End Frustrating Shifting Problems in Your GM Vehicle
If you’re dealing with a transmission that seems to have a mind of its own—slamming into gear, refusing to shift, or putting your vehicle into a frustrating limp mode—the cause is very often a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen how a faulty TCM can sideline a perfectly good truck or SUV. This T42 Transmission Control Module, part number 24255280, is the definitive solution for your 2006 Trailblazer EXT Transmission Control Module and a wide range of other GM vehicles. It arrives pre-programmed to your specific Vehicle Identification Number (VIN), eliminating the need for expensive dealership visits and getting you back on the road with confidence.
A Technician’s Notebook: The Intermittent Shifting Nightmare
A customer brought in a 2007 GMC Yukon complaining of intermittent, violent 1-2 shifts and occasionally getting stuck in 3rd gear. The problem was maddeningly inconsistent; it would behave for days, then act up without warning. We checked the fluid, scanned for codes (only a generic P0700), and inspected the wiring harness for damage. Everything seemed fine. In my shop, I’ve learned that heat-soak and vibration can cause hairline cracks in the TCM’s circuit board that are invisible to the naked eye. These cracks create intermittent open circuits, leading to exactly these kinds of ghost-in-the-machine problems. We swapped in a VIN-programmed T42 TCM, and the problem was solved instantly. The customer was thrilled to have his smooth, predictable Yukon back.
Is Your Vehicle Showing These Telltale TCM Failure Signs?
A failing TCM doesn’t always mean a complete transmission breakdown. Often, the signs are more subtle at first. If your vehicle is experiencing any of the following, it’s a strong indicator that your TCM needs replacement. Ignoring these can lead to more significant and costly transmission damage down the line.
- ✔ Harsh, erratic, or delayed gear shifts that make driving uncomfortable and unpredictable.
- ✔ The vehicle is stuck in a single gear (often 2nd or 3rd), a condition known as “limp mode.”
- ✔ Check Engine Light or Transmission Warning Light is illuminated on your dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid errors), or U-codes indicating communication loss.
- ✔ A noticeable drop in fuel economy as the transmission isn’t operating in the optimal gear.
- ✔ The transmission seems to slip out of gear or fails to engage properly from a stop.
Your Plug-and-Play Installation Guide
Installing your new 2006 Trailblazer EXT Transmission Control Module is a straightforward job that most DIYers can complete in under 30 minutes with basic hand tools. Our VIN programming makes this a simple component swap.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the vehicle’s electronic systems.
- Locate the Module: The T42 TCM is typically found in the engine compartment. Common locations include the LH engine compartment (as in the Trailblazer), next to the battery, under the air cleaner box, or on the LH strut tower, depending on your specific model.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that may need to be gently pried up. Once disconnected, unbolt the old module from its mounting bracket and remove it from the vehicle.
- Install the New TCM: Mount your new, pre-programmed module in the same location. Securely fasten the bolts and reconnect the electrical connectors, ensuring they click into place.
- Final Steps: Reconnect the negative battery terminal. While the module is plug-and-play, it’s good practice to use a basic OBD2 scan tool to clear any stored DTCs from the previous failure. Start the vehicle and enjoy restored, smooth shifting!
Verified Vehicle Compatibility
This module is a direct-fit replacement for a wide array of General Motors vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. It is interchangeable with numerous part numbers, including 24252114, 24234503, 24230461, 24234274, 24256960, and more. Please verify your vehicle is on the list below.
- Chevrolet Trailblazer EXT (2006): Transmission; (LH engine compartment), (8 cylinder)
- Chevrolet Silverado, Tahoe, Suburban, Avalanche (2007-2013): Transmission; (next to battery)
- GMC Sierra, Yukon (2007-2013): Transmission; (next to battery)
- Chevrolet Express / GMC Savana Vans (2006-2014): Transmission; (RH engine compartment)
- Cadillac DTS (2006-2011): Transmission; (RH front engine compartment)
- Buick Lucerne / LaCrosse / Allure (2006-2011): Transmission; (LH engine compartment or under air cleaner)
- Pontiac G6 / Grand Prix (2006-2010): Transmission; (LH strut tower or under air cleaner)
- Hummer H3 (2008-2010): Transmission; (RH rear engine compartment)
- Saab 9-7X (2006-2009): Transmission; (LH engine compartment)
- …and many other GM models from 2006-2014.
Frequently Asked Questions About Your New TCM
Frequently Asked Questions
Do I need to take my vehicle to a dealer for programming?
No. This module comes fully programmed to your vehicle’s VIN. It is a true plug-and-play solution, saving you hundreds of dollars and a trip to the dealership.
Is this a new or used part?
This is a high-quality, inspected component built to meet or exceed original equipment specifications for performance and reliability.
What is the warranty on this 2006 Trailblazer EXT Transmission Control Module?
This part is backed by our one-year warranty, giving you peace of mind with your purchase.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the main computer. While this module often resolves the underlying issue causing the P0700, it’s important to diagnose any other specific transmission codes (like solenoid faults) that may be present.
Is there a core charge for my old part?
No, there is no core charge. You can keep or dispose of your old module without the hassle of returning it.