Transmission Interchange

[baadharley]

I just swapped by bad 2012 2GBS for a 2014 4GBS as well. I left the 2014 stock and had zero issues. Please start by checking the electrical connections. The connector on the ECU is known to easily break when you disconnect it.

One thing I'll mention that I DID remove the ECU/connectors with the battery tray, so as not to damage it...all was put back together before connecting the battery. I just confirmed and disconnected both connectors on ECU and no bent pins, fully inserted. Also, checked the TCM connector and same there. Looked at all fuse links/battery cable and all look good...so, unfortunately leaning towards having to swap out with the old TCM. Thx

 

[baadharley]

I just swapped by bad 2012 2GBS for a 2014 4GBS as well. I left the 2014 stock and had zero issues. Please start by checking the electrical connections. The connector on the ECU is known to easily break when you disconnect it.

OK, so went to scrapyard today and 'thought' they gave me back my original 2GBS trans, but it was on its side, they were busy, and I neglected to Verify it-my bad. Anyway, what they gave me is a 4BKS. Since I didn't have enough time to go back today, I thought as a 'test' would connect this one and plug into the TCM harness, as it was hanging from the cherry picker. Low and behold, the trans selector showed Park and the engine now starts...

This leads me to believe that 'something' is Wrong with the 4GBS 33k trans I recieved TCM or otherwise?? Sooooo, question is this...do I chance going with the 4BKS TCM, valve bodies, not knowing the mileage, fitment, etc??? Or request back my 2GBS for the parts...or be more risky and get the parts out of another 4GBS??

Any ideas/thoughts are appreciated. Though I AM relieved the TCM was the issue. Thx!

 

[baadharley]

Hey ALL-I am glad to report after all the mishaps with the stupid scrapyard...I swapped out the valve body AND solenoid pack from my original 2GBS trans to the 4GBS trans. Happy to say ALL works/shifts just fine. No trans codes or issues. One good/bad thing is...with the 3.47 vs. 3.72 gears is...it has like WAY more horsepower off the line...but I'm sure will suffer hwy miles...but seems to make it an overall more Peppy car.

Thanks ALL for your help on here...hope I can help others feel they can do this THEMSELVES!!

 

[Rockabetty78]

Hawkeye75,
I'm in the same boat. I have a 2012 LT Hatchback and found a 2014 transmission with the same three letter identifier. Did you install the 2014...any issues?

What is the "3 letter identifier and where can I find it? Swapping out my 2013...at a shop. Already got replacement. Wanna be absolutely sure I bought the right one and has all necessary components. What do I need to look for? Is it supposed to come with its own control module and solenoid or can I use the old ones? And the new transmission will need to be reprogrammed?? Why and is it mandatory? Is there anything else I need to know regarding the swap, necessary components, programming etc? I've had a bad luck with sexist mechanics that tried taking advantage of me thinking I'm ignorant of all things automotive when I needed some suspension work done and just ended up doing it myself. Luckily I know my stuff in that regard but not so much when it comes to transmission. I wanna be as well informed as possible in case they try that crap again.

 

[orangeltz13]

Update on Trans after install

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.

You rock man! I don't have the skill set to r & r a transmission. You get an A+ from me!

 

[baadharley]

What is the "3 letter identifier and where can I find it? Swapping out my 2013...at a shop. Already got replacement. Wanna be absolutely sure I bought the right one and has all necessary components. What do I need to look for? Is it supposed to come with its own control module and solenoid or can I use the old ones? And the new transmission will need to be reprogrammed?? Why and is it mandatory? Is there anything else I need to know regarding the swap, necessary components, programming etc? I've had a bad luck with sexist mechanics that tried taking advantage of me thinking I'm ignorant of all things automotive when I needed some suspension work done and just ended up doing it myself. Luckily I know my stuff in that regard but not so much when it comes to transmission. I wanna be as well informed as possible in case they try that crap again.

Hi there. There 'should' be a white sticker on the top of the trans(if it has not been removed/destroyed) that shows the code in big letters. My original was a 2GBS that I replaced with a 4GBS. Others on here had no issue just directly swapping these out w/o having to reprogram the TCU. However, in my case, the new 4GBS trans did nothing-car would not turnover, nor any PRND on display. I'm assuming the new one had a bad TCU. I swapped out the complete valve body/solenoids AND TCU inside the trans and have had no problems on the 500mi or so I've put on the car since replacement and did not have to reprogram, nor any codes.

To answer your questions...the trans should come complete with torque convertor and the TCU which is behind the plastic vertical cover where the wiring harness plugs into. I would first try swapping the complete trans and try it first w/o doing anything else. My understanding is you can go with any year, as long as it has the 'GBS' identifier. The first 'number' like the 4 in 4GBS just refers to the model year.

Hopefully, this helps and best of luck!

 

[Rockabetty78]

THANKS!

 

[SKIM MILK]

Just want to say, y'all saved me $5000 by encouraging me to use a 2015 transmission in my 2012. Even my repair guy said it wasn't supported but I told him I'd take the risk and still pay him for his labor, worked out great!

 

[hawkeye75]

Just want to say, y'all saved me $5000 by encouraging me to use a 2015 transmission in my 2012. Even my repair guy said it wasn't supported but I told him I'd take the risk and still pay him for his labor, worked out great!

Yes, thank goodness I did my own research cause the 2012 year transmission is the only year that is "officially" interchangeable to itself, so that info is what many transmission shops must pass on to their customers.

 

[Swillard1291]

Quote form 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.

Does it matter which identifier it has? As long as it’s for the engine you have?

 

[butterman2473]

Quote form 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.

Are the 3gss and 3grs interchangeable?

 

[butterman2473]

Just want to say, y'all saved me $5000 by encouraging me to use a 2015 transmission in my 2012. Even my repair guy said it wasn't supported but I told him I'd take the risk and still pay him for his labor, worked out great!

If you don't mind me asking...what did your mechanic charge for the r&r labor?