Restore Peak Transmission Performance in Your 2008-2010 Hummer H3
Is your Hummer H3 suffering from erratic shifting, getting stuck in gear, or throwing transmission-related check engine lights? These are classic signs of a failing Transmission Control Module (TCM). The TCM is the electronic brain of your automatic transmission, responsible for managing gear changes, fluid pressure, and torque converter operation. When it fails, it can lead to poor performance, decreased fuel economy, and potentially catastrophic transmission damage. This genuine OEM-quality T42 TCM, part number 24240400, is the definitive solution to get your H3 running smoothly again.
From the Diagnostic Bay
We recently had a 2009 Hummer H3 towed in that was stuck in ‘limp mode’—it wouldn’t shift out of 3rd gear. The owner was worried he needed a full transmission rebuild. After hooking up the scan tool, we saw a P0700 code and several solenoid circuit faults. A quick check of the wiring harness showed no damage. We knew from experience that these symptoms often point directly to an internal failure in the TCM. We installed one of our VIN-programmed T42 modules, cleared the codes, and the H3 was shifting perfectly on the test drive. It’s a common issue, but a straightforward fix with the right part.
Diagnosing a Faulty HUMMER H3 TCM
A failing TCM can manifest in various ways, often mimicking mechanical transmission problems. Before condemning your transmission, check for these common electronic symptoms. This module is the key to resolving these issues and restoring the communication between your engine and transmission for dependable operation on and off the road.
- ✔ Erratic and Harsh Shifting: Your H3 may slam into gear, hesitate between shifts, or refuse to shift at all.
- ✔ Stuck in Limp Mode: The vehicle may be locked in a single gear (often 2nd or 3rd) to prevent further damage.
- ✔ Warning Lights: The Check Engine Light or a specific transmission warning light will illuminate on your dashboard.
- ✔ Diagnostic Trouble Codes (DTCs): You’ll often see codes like P0700 (Transmission Control System Malfunction) or other solenoid-specific codes (e.g., P0750, P0753, P0758).
- ✔ Poor Fuel Economy: Inefficient shifting and torque converter lock-up can lead to a noticeable drop in MPG.
- ✔ No Communication: In some cases, a scan tool may be unable to communicate with the TCM, indicating a complete failure.
The Plug-and-Play Advantage: VIN Programming Included
Don’t waste time and money on a trip to the dealership. This T42 Transmission Control Module comes pre-programmed to your Hummer H3’s specific Vehicle Identification Number (VIN). This critical step ensures that the module has the latest GM software and is perfectly calibrated for your vehicle’s specific configuration right out of the box. This eliminates compatibility issues and allows for a simple, direct installation without the need for expensive dealer-only programming tools. It’s a hassle-free solution designed for both professional technicians and savvy DIYers.
Installation and Compatibility
For the 2008-2010 Hummer H3, the TCM is located in the right-hand rear of the engine compartment. Installation is straightforward and can typically be completed in under an hour. Simply disconnect the battery, unplug the electrical connectors from the old module, unbolt it, and install the new one in its place. Once reconnected, clear any remaining DTCs with a standard OBD-II scanner. This module is a direct replacement for service number 24240400 and interchanges with numerous other GM part numbers, including 24252114, 24234503, and 24256960, ensuring wide compatibility across the GM family.
Frequently Asked Questions
What does a TCM do on a HUMMER H3?
The Transmission Control Module (TCM) acts as the computer for your automatic transmission. It gathers data from various sensors and uses it to control shift timing, solenoid activation, and torque converter lockup, ensuring smooth and efficient operation.
Is this TCM difficult to install myself?
For someone with basic mechanical skills, the installation is quite manageable. It involves disconnecting the battery, locating the module in the engine bay, and swapping it out. Since our modules are VIN-programmed, no special computer programming is required, making it a true plug-and-play part.
What does ‘VIN Programmed’ mean for my HUMMER H3?
VIN programming means we load the module with the specific software and calibrations for your vehicle’s exact build, based on its unique VIN. This ensures seamless integration and optimal performance without needing a trip to the dealership for costly programming.
Will this part fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. While this module often resolves the root cause of a P0700 code (especially when paired with other solenoid or communication codes), you should always ensure other potential issues like wiring or sensors have been checked.
Do I need to send my old TCM back?
No, there is no core charge for this part. You can keep your old module, which saves you the time and expense of return shipping.