Restore Smooth Shifting to Your Chevrolet Trailblazer
If your 2006-2009 Chevrolet Trailblazer is suffering from erratic shifting, getting stuck in gear, or has an illuminated check engine light, a failing Transmission Control Module (TCM) is the likely culprit. As a seasoned technician, I’ve seen countless GM vehicles, including the Trailblazer, sidelined by these exact issues. This T42 TCM, part number 24256960, is the definitive solution. It arrives expertly programmed to your vehicle’s specific VIN, eliminating the need for expensive dealership visits and getting you back on the road with confidence. This module is the brain of your automatic transmission, precisely managing shift points, torque converter clutch engagement, and line pressure to restore the smooth, reliable performance you expect.
From the Diagnostic Bay
I remember a 2008 Trailblazer that came into the shop with a classic ‘limp mode’ complaint—stuck in 3rd gear. The owner had already replaced a shift solenoid with no luck. The scanner showed a generic P0700 code, but digging deeper revealed intermittent communication loss with the TCM. These T42 modules, especially when exposed to years of engine bay heat, can develop internal circuit failures that cause these ghost-like problems. Installing a VIN-programmed module like this one resolved the communication issue instantly, and the transmission began shifting perfectly on the first test drive. It’s a textbook example of why starting with the ‘brain’ is often the right call.
Is Your Trailblazer Exhibiting These Symptoms?
A faulty TCM can manifest in several ways. If you’re experiencing any of the following, it’s a strong indicator that your module needs replacement. A proper diagnosis with a scan tool is always recommended, but these are the tell-tale signs I see most often.
- ✔ Harsh, delayed, or unpredictable 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 (Transmission Control System Malfunction) or various solenoid-specific codes (e.g., P0751, P0756).
- ✔ Poor acceleration and decreased fuel economy.
- ✔ Complete loss of communication with the TCM, preventing diagnostics.
A Straightforward Guide to Installation
One of the best features of this module is its simple, DIY-friendly installation. For the 2006-2009 Trailblazer, the process is quick and requires only basic hand tools.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning any electronic component replacement.
- Locate the TCM: On your Trailblazer, the TCM is typically found in the left-hand (driver’s side) of the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Then, unbolt the module from its mounting bracket and remove it from the vehicle.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the electrical connectors. Ensure 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 scan tool to clear any stored DTCs from the vehicle’s memory.
Verified Vehicle Compatibility
This T42 Transmission Control Module is a direct-fit replacement for part number 24256960 and is interchangeable with service numbers like 24242391, 24234503, and 24252114. While this page focuses on the 2006-2009 Trailblazer TCM, it also fits a wide array of other GM vehicles. Please verify your part number or consult the list below:
- Chevrolet Trailblazer: 2006-2009 (8 cylinder, LH engine compartment)
- GMC Envoy: 2006-2009 (8 cylinder, LH engine compartment)
- Chevrolet Silverado / GMC Sierra: 2007-2013 (various models, typically next to battery)
- Chevrolet Tahoe / GMC Yukon: 2007-2009 (typically next to battery)
- Chevrolet Impala / Monte Carlo: 2006-2011 (lower air cleaner housing)
- Hummer H3: 2008-2010 (RH rear engine compartment)
- Saab 9-7X: 2006-2009 (LH engine compartment)
- …and many other GM cars, trucks, and vans. Please check the full fitment list for your specific model.
Frequently Asked Questions
Do I need to take my vehicle to the dealer for programming?
No. This module comes fully pre-programmed to your vehicle’s VIN. It is ready for installation right out of the box, saving you time and money on dealership service fees.
Is this a difficult part to install myself?
Not at all. For most DIYers with basic tools, this is a very straightforward job that can be completed in under 30 minutes. Just locate the old module, disconnect the battery, swap the parts, and reconnect everything.
What is a ‘core charge’?
A core charge is a deposit you pay until you return your old part. We do not require a core charge for this TCM, so you can keep your old part without any hassle.
What warranty is included with this 2006-2009 Trailblazer TCM?
This part is backed by our comprehensive one-year warranty, giving you peace of mind and protection against any defects in materials or workmanship.
Will this fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. While a faulty TCM is a very common cause, this code can also be triggered by other transmission issues. However, if you are also experiencing shifting problems, replacing the TCM is a very likely solution.