Fixed:Everyone’s fav topic: 6l80 issues

[usaf27]

Don’t give up. I have faith in you!

 

[Starkworks]

@NickTransmissions - I think I may have found the issue. The low reverse sprag spins clockwise and locks counter clockwise.

 

[NickTransmissions]

@NickTransmissions - I think I may have found the issue. The low reverse sprag spins clockwise and locks counter clockwise.

Assuming the outer race is spinning clockwise instead of counter clockwise when you hold the inner race, that would do it... I didn't think to mention that as a cause as there's usually no reason to take it apart and I don't believe you can install it upside down or backwards as an assembled component. I've also never installed it upside down or assembled it backwards so glad to know what happens when it's not correct.

 

[Starkworks]

Assuming the outer race is spinning clockwise instead of counter clockwise when you hold the inner race, that would do it... I didn't think to mention that as a cause as there's usually no reason to take it apart and I don't believe you can install it upside down or backwards as an assembled component. I've also never installed it upside down or assembled it backwards so glad to know what happens when it's not correct.

@NickTransmissions - I pulled everything apart initially not knowing what was looking for. When I reassembled, I installed the plastic cage upside down. Had no idea the notches need to be facing up. Geez lol. This has been a journey, but it’s all back together and running. Wasn’t able to get the TEHCM relearned. Shifts aren’t terrible. Seemed to get a bit better the more I drove it. Still going to look for someone local to properly program it.

But I do want to say, thank you! Without your videos and recommendations here, I would be stuck. I knew it was going to be a journey with my first rebuild.

 

[NickTransmissions]

@NickTransmissions - I pulled everything apart initially not knowing what was looking for. When I reassembled, I installed the plastic cage upside down. Had no idea the notches need to be facing up. Geez lol. This has been a journey, but it’s all back together and running. Wasn’t able to get the TEHCM relearned. Shifts aren’t terrible. Seemed to get a bit better the more I drove it. Still going to look for someone local to properly program it.

But I do want to say, thank you! Without your videos and recommendations here, I would be stuck. I knew it was going to be a journey with my first rebuild.

You're welcome! Glad you got it back together and running again, man. The TEHCM will eventually relearn itself and adjust to your driving style.

 

[alpha_omega]

@Starkworks -

6. If all of the above is done and you still have the same problems, replace the TEHCM - a brand new one from General Motors will run ~$1,050 plus core and programming.
- Sonnax reman TEHCMs are $550-$600 plus core and programming
- Street Smart Transmissions remans are $550-$650 w/programming (you give them your VIN so they program it to your vehicle)

Do you recommend one of these options you listed over the others?

GM (OEM)
Sonnax
Street Smart

 

[alpha_omega]

@NickTransmissions - I pulled everything apart initially not knowing what was looking for. When I reassembled, I installed the plastic cage upside down. Had no idea the notches need to be facing up. Geez lol. This has been a journey, but it’s all back together and running. Wasn’t able to get the TEHCM relearned. Shifts aren’t terrible. Seemed to get a bit better the more I drove it. Still going to look for someone local to properly program it.

But I do want to say, thank you! Without your videos and recommendations here, I would be stuck. I knew it was going to be a journey with my first rebuild.

Thank you for posting your journey. Your humbling experience helps those who might be on the fence about tackling a project like this. We all start somewhere. This is no simple task either, so you should be proud and give yourself plenty of credit. Third times the charm. Ha! Hopefully Autel gets you taken care of so you’re all set for the next one. Nice work.

Next time you’ll have to take photos or it never happened.

 

[NickTransmissions]

Do you recommend one of these options you listed over the others?

GM (OEM)
Sonnax
Street Smart

GM new.

 

[claudiamaleah]

Hey-sorry if this isn’t the appropriate way to go about asking questions. I just heard you were the person to ask when it comes to transmissions so here goes. I have a 2011 Chevy Tahoe and it has a 6L80 transmission-I bought a transmission from someone and my husband removed the tcm that came on it and put the one from my original transmission on it hoping to prevent us having to reprogram the whole transmission. Now my husband has replaced the transmission now and my truck will not go in gear and it is throwing TCM malfunction codes. So should we put the tcm that came with the transmission in and replace the original one and then just get the transmission reprogrammed. And is there any way to reprogram yourself without having to take it to the dealership. And if it takes a particular scanner and/or tools-what are those scanners and tools? And would that cause the truck not to go in gear?

 

[Fless]

Hey-sorry if this isn’t the appropriate way to go about asking questions. I just heard you were the person to ask when it comes to transmissions so here goes. I have a 2011 Chevy Tahoe and it has a 6L80 transmission-I bought a transmission from someone and my husband removed the tcm that came on it and put the one from my original transmission on it hoping to prevent us having to reprogram the whole transmission. Now my husband has replaced the transmission now and my truck will not go in gear and it is throwing TCM malfunction codes. So should we put the tcm that came with the transmission in and replace the original one and then just get the transmission reprogrammed. And is there any way to reprogram yourself without having to take it to the dealership. And if it takes a particular scanner and/or tools-what are those scanners and tools? And would that cause the truck not to go in gear?

I'll assume that you're asking @NickTransmissions so we need to tag him like I did here. Otherwise he probably won't see your ask.

 

[NickTransmissions]

Hey-sorry if this isn’t the appropriate way to go about asking questions. I just heard you were the person to ask when it comes to transmissions so here goes. I have a 2011 Chevy Tahoe and it has a 6L80 transmission-I bought a transmission from someone and my husband removed the tcm that came on it and put the one from my original transmission on it hoping to prevent us having to reprogram the whole transmission. Now my husband has replaced the transmission now and my truck will not go in gear and it is throwing TCM malfunction codes. So should we put the tcm that came with the transmission in and replace the original one and then just get the transmission reprogrammed. And is there any way to reprogram yourself without having to take it to the dealership. And if it takes a particular scanner and/or tools-what are those scanners and tools? And would that cause the truck not to go in gear?

Odd that the original TEHCM wouldn't control the replacement transmission as it would have no idea it's bolted to another 6L80 and even if it did, it shouldn't matter, at least with that vintage/year range. Later TEHCMs are a little different but shouldn't apply for your Tahoe.

ETA: Make sure the main case connector is fully plugged into the pass through connector sleeve into the TEHCM - this actually trips up quite a lot of folks and the symptoms / codes you're getting are what you see when the TEHCM isn't plugged in. Disregard if you've already confirmed it's fully plugged in.

Please post your specific codes here so we can see what they are.

To program a new or reman TEHCM, you can purchase a Programming subscription for a single vehicle (based on VIN) to AC Delco's Technical Delivery Service (TDS) then acquire the cable needed to link your laptop to the vehicle. Then run the program based on the instructions/process on the TDS website.

Do you have any history on the 6L80 that your husband purchased (mileage, potential issues, etc)? I never recommend anyone purchase a used transmission given they are very much a crap shoot, especially 4L60Es...6L80s have a little bit better of a track record but still risky...