If your 2006-2009 Chevrolet Trailblazer is suffering from harsh shifts, getting stuck in gear, or throwing transmission-related trouble codes, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen firsthand how a failing Transmission Control Module (TCM) can bring an otherwise solid SUV to a frustrating halt. This isn’t just an inconvenience; it’s a critical failure that compromises your vehicle’s performance and safety. This T42 TCM, part number 24255280, is the definitive, reliable solution to restore your transmission’s precise operation.
From the Diagnostic Bay: A Trailblazer’s Ghost
I remember a 2008 Trailblazer that came into my shop with what the owner called “ghostly” shifting. It would work perfectly for days, then suddenly slam into gear or refuse to shift past 2nd. He had already replaced two shift solenoids with no luck. After connecting my scan tool, I saw intermittent communication loss with the TCM. The culprit wasn’t the internal transmission parts; it was the brain itself. Heat cycles and vibrations had damaged the module’s internal circuits. Installing a pre-programmed 2006-2009 Trailblazer TCM didn’t just fix the problem—it provided a permanent solution in under an hour, saving the customer from a costly and unnecessary transmission rebuild.
Is Your Trailblazer Showing These Telltale Signs?
A faulty TCM often mimics other transmission problems, but there are key symptoms to watch for. If you’re experiencing any of the following, a failing module is the likely cause:
- ✔ Harsh, banging shifts or delayed gear engagement.
- ✔ The vehicle is stuck in “limp mode” (usually second or third gear).
- ✔ An illuminated Check Engine Light with Diagnostic Trouble Codes (DTCs) like P0700 (Transmission Control System Malfunction), P0750-P0758 (Solenoid Faults), or U0101 (Lost Communication with TCM).
- ✔ Inability to upshift or downshift, leading to poor acceleration and terrible fuel mileage.
- ✔ The transmission seems to slip between gears or feels like it’s in neutral when it should be in drive.
The Power of Plug-and-Play: Why VIN Programming is Essential
The single biggest advantage of this module is that it arrives at your door fully programmed to your Trailblazer’s specific Vehicle Identification Number (VIN). In the past, this was a job only a dealership could do, costing you hundreds in labor and programming fees. We handle all of that for you. By loading the latest GM software updates based on your VIN, we ensure this 2006-2009 Trailblazer TCM communicates flawlessly with your vehicle’s engine computer and other systems right out of the box. This eliminates compatibility errors, optimizes shift points, and ensures a smooth, successful repair without any extra steps.
A Straightforward Guide to a 30-Minute Install
You don’t need to be a master mechanic to replace this module. For the Trailblazer, the TCM is conveniently located and easy to access.
- 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 2006-2009 Trailblazer, the TCM is typically found in the engine compartment on the driver’s side (LH side).
- Disconnect and Remove: Carefully unplug the electrical connectors from the old TCM. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the electrical harnesses. Ensure they click into place.
- Final Steps: Reconnect the battery terminal. Start the vehicle and allow it to idle for a few minutes. While the module is plug-and-play, it’s good practice to use a basic OBD2 scan tool to clear any stored fault codes from the previous failure.
Verified Vehicle Compatibility List
This T42 Transmission Control Module is a direct-fit replacement for the following vehicles, among others. It is interchangeable with part numbers 24242391, 24234503, 24252114, and more.
- Chevrolet Trailblazer: 2006, 2007 (8 cylinder), 2008, 2009 – Located in LH engine compartment.
- GMC Envoy / Envoy XL: 2006, 2007 (8 cylinder), 2008, 2009 – Located in LH engine compartment.
- Saab 9-7X: 2006, 2007, 2008, 2009 – Located in LH engine compartment.
- Chevrolet Silverado / GMC Sierra 1500: 2007-2013 – Location varies (often next to battery).
- Chevrolet Tahoe / GMC Yukon: 2007-2009 – Location varies (often next to battery).
- And many other GM cars, trucks, and SUVs from 2006-2014. Please verify your part number.
Frequently Asked Questions
Why is VIN programming so important?
VIN programming loads your vehicle’s specific calibration file onto the module. This ensures the transmission shifts at the correct times, the torque converter locks up properly, and it communicates correctly with the engine, preventing performance issues and fault codes.
Do I need any special tools for installation?
No. Basic hand tools like a socket set are all that’s required to unbolt the old module and install the new one. The most important part is that no special programming tools are needed.
Is there a core charge for my old part?
No, there is absolutely no core charge. You can keep your old module or dispose of it without the hassle of returning it, saving you time and money.
What kind of warranty is included?
This module is backed by our comprehensive one-year warranty, giving you peace of mind and protection against any defects. We stand by the quality and reliability of our parts.