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Discussion Starter · #1 ·
So as stated my cruze is having some oh so wonderful transmission problems. I've been messing with it for a few weeks now and while I've made progress I've come into other issues.

So let's hit it from the top, approx. 3 weeks ago my wife was pulling into the gas station and the car lost all forward moving capabilities, basically it was treating Drive like Neutral, but could Reverse it's way across the Atlantic if it wanted. So I headed over with some basics, No related DTCs (CEL not illuminated), looked at the shift linkage, all was fine. Checked the transmission level added barely a pint before it started dripping out the check hole. (Note: the fluid looked pretty dark at this time) but still no forward movement, couldn't hear the transmission sound like its even trying to shift, so we towed it to the house.

Next day I drained and filled the trans hoping it was just dirty fluid (Note: I didn't filter the trans fluid for chunks but it did seem quite speckled with shiny flakes) Alas, it still made no attempt to move forward in Drive, and would continue to roll in whatever direction gravity would take it.

So I searched the web (found myself on this forum a few times actually) and the common consensus is GMs wonderful innovation (please watch your step, sarcasm may be dripping) the TEHCM, other than not having any DTCs this made the most sense for my problem. 300 dollars later I've installed and programmed the new TEHCM. I replaced the cooler lines since the compression fittings where starting to leak, and got it topped of on fluids, hop in and slowly go through the gears. And.... IT shifted into Drive!!

Wouldn't it be awesome if that was the end? Yea.. went for a test drive and the transmission is acting like its in 3rd gear and only using 3rd, still no DTCs, and unless I got a faulty TEHCM from dorman what else could I look at?
 

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One of the most important things to know when diagnosing an automobile, is its odometer mileage.
 

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Did you attempt driving in slapshift and manually changing the gears? I would try manually shifting through all the gears a few times next time you drive it. Depending on mileage I know changing the trans fluid can sometimes be detrimental to the trans but that’s usually only on older vehicles.
 

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Discussion Starter · #5 ·
Did you attempt driving in slapshift and manually changing the gears? I would try manually shifting through all the gears a few times next time you drive it. Depending on mileage I know changing the trans fluid can sometimes be detrimental to the trans but that’s usually only on older vehicles.
Yup, manually shifting doesn't change a thing, the dashboard will say I'm in M1-6 but the transmission refuses to shift up or down.
 

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Discussion Starter · #6 ·
UPDATE: took it to work as a test drive and my check engine light came on! Oddly I don't think I've ever been so excited to have a check engine light, pulled a P0777 and P0700.

P0777 makes perfect sense, only working gears are 3RD and Reverse and manual mode is inop thanks to fail safes.

So my next options seem to be warranty and RE-replace my TEHCM, or find a high end scan tool to command the control valve system cleaning. Has anyone tried the cleaning and had favorable results? Or am I better off replacing the TEHCM again?
 

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Discussion Starter · #7 ·
UPDATE #2: although I feel like posting here is about pointless at this point, if anyone needs this info for future reference I'll see it through till the problem is solved or the car is gone.

Went for another drive with the car, it feels like it tries to shift a couple times but never leaves 3RD gear, meanwhile it seems the check engine light has decided to turn itself off, which I would be totally cool with its decision if the **** thing would shift.

In the next day or two I will get a proper scan tool hooked to the car to run the cleaning procedure on the TEHCM, I'll post results, hopefully that will be the end of it.
 

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UPDATE #2: although I feel like posting here is about pointless at this point, if anyone needs this info for future reference I'll see it through till the problem is solved or the car is gone.
Hang in there @Slverdgr, hopefully some more ideas/suggestions will come Monday.

Thank you for the updates, keep ‘em coming.
 
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Just curious, did you pick up a TCM for a 6T40 or 6T30? The 1.8L actually uses a 6T30, but I'm not altogether sure if the TCM is different or not between the two. I DO know that the 2011 was a one-year-only ECM, though.
 

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Discussion Starter · #10 ·
Just curious, did you pick up a TCM for a 6T40 or 6T30? The 1.8L actually uses a 6T30, but I'm not altogether sure if the TCM is different or not between the two. I DO know that the 2011 was a one-year-only ECM, though.
Fantastic question actually, everything I've read says I have the 6T40 transmission, and the TCM says it's for the 6T40, where can I check if mines the 6T30?

(Side note: Dorman took my VIN number when I ordered the TEHCM, so I'd assume everything should match up? As well the software running my current TEHCM was the same software I copied over from the previous TEHCM)
 

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Fantastic question actually, everything I've read says I have the 6T40 transmission, and the TCM says it's for the 6T40, where can I check if mines the 6T30?

(Side note: Dorman took my VIN number when I ordered the TEHCM, so I'd assume everything should match up? As well the software running my current TEHCM was the same software I copied over from the previous TEHCM)
6T30 was all 1.8L engine Cruzes. I suspect the control module is probably the same; typically with GM transmissions, they only change things internally - such as the clutch packs, chain drive, etc.

GM 6-Speed 6T30 MH9 Transmission Info, Specs, Wiki | GM Authority
 

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Discussion Starter · #13 ·
6T30 was all 1.8L engine Cruzes. I suspect the control module is probably the same; typically with GM transmissions, they only change things internally - such as the clutch packs, chain drive, etc.
So that being said, does anyone know if the 6T40 TEHCM works for the 6T30 transmission?

Also if all 1.8L have the 6T30 why does everything I pull up say my vin has the 6T40 (MH8) in it?
 

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So that being said, does anyone know if the 6T40 TEHCM works for the 6T30 transmission?

Also if all 1.8L have the 6T30 why does everything I pull up say my vin has the 6T40 (MH8) in it?
To further complicate things, it appears that the TEHCM/transmission as a whole changed generations between the 2011-2012 model year. 2012 was the "Gen 2" 6T30/40; 2011 was the "Gen 1"

https://d2q1ebiag300ih.cloudfront.n...485/sonnax_trans_report_v5n3.pdf?v=1483625353

http://www.searchautoparts.com/motorage/powertrain-pro-automatic-transmission/look-ford-and-gms-jointly-built-6t40-transmission?page=0,0
 

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Discussion Starter · #15 ·
Well that was some interesting reading, but it looks like I need to check if P0842 is invalid or not to determine my generation
 

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Discussion Starter · #16 ·
Bump..

..Also, Has anyone tried the cleaning program in the TCM before?

Does it actually do anything or should I just replace it again? (Haven't gotten the car to the shop yet, trying to get funds together)
 

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Discussion Starter · #17 ·
UPDATE:

The Cruze is at a Chevy dealership not far from me at the moment getting the cleaning procedure done, I talked with the tech a few moments ago and he verified that my 2011 Chevy Cruze 1.8L does indeed have the 6T40 transmission in it, so I should have the correct TCM in the transmission. Will update once I get a call from the dealership.
 

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Discussion Starter · #18 ·
FINAL UPDATE:

SUCCESS! the cleaning function freed up the stuck solenoid and I've got all my drive gears back! She shifts a little rough but we all know the story with that adaptive function, I'm just happy It will actually get up and move now.

Thank you for those who offered words of encouragement and help.
 

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Yeah, Same here, I used my VIN number to order my parts to match the required specs instead of listening to jargon. It definitely helps to know how the [your] car war built versus a genic model goto package.

I didn't even half to pull the transmission to do all that being all under the from cover. Wink Wink

I just changed my TEHCM, Solenoids and Filter in less than 4 hours. My transmission shifts like a dream, flows with good pressure too being I keep slightly overfilled. It sure can can grab some pavement too, that little thang.

How's that cigar?
 
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