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How to "re-flash a transmission

61K views 19 replies 12 participants last post by  reedfranklin 
#1 ·
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?
 
#2 ·
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.
 
#3 ·
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.
 
#4 ·
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.
 
#5 ·
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?
 
#6 ·
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.
 
#7 ·
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.
 
#8 ·
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. :angry1:



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....:beerchug:
 
#10 ·
My 94 Voyager shifts hard into D and R when cold , so hard it will kill the motor.
I left the batt. disconected for many months could this be the cause?, I changed the solenoid pack and it acts the same.
after it warms up and you drive a few miles it drives and shifts properly, let it cool down and it does it again.
Could it be the TCM?
any help ids greatly appreciated
 
#11 ·
Welcome reedfranklin,

I am very curious to know what you find out about this symptom.
Please, if you find something out, please return here and let us know. I am subscribed to this thread.

Again, welcome to the Mopar minivan PitCrew!
Cheers!
 
#13 ·
It has a solenoid pack. Sounds like too high rpms at startup? Stalls the engine? Maybe the OP can tell us more.
 
#15 ·
What fluid is in the transmission?
 
#18 ·
https://www.motor.com/magazine-summary/torque-converter-lock-may-1999/

Good link on trannys, from I've read about how modern TCs work , I think its probably the vale body , I am guessing a valve is sticking open or closed or not sealing properly causing the converter to stay locked up, maybe a seal is not sealing the pressure off ?
Idont know exactly how it works,
Can a vale body be replaced without an entire rebuild?
 
#19 ·
here's a good article, according to this , this year does not have a valve body, it uses the solenoid pack to to apply pressure for shifts and the torque converter, since I changed the pack and it does the does the same thing. It is something other than the solenoid pack , I have a DRB 2 and flash kit coming and a another TCM so I will flash it and see if it helps
any ideas?


https://www.allpar.com/mopar/transmissions/41TE.html
 
#20 ·
Here is another good post , how factual IDK but he is obviously a Chrysler fan(critic), this article is not very encouraging because I am certain my old van got something other than ATF+2 and ATF+3 along the way. Especially with mechanics not knowing the
requirements. ATF+2 is far gone and ATF+3 is not for sale anywhere I have found yet.
my antique has car outlived the fluids it needs to operate properly, LOL

http://jerickweb.50webs.com/autobin/Chry_Trans_Tip.html
 
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