6L80 1-2 gear issue - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

PlymouthBarracuda · 04-26-2025, 05:53 AM

Hello guys,

Suddenly, I started getting a hard shift from 1st to 2nd gear in all driving modes, right from the first drive in the morning. I reset the transmission adaptations, and now the hard shift only happens when the transmission fluid is warm (around 90°F) or hotter. The fluid was changed 6 months ago and everything was fine until now.
I went to some local guys, and they tried two different used valve bodies, but the issue didn't go away.
Can anyone suggest what could be causing this? I'm not seeing any OBD scanner codes.

1JEWLDSSRS · 04-26-2025, 08:13 AM

this could possibly be your problem. When mine failed, I didn't get any codes.

https://www.sonnax.com/tech_resource...m-applications

1JEWLDSSRS · 04-26-2025, 08:15 AM

https://d2q1ebiag300ih.cloudfront.ne...f?v=1539892125

PlymouthBarracuda · 04-26-2025, 11:35 AM

Quote:

Originally Posted by 1JEWLDSSRS

this could possibly be your problem. When mine failed, I didn't get any codes.

https://www.sonnax.com/tech_resource...m-applications

This article is for 6T40/6T45/6T50/6T70/6T75 transmissions. Is this mod applicable for 6L80e also ?

1JEWLDSSRS · 04-27-2025, 08:06 AM

Quote:

Originally Posted by PlymouthBarracuda

This article is for 6T40/6T45/6T50/6T70/6T75 transmissions. Is this mod applicable for 6L80e also ?

It's not a mod, it is a problem, and a fix. And yes sir,it is also for the 6l80 and the 6L90, any GM trans with the TECHM unit in it. What happened with mine was the "input speed sensor" failed, and got a code for that, when my tech took it all apart to replace the "input/output speed sensor", which are both on the same harness, you just can't replace one or the other, they both get replaced, he decided to take the TECHM apart just to check the switches, and found 3 were blown out and 1 broken! Like I stated, never got any codes for their failure, replaced the harness and switches and all was good from there on. Good luck!

Name: TEHCM LAMINATES.jpg
Views: 64
Size: 163.4 KB

Name: TEHCM LAMINATES.jpg
Views: 64
Size: 163.4 KB

PlymouthBarracuda · 05-01-2025, 05:41 AM

Quote:

Originally Posted by 1JEWLDSSRS

It's not a mod, it is a problem, and a fix. And yes sir,it is also for the 6l80 and the 6L90, any GM trans with the TECHM unit in it. What happened with mine was the "input speed sensor" failed, and got a code for that, when my tech took it all apart to replace the "input/output speed sensor", which are both on the same harness, you just can't replace one or the other, they both get replaced, he decided to take the TECHM apart just to check the switches, and found 3 were blown out and 1 broken! Like I stated, never got any codes for their failure, replaced the harness and switches and all was good from there on. Good luck!

Attachment 1163471

I'll do this, thanks.

I have P0842-00 code that not throwing CEL. Are these somehow related? Maybe my TCM is already dying?

PlymouthBarracuda · 05-01-2025, 05:46 AM

Quote:

Originally Posted by 1JEWLDSSRS

https://d2q1ebiag300ih.cloudfront.ne...f?v=1539892125

I have P0842-00 code that not throwing CEL. Are these somehow related? Maybe my TCM is already dying?

1JEWLDSSRS · 05-01-2025, 08:48 AM

could very well be. Here are some things for your mechanic to consider. Sometimes just a simple fluid/filter change takes care of the issue, if it is dirty or low..But I'm sure you already did that.

https://www.yourmechanic.com/article...y-yourmechanic

PlymouthBarracuda · 05-04-2025, 12:14 PM

I bought this set, but I’m really curious. After the last adaptation reset, I drove perfectly for 4 days. Today it started again — a “jerk” on 2nd gear. If the switch membrane is torn, how did I manage to drive fine for 4 days?

1JEWLDSSRS · 05-05-2025, 09:25 AM

Quote:

Originally Posted by PlymouthBarracuda

I bought this set, but I’m really curious. After the last adaptation reset, I drove perfectly for 4 days. Today it started again — a “jerk” on 2nd gear. If the switch membrane is torn, how did I manage to drive fine for 4 days?

It's just one of those quirks I guess. Like I said before, I never knew my laminates were torn/broken until I had an issue with the input/output sensor, and we checked the laminates when were in there just for good measure since we were replacing the harness. Not saying this will fix your issue, just saying it might be something for you to look into in your diagnosis. Good luck.

1JEWLDSSRS · 05-06-2025, 06:46 PM

Some more info on how our "electronic" transmissions work.

https://images.oreillyauto.com/parts...vice-guide.pdf

04-26-2025, 05:53 AM	#1
PlymouthBarracuda Drives: 2011 Chevrolet Camaro SS L99 AT Join Date: Oct 2021 Location: London, UK Posts: 81	6L80 1-2 gear issue Hello guys, Suddenly, I started getting a hard shift from 1st to 2nd gear in all driving modes, right from the first drive in the morning. I reset the transmission adaptations, and now the hard shift only happens when the transmission fluid is warm (around 90°F) or hotter. The fluid was changed 6 months ago and everything was fine until now. I went to some local guys, and they tried two different used valve bodies, but the issue didn't go away. Can anyone suggest what could be causing this? I'm not seeing any OBD scanner codes. __________________ 2011 Chevy Camaro SS AT L99 / Stock / Daily Driver 1972 Plymouth Barracuda RB V8 3X2-barrel Holley R-4382A/R-4375A/R-4383A (Hamtramck) / Stock / Weekend Driver

04-26-2025, 08:13 AM	#2
1JEWLDSSRS Drives: 2011 SS-RS Join Date: May 2011 Location: FLORIDA Posts: 13,340	this could possibly be your problem. When mine failed, I didn't get any codes. https://www.sonnax.com/tech_resource...m-applications __________________ TSP STAGE 3 CAM,231/246 @112 LSA 614/641 LIFT, CIRCLE D 5C-4200-4500 CONVERTER,LOD INTAKE.CORSA EXHAUST. DSS 1 PC DS. PEGASUS SOLID CRADLE MOUNTS. 486RWHP/475RWTQ.LOTS MORE.

05-01-2025, 08:48 AM	#8
1JEWLDSSRS Drives: 2011 SS-RS Join Date: May 2011 Location: FLORIDA Posts: 13,340	could very well be. Here are some things for your mechanic to consider. Sometimes just a simple fluid/filter change takes care of the issue, if it is dirty or low..But I'm sure you already did that. https://www.yourmechanic.com/article...y-yourmechanic __________________ TSP STAGE 3 CAM,231/246 @112 LSA 614/641 LIFT, CIRCLE D 5C-4200-4500 CONVERTER,LOD INTAKE.CORSA EXHAUST. DSS 1 PC DS. PEGASUS SOLID CRADLE MOUNTS. 486RWHP/475RWTQ.LOTS MORE.

05-04-2025, 12:14 PM	#9
PlymouthBarracuda Drives: 2011 Chevrolet Camaro SS L99 AT Join Date: Oct 2021 Location: London, UK Posts: 81	I bought this set, but I’m really curious. After the last adaptation reset, I drove perfectly for 4 days. Today it started again — a “jerk” on 2nd gear. If the switch membrane is torn, how did I manage to drive fine for 4 days? __________________ 2011 Chevy Camaro SS AT L99 / Stock / Daily Driver 1972 Plymouth Barracuda RB V8 3X2-barrel Holley R-4382A/R-4375A/R-4383A (Hamtramck) / Stock / Weekend Driver

05-06-2025, 06:46 PM	#11
1JEWLDSSRS Drives: 2011 SS-RS Join Date: May 2011 Location: FLORIDA Posts: 13,340	Some more info on how our "electronic" transmissions work. https://images.oreillyauto.com/parts...vice-guide.pdf __________________ TSP STAGE 3 CAM,231/246 @112 LSA 614/641 LIFT, CIRCLE D 5C-4200-4500 CONVERTER,LOD INTAKE.CORSA EXHAUST. DSS 1 PC DS. PEGASUS SOLID CRADLE MOUNTS. 486RWHP/475RWTQ.LOTS MORE.