Owners of General Motors vehicles with the 6L90 transmission have experienced problems. Those with significant repair histories may be entitled to remedies under state lemon laws or compensation for breach of warranty and loss of use.
- Overview of the General Motors 6L90 Transmission
The 6L90 transmission is a six-speed hydraulically operated automatic transmission designed for longitudinal engines and particularly for rear-wheel and rear-focused four-wheel drive vehicles. Built-in 2007, this tranny consists of six forward gears and one reverse gear. The first gear ratio is 4.03, second:2.36, third: 1.53, fourth:1.15, fifth: 0.85, sixth:0.67, and the reverse at 3.07. https://rxmechanic.com/6l90-transmission/
2. Common Problems with 6L90 Transmission
Common issues reported by users and mechanics include slipping gears, rough shifting, fluid leaks, etc.
Users have reported instances of rough or harsh shifting, especially during gear changes. This can result in a jerky ride and potential discomfort for both the driver and passengers.
Slipping Gears: Slippage occurs when the transmission unexpectedly changes gears or has difficulty staying in a specific gear. This can lead to a loss of power, reduced fuel efficiency, and potential safety concerns.
Fluid Leaks: Like any transmission, the 6L90 can develop fluid leaks. Leaks may be caused by various factors, including worn seals or gaskets. Low transmission fluid levels can result in poor performance and potential damage to the transmission.
Overheating: Some users have reported issues with the transmission overheating. Overheating can lead to accelerated wear and tear on internal components, potentially causing long-term damage.
Torque Converter Problems: Malfunctions in the torque converter, a critical component for transmitting power from the engine to the transmission, can result in issues such as stalling, strange noises, or poor acceleration.
Electrical Issues: Modern transmissions often incorporate electronic components for optimal performance. Electrical problems, such as sensor malfunctions or issues with the transmission control module, can lead to erratic behavior and performance issues.
Software and Calibration Concerns: In some cases, users have reported problems related to the transmission’s software or calibration. Issues in the software can affect the shifting patterns and overall performance of the transmission.
This often stems from a solenoid stuck in the off position. It could also result from issues with the valve body, preventing fluid movement to valves. This problem can be fixed by replacing the valve body so fluid can enter the right valves to activate the right clutch or band for proper gear switching. Ensuring the solenoid moves freely could also save this situation.
Transmission overheating
There have also been reported cases of the 6L90 overheating. Overheating most times results from dirty or low fluid levels. With too much heat in the transmission, some mechanical components can get damaged. Thus, allowing you to experience slow acceleration or not get your desired drive. https://rxmechanic.com/6l90-transmission/
3. Investigation
“GM 6L90 transmission problems have caused the National Highway Traffic Safety Administration to open an investigation based on five alleged transmission failures. All the General Motors 6L90 transmission failures occurred in 2016-2018 and 2021-2022 Chevrolet Express and GMC Savana cutaway vans. Specifically, the complaints allege the vehicles lost motive power when shifting the 6L90 transmissions into DRIVE or REVERSE.” https://www.carcomplaints.com/news/2023/gm-6l90-transmission-problems-investigated.shtml
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