcm terminals related to temp sensor
    - replaced pcm
    - flash and tuned with a completely different calibration
    - turned off the codes associated with the temp sensor
    - adjust values in calibration that determines at what temperature the display will set
    - swapped cluster
    - blew trans lines out just to be sure

    TRANSMISSION IS NOT RUNNING HOT! THE TRANSMISSION SHIFTS JUST FINE AND FIRM, NO SLIPPING NO OVERHEATING.
    Temperature sensor is registering the correct temp and it's working, but for some reason the pcm wants to send the message, thru serial, that the trans is hot.

    Everything electrical and mechanical has been replaced or swapped.

    Using hptuners, there is a value under Trans Diag, that value allows the user to set the Hot Mode of the transmission, however, when this value is set to say 700 degs, it makes no difference, the Transmission Hot message still displays.
    Duration for this code to set is 10mins, while driving and after ten minutes, it sets just as if the trans was hot. Changing any of these values in the calibration has no effect.

    We always have bad luck with transmissions and converters, could these two possibly cause this issue?

    Just a last minute addition: I tried my '05 avalanche cluster just to be sure, no trans temp gauge, but it still set around 175 degs.

    thanks for any input,
    allen

  2. #2
    Join Date
    Sep 2008
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    Arizona/Utah
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    Dang gremlins!!!
    ECSB 2kSierra 2wd 4.8L-K&N-HPtuners-Calspeed LT's-Magnaflow-Tahoe20's-HankookRH06

    waiting to go in... 3.90s, 214/220cam

  3. #3
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    Jul 2010
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    Douglasville Ga
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    Any luck yet? Strange issue no doubt.

  4. #4
    Join Date
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    Quote Originally Posted by vortecyota View Post
    Any luck yet? Strange issue no doubt.
    no resolution yet.

    Is there any possible way a converter or transmission can cause this?

    Recap: for some reason the pcm is sending the data to display Transmission Hot, even though the actual temperature is somewhat cool. Display will light up after 174degs or so. Also, if highway cruising allows the trans to cool, the light will turn off.

  5. #5
    Join Date
    Jul 2010
    Location
    Douglasville Ga
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    A high stall will certainly generate more heat than a low stall but when locked up wont generate any. 174 sounds too cool for a trans hot alert. How hot does it get in stop and go?

    Sounds like one of those crazy side effects of a segment swap. What temp does it run during lock up at cruising speeds? It should cool down after a couple minutes of steady lockup.

  6. #6
    Join Date
    Sep 2008
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    What year trans?
    ECSB 2kSierra 2wd 4.8L-K&N-HPtuners-Calspeed LT's-Magnaflow-Tahoe20's-HankookRH06

    waiting to go in... 3.90s, 214/220cam

  7. #7
    Join Date
    Mar 2003
    Location
    San Antonio, TX
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    174deg is too cool, 284deg is the trigger temp for hot temp mode. that's what i don't understand.
    It always stays under 200deg.

    No segment swap was done, this is a stock HD 6.0L / 80e file.

    Transmission is a late model type.

  8. #8
    Join Date
    Apr 2011
    Location
    Jennings, louisiana
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    I had the same problem with my 06 2500 hd, but mine was reaching temps of 250 or better. Trans would wine more then normal and then one day it fixed it self.

    slowly getting somewhere, 12.75 @ 105 1.77 60', 414rwhp/417rwtq

  9. #9
    Join Date
    Aug 2004
    Location
    Magnolia, TX
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    Do you have an extra pcm you can swap in it? Bad pcm?

  10. #10
    Join Date
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    That's listed above. Already did that.

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