The 6T70 / 6T75 TEHCM is a single unit that contains the transmission control module (TCM), shift solenoids, and pressure control switches. TEHCM stands for Transmission Electro-Hydraulic Control Module. The 6T70 / 6T75 TEHCM is used in the GMC Acadia 6T75 transmission, Buick Enclave 6T75, Chevrolet Malibu 6T70, Chevrolet Equinox 6T70 and many others. Although they were designed to make repairs somewhat easier, 6T70 / 6T75 TEHCM problems still happen. So let’s find out what you can do about them.
What Transmission Do I Have?
6T70 / 6T75 TEHCM Applications & Compatibility
The 6T70 / 6T75 TEHCM is a single component that contains the following transmission parts:
6T70 / 6T75 line pressure control solenoid
6T70 / 6T75 clutch pressure control solenoid (4)
6T70 / 6T75 shift solenoid (2)
6T70 / 6T75 TCC pressure control solenoid (torque converter clutch)
6T70 / 6T75 TCM
6T70 / 6T75 TEHCM Problems
- 6T70 / 6T75 pressure control switch failure
- 6T70 / 6T75 solenoid failure
- 6T70 / 6T75 torque converter engagement and disengagement problems
- Slipping
- Limp mode
- Unusually harsh shifts
- Failed shifts
- Loss of gears
Common Causes of 6T70 / 6T75 TEHCM Problems
- Debris contamination due to poor maintenance and dirty transmission fluid
- OE component design flaws
- High mileage
- Extended severe use (towing, driving in the mountains etc.)
Common 6T70 / 6T75 TEHCM Diagnostic Trouble Codes | DTC
6L & 6T Programming Problems
In this new global economy, General Motors, along with many other major manufacturers, have switched to “global platforms” that meet the government regulations in all markets. From emissions to safety compliance, these new global cars are saving GM a boatload of money because they only have to manufacture single components to be used around the world. An unfortunate byproduct of the GM Global A Architecture electrical system, is that Europe and Australia require automakers to secure vehicle modules in a single “environment” to prevent them from being used on other vehicles and ultimately sold on the black market. This theft deterrence measure also allows GM to simplify its diagnostic processes, which obviously saves them money. But all of that can create problems with programming and replacement.
The following modules cannot be swapped into another vehicle:
Engine Control Unit/ECU
TEHCM
Transmission Control Module/TCM
Body Control Module/BCM
Electronic Brake Control Module/EBCM
Vehicle Communications Interface Module
Hybrid Powertrain Control Module
Sensing and Diagnostic Module/SDM
Electric power steering
Instrument panel cluster
Radio
These modules are hardcoded with the vehicle’s VIN number, which allows the GM Global A Architecture to recognize the different modules on the network. There is no way to change the VIN number as there was before. Therefore, if a used 6L or 6T TEHCM is installed, the ECU will automatically command it into limp mode, where it will prevent the engine from starting, thus rendering it useless.
Installing software updates to a GM 6L or 6T TEHCM
Thanks to advances in manufacturing and technology, today’s transmissions are much more efficient than they have ever been. The downside of that is, the electronics now command the mechanical functions. Which means that software updates can often fix a mechanical issue. However, the GM Global A Architecture often prevents software updates to the 6L or 6T transmission. The technician may see a “program failed” error message when they go to install a software update to the TCM/TEHCM, at which point, the transmission will be in locked in limp mode.
This issue is sometimes caused by low battery voltage, a wiring issue, interference from aftermarket components, or an issue with the connection between the vehicle and the scan tool or pass-through device. It could also be that the new software/calibrations are not compatible with the TEHCM.
Common reprogramming diagnostic trouble codes
U0101
E4398
E4399
E4403
E4414
E4423
E4491
M4404
M4413
Reprogramming a GM 6L or 6T TEHCM
Because of how the GM Global A Architecture functions, it is now impossible to overwrite the VIN number programmed into the TEHCM. Which means a ‘blank’ TEHCM will have to be installed, in order to program it work with the vehicle.
Vehicles with the GM Global A Architecture include:
2010 – 2012 Buick LaCrosse
2010 – 2012 Buick Regal
2012 Buick Verano
2010 – 2012 Cadillac SRX
2013+ Cadillac ATS
2013+ Cadillac XTS
2012 Chevrolet Sonic
2011 – 2012 Chevrolet Cruze
2011 – 2012 Chevrolet Volt
2010 – 2012 Chevrolet Camaro
2010 – 2012 Chevrolet Equinox
2012 Chevrolet Orlando
2013+ Chevrolet Malibu
2013+ Chevrolet Spark
2013+ Chevrolet Captiva
2010 – 2012 GMC Terrain
Solving 6T70 / 6T75 TEHCM Problems
Due to the design of the 6T70 / 6T75 TEHCM, it’s not possible to simply replace a failed component like a 6T70 / 6T75 pressure switch or solenoid. Instead, you have to install a new 6T70 / 6T75 TEHCM to make sure that all of the components work together properly and wear at the same rate. There are of course, many aftermarket kits that say they can allow you to replace individual components on the TEHCM. But that will only offer a short-term fix, because other components within the TEHCM may be damaged or worn as well. If you replace say, a pressure switch. It will start operating in a much higher capacity than the other switches on the TEHCM, which can lead to increased wear and component failure.
The 6T70 / 6T75 TEHCM is located inside of the transmission on the 6T70 / 6T75 valve body. Objectively, it is a fairly simple repair: simply remove the transmission pan, remove the valve body, unbolt the TEHCM from the valve body and install the new one. But it does take a bit of experience to not damage anything on the valve body or inside the transmission during the install. You must also have the correct tools and a clean workspace to do the job. If you try to go to the cheap route and just replace an individual solenoid or pressure switch, you’ll have to pay the labor charge all over again when one of the other components fail. So if you want to keep your vehicle on the road for as long as possible. And avoid paying more money to fix transmission problems that could have been avoided, you should consider upgrading to a remanufactured 6T70 / 6T75 TEHCM from a company like Street Smart Transmission.
Remanufactured 6T70 / 6T75 TEHCM
The 6T70 / 6T75 TEHCM is a complicated little device that sends and receives data from the ECU to the TCM, then distributes actionable commands out to the various components like shift solenoids and pressure switches. It also receives data from the various components, which it then sends back to the TCM and ECU, so it can decide which shift program to use for a given situation. All of this happens along the data bus, which is extremely important to making everything work. That’s why each Street Smart Transmission 6T70 / 6T75 TEHCM build starts with a thorough test of the electrical and communications system. If the core fails, it’s either repaired or completely discarded. Next, all of the pressure switches are replaced with upgraded switches that can withstand heat, vibration and stress much better than the OE pressure switches. New solenoid retainers, filter plates, fluid conduits, pushrods, O-rings and connectors seals are also installed (each remanufactured TEHCM comes with all gaskets, seals and grommets that will be needed for the installation). Once complete, each remanufactured 6T70 / 6T75 TEHCM then undergoes an automated vehicle simulation test, that accurately re-creates on-road driving conditions. This ensures full functionality and a hassle-free installation.
What Transmission Do I Have?
So if you’re serious about extending the life of your vehicle, click here to learn more about the remanufactured 6T70 / 6T75 TEHCM from Street Smart Transmission.
