Informative 6T40 Automatic Transmission PDF

[Pirate Luke]

Came across these webinar PDFs when looking at some things for my transmission. Its got a lot of great specific technical info and pictures about the Automatic transmissions (6T40) in our Sonics. It's a good read, thought I'd share it.

http://www.atra.com/Webinars/GM/6T40_45_Diag_Fixes.pdf

https://d2q1ebiag300ih.cloudfront.net/uploads/tech_resource/file/550/sonnax_6t40_webinar.pdf?v=1520285536

 

[skurtov]

Thanks bra

 

[JTee2017]

Came across these webinar PDFs when looking at some things for my transmission. Its got a lot of great specific technical info and pictures about the Automatic transmissions (6T40) in our Sonics. It's a good read, thought I'd share it.

http://www.atra.com/Webinars/GM/6T40_45_Diag_Fixes.pdf

https://d2q1ebiag300ih.cloudfront.net/uploads/tech_resource/file/550/sonnax_6t40_webinar.pdf?v=1520285536

Thanks for posting. I had one of these downloaded and saved previously from another post. Both are good to know references and give great insight into the updates that also were applied. Applies pretty much to the 6T30 as well used with the 1.8L Sonic engine.

 

[Thewrenchartist]

Very Informative Document

Thank you very much for posting this very informative document. It helped answer some of the questions that I had.

By the way, I'm still perplexed by the transmission applications for the Sonic. I have a 2012 Sonic LT with an automatic transmission labeled 2GBS. My transmission blew recently and I've found a good replacement automatic transmission from a 2015 Sonic LT. This one is labeled 5GBS. When put side-by-side, they both look exactly the same.

My question is: Do the 2012 Sonic LT Automatic and 2015 Sonic LT Automatic share the same transmission? I would really appreciate any clarification on this.

Thank you!

 

[92dakota]

if i understood my cousin correctly, the first digit usually coincides with year or revision.. .. kind alike ford with 1FXXX 2FXX 6FXXX part numbers.. after dealing with getting my 2012 LTZ tranny rebuilt i learnt alot... never again LOL but also from what was said in my thread a used tranny, from newer will work, computer dosent seem to have an issue either...

 

[Thewrenchartist]

Thanks so much, 92dakota, for this info. What confused me is that every time I search for a 2015 6 Speed auto transmission from Ebay, the results are not compatible with my 2012 Sonic.

So, I have found a good 2015 auto transmission with 10k miles at a junkyard. I will install and use my existing TCM.

 

[92dakota]

Thanks so much, 92dakota, for this info. What confused me is that every time I search for a 2015 6 Speed auto transmission from Ebay, the results are not compatible with my 2012 Sonic.

So, I have found a good 2015 auto transmission with 10k miles at a junkyard. I will install and use my existing TCM.

This is a quote from blue moon sonic on my thread …

As a side note, you don't need a year correct transmission in these cars. I have a 2014 trans in my 2012 with no issues despite the TCM programming and hardware differences between the two. You can even throw the RS auto in there and it'll make the car less lethargic to drive due to the final drive ratio change.

 

[Thewrenchartist]

Wow, this is great news! Thanks, 92dakota. I'll install my second transmission on this Sonic with confidence.

 

[Thewrenchartist]

Hello guys, I would like to double-check something with you.

I will be installing a 2015 transmission on my 2012 Sonic. I've heard that the TCM is programmed to the car's VIN and will not work with another vehicle, and that the TCM cannot be programmed a second time. I don't know if that's true or not, but anyway since my 2012 TCM is already programmed to my car, can I detach it from the solenoid module and install it on the 2015 TCM? I'm talking about the little stainless square box with the bar code on it (as pictured). Will the 2012 computer work with 2015 solenoid module? Or is my best option to keep the 2015 TCM on the transmission as it it and have it programmed at the Chevrolet dealer after installation?

I would appreciate any advice on this. Thanks!

 

[Thewrenchartist]

Hello guys,

Just wanted to give you a quick update on the transmission replacement on my Sonic. Over the weekend (After Thanksgiving), I finished putting everything back together.
1. The 2015 Sonic trans bolted perfectly onto my 2012 Sonic engine. The only difference was one bolt on the bottom that was not the same size.
2. I refilled the trans with Amsoil Signature ATF. I added about 7.2 quarts while the engine was running and the trans on Park until the fluid came out of the level hole on the driver side of the transmission.
3. I shifted several times from P to all the other gears and back while the car was parked inside my garage.
4. There are no error codes displayed for the transmission (Fingers crossed).
5. I will be testing the car on the road sometimes this week and will let you know how it drives.
6. The only new issues I have now are: a) Code P0171 System too lean (Bank 1) b) The brake pedal is very hard.

Regarding transmission programming, can anyone confirm whether I need to go to the dealer or not to have the transmission programmed or can I just leave it as it is since there are no transmission codes?

Thanks a lot!

 

[Thewrenchartist]

I tested the car on the road and it shifts smoothly. Apparently, I don't have to re-flash the transmission.

By the way, the code P0171 was due to a tube that was inadvertently disconnected from the brake booster while I was installing the transmission. Everything works fine now.

I want to thank all of you for your assistance.

 

[Pirate Luke]

Thanks for sharing all that information, I'm sure anyone using it in the future will greatly appreciate it!

 

[Blue Moon Sonic]

Hello guys,

Just wanted to give you a quick update on the transmission replacement on my Sonic. Over the weekend (After Thanksgiving), I finished putting everything back together.
1. The 2015 Sonic trans bolted perfectly onto my 2012 Sonic engine. The only difference was one bolt on the bottom that was not the same size.
2. I refilled the trans with Amsoil Signature ATF. I added about 7.2 quarts while the engine was running and the trans on Park until the fluid came out of the level hole on the driver side of the transmission.
3. I shifted several times from P to all the other gears and back while the car was parked inside my garage.
4. There are no error codes displayed for the transmission (Fingers crossed).
5. I will be testing the car on the road sometimes this week and will let you know how it drives.
6. The only new issues I have now are: a) Code P0171 System too lean (Bank 1) b) The brake pedal is very hard.

Regarding transmission programming, can anyone confirm whether I need to go to the dealer or not to have the transmission programmed or can I just leave it as it is since there are no transmission codes?

Thanks a lot!

I'm just going to give a heads up on this swap since I have done exactly what you have done and have been running for about a year now with the swapped transmission with zero codes.

If you are BNR tuned, You can load the tune file and go without issues, however there is no guarantee that Jerry will be able to successfully program the TCM. I'll have to figure out how EFI live works with TCM programming when tuned.

If you are Trifecta Tuned, You will need to ask Steve or Vince to have 2 separate files sent to you after you give them the TCM readout for the VIN.
The reason for this is because the PCM and the TCM aren't able to communicate with each other when the VIN doesn't match which prevents a single file from being used when programming with EZ-Flash. This is why they split the files. They have one specific to the TCM and one for the PCM for the different VINS. This allows you to Flash the car with a tune specific to the PCM and TCM separately in EZ-Flash

Also because of the PCM and TCM communication issue, a dealership won't really be able to flash the TCM to match the VIN of the car. It's wonky, but least you can tune the car after a trans swap.

 

[Pirate Luke]

@Thewrenchartist, can you expand on if you transferred the 2012 transmission control module or kept the 2015? Also, anyone who knows the answer to this can they weigh in? I'm curious about this. If that wouldn't work, is there any way around the VIN differences when tuning besides making two separate files?

I will be installing a 2015 transmission on my 2012 Sonic. I've heard that the TCM is programmed to the car's VIN and will not work with another vehicle, and that the TCM cannot be programmed a second time. I don't know if that's true or not, but anyway since my 2012 TCM is already programmed to my car, can I detach it from the solenoid module and install it on the 2015 TCM? I'm talking about the little stainless square box with the bar code on it (as pictured). Will the 2012 computer work with 2015 solenoid module?

 

[Thewrenchartist]

I didn't re-flash the TCM. I was going to, but after testing the car on the road, I decided that it was probably not necessary since the transmission ran SO smoothly. I've been driving the car without any problems whatsoever since I swapped the transmission in November 2018. I think I have put about 3000 miles on the car ever since.

@ Pirate Luke, to answer your question, I kept the same module that came with the 2015 transmission. The only thing I replaced was the control solenoid valve filter plate. So I had to remove the 13 or so long bolts to do that.

Now I have two (2) 2012 transmissions in my garage. I'll probably try to fix them with upgraded parts or sell them.

By the way, the code P0171 was due to a tube that was inadvertently disconnected from the brake booster while I was installing the transmission. Everything works fine now.

 

[Gobinator98]

I know this thread is over a year old but what parts did you buy when installing the transmission? I’m planning on doing the same with a 2015 sonic transmission that I got with 43,000 for 182 dollars. Did you have to replace the engine to transmission bolts? Is there any other parts that I should replace?


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[Pirate Luke]

I know this thread is over a year old but what parts did you buy when installing the transmission? I’m planning on doing the same with a 2015 sonic transmission that I got with 43,000 for 182 dollars. Did you have to replace the engine to transmission bolts? Is there any other parts that I should replace?

I too would like the answer to this question because it's looking like it might be about time for me to do a swap. Have 130k miles on mine and it started kicking between 1st-2nd gears very rarely about a year ago, and recently started raising rpm as it tries to find 2nd gear but only during the first acceleration after start.

Yesterday I noticed it was making an audible sound almost like a whirring noise and it only does it while in R,D, or M and temps get much higher than usual. I'm going to pray it's just low on fluid and check that out this evening. Will update once I know more.

 

[Gobinator98]

I too would like the answer to this question because it's looking like it might be about time for me to do a swap. Have 130k miles on mine and it started kicking between 1st-2nd gears very rarely about a year ago, and recently started raising rpm as it tries to find 2nd gear but only during the first acceleration after start.

Yesterday I noticed it was making an audible sound almost like a whirring noise and it only does it while in R,D, or M and temps get much higher than usual. I'm going to pray it's just low on fluid and check that out this evening. Will update once I know more.

Mine has had weird shifting ever since I got the car but it really has been slamming hard between 5-4 while downshifting. I know it’s not low on fluid because there is not leaks and it’s only started happening within the last 6 months.
My current transmission has 143, xxx miles on it. And the engine was replaced at 125,400 miles with one that had 31,000 on it.

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[Pirate Luke]

So I'm definitely not leaking any fluid. Drained a quart to check for any metal shavings and nothing. Got it up to temp and added basically the same I took out and it started coming out of the full/fill hole and still looked a pretty clean red color after 35k miles. I took it for a city drive and the trans fluid temps got up to 180F. I've never seen it go over 140 unless it's really hot out and I'm stopping and going a lot and even then it never goes above 150F.

Starting to think it's something to do with my trans cooling system. Anyone familiar with that system/know of any common issues?

 

[Gobinator98]

So I'm definitely not leaking any fluid. Drained a quart to check for any metal shavings and nothing. Got it up to temp and added basically the same I took out and it started coming out of the full/fill hole and still looked a pretty clean red color after 35k miles. I took it for a city drive and the trans fluid temps got up to 180F. I've never seen it go over 140 unless it's really hot out and I'm stopping and going a lot and even then it never goes above 150F.

Starting to think it's something to do with my trans cooling system. Anyone familiar with that system/know of any common issues?

I don’t know of any issues for the trans cooling system, as I know mine doesn’t have issues with the cooling because mine gets up to temp like it should. I’d probably make a new thread asking about your unique problem.


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