If your 2008-2010 HUMMER H3 is suffering from unpredictable shifting, getting stuck in gear, or has the check engine light glaring at you, a failing Transmission Control Module (TCM) is the likely culprit. As a seasoned technician, I’ve seen countless GM vehicles, including the rugged H3, sidelined by these exact issues. A faulty TCM doesn’t just make for a frustrating drive; it can compromise your vehicle’s off-road readiness and daily reliability. This isn’t a problem you can ignore.
This T42 TCM, corresponding to part number 24238856, is the definitive solution. It’s not just a replacement part; it’s a fully integrated fix that arrives pre-programmed to your H3’s specific Vehicle Identification Number (VIN). This critical step ensures that the module communicates flawlessly with your vehicle’s engine computer and transmission from the moment you install it, eliminating the need for an expensive and time-consuming trip to the dealership for programming.
Case Study: A Tricky Diagnosis
A customer brought in a 2009 H3 that would intermittently go into ‘limp mode,’ locking itself in 3rd gear. The dash was lit up with a check engine light, and a scan revealed a P0753 (Shift Solenoid ‘A’ Electrical) code. The owner had already replaced the solenoid inside the transmission pan, but the problem persisted. After confirming the wiring harness was intact, my diagnostic process pointed to the brain—the TCM. The internal drivers for the solenoid circuit had failed. 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 classic case where the root cause isn’t the component being flagged, but the controller itself.
Is Your H3 Showing These Telltale Signs?
- ✔ Harsh, slamming shifts or delayed gear engagement.
- ✔ Vehicle is stuck in one gear (often called “limp mode”).
- ✔ Check Engine Light or Transmission Warning Light is on.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750-P0758, or other transmission-related faults.
- ✔ Inconsistent upshifting or downshifting, leading to poor acceleration.
- ✔ A noticeable drop in fuel economy.
Your Straightforward 30-Minute Installation Guide
Getting your HUMMER H3 back in top form is a simple, direct process that any DIY enthusiast can handle. For the 2008-2010 H3, the TCM is conveniently located in the engine compartment.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: On your H3, find the TCM in the right-hand rear of the engine compartment. It’s a silver box with electrical connectors.
- Swap the Connectors: Carefully unclip the wiring harness connectors from the old TCM. Unbolt the old module and secure the new one in its place.
- Reconnect Everything: Firmly plug the wiring harnesses into your new, pre-programmed TCM. Reconnect the negative battery terminal.
- Final Steps: Start the vehicle. While the module is plug-and-play, it’s best practice to use a basic OBD2 scan tool to clear any stored fault codes from the previous failure.
Verified Compatibility for Your GM Vehicle
While this is a perfect fit for the 2008-2010 HUMMER H3 TCM, this versatile T42 module also serves as a direct replacement for a wide range of GM vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. It is interchangeable with multiple part numbers, including 24252114, 24234503, and 24239224. Key compatible models include:
- ✔ Chevrolet Silverado, Tahoe, Colorado, Impala, HHR
- ✔ GMC Sierra, Yukon, Savana, Canyon
- ✔ Cadillac DTS
- ✔ Buick LaCrosse, Lucerne
- ✔ Pontiac G6, Grand Prix
- ✔ Saab 9-7X
Frequently Asked Questions
Do I need to have a dealership program this module?
No. We pre-program the module to your vehicle’s VIN before shipping. This ensures it is ready for immediate installation and operation, saving you time and money.
Will this fix a P0700 transmission fault code?
A P0700 code indicates a general fault request from the TCM. While this module often resolves the underlying issue causing the P0700 (like a solenoid circuit fault), you should always diagnose any other specific codes that accompany it. In many cases, replacing a faulty TCM will clear this code.
Where is the TCM located on my 2009 HUMMER H3?
On the 2008-2010 Hummer H3, the Transmission Control Module is located in the engine bay, on the right-hand (passenger) side, towards the rear.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part, so you don’t have to worry about the cost or hassle of shipping it back.
What kind of warranty is included?
This module comes with a one-year warranty, giving you peace of mind and confidence in your repair.