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I Think I Fixed My Rough Shifting 8sp Transmission

247K views 603 replies 170 participants last post by  Jason164 
#1 · (Edited)
Since day one I have had issues with my 8sp transmission in my 2014 V6 GC Limited 4x4 (current mileage 1100)...namely downshifts into 1st and 2nd were slow & rough, and sometimes I would even get a clunk from the drivetrain. In addition, the tranny seemed to hunt for gears at times, when I would floor the gas the transmission would hang in neutral for a few, and most the time the transmission did not seem to downshift quickly enough when taking my foot off the gas pedal.

So what I thought I'd try was "Reset" by means of a battery disconnect. I have powered seats, so...

1) I raised and moved forward the passenger seat as far as it would go.

2) I pulled off the battery cover on the floor under the seat (no tools required, simply stick your finger tips in there and pry/pull off). Only 4 tabs holds the cover on.




3) Then I disconnected the negative side of the battery, pumped the brakes to dissipate residual power in the system, and let it sit for 15 minutes.




4) Then I just reconnected the negative side, reinstalled the cover, put the passenger seat back down, and started the engine...letting it idle for about 5 minutes, then took it on a short 15 minute run around town. I DID NOT LOSE ANY UConnect settings, radio pre-sets, or any other interior settings.

All I can say is WOW...my GC is a totally different animal! It's now been two days, and the rough down shifts into 1st and 2nd are still gone, no more hunting for gears, when I floor the gas it finds a gear faster, and when I take my foot off the gas pedal, the transmission immediately starts to downshift.

I will be keeping my eye on this, and will report any new findings.
 
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#27 ·
If it stays this way they should be naming a Star case after you. ;)
Call it..."The Sean Transmission Reset".

:D

Going on 5 days now, and my transmission is still shifting like a pro...even in "ECO" mode...smooth as butter.

I learned this trick from my Subaru days when you had to reset the ECU with every new engine modification.
 
#10 ·
I might give this a try. My first and second gears (esp. in ECO) are rough going up and down, more so in stand-still traffic around 5-15 mph stop and go. I only have 700 miles on it so it might still be breaking in.

Anyone else try this yet?
 
#23 ·
I'm confused as to why this worked but whatever.
I would guess that dynamic parameters which are "learn" during driving are kept in memory and not flash storage. Disconnecting the battery resets the memory forcing the computer to restart the learning sequence. For some reason, the initial learning cycle does a poor job for some scenarios.

In theory, updating the software even with the same version would do the same without actually fixing the root cause.

Also possible the memory is not ECC and a bad memory bit mucked with the parameters, but given multiple reports of the same issue I would guess a software problem that occurs in some specific case. Tracking that down would be fun.

Obviously I'm only guessing...
 
#13 ·
But will the problem come back after the system learns how you drive? I might try this as well since I have a very rough shifting system. Today I ran it to high RPMs in 1st and when I shifted to 2nd it over revved and sat in neutral for several seconds. Almost got rearended because of it.
 
#16 ·
My transmission has given me all sorts of problems... the dealer and Chrysler keep blaming it on lots of different things. I have had a catalytic converter replaced, two oxygen sensors replaced, and the ABS module replaced.

Why am I posting about it here? Because today, as I was on my way to the dealer for a check engine light, the Jeep shut down on me. After a minute or two of blocking traffic and getting honked at, I got it restarted, and after it restarted, the transmission drove better than it has in a month. Much smoother, no hiccups as it tried to change gears, etc... Maybe the engine shutdown forced the same type of reaction that disconnecting the battery caused for you folks.
 
#17 · (Edited)
My transmission has given me all sorts of problems... the dealer and Chrysler keep blaming it on lots of different things. I have had a catalytic converter replaced, two oxygen sensors replaced, and the ABS module replaced.

Why am I posting about it here? Because today, as I was on my way to the dealer for a check engine light, the Jeep shut down on me. After a minute or two of blocking traffic and getting honked at, I got it restarted, and after it restarted, the transmission drove better than it has in a month. Much smoother, no hiccups as it tried to change gears, etc... Maybe the engine shutdown forced the same type of reaction that disconnecting the battery caused for you folks.
Holy crap! Your Jeep done did a "Blue Screen of Death". It sounds like these Jeeps are being run by a Microsoft Windows operating system! Problems with the Uconnect system...download an update. Tranny problems...reboot the Jeep! :lol:
 
#21 ·
So I just gave this little "fix" a try this afternoon. Granted my Jeep only has 600 miles on it and might need some breaking it, but I definitely was a little annoyed at the transitions when downshifting at lower gears. Especially when coming to stop before a light - it definitely was not a smooth coasting ride. I disconnected the battery and let it sit for 30 min, and when i went out for a drive, it was noticeably better. Like other people said, I'm not quite sure why this helping the situation, but I'm really happy that it did. Also, just to note, I've been driving with eco mode off, so that wasn't the initial problem.
 
#24 ·
I would almost have to guess that there is some sort of default bank of data in there from the get-go to help with break-in of the transmission or something. Maybe disconnecting the battery clears all of that and allows a full learning process. In my mind, same concept as a default set of MPG data stored which would then affect the Average MPG value that the owner would actually get in the vehicle. Resetting it makes the calculations start from scratch.

Clearly just shooting from the hip here but I can't see the how battery disconnect would cause any issues. Might give it a shot tomorrow since there's already a few thumbs up here from others.
 
#32 ·
I would almost have to guess that there is some sort of default bank of data in there from the get-go to help with break-in of the transmission or something. Maybe disconnecting the battery clears all of that and allows a full learning process. In my mind, same concept as a default set of MPG data stored which would then affect the Average MPG value that the owner would actually get in the vehicle. Resetting it makes the calculations start from scratch.

Clearly just shooting from the hip here but I can't see the how battery disconnect would cause any issues. Might give it a shot tomorrow since there's already a few thumbs up here from others.
Maybe the transmission is really tight and the initial learning doesn't handle the initial break-in period well. That it, it understands a new transmission, but doesn't adjust quickly enough after it loosen up a bit. In theory, after a while it should settle down. The battery reset permits a new learning process with a smoother transmission (now that it has some millage on it).
 
#26 ·
I did the 30 minute battery reset tonight and took a test drive. Yep, way better. Still a few bumps downshifting to 2nd gear, but not a clunk like before. I would say 90% of the shifts were perfectly smooth. We'll see if it stays this way.
 
#29 ·
After resetting mine last night, the drive to work today was very smooth. Eco mode even shifts faster and doesn't lag so much. :)
 
#30 ·
Yeah Eco mode is so much better now after doing the reset. I've noticed no noise/clunk when down shifting that was my main reason for trying this fix. I can actually drive around San Francisco now up and down the hills with out constant shifting it seems to be holding the gear longer when going up hills. Down shifts are a little weird sometimes but I think that's on my end just need to get use to 8 speed trans & Eco mode. The jerk & clunk is gone though Thanks OP I would have never thought of disconnecting the battery to rid a transmission problem.
 
#34 ·
Could the harsh downshifting come from the way the vehicle is driven in the factory for the first time off the assembly line? The computer has that first start and drive in it's memory?
By disconnecting the battery you have reset the computer? I worked for Ford for a number of years and at the end of the line when the vehicle was first started the guys would peel out off the end of the line and drive to the rail header. Just a thought. I have about 6K on the clock and I am going to try this fix over the weekend.
 
#35 ·
The learning process is supposed to be continuous. If it is still working based on that first shot off the line, the learning process is not working. That is sure a possibility.


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#36 ·
Wonder if there is a fuse that we can pull to do the same thing. I pull a specific fuse on my 2010 Challenger R/T every once in a while to wake the car up. Throttle response and shift points reset. But like most are saying adaptive learning starts up again and have to do a reset. Guess I'll try the battery reset on the GC unless I can find the right fuse.
 
#314 · (Edited)
Wonder if there is a fuse that we can pull to do the same thing. I pull a specific fuse on my 2010 Challenger R/T every once in a while to wake the car up. Throttle response and shift points reset. But like most are saying adaptive learning starts up again and have to do a reset. Guess I'll try the battery reset on the GC unless I can find the right fuse.
Yup that's what happens.

I pulled battery cable and things did seem to reset.

This is on Jeep built after July 14th so it should have new Transmission Firmware.

It was better (still not as good as Non Eco mode) but better than it was.
Over time it came back.

I cleared Fault Codes last night and the software says Engine may run rough as it relearns/recalibrates itself. I suspect it may have wiped Transmission learning too. Because ECO felt better this morning.

But I have to be careful. Most of the time it's fine.

It's just in certain situations, it's down right dangerous.

It's like your going 30 mph (or so) and it just up shifted, say to 6th and you need to goose it to get yourself to where you feel you want to be. And you just goose it, a little. And you get NOTHING. Your immediate reflex is, to GET Where you planned to be, is goose it more. If you waited it would eventually downshift mildly. But since you goosed it more (to get things going) it down shifts a LOT. Like it might go down to 3rd gear. And now your passengers are panicked. Engine is racing. And you go PAST where you wanted to be. It really sucks when it does this. And there is no reason it needs to and doesn't save gas. In fact, it wastes it.

It does not do this in Non Eco. Mostly because it will be 1 gear lower in the first place and may not need to downshift at all. And if you do, it responds quicker to mild acceleration, with a mild downshift (1 gear). Which is all you wanted !!

It's hard to anticipate you need it with Paddle Shifters or Sport mode (which engage great) it's the driver that can't engage it fast enough sometimes.
 
#38 ·
Nobody mentioned (or I missed) what size wrench was needed to remove the battery cable. Turns out I didn't need any. It was only sitting about half way down on the post, and came off in my hand. I had to loosen the nut almost two full turns to get it all the way back on.

I still went through the steps that were listed, but a loose battery clamp could account for the surprises I've been getting.

Most everything stayed, but there were a few exceptions. The radio volume was set to zero, the a/c was off, when I put it back to auto the temp had changed from 68 to 72.

Time will tell.
 
#39 ·
Just did mine this morning. Just a little twisting back and forth on the clamp and it popped right off. I must say, i just had a glorious 20 minute drive. Vehicle was much more decisive with shifts, much smoother shifts and finally just a pleasure to drive.

Now for the bad news, I've got a lovely "Radio Locked. Please start vehicle" message on my 8.4AN. It still played my IPod, switched to radio when I hit the Radio button but of course i can't see anything on the screen. Very weird. Gonna let it sit for a little while and go fire it up later and see if it magically goes away. I've already restarted the vehicle once before the test drive and that didn't fix anything. It flashes the screen for a second when i hit the Screen Off button but it's there when i turn it back on. Anybody know of a way to reboot the RA4? If nothing else, I'll at least have a reason to give the Assist button a try today.

Vehicle runs like a beast now so I have no complaints....prob something simple and stupid with the screen.
 
#40 ·
False alarm....all is fine after letting it sit for a while. Weird, but I'll take it. BTW, I did notice that i had reset my Equalizer settings after the battery pull. Everything else was still stored - phone, radio presets, and settings.

Sean is officially my hero for the month of June....
 
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