If your 2008-2010 HUMMER H3 is suffering from transmission problems like harsh shifting, getting stuck in gear, or a persistent check engine light, a failing Transmission Control Module (TCM) is the most likely culprit. 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 inconvenience; it’s a critical failure that affects your H3’s performance, safety, and fuel economy. This T42 TCM, part number 24240400, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
The TCM is the electronic brain of your automatic transmission. It processes data from various sensors to control shift points, torque converter clutch engagement, and line pressure. When it fails, the communication breaks down, leading to the frustrating symptoms you’re experiencing. Our VIN programming service eliminates the need for an expensive trip to the dealership for coding. We load the latest GM software onto the module using your VIN, ensuring it works seamlessly with your H3’s systems right out of the box. This restores the crisp, predictable shifting your vehicle had when it was new.
Is Your H3 Showing These Telltale Transmission Faults?
A failing TCM often displays a clear pattern of symptoms. If you’re noticing any of the following, it’s a strong indicator that your module needs replacement:
- ✔ Harsh, delayed, or unpredictable gear shifts that make driving feel unsafe.
- ✔ Vehicle enters “limp mode,” often getting stuck in 2nd or 3rd gear.
- ✔ Check Engine Light or Transmission Warning Light is illuminated on the dash.
- ✔ Common Diagnostic Trouble Codes (DTCs) stored, such as P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid codes), or communication errors.
- ✔ A noticeable drop in fuel efficiency as the transmission operates inefficiently.
- ✔ Complete failure to shift gears or engage Drive or Reverse.
Case Study: A Tricky Diagnosis
A customer brought in their 2009 Hummer H3, complaining it would randomly slam into gear and occasionally get stuck in 3rd. They had already replaced two shift solenoids at another shop with no success. After a quick scan, I saw a P0700 code and a history of intermittent solenoid circuit faults. Experience told me this wasn’t a mechanical issue, but an electrical one. The TCM was erratically commanding the solenoids. We installed a VIN-programmed 2008-2010 HUMMER H3 TCM, cleared the codes, and the H3 was shifting perfectly within an hour. The customer saved hundreds by avoiding further guesswork and unnecessary parts.
A Straightforward Guide to Installation
Replacing the TCM on your Hummer H3 is a job most DIY enthusiasts can handle in their own driveway in under 30 minutes. No specialized tools are required.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work. This prevents short circuits and helps reset the vehicle’s electronic systems.
- Locate the Module: On the 2008-2010 HUMMER H3, the TCM is located in the engine compartment, specifically at the right-hand rear side.
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly to avoid damaging them. Then, unbolt the old TCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Mount the new, pre-programmed TCM in place and secure the bolts. Reconnect the electrical connectors, ensuring they click securely into place.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it idle for a few minutes. While our module is plug-and-play, it’s good practice to use a basic OBD2 scanner to confirm no old fault codes are present.
Verified Fitment For These GM Vehicles
This T42 Transmission Control Module is a direct replacement for part number 24240400 and is compatible with a wide range of GM vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. While this page is dedicated to the 2008-2010 HUMMER H3 TCM, it also fits the following models:
- Chevrolet Colorado (2008-2012)
- GMC Canyon (2008-2012)
- HUMMER H3 (2008-2010)
- Chevrolet & GMC Full-Size Trucks/SUVs (Various 2007-2013)
- And many other GM cars, trucks, and vans from 2006-2014.
Frequently Asked Questions
Frequently Asked Questions
What does ‘VIN Programmed’ actually mean?
It means we flash the module with your vehicle’s unique 17-digit Vehicle Identification Number (VIN) before shipping. This ensures the TCM has the correct software and calibration files for your H3’s specific configuration, making the installation plug-and-play without requiring a trip to a dealer.
Do I need to send my old TCM back?
No, there is absolutely no core charge or need to return your old part. You can dispose of it or keep it, saving you time and return shipping costs.
Will this fix a P0700 code?
Yes, in most cases. A P0700 code is a general fault code indicating the TCM has detected a problem. If the TCM itself is the source of the failure, replacing it with our programmed unit will resolve the P0700 and any related transmission codes.
What is the warranty on this part?
This module is backed by our one-year, hassle-free warranty, giving you peace of mind and confidence in your repair.