Restore Peak Performance to Your GM Transmission
If your 2006 Chevrolet Trailblazer EXT is suffering from harsh shifting, getting stuck in gear, or has an illuminated 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 hundreds of these T42 modules cause headaches for drivers. This isn’t just an inconvenience; it’s a reliability issue that can leave you stranded. This direct-fit 2006 Trailblazer EXT TCM, part number 24256960, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
The TCM is the brain of your automatic transmission, controlling everything from shift points to torque converter lockup. When it fails, communication between the engine and transmission breaks down, leading to the frustrating symptoms you’re experiencing. Our modules are loaded with the latest GM software, ensuring they correct common factory flaws and provide smooth, decisive shifting right out of the box. You’re not just buying a part; you’re buying a permanent fix that restores your vehicle’s original drivability and efficiency.
Case Study: A Tricky Diagnosis
A customer brought in a 2006 Trailblazer with a classic complaint: it would randomly refuse to shift out of 3rd gear (limp mode) and had a persistent P0700 code. They had already replaced two shift solenoids based on another shop’s advice, with no improvement. After a quick data stream analysis, I noticed erratic voltage readings from the TCM. Instead of more guesswork, we installed one of our VIN-programmed modules. The entire job took less than 25 minutes in the bay. A test drive confirmed smooth shifting through all gears, and the codes never returned. This is the power of a correct, pre-programmed part—it eliminates variables and provides a first-time fix.
Is Your Trailblazer Exhibiting These Telltale Signs?
A faulty TCM can manifest in several ways. If you’re noticing any of the following, it’s time for a replacement:
- ✔ Harsh, jerky, or delayed gear shifts.
- ✔ The vehicle is stuck in a single gear (often called “limp mode”).
- ✔ Check Engine Light or Transmission Warning Light is on.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, or other solenoid-related faults.
- ✔ Complete failure to shift up or down.
- ✔ A noticeable drop in fuel economy.
- ✔ Intermittent loss of communication with the module, causing unpredictable behavior.
Your 30-Minute Path to Smoother Shifting
One of the best features of this module is its straightforward installation. You don’t need a lift or specialized tools, making it a perfect job for a DIY enthusiast or a quick task for a professional mechanic. For the 2006 Trailblazer EXT TCM, the module is typically found in the engine compartment on the driver’s side.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- Locate the Module: On your Trailblazer EXT, find the TCM in the left-hand (driver’s side) of the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly. Then, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt the new, VIN-programmed TCM into place and securely reconnect the electrical harnesses. You should hear a click as they lock in.
- Reconnect and Verify: Reconnect the battery terminal. Start the vehicle and allow it to idle for a moment. Use a basic OBD2 scanner to clear any stored fault codes and confirm the repair.
Verified Fitment for Your GM Vehicle
This T42 TCM is a direct replacement for a wide range of General Motors vehicles, ensuring broad compatibility. It interchanges with part numbers including 24252114, 24234503, 24230461, 24234274, 24255280, and 24256960. While this page focuses on the 2006 Trailblazer EXT TCM, it also fits the following models (please verify location and options):
- Chevrolet Trailblazer EXT (8 cylinder): 2006 (LH engine compartment)
- Chevrolet Silverado / GMC Sierra: 2007-2013 (various, typically next to battery)
- Chevrolet Tahoe / GMC Yukon: 2007-2009 (next to battery)
- Chevrolet Impala / Monte Carlo: 2006-2011 (lower air cleaner housing)
- Chevrolet Express / GMC Savana Van: 2006-2014 (RH engine compartment)
- Cadillac DTS: 2006-2011 (RH front engine compartment)
- Hummer H3: 2008-2010 (RH rear engine compartment)
- Pontiac G6 / Grand Prix: 2006-2010 (LH strut tower)
- …and many more GM models from 2006-2014.
Frequently Asked Questions
What exactly does VIN programming do for me?
VIN programming ensures the module is loaded with the precise software and calibrations for your Trailblazer’s specific configuration (engine, transmission, axle ratio). This eliminates compatibility errors and the need for an expensive programming session at a dealership, making it a true plug-and-play part.
Do I need to send my old part back? Is there a core charge?
No. We do not require a core return for this part. You can keep or dispose of your old module without any additional hassle or charges.
Will this part fix a P0700 transmission code?
A P0700 code is a general fault request from the TCM to the main computer (PCM) to turn on the check engine light. While this module often resolves the underlying issue causing the P0700, you should scan for more specific codes (like P0750-P0758) to confirm the diagnosis. In most cases where the TCM is faulty, this part is the correct fix.
Is any special relearn procedure required after installation?
No dealership-level relearn is needed due to the VIN programming. After installation, the vehicle may go through a brief period of adaptive learning as you drive, where it fine-tunes shift points. This is a normal, automatic process.
How can I be sure this is the problem and not a solenoid?
While a failed solenoid can cause shifting issues in a single gear, a failing TCM often causes more widespread, erratic problems, like harsh shifting across all gears, communication loss, or multiple solenoid codes at once. If the symptoms are intermittent and unpredictable, the TCM is the more probable cause.