If your 2008-2010 Hummer H3 is suffering from harsh shifting, getting stuck in gear, or throwing transmission codes, the culprit is often a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen firsthand how a faulty TCM can sideline even the most rugged vehicles. This isn’t just an annoyance; it’s a critical failure that compromises your H3’s performance and reliability, whether you’re on the highway or a trail. This T42 TCM, part number 24235340, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
The TCM is the brain of your automatic transmission, controlling everything from shift points to torque converter lockup. When it fails, communication breaks down, leading to the unpredictable and often dangerous symptoms you’re experiencing. Our process eliminates the guesswork and the expensive trip to the dealership. We flash the module with the latest GM software updates for your exact Hummer H3, ensuring it works perfectly right out of the box. This restores the crisp, predictable shifting you expect and resolves the underlying electronic faults causing your check engine light to stay on.
Is Your H3 Showing These Telltale Signs?
- ✔ Abrupt, harsh, or delayed gear shifts that slam the drivetrain.
- ✔ The vehicle is stuck in a single gear, often called “limp mode,” to prevent further damage.
- ✔ An illuminated Check Engine Light or Transmission Warning Light with diagnostic trouble codes (DTCs) like P0700, P0750, P0753, P0758, or other solenoid-related faults.
- ✔ Complete loss of gear engagement or inability to shift out of Park.
- ✔ Poor acceleration and a noticeable drop in fuel economy.
Case Study: The Ghost in the Transmission
A customer brought in a 2009 Hummer H3 with a frustratingly intermittent problem. It would drive perfectly for days, then suddenly refuse to shift past 2nd gear. They had already replaced two shift solenoids at another shop with no success. After hooking up my scan tool and monitoring live data, I noticed the command signals from the TCM were dropping out randomly, especially after the engine bay got hot on long drives. The module itself was the problem. We installed a VIN-programmed 2008-2010 Hummer H3 TCM, and the problem was solved permanently. Heat and vibration are the top killers of these modules, and a quality replacement is the only long-term fix.
Your 30-Minute Path to Smooth Shifting
Installing this 2008-2010 Hummer H3 TCM is a straightforward job that most DIYers can handle in their own driveway. No special programming tools are required.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system’s adaptive memory.
- Locate the Module: On the Hummer H3, the TCM is typically found in the engine compartment on the right-hand (passenger) side, near the rear of the engine bay.
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly. Then, unbolt the old module from its mounting bracket.
- Install the New TCM: Mount the new module securely onto the bracket and reconnect the electrical harnesses. Ensure they click into place.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it idle for a few minutes. While the module is plug-and-play, it’s always best practice to use a basic OBD2 scanner to clear any stored fault codes from the previous failure.
Confirmed Vehicle Compatibility
This module is a direct-fit replacement for the specified models. While it is programmed for your 2008-2010 Hummer H3 TCM, it is also physically compatible with a wide range of other GM vehicles. Please verify the part number and your vehicle details at checkout.
- HUMMER H3: 2008-2010 (Transmission; RH rear engine compartment)
- Chevrolet Colorado: 2008-2012 (Transmission; RH rear engine compartment)
- GMC Canyon: 2008-2012 (Transmission; RH rear engine compartment)
- …and many other GM cars, trucks, and SUVs from 2006-2014. See the full fitment list for details.
Frequently Asked Questions
Do I need to take this part to a dealer for programming?
No. This Transmission Control Module comes fully programmed to your vehicle’s VIN. It is ready for installation right out of the box, saving you hundreds of dollars in dealership programming fees.
What is the warranty on this TCM?
This part is backed by our one-year warranty, covering any defects in materials or workmanship. We stand behind the quality and reliability of our electronic modules.
Is this a new or used part?
This is a high-quality, OEM-standard replacement part that has been expertly programmed and tested to meet or exceed original factory specifications for performance and longevity.
Where is the TCM located on my 2008 Hummer H3?
On the 2008-2010 Hummer H3, the TCM is located in the engine bay, on the right-hand (passenger) side towards the rear.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the main engine computer (ECM) to turn on the check engine light. In many cases, a failing TCM is the root cause of this code and other transmission-specific codes. Replacing the module will often resolve the issue, but proper diagnosis is always recommended.