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Thread: How to prevent 1-2 upshift in manual low 4L80e

  1. #1

    How to prevent 1-2 upshift in manual low 4L80e

    I have a 2002 truck PCM controlling a 6 liter/4L80e combo. I have recently installed a transbrake which is activated by placing the shifter in manual low then engaging a solenoid. I need to know how to prevent the PCM from commanding a 1-2 shift at all times while shifter is in low to prevent accidental engagement of the brake. Am I overlooking something in the program or is this even possible?

  2. #2
    send your file to support and i'll take a look

    Chris...
    I count sheep in hex...

  3. #3
    File sent. Thanks!

  4. #4
    Tuner in Training
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    can i get a update on this i would like to know also please :]
    LQ4 408, Pt-88, FIC 80# Injectors, 4l80e Stage 2, 2002 Gm Computer 3Bar Sd, 3.42 Gears, 30" Tire

  5. #5
    i got the file but i don't follow what you are trying to do.

    you want the trans to stay in 1st gear at all times when the selector is in low?
    I count sheep in hex...

  6. #6
    Yes, as it is now it will upshift to second even if the shifter is in low and I need manual low to hold 1st gear until the shifter is moved to 2nd.

  7. #7
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    I'm interested in this too. It's my understanding (from the owners manual actually), that the 2500 trucks (like mine) upshift to second, even when the selector is in low, but the 2500HD's stay in first. I don't see how to change this in HPT.

  8. #8
    Advanced Tuner jakebdb56's Avatar
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    put a trans go HD2 shift kit in it...
    '20 AT4
    '01 Suburban 2500 Dad Wagon

  9. #9
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    Was there a solution to this found in the calibration ? Someone suggested to me that it is possible to alter the calibration in EFI Live to prevent the 1-2 shift when in manual low. I don't have EFI Live so I cannot confirm this. I'm currently working on a car equipped with a 4L80E and a trans brake , and the transmission builder was specific about not letting the car do a 1-2 shift while in manual 1st gear .

    Thank you

    Chris

  10. #10
    Senior Tuner Google's Avatar
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    Quote Originally Posted by hexdummy View Post
    Was there a solution to this found in the calibration ? Someone suggested to me that it is possible to alter the calibration in EFI Live to prevent the 1-2 shift when in manual low. I don't have EFI Live so I cannot confirm this. I'm currently working on a car equipped with a 4L80E and a trans brake , and the transmission builder was specific about not letting the car do a 1-2 shift while in manual 1st gear .

    Thank you

    Chris

    Yes it is in there, but you will have to send your file into support and wait a few weeks! I have one I am waiting on as well.



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    We Can Fix Your Bricked PCM Or Your YYYYYY OS ID

  11. #11
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    Interesting , I will send Bill an email, thanks .

  12. #12
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    Looking into this a little further , it appears that the other software adds these WOT shift parameters :

    2002 Camaro 5.7 (12212156 4L60E):

    Manual 1st gear selected , 1-> 2 shift vehicle speed (set to 256 MPH)
    Manual 1st gear selected , 2-> 3 shift vehicle speed (set to 0 MPH)
    Manual 2nd gear selected , 2-> 3 shift vehicle speed (set to 0 MPH)

    2002 Silverado 6.0 (12212156 4L80E):

    Manual 1st gear selected , 1-> 2 shift vehicle speed (set to 255 MPH)
    Manual 1st gear selected , 2-> 3 shift vehicle speed (set to 255 MPH)
    Manual 2nd gear selected , 2-> 3 shift vehicle speed (set to 255 MPH)



    So , it appears to me that neither the Camaro or the Silverado calibration is set so that it will do a 1-2 shift in manual first but I'm not sure how to interpret the manual first 2->3 shift setting in the Camaro calibration . Any chance HPT will add the calibration parameters ?

  13. #13
    Senior Tuner Google's Avatar
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    Quote Originally Posted by hexdummy View Post
    the manual first 2->3 shift setting in the Camaro calibration . Any chance HPT will add the calibration parameters ?
    From what I have seen, the manual first 2->3 is, if it is left in manual first it can be setup to shift 1->2 at the desired mph then if the shifter is not moved will complete the 2->3 shift at the desired mph. For those that forget to shift or that do not want to shift into 4th in the quarter mile.

    Reply sent.

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    We Can Fix Your Bricked PCM Or Your YYYYYY OS ID

  14. #14
    i already added them for a couple of OS's, i was waiting on confirmation they actually worked before i added them to all.
    I count sheep in hex...

  15. #15
    Senior Tuner Google's Avatar
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    Quote Originally Posted by Chris@HPTuners View Post
    i already added them for a couple of OS's, i was waiting on confirmation they actually worked before i added them to all.


    When I get my file back from you I will let you know if it works or not.. I know it works in the 2002 I just tried using it on.




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  16. #16
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    and the result

  17. #17
    Advanced Tuner gman4dx266's Avatar
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    Quote Originally Posted by REDR8CLUBBY2010 View Post
    and the result
    Didnt work for me. 2002 1500HD 4l80/6.0

    The 1>2 manual upshift table was 256'd out from the factory. Sometimes you can roll 1st all the way up and peg the limiter and it will stay in first. Sometimes it will bark the tires going in to 2nd (probably because of it applying the intermediate band as well as the clutches). Then when slowing back down, usually under 15mph you'll feel the jerk of it coming out of 2nd back in to first. Truck has the transgo HD2 in it, but I dont see how anything in the kit would or should make it manual unless you get the HD3 full manual kit

  18. #18
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    I also need to prevent 4L80 from shifting 1->2, do I have to send the file too? OS is 9381344, it's 00 f-body PCM.
    LS1 383ci 98' FBody, turboed, 00' PCM, 4L80E, 90# FIC injectors
    110ci Nissan 200SX, 25psi, 370whp

  19. #19
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    I also need this done. Should i just note to have chris look at it?

  20. #20
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    Any updates on this issue, I'm starting a 4l80 transbrake swap car and need to know what PCM and harness to start with