[L2SS455]

Product Safety Recall

Momentary Wheel Lock-Up

Released: 2025-03-06

GM Program #

N242480630

Status

Incomplete. Remedy not available

NHTSA

AWAITING#

Date Issued:

2025-03-06

Description

General Motors has decided that a defect which relates to motor vehicle safety may exist in certain: 2019 – 2020 model year Cadillac CT6, 2020 – 2021 model year Cadillac CT4 and CT5, and 2020 – 2022 model year Chevrolet Camaro vehicles equipped with a 10-speed transmission. A transmission control valve in some of these vehicles may be susceptible to excess wear over time, resulting in a gradual loss of pressure within the valve that can cause harsh shifting. In rare cases, the wheels may experience a momentary lock up.

Safety Risk Description

If the wheels lock-up momentarily while driving, there is increased risk of a crash.

Repair Description

Dealers will install new transmission control module software that will monitor valve performance and detect excess wear approximately 10,000 miles before a wheel lock up condition could occur. Once detected, the transmission will be limited to fifth gear, preventing the possibility of a wheel lock up condition, which occurs in a downshift from eighth gear. A service engine light and reduced propulsion message will also display in the instrument panel.

[DamonZ28]

At which time they would repair at Chevrolet's expense, I certainly would hope.

[Mark114]

It sounds like there was a similar recall for GM diesel trucks and SUVs in 2024. N242454440

[FlukeSS]

This is what happens if you do not get the software update to the TCM.

Again as a reminder there is NO FIX for this issue by GM because they are refusing to fix it. Apparently there is an aftermarket fix for this by Next Gen Diesel. They did thorough testing and figured out what causes it and what happens. They also confirm the issue does not affect Ford A10's and the carbon upgrade package on Fords replaces the Valve body and again no issue. Only Allison and Generation 2 A10s on GM vehicles. Generation 1 A10's do not have the issue, so GM changed the Valve body in Generation 2 A10's which caused this issue. And yes, your A10 can in fact blow up (get destroyed) because of this issue.

People really need to watch this video.



Quoted from Next Gen Diesel: https://nextgendiesel.com/blogs/tran...ow-we-fixed-it

"So How do I Fix It?:

Before we get to this, we need to identify if your transmission has been significantly damaged or not. The strongest and most accurate indicator of this will be fluid complexion. If the fluid looks new or almost new, you can likely perform a valve body upgrade to correct the condition. If the you wipe the fluid on a white towel and it appears any darker than a red wine, it is contaminated with a large enough amount of clutch material to where this is a meaningful amount of wear inside the transmission. This does not automatically mean the transmission is “toast” but it does mean that a large amount of wear has taken place. In this scenario, upgrading the transmission is the best option. If you’re unsure how to decipher your fluids color, simply send us a picture and we’ll have an expert review it.

In short, if your fluid looks like the jar on the left, it’s transmission time. Of the fluid looks like the jar on the right, it’s valve body time unless you’d like to perform a transmission upgrade voluntarily.

A simple “spring kit” or “updated valve body” is not a fix for this problem.



TCM Tuning and spring kits did not have any significant impact on the problem either; better or worse.

Conclusion:

Don’t let General Motors or their proxies at the dealership lie to you. We can’t shout this loud enough. There is a fix, and there has been a fix the entire time they knew about this problem and even before. We want to get this information out to as many consumers and technicians as possible so that these vehicles can get back on the road reliably and safely.

In fact, many dealerships have bought these parts off us at their own expense because they know that if the vehicle is down for an extended period of time, they may be legally required to purchase it back off you. A $100,000 truck is much more costly then a few thousand dollars in parts and wrench time.

If you’ve been effected by this recall/problem and need outside support, Next Gen Drivetrain™ is the only name you need to know. Our staff are trained at length on this recall, and we’re providing support all over the planet.

Not going to quote everything they said, use the link and read what they found.

[arpad_m]

The 10L80/10L90 had been stable for many years, but GM had to go in and mess with the internals.. then of course they would manage it the exact same way they did with the 8L90 shudder issue. Their automatic transmission "landscape" feels like a minefield.

[radz28]

This is concerning...

[FlukeSS]

GM's idea of a fix for this issue when you bring it into the dealership?

Replace the defective valve body with the same defective valve body. Its why people have their trans taking a shit right after they get them "fixed" by a dealership.

There is no mileage buffer either. Some reported issues have cars with 3000-5000 miles on them, and others with 120,000 miles having the issue.

[L2SS455]

[tortilla-flats]

Help me understand what what I'm missing. If this is the result of an upgraded valve body, why aren't the 2023-2024 models impacted? Is the valve body further upgraded? v3?

[FlukeSS]

Originally Posted by tortilla-flats

Help me understand what what I'm missing. If this is the result of an upgraded valve body, why aren't the 2023-2024 models impacted? Is the valve body further upgraded? v3?

There are 3 types of A10's

1. Allison A10 (Trucks normally as far as I know) (Also GM paid to license the name Allison otherwise its the same A10 transmission)
2. Generation 1 A10's (Our cars / Ford 10R60/80/90)
3. Generation 2 A10's (Also our cars)

Generation 1 A10's do not have the problem.

Only Allison and Gen 2 A10's have the issue. GM changed the valve body on Gen 2, and now its ef'd.

Next Gen DriveTrain developed a fix for this valve body. GM refuses to fix the issue to push people out of warranty. When Dealerships/GM do fix these issues they replace the defective valve body with the SAME defective valve body.

And Some 2023 and 2024's are affected by this but no official annoucement from GM. More so if they use the Gen 2 A10.

You'll want to read Next Gen Drivetrains article about it as they did extensive testing about it and developed a fix for it. Even Chevy Dealers are buying this fix at their cost from Next Gen Drivetrains to avoid buying the cars back under lemon law.

Also, we discovered that the Ford 10 Speed (this transmissions fraternal twin) did NOT have this problem. This means that the problem is logically caused by something the General Motors variant has that the Ford variant does not.

Further, we discovered that customers who installed our Project Carbon® General Motors 10-Speed Valve Body Upgrade Kit almost always fixed the problem, and that customers who installed our re-engineered Project Carbon® General Motors 10-Speed Valve Body always fixed the problem.

This means that the problem is clearly caused by a hydro-mechanical difference between a Ford and General Motors valve body. But, we discovered something else that was even more alarming. Are you ready for this?

There are two generations of the 10 speed General Motors transmissions, but only one type of the 10 speed Allison which is most similar to the later generation of the 10 speed General Motors unit. Why is this important?

We have zero recorded events of the first generation of the valve body having this symptom. The first generation of this valve body is almost identical to the Ford 10R80. This helped us narrow it down even further because we now know that the problem is something that was changed between the first generation and second generation 10 speed General Motors transmission.

Also, we know that the problem is a part that is mutual in design between the Allison variation of this transmission and the General Motors variation of the transmission. At this point, there are only so many parts remaining.

Lastly and perhaps most importantly, the problem becomes more likely as the transmission ages, implying it’s caused by a component wearing out or degenerating rather than a spontaneous electronic failure.

So what ultimately was the problem? A combination of crossleaks in the valve body that become worse over time can trigger the transmission to apply a fourth clutch pack erroneously in some of the higher gears, causing a bind-up condition that locks the output shaft of the transmission and subsequently the rear axle.

https://nextgendiesel.com/blogs/tran...ow-we-fixed-it

[Roddrz]

I've ordered the transmission upgrade kit from Next Gen Drivetrain. I'll document the installation process and performance results, and share my experience.

[FlukeSS]

Originally Posted by Roddrz

I've ordered the transmission upgrade kit from Next Gen Drivetrain. I'll document the installation process and performance results, and share my experience.

[FlukeSS]

Took my car into that Chevy dealer I don't trust, asked them if they would consider getting the part from Next Gen Drivetain. They told me flat out they will not work on the car at all because GM has no fix for it.

Color me surprised.

[Roddrz]

Originally Posted by FlukeSS

Took my car into that Chevy dealer I don't trust, asked them if they would consider getting the part from Next Gen Drivetain. They told me flat out they will not work on the car at all because GM has no fix for it.

Color me surprised.

Although the dealership's lack of warranty support is unfortunate, this situation has revealed an opportunity to implement transmission performance improvements that might otherwise have gone unconsidered...

FlukeSS, the manufacturer's warranty response and customer service approach falls short of industry standards. This experience will be a significant consideration in future vehicle purchasing decisions and recommendations to family, friends and colleagues.

No one is impressed by GMs handling of this situation, especially when we are out of pocket $2000 plus PITA.

The transmission upgrade modification package enhances shift performance and vehicle acceleration.

A ZL1 transmission cooler and by-passing the engine radiator to the transmission can result in 50-degrees reduction in transmission temperatures.

Operating the tranny at 145 degrees Fahrenheit is a very good operating temperature for extending the life of the tranny.

The thermostat is internal to the case and can be bypassed when installing the kit to improve cooling, if required.

Parts List to Install GM ZL1 Transmission Radiator Cooler
Hang Cooler from front lower bumper, but above both Facia stiffener and air baffle.

ZL1 Radiator Cooler - GM 23385931
ZL1 Lower Deflector - GM 84084634
Radiator Support Baffle (top) - GM 23290144
Mount Bracket Right - GM 23207708
- Passenger Side, Transmission Fluid Auxiliary Cooler Bracket
Mount Bracket Left - GM 23207707
- Driver Side, Transmission Fluid Auxiliary Cooler Bracket

Derale Temperature Switch 185F On 165F Off

10 inch radiator fan