How to "re-flash a transmission



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Thread: How to "re-flash a transmission

  1. #1
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    How to "re-flash a transmission

    Can an individual "re-flash" the transmission after changing the transmission fluid or does a dealer have to do this? How is the "re-flashing" done?

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    The transmission continiously "learns" your driving style.
    Some people complain of harsh or sloppy shifts after a fluid change, and a dealer can "reset" the transmission control module (TCM) parameters to what they were from the factory and let it re-learn from new.
    I am not sure if just disconnecting the battery does this or not.
    Just a note: If you have five dollars and Chuck Norris has five dollars, Chuck Norris has more than you.

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    There are also periodic updates to the module. Simply disconnecting the battery does not perform the updates. Often "Flashing the TCM" means providing an update.
    Michael
    Centreville, VA
    Currently driving:
    2005 Dodge Grand Caravan SXT, 120K mi.
    Former owner of:
    1988 Dodge Caravan SE, 2.5L I4 (1988-1995, 99K mi); 1995 Plymouth Grand Voyager SE "Rallye", 3.3L (1995-2004, 169K mi); 2003 Grand Caravan Sport, 3.8L, (2004-2008, 106K mi), 2008 Nissan Quest, (2008-2010, 25K mi)

    Other vehicles:
    2008 Lexus RX400h (Dark Gray), 98K mi; 2005 Hyundai Elantra GT (Blue), 75K mi

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    I also do not think that disconnecting the battery resets the parameters to the default (factory) settings. This seems to hold true anecdotally at least with my van -- I never notice a difference in the shifting after disconnecting the battery. Also, if the memory is indeed "flash" memory, it does not get cleared when powered down.
    2009 Dodge Grand Caravan SXT (3.8L), Light Sandstone Metallic, 125K miles
    2005 Volvo XC70, 160K miles

    Previous van: 2002 Chrysler T&C, eX (3.8L)

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    It really needs to be a dealer thing. IT may take weeks for your tranny to "relearn" how to shift. How much more than $90 worth of damage are you doing in the meantime?
    IAFarmer

    Current Rides

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    Good point. I have been wondering about this myself. After reading that, it seems silly to not have it done.

    100 bucks and an hour might save you a few thousand and a week down the road. It's a no brainer.
    When troubleshooting, always assume the simplest cause first!

    '02 Chrysler Voyager
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    You don't need to reset your trans controller after changing the fluid.
    The trans controller adapts based on internal wear and driving style.
    Just changing the fluid isn't enough to throw things out of whack.
    As long as you used the proper fluid and filter and have the fluid at the proper level your good to go.

    You only swapped out 1/4 to 1/3 of the fluid anyway.
    2003 GRAND CARAVAN SPORT
    1997 RAM 1500 SPORT 4x4
    2003 ALERO

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    You don't need to reset your trans controller after changing the fluid.
    The trans controller adapts based on internal wear and driving style.
    Just changing the fluid isn't enough to throw things out of whack.
    As long as you used the proper fluid and filter and have the fluid at the proper level your good to go.
    Changing the fluid CAN result in the rough downshift, even with all MOPAR fluids and filters. IAFarmer and I are the poster children for that.



    You will do no damage with the rough shifts (though, it IS very disconcerting) until the TCM "learns" to shift with the new fluid. Is it worth $100 to eliminate? You be the judge....


    We had the rough-downshift after fluid & filter at 62K miles. Took about three weeks (1000 miles) to smooth out again. We made an appt for the re-flash, but by the time the 2-week waiting time came up, the trans was 90% better so we cancelled it.

    Now, a year later, all is still well....
    Atwell "Buff" Haines
    Northern NJ
    2002 Grand Caravan ES "Extra Special"...
    Blue
    3.8L, Touring Suspension, 17" Alloys, and Autostick

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    Interesting...
    I've done hundreds of trans services on these transmissions and I can't say I've ever had a customer complain of a rough shift after a simple trans service.
    2003 GRAND CARAVAN SPORT
    1997 RAM 1500 SPORT 4x4
    2003 ALERO

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