Restore Peak Performance to Your HUMMER H3
If your 2008-2010 HUMMER H3 is suffering from unpredictable shifting, getting stuck in gear, or throwing transmission codes, the culprit is often a failing Transmission Control Module (TCM). As the electronic brain of your automatic transmission, a faulty TCM can cripple your vehicle’s reliability, turning every drive into a guessing game. In my 20 years of diagnostics, I’ve seen countless GM vehicles, from workhorse Silverados to rugged H3s, sidelined by these exact issues. This isn’t just an annoyance; it’s a critical failure that compromises your vehicle’s performance and safety.
This OEM-quality T42 Transmission Control Module is the definitive solution. We take the guesswork and dealership hassle out of the equation by pre-programming it to your H3’s specific Vehicle Identification Number (VIN). This ensures it arrives ready for a true plug-and-play installation, loaded with the latest GM software updates for optimal shift patterns, torque converter lockup, and fuel efficiency. Don’t let a bad module keep your H3 off the road or trail—get the reliable, pre-programmed fix you need.
Case Study: A Tricky Diagnosis
A customer brought in a 2009 HUMMER H3 that would intermittently refuse to shift past 2nd gear and had a persistent P0700 code. They’d already replaced a shift solenoid with no luck. After connecting my scan tool, I saw communication dropouts from the TCM. In these trucks, the TCM is mounted in the engine bay (RH rear side), where it’s exposed to constant heat and vibration. Over time, these conditions cause internal solder joints to fail. We installed a VIN-programmed 2008-2010 HUMMER H3 TCM, cleared the codes, and the truck’s shifting was immediately crisp and correct. The pre-programming saved the customer hundreds compared to a dealership visit.
Is Your H3 Showing These Telltale Signs?
- âś” Unpredictable, harsh, or delayed gear shifts.
- âś” Vehicle is stuck in “limp mode” (often 2nd or 3rd gear).
- âś” The Check Engine Light or transmission warning light is on.
- âś” Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction) or various solenoid-specific codes (e.g., P0750, P0753).
- âś” A noticeable decrease in fuel economy.
- âś” The transmission feels like it’s slipping between gears.
- âś” Complete failure to shift or engage a gear.
A Straightforward Guide to Installation
Replacing the 2008-2010 HUMMER H3 TCM is a job most DIYers can handle in under 30 minutes with basic tools. No complex procedures are required.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- Locate the Module: On the HUMMER H3, the TCM is typically found in the engine compartment, on the right-hand (passenger) side towards the rear.
- Disconnect and Remove: Carefully unplug the electrical connectors. Note the locking tab positions to avoid damage. Then, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Securely reconnect the electrical connectors until they click.
- Final Steps: Reconnect the negative battery terminal. Start the vehicle and use a basic OBD2 scan tool to clear any stored fault codes from the previous module failure. Your H3 is now ready to drive.
Will This Fit My Vehicle?
This T42 TCM is a direct replacement for part number 24235754 and is compatible with a wide range of 2006-2014 General Motors vehicles equipped with 4-speed automatic transmissions like the 4L60E and 4L65E. While this page focuses on the 2008-2010 HUMMER H3 TCM, it also fits the following models (please verify location in your specific vehicle):
- HUMMER: H3 (2008-2010)
- Chevrolet: Avalanche 1500 (2007-2008), Cobalt (2006-2010), Colorado (2008-2012), Express Vans (2006-2014), HHR (2006-2011), Impala (2006-2011), Malibu (2006-2010), Monte Carlo (2006-2007), Silverado 1500/2500 (2007-2013), SSR (2005-2006), Suburban 1500 (2007-2008), Tahoe (2007-2009), Trailblazer (2006-2009)
- GMC: Canyon (2008-2012), Envoy / Envoy XL (2006-2009), Savana Vans (2006-2014), Sierra 1500/2500 (2007-2013), Yukon / Yukon XL 1500 (2007-2009)
- Buick: Allure (2006-2009), LaCrosse (2006-2009), Lucerne (2006-2011), Rainier (2006-2007), Rendezvous (2006-2007)
- Cadillac: DTS (2006-2011)
- Pontiac: G5 (2007-2010), G6 (2006-2010), Grand Prix (2006-2008), Pursuit (2006), Montana (2006-2009)
- Saturn: Aura (2007-2009), Ion (2006-2007), Vue (2007-2010)
- Saab: 9-7X (2006-2009)
Frequently Asked Questions
Do I need to program this module at a dealership?
No. This module arrives pre-programmed to your vehicle’s VIN. It is ready for installation right out of the box, saving you time and money.
Where is the TCM located on my 2009 HUMMER H3?
On the 2008-2010 Hummer H3, the TCM is located in the engine compartment on the right-hand (passenger) side, near the firewall.
Will this fix my check engine light and P0700 code?
A P0700 code is a general fault code indicating the TCM has detected a problem. A failing TCM is a very common cause. Replacing it with this module will often resolve the underlying issue that triggers the P0700 and other related transmission codes.
Do I need to send my old part back?
No, there is no core charge for this part. You can keep or dispose of your old module without any hassle.
What tools are required for installation?
You will only need basic hand tools, such as a socket set to remove the mounting bolts and potentially a small flathead screwdriver to help release the connector clips. An OBD2 scanner is recommended to clear old codes post-installation.