# Intermittent Transmission Issues



## Snipesy (Dec 7, 2015)

Beyond making sure it has enoguh fluid, try resetting it. (Unplugging the battery for awhile). This TCM is a whiny little...


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## Tomko (Jun 1, 2013)

Odometer reading?

Miles since the last fluid change?


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## MP81 (Jul 20, 2015)

Unless it's leaking again, fluid should be good. Then again, it's not an easy one to check, given the weird-as-**** refill procedure that ends with you counting the number of drips per second, then adding a set amount of fluid past that. I should be able to see a leak fairly easy on the aeroshield, though. If that's the case, I'm going to be rather upset - those lines are absolutely terrible to do. 

Unplugging the battery isn't a bad idea. I need a reason to install your old CAI anyway, so this would give me the battery disconnect you suggested for that, as well.

This Aisin trans has got to be one of my least favorite transmissions I've ever encountered.


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## jblackburn (Apr 14, 2012)

Seems like a couple people have had their CTD transmissions replaced for exactly the same behavior.


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## IndyDiesel (May 24, 2015)

Sounds like a transmission replacement is in order. My first reaction is do you have the correct fluid amount in the transmission? It’s almost impossible to really know.


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## MP81 (Jul 20, 2015)

Tomko said:


> Odometer reading?
> 
> Miles since the last fluid change?


81,827 miles when I put 2.5 gallons of DEF in yesterday. 73,759 is when the trans lines went in, 3/27/18,.



jblackburn said:


> Seems like a couple people have had their CTD transmissions replaced for exactly the same behavior.


Yeah...it did sound quite familiar...



IndyDiesel said:


> Sounds like a transmission replacement is in order. My first reaction is do you have the correct fluid amount in the transmission? It’s almost impossible to really know.


Assuming it hasn't leaked any out - it _should_ yes. I followed the funky Aisin AF40-6 refill procedure after I did the trans cooler lines. Wait for drips to be ~1 per second, reinstall check plug (which, oddly enough, is on the bottom of the engine - inside of the larger drain plug), turn engine off. Add X amount of trans fluid. Reinstall fill plug. 

Trans had been great - almost like it was new - up until a month or so ago when my wife started complaining about it, but I hadn't had the "good fortune" of experiencing the problem until yesterday.

The issue is that it doesn't always happen. Our luck would be we drop the car off, dealer finds nothing wrong, then we get it back, and it acts up. Repeat.


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## IndyDiesel (May 24, 2015)

MP81 said:


> Assuming it hasn't leaked any out - it _should_ yes. I followed the funky Aisin AF40-6 refill procedure after I did the trans cooler lines back in March. Wait for drips to be ~1 per second, reinstall check plug (which, oddly enough, is on the bottom of the engine - inside of the larger drain plug), turn engine off. Add X amount of trans fluid. Reinstall fill plug.
> 
> Trans had been great - almost like it was new - up until a month or so ago when my wife started complaining about it, but I hadn't had the "good fortune" of experiencing the problem until yesterday.


I have had good luck with mine, makes me a bit anxious to go out of warranty and have a $5000 plus transmission replacement. You didn’t really have a warning until now. If this was a gen 2 Diesel you would be out of warranty.


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## MP81 (Jul 20, 2015)

I guess it hasn't been terrible - a lot of the issues prior were due to the leaking trans lines I wasn't aware of until I did the initial fluid change to Amsoil in January. It's always been a bit clunky for my tastes, on occasion.

But yes, I'd like this all taken care of before the PT warranty is up...


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## Taxman (Aug 10, 2017)

MP81 said:


> But yes, I'd like this all taken care of before the PT warranty is up...


Then take it in this week.
Don't try to fix it yourself. 
Chances are high the diagnosis will be 'transmission fault, replace'.


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## MP81 (Jul 20, 2015)

Oh, I'm not fixing this at all by myself. This car is still under warranty, unlike half the other bullshit we've had to fix, they can fix this, for free.

And that's the thing..._if_ it decides to act up. If it's not, it's perfectly normal, so they wouldn't be able to experience it.


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## Snipesy (Dec 7, 2015)

Yeah I wouldn't install your CAI until it's settled with.

No it doesn't void anything. Not even a 'delete tune' voids anything. But techs are stubborn and most people don't want to have to sue every time something breaks in their car.


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## Taxman (Aug 10, 2017)

Does it tend to happen for the first xx miles of the day, or is that just how it went this weekend?


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## MP81 (Jul 20, 2015)

Taxman said:


> Does it tend to happen for the first xx miles of the day, or is that just how it went this weekend?


Seems like it kind of just happens whenever it feels like - sometimes it'll do it a lot more, sometimes not at all. She said it doesn't do it on the freeway...but given you don't spend much time stopped, I would expect it wouldn't even have the chance to show up. It did not seem to do it the first 15-20 min or so of our drive on Saturday, then all of a sudden the car was rolling backwards instead of moving forwards, and then the big jolt. That's when my wife said "this is what I was talking about".


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## IndyDiesel (May 24, 2015)

MP81 said:


> Seems like it kind of just happens whenever it feels like - sometimes it'll do it a lot more, sometimes not at all. She said it doesn't do it on the freeway...but given you don't spend much time stopped, I would expect it wouldn't even have the chance to show up. It did not seem to do it the first 15-20 min or so of our drive on Saturday, then all of a sudden the car was rolling backwards instead of moving forwards, and then the big jolt. That's when my wife said "this is what I was talking about".


Maybe it would be better to get it doing it on an incline and floor it and fix the transmission for good? :shoot::shoot:


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## MP81 (Jul 20, 2015)

Hahaha, kill it with fire! Either fix it, or make it permanently exhibit a problem requiring a replacement, haha!

I'd need a HANS device, if I did that. Just what I'm guessing was a medium amount of throttle that my wife applied, it was nearly painful.


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## revjpeterson (Oct 2, 2013)

I'm in exactly the same scenario right now, but closer to my warranty cutoff. I'm at 95,000 and my warranty expires on Sept. 27. Same AMSOil fluid, replaced the lines about a year ago, behavior is intermittent, rollback, slams into gear from neutral taking off from a stop, etc. I also get some wicked 5-4 and 4-3 downshifts when slowing down or getting off/on throttle on hilly terrain, but that is intermittent too. 

I need to get it dealt with in the next 6 weeks, but the behavior hasn't been consistent enough for me to risk the $105 diagnostic fee if I take it in and they can't duplicate. I'm hoping it really goes south in the next 6 weeks, or that GM will offer some kind of remedy when I contact them directly that doesn't involve me risking paying an hour's labor for nothing.


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## Jondaytona (Apr 26, 2018)

I've been running AmsOil in near everything I've owned for the last almost 20yrs. The more I hear about how picky manufacturers are with their fluids in their new cars has started to make me think twice about AmsOil lately. This thread don't help, makes me suspicious of how the fluid is treating the Aisin trans. I've got to do my first oil change on my Cruze and not even sure which brand of engine oil to go with anymore. Although, when I called the Chevy dealer, to buy the oil they use seems to be cheaper than if I were to go to the local parts store(with my discount). I'm thinking factory fluids is best anymore...I dunno.


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## IndyDiesel (May 24, 2015)

Jondaytona said:


> I've been running AmsOil in near everything I've owned for the last almost 20yrs. The more I hear about how picky manufacturers are with their fluids in their new cars has started to make me think twice about AmsOil lately. This thread don't help, makes me suspicious of how the fluid is treating the Aisin trans. I've got to do my first oil change on my Cruze and not even sure which brand of engine oil to go with anymore. Although, when I called the Chevy dealer, to buy the oil they use seems to be cheaper than if I were to go to the local parts store(with my discount). I'm thinking factory fluids is best anymore...I dunno.


I used AmsOil in transmission and no issues. My better guess is the stupid method of trying to put the proper amount of transmission fluid in it since it doesn’t have a dipstick. When just doing a change you just put back in what you took out, if you have a transmission line leak, it’s a guessing game in my book. I seriously doubt I keep my CTD past the warranty.


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## MP81 (Jul 20, 2015)

IndyDiesel said:


> I used AmsOil in transmission and no issues. My better guess is the stupid method of trying to put the proper amount of transmission fluid in it since it doesn’t have a dipstick. When just doing a change you just put back in what you took out, if you have a transmission line leak, it’s a guessing game in my book. I seriously doubt I keep my CTD past the warranty.


That's why I went with the "real" fill procedure, since the lines leaked out who knows how much, and then who knows how much more during removal. The only real guessing game there is how much fluid to add before you check the fluid level.


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## Rivergoer (Mar 30, 2017)

What’s the harm in adding another 1/2 quart or so just for s#its and grins?


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## MP81 (Jul 20, 2015)

Rivergoer said:


> What’s the harm in adding another 1/2 quart or so just for s#its and grins?


An upset overfilled transmisison, haha.


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## revjpeterson (Oct 2, 2013)

MP81 said:


> Rivergoer said:
> 
> 
> > What’s the harm in adding another 1/2 quart or so just for s#its and grins?
> ...





Rivergoer said:


> What’s the harm in adding another 1/2 quart or so just for s#its and grins?


If I get to the end of my warranty in 6 weeks, and they haven't done anything, I'm planning to do a level check, then when I refill the lost fluid, overfill it by 4 ounces or so to see how it changes the behavior. If it improves but not completely, I may add another 2-4 ounces at a time until I see complete improvement or it gets worse again, and I know where the optimal level seems to be. I'm also considering using an additional friction modifier to see if I can squeeze any improvement out that way. For the next 6 weeks, though, I'm just waiting and hoping it will completely take a dump or show consistent enough symptoms to repair/replace under warranty.


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## MP81 (Jul 20, 2015)

It definitely seemed to be very happy, for months, when I filled it following the "proper" procedure.

So, either it leaked fluid out again, or something is physically just taking a ****. Based on the fact the couple failures seem to be similar to what we're experiencing, I'm thinking this likely has nothing to do with fluid - especially since it's so intermittent. When our fluid was low, you could basically count on it to be useless.


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## jblackburn (Apr 14, 2012)

MP81 said:


> It definitely seemed to be very happy, for months, when I filled it following the "proper" procedure.
> 
> So, either it leaked fluid out again, or something is physically just taking a ****. Based on the fact the couple failures seem to be similar to what we're experiencing, I'm thinking this likely has nothing to do with fluid - especially since it's so intermittent. When our fluid was low, you could basically count on it to be useless.


The stop-neutral feature on the Aisin 55-50SN was problematic for 99% of them. Often a huge jolt or slow engagement as they got up there in mileage.

Most that owned that transmission disabled it or had to replace solenoids.

Surprisingly, it doesn't seem to be an issue for the 6T GM transmissions, but there may be something about the Aisin boxes that still don't like it.


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## MP81 (Jul 20, 2015)

jblackburn said:


> The stop-neutral feature on the Aisin 55-50SN was problematic for 99% of them. Often a huge jolt or slow engagement as they got up there in mileage.
> 
> Most that owned that transmission disabled it or had to replace solenoids.
> 
> Surprisingly, it doesn't seem to be an issue for the 6T GM transmissions, but there may be something about the Aisin boxes that still don't like it.


You could be onto something there. If that starts to go out, you're essentially neutral-slamming the transmission because you're giving it throttle, but it hasn't put itself into gear yet. That's good for it.


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## Chris Tobin (Feb 23, 2016)

jblackburn said:


> The stop-neutral feature on the Aisin 55-50SN was problematic for 99% of them. Often a huge jolt or slow engagement as they got up there in mileage.
> 
> Most that owned that transmission disabled it or had to replace solenoids.
> 
> Surprisingly, it doesn't seem to be an issue for the 6T GM transmissions, but there may be something about the Aisin boxes that still don't like it.





MP81 said:


> You could be onto something there. If that starts to go out, you're essentially neutral-slamming the transmission because you're giving it throttle, but it hasn't put itself into gear yet. That's good for it.


Next time it acts up ask your wife to switch it over to manual shift mode and see if it resumes normal operation to prove that theory... As I understand it putting it into manual shift mode disables the stop-neutral feature...


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## MP81 (Jul 20, 2015)

Good idea - I'll tell her that.

Now, whether or not she remembers to do it, that is a different story.


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## lsone (Jan 23, 2016)

Ive had the same issues. Ever since I went to amsoil, Ive been dealing with this for roughly 30,000km. Had amsoil in it for 70,000km. Cars been deleted for 75,000km or so. 

I want to say its a solenoid that sticky or failing. I have a suspicion that the amsoil has swollen an o ring enough to cause this. My reason being is when the car finally smashes into gear, its aggressive. If the solenoid was failing... It wouldn't last this long. At least with my transmission experience. 

The unfortunate reality is everyone wants to remove and replace the transmission. Im not totally convinced that is required... Also, sonnax has a decent read up on behavior issues. My 1-2 shift has always been very rough, however while live scanning it, the car locks and unlocks the converter a ton and seems to be doing its job(has never felt different). We just need to confirm what solenoid controls the neutral while sitting portion.

https://www.sonnax.com/tech_resources/332-adjusting-clutch-control-valves-on-aisin-fwd-6-speeds


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## MP81 (Jul 20, 2015)

Yeah, I'm not sure what the dealer would replace - whether it be the solenoid or the whole trans.

Putting it in manual mode makes the problem disappear entirely.


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## Louis (Dec 28, 2015)

Check the transmission cooler lines for 'sweating' where the metal pipe is connected to the 'rubber'. This a compression union and known location for leaks. This is where mine was leaking, very slowly.
-Louis


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## XtremeRevolution (Jan 19, 2012)

Jondaytona said:


> I've been running AmsOil in near everything I've owned for the last almost 20yrs. The more I hear about how picky manufacturers are with their fluids in their new cars has started to make me think twice about AmsOil lately. This thread don't help, makes me suspicious of how the fluid is treating the Aisin trans. I've got to do my first oil change on my Cruze and not even sure which brand of engine oil to go with anymore. Although, when I called the Chevy dealer, to buy the oil they use seems to be cheaper than if I were to go to the local parts store(with my discount). I'm thinking factory fluids is best anymore...I dunno.





lsone said:


> Ive had the same issues. Ever since I went to amsoil, Ive been dealing with this for roughly 30,000km. Had amsoil in it for 70,000km. Cars been deleted for 75,000km or so.
> 
> I want to say its a solenoid that sticky or failing. I have a suspicion that the amsoil has swollen an o ring enough to cause this. My reason being is when the car finally smashes into gear, its aggressive. If the solenoid was failing... It wouldn't last this long. At least with my transmission experience.
> 
> ...


Regarding both of the above posts, this has nothing to do with the fluid. The fluid meets the requirements of AW-1. Automatic transmissions aren't picky about what ATF they use unless the manufacturer specifically designs them for a different viscosity (Honda is doing this lately). The clutch material is more or less the same across transmissions, it's just a matter of the line pressure used to engage those shifts. Don't believe the lie that you need to use an OEM transmission fluid in order for a transmission to function without problems; that's absolutely false. These specifications overwhelmingly deal with oxidation stability and and shear stability; the fluid's ability to withstand stress and abuse over time, not with specific friction characteristics. 

Furthermore, AMSOIL doesn't swell seals. It just doesn't happen. We don't use rubber anymore like transmissions used to long ago. All of the seals we have now are synthetic polymers like nitrile/Buna-N. A swelling seal would not cause any of the aforementioned issues, especially given the kind of line pressure we are dealing with. 

Aggressive shift engagement suggests the transmission may be either over or under filled. I don't think this is a solenoid issue. Are all of you bringing the transmission up to the required temperature range before checking fluid? I haven't checked the diesel, but on the 1.4T automatics, the range is 185-203F, which is actually not that easy to achieve without throttle braking for several minutes on end to heat up the fluid in the torque converter. Overfilling results in aeration of the fluid. 

Is this symptom constant or intermittent? Does the issue occur only when hot, or regardless of transmission temperature? 

I want to assure you, my stating that the fluid has nothing to do with this, is in no way an attempt to protect my own reputation or AMSOIL's brand reputation. I firmly believe that the fluid has nothing to do with this issue, and that were another fluid used for the same duration, the same symptoms would be experienced. It doesn't matter whose AW-1 spec fluid is being used, these fluids are all designed to be compatible with all transmission seals and clutch packs. The biggest difference between them is durability.


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## MP81 (Jul 20, 2015)

@Snipesy, is there something in the computer logs that can be seen that points to this happening?

My wife said she had a particularly heavy "slam" yesterday, but given how inconsistently it happens, I'm not sure we'll ever be able to get the dealer to see it, as it will probably decide to act fine while it is there.

Shifting it into manual - and thus, disengaging the neutral-stop feature - seems to entirely solve the issue.


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## Snipesy (Dec 7, 2015)

MP81 said:


> @*Snipesy* , is there something in the computer logs that can be seen that points to this happening?
> 
> My wife said she had a particularly heavy "slam" yesterday, but given how inconsistently it happens, I'm not sure we'll ever be able to get the dealer to see it, as it will probably decide to act fine while it is there.
> 
> Shifting it into manual - and thus, disengaging the neutral-stop feature - seems to entirely solve the issue.




I'm sure it detects it but that's all proprietary Aisin stuff. Not even GM tools can detect it and frankly I don't even know where to begin with it.


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## Aussie (Sep 16, 2012)

jblackburn said:


> Surprisingly, it doesn't seem to be an issue for the 6T GM transmissions, but there may be something about the Aisin boxes that still don't like it.


I have the 6T45 transmission in my 2012 diesel and it seems fine so far. I did notice that if I put the shift in manual mode the transmission doesn't go into neutral when the car is stopped, maybe it is worth trying to see if it makes a difference?


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## MP81 (Jul 20, 2015)

Snipesy said:


> I'm sure it detects it but that's all proprietary Aisin stuff. Not even GM tools can detect it and frankly I don't even know where to begin with it.


So, basically, our best shot would be to take it to the dealer and kidnap a tech to ride with us as we demonstrate the issue, when the transmission is currently misbehaving. 

It likes to do it more in stop and go traffic, but it doesn't seem to always correlate with temp. It will do it for a while, then stop doing it while in the same traffic. So just sounds like a solenoid (or whatever controls it - TCM?) going out. The sometimes it doesn't do it at all.



Aussie said:


> I have the 6T45 transmission in my 2012 diesel and it seems fine so far. I did notice that if I put the shift in manual mode the transmission doesn't go into neutral when the car is stopped, maybe it is worth trying to see if it makes a difference?


It solves the issue entirely, not going into neutral when stopped.


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## Grazitp (Oct 25, 2014)

I have not been on the site I a while but had the same problem with my transmission Car would SLAM into gear from a stop. Took to dealer multiple times Without any satisfaction. Always got the same response, "we cant find anything wrong". Trans lines replaced and fluid changed with GM fluid made no difference. Finally in June, 2 months before warranty expired dealer drove car and experienced Slamming into gear. Replaced transmission and has ben working fine since. Only issue I have now is a loss in mileage, (4-6mpg) since trans was replaced.


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## BDCCruze (Jul 12, 2017)

Few things on this.

First, I have seen a surprisingly little amount of transmission fluid make the difference before. Family member had a Chrysler and it would have intermittent issues where it wouldn't move. Still had transmission fluid on the dipstick, though at the bottom. Adding less than 1 quart fixed it.

Secondly, Amsoil does make compatible Transmission fluid, but are you sure you used the _right_ version? They have non-compatible versions as well. Do you still have the receipt or empties to take a picture of? If you take it in for service I would not admit guilt that you touched the transmission fluid because it probably voided your warranty.


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## cooter2 (Oct 8, 2018)

I am having the same slamming into gear issue from neutral issue. I noticed that it only happens when the transmission is warmed up, does not happen for me just after starting the car. My car is very high mileage 166k. I don't know if the fluid was changed prior to me getting it, but that is my next to-do on the tranny. I can confirm putting it in manual "fixes" it. I also replaced the Brake Position Sensor. Thought that fixed it, it got better for a few days, but today I noticed it was back. 

I would be willing to try others ideas of they have any success.

I found this, may help us figure this issue out: https://workshop-manuals.com/vauxha...ransmission_range_selector_lever_replacement/


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## andrewjwill (Feb 1, 2019)

I am having the EXACT same issue. Slamming intermittently always from a stop. Never when shifting. Does downshift into 4th pretty hard when slowing down on a hill. I have not been able to figure out the problem and there are no codes. Dealer said they cant detect a problem and no trans codes. It wont do it for the techs but 3 people now have experience it. 60,000 miles on mine and started sometime between 45-50,000 miles. I had some sensors recently replaced that they said could have been the issue but didnt solve it at all.


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## MP81 (Jul 20, 2015)

Ours hasn't done it at all since summer, and our PT warranty is done in May (wonder if I can get a GM extended PT warranty or anything before then). 

The car has been at the dealer since Wednesday afternoon to replace the passenger halfshaft (ripped boot) and I haven't received even a call that it would take longer than the day I expected - maybe two if they had to order the axle, since I highly doubt they had a CTD axle on hand, but it should be a quick replacement, as it's just a halfshaft. 

My buddy jokingly asked "what did they break?" - I truly hope they broke the transmission.


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## MP81 (Jul 20, 2015)

Bumping this back up, as the weather has every-so-slightly begun to remember it's not winter anymore.

And with it, means the transmission has become somewhat problematic again. Doesn't seem to be doing the neutral slam just yet, but it is making for some extremely violent downshifts. If I were to guess, on the 3-2, based on the speed my wife was going when I was in the car with her. 

I still have the borescope from AutoZone that I rented to find the pintle cap that conveniently fell down into the intake port of my brother's 3100 which I had just replaced the gaskets on (was reassembling the vehicle at this point, so the lower intake was on, and I was not taking it back off), so I am going to utilize that to have a look underneath and see if the lines are leaking again or...hopefully...the case is leaking at the seams.

The latter would be most beneficial, as that means trans replacement - something that needs to happen soon, as PT warranty is up in about one month.


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## BDCCruze (Jul 12, 2017)

Since almost new mine has sometimes downshifted hard. I believe these are dual clutch transmissions. That means it attempts to predict the next gear since it is basically an automatically shifting manual. If it thinks you are going to accelerate but you actually brake, the way it downshifts will be jarring. 

For example, if you are in 2nd and accelerating it will prep 3rd. But if you suddenly brake it has to go back to 1st where it was ready to go into 3rd. This behavior makes predictable shifts very smooth and improves fuel economy, but does have some downsides.


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## jblackburn (Apr 14, 2012)

BDCCruze said:


> Since almost new mine has sometimes downshifted hard. I believe these are dual clutch transmissions. That means it attempts to predict the next gear since it is basically an automatically shifting manual. If it thinks you are going to accelerate but you actually brake, the way it downshifts will be jarring.
> 
> For example, if you are in 2nd and accelerating it will prep 3rd. But if you suddenly brake it has to go back to 1st where it was ready to go into 3rd. This behavior makes predictable shifts very smooth and improves fuel economy, but does have some downsides.


Traditional torque converter automatic.

Just crap programming.


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## BDCCruze (Jul 12, 2017)

jblackburn said:


> Traditional torque converter automatic.
> 
> Just crap programming.


Oh hmm, according to the Wiki article "The shifting of gears is managed by a sophisticated computer programme which oversees a clutch-to-clutch actuation. Gear changes are accomplished by one clutch engaging the instant the clutch from the previous gear disengages." Of course Wiki isn't always right but to me that sounded like dual-clutch.

Anyways, thanks for clarifying that.


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## jblackburn (Apr 14, 2012)

BDCCruze said:


> Oh hmm, according to the Wiki article "The shifting of gears is managed by a sophisticated computer programme which oversees a clutch-to-clutch actuation. Gear changes are accomplished by one clutch engaging the instant the clutch from the previous gear disengages." Of course Wiki isn't always right but to me that sounded like dual-clutch.
> 
> Anyways, thanks for clarifying that.


Not sure how many clutches are in the Aisin in the diesel specifically, but most automatics these days like the 6T/9T GM transmissions have a bunch of clutch plates internally to control changes between certain gears, and a series of solenoids that activate those clutches. They also use the torque converter in between shifts as another sort of clutch to ease shift shock between gear changes. These are traditionally slower to change gear than DSGs, but are much smoother in low speed and stop-and-go driving.

The clutch plates are on the left side of the image for the 6T40 - quite a few more than just the two found in a dual-clutch.










A dual clutch is more like a manual transmission setup controlled by a computer - more commonly used in performance-oriented cars (VW GTI, Porsche PDK, exotics) for their quick gear changes, but most American drivers don't like them because they're jerky and clumsy at low speed. The cars I've driven with one - Hyundai Elantra Sport, Mercedes CLA, and even the VW GTI (Mk7) - are terrible in traffic or creeping forward on hills. Odd gears are shifted by one clutch; even by the second, so it's much quicker to change gears.


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## Aussie (Sep 16, 2012)

My 2012 Holden Cruze diesel uses a 6T45 transmission which is a stronger version of the 6T30/40 transmissions. I have the full specifications, but this part explains the difference. The 6T45 is also used with the 1.6T engine.

The primary difference between two variations of the six-speed automatic transaxle being the 6T45 has greater torque handling capability. The output chain is 1.25-in wide in 6T45, versus 1-in wide for the 6T40. The input gearset of the 6T45 uses fivepinion gears, versus four pinions for the 6T40. In addition, the case of the 6T45 is slightly larger and includes a heavier ribbed case for strength.


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## Aussie (Sep 16, 2012)

This explains how the 6T transmissions work.

Three planetary gearsets are used with three stationary clutches and two rotating clutches, which save space compared to freewheeling designs. Freewheeling mechanisms allow perfect timing between shifts, but also take up more space and add more components to the transmission. However, due to the electronic controls, the clutch-to-clutch concept of the 6T40 / 6T45 delivers the same accurate shift timing. Gear changes from second to sixth gear ratios are accomplished with a precise clutch-to-clutch action, where the clutch is engaged in one gear at exactly the same time it is released in another. The first-to-second upshift, however, is a freewheeling action, where the second gear clutch engages while the first gear one-way clutch spins freely. This allows a greater degree of smoothness at lower vehicle speeds.


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## MP81 (Jul 20, 2015)

jblackburn said:


> Traditional torque converter automatic.
> 
> Just crap programming.


Yeah, I've never been impressed with the AF40-6 in this car, but when we first got the car it was, if a little clunky. I've always been impressed with the calibration focusing on actually downshifting and engine braking without requiring you to slap it over to manual (unless you want more), but this 3-2 slam is new. 

I took a peak underneath over the weekend and it doesn't seem like the lines are leaking (again, yet), but I would sure love to see some weeping at the case split - as that's pretty definitive of "replace it now".


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## MP81 (Jul 20, 2015)

I'm wondering...does anyone have the specific transmission fill procedure from the service manual for this car?

If I recall, the Chilton manual stated that after the check plug drips at a very-scientific rate of one drip per second, to close the check plug, turn off the vehicle, and add 0.4L of trans fluid.

However, "AutoMate" is what I have access to now, and it does not state anything about an additional 0.4L of fluid.

It has me curious - could all these issues be due to _too much_ fluid. It was getting extremely bad sitting in a 15 minute traffic jam in 90 degree heat last Thursday, to the point where I had to leave it in manual mode so it wouldn't shift to neutral - one time I did that, it still slammed into gear after a second or two of me moving it over to manual mode.

It was also getting real jerky on the one downshift on Sunday, and that was right away on a cold start, when it was not nearly as hot out - so that's obviously not temperature dependent.


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## MP81 (Jul 20, 2015)

Bump! I feel like I remember seeing something somewhere, but cannot remember where.


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## oreo382 (Sep 17, 2014)

I remember reading something about the wrong length of drain tube in the trans,hence the need to add an extra 0.4l after it stops dripping.Maybe they corrected this and hence the AutoMate difference.I wish I could remember where I read that but I do remember it.


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## boraz (Aug 29, 2013)

MP81 said:


> I'm wondering...does anyone have the specific transmission fill procedure from the service manual for this car?
> 
> If I recall, the Chilton manual stated that after the check plug drips at a very-scientific rate of one drip per second, to close the check plug, turn off the vehicle, and add 0.4L of trans fluid.
> 
> ...











HOW TO: Service "Lifetime Fill" Tranmission...


HOW TO: Service "Lifetime Fill" Tranmission fluid for Diesel AW AF-40-6 Transmission There seems to be quite a bit of apprehension in performing any kind of service on this transmission in our Cruze diesel that is labeled a "lifetime fill" by GM but has a 50k severe service schedule in many...




www.cruzetalk.com





thats for the transmission itself, taken from other car forums that have this trans

i think the actual instructs from the fsm are in there, i remember somone posting it at some point.

you are sposed to do the fill check when the atf is a specific temp....75degrees iirc, but im sure its in the link


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## MP81 (Jul 20, 2015)

I think I need to get this car raised up a bit, and check the trans temp with the biscan app this time, and ignore the 0.4L extra fluid that I had seen, wherever it was, as it appears we do _not_ need the extra addition once it reaches the super-scientific drip rate of ~one drip per second. All these issues literally could just be from fluid foaming from too much.

I just hate pulling that aeroshield off so, so much. Almost all the clip centers that you pull out have broken so you can't use a panel puller tool under to pull them out, so I guess pliers it is...


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## revjpeterson (Oct 2, 2013)

MP81 said:


> I think I need to get this car raised up a bit, and check the trans temp with the biscan app this time, and ignore the 0.4L extra fluid that I had seen, wherever it was, as it appears we do _not_ need the extra addition once it reaches the super-scientific drip rate of ~one drip per second. All these issues literally could just be from fluid foaming from too much.
> 
> I just hate pulling that aeroshield off so, so much. Almost all the clip centers that you pull out have broken so you can't use a panel puller tool under to pull them out, so I guess pliers it is...


I'm considering just leaving the aeroshield off once I do my delete next week. I've found when it's off, I can drain and fill the transmission and pull the level check plug without lifting the car, just by laying on my back in front of the left-front tire and reaching my arm underneath. You can't get a good view, but as long as you know where it is already, and know the size wrenches you need, it's within reach.


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## RacerMike7 (May 17, 2020)

MP81 said:


> Yeah, I'm not sure what the dealer would replace - whether it be the solenoid or the whole trans.
> 
> Putting it in manual mode makes the problem disappear entirely.


My 2014 CTD started the slamming into 1st gear just recently. 135,000 on vehicle. Its so bad I thought I was rear ended. Completely goes away when in manual shift gate. Fluid level is fine. Anyone figure out how to disable solenoid?


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