Restore Smooth, Reliable Shifting to Your GM Vehicle
If you’re dealing with the headaches of a faulty transmission—harsh bangs into gear, getting stuck in limp mode, or a persistent check engine light—you know how frustrating it can be. As a technician with over two decades of experience under the hood, I’ve seen countless drivers sidelined by a failing Transmission Control Module (TCM). The TCM is the electronic brain of your automatic transmission, and when it malfunctions, it can make your 2006 Trailblazer EXT feel unpredictable and unsafe. This T42 series TCM, part number 24240449, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
Case Study: The Elusive Limp Mode
A customer brought in a 2008 GMC Sierra stuck in what he called “permanent limp mode.” It would only drive in third gear, and the dash was lit up with a check engine light. He’d already replaced two shift solenoids based on some forum advice, with no luck. A quick scan showed a P0700 (Transmission Control System Malfunction) and an intermittent solenoid circuit code. Instead of throwing more parts at it, we tested the TCM. The culprit was internal circuit failure, a common issue in these modules after years of heat cycles. We installed a VIN-programmed T42 TCM, cleared the codes, and the truck was shifting perfectly within 30 minutes. This is why a quality, pre-programmed module is non-negotiable for a reliable repair.
Is Your Trailblazer Showing These Symptoms?
A failing TCM often gives clear warning signs. If you’re experiencing any of the following, it’s highly likely your module is the root cause. Ignoring these can lead to more severe transmission damage.
- ✔ Harsh, erratic, or delayed gear shifts that make driving uncomfortable.
- ✔ Vehicle is stuck in a single gear (limp mode), typically 2nd or 3rd.
- ✔ Check Engine Light or Transmission Warning Light is on with Diagnostic Trouble Codes (DTCs) like P0700, P0750, or other solenoid-related faults.
- ✔ Complete loss of upshifting or downshifting capabilities.
- ✔ A noticeable drop in fuel economy or signs of the transmission overheating.
- ✔ Intermittent communication loss with the module, causing unpredictable performance.
A Straightforward Guide to Installation
One of the best features of this module is its simple installation. You don’t need to be a master mechanic to get this done in your own driveway. Most installations take less than 30 minutes.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and reset the system.
- Locate the Module: On your 2006 Trailblazer EXT, the TCM is typically found in the left-hand (driver’s side) engine compartment. On other GM models, it might be next to the battery, under the air cleaner box, or on the frame rail.
- 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, pre-programmed TCM into place. Reconnect the electrical harnesses, ensuring they click securely into place.
- Final Steps: Reconnect the battery terminal. While the system may reset, it’s best practice to use a basic OBD2 scan tool to clear any stored fault codes. Start the vehicle and enjoy restored shifting performance.
Why Choose a VIN-Programmed 2006 Trailblazer EXT Transmission Control Module?
This isn’t just a replacement part; it’s a comprehensive repair solution. We program the module with the latest GM software updates specific to your vehicle’s VIN. This critical step ensures that the TCM communicates flawlessly with your engine computer and other vehicle systems, optimizing shift points, torque converter lockup, and fuel efficiency right out of the box. You get OEM-level performance without the dealership price tag or the hassle of scheduling a programming appointment. Built to strict quality standards and backed by a one-year warranty, it’s a repair you can count on.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for a wide range of General Motors vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. It is a compatible replacement for part numbers 24252114, 24234503, 24230461, 24234274, 24235340, 24235754, 24238856, 24239224, 24240449, and more. Fitment includes, but is not limited to:
- Chevrolet: Trailblazer (8 cyl), Trailblazer EXT (8 cyl), Tahoe, Silverado 1500/2500, Suburban 1500, Express Van, Impala, Cobalt, HHR, Monte Carlo, Colorado
- GMC: Envoy (8 cyl), Envoy XL (8 cyl), Yukon, Yukon XL 1500, Sierra 1500/2500, Savana Van, Canyon
- Buick: Rainier, LaCrosse, Lucerne, Allure
- Cadillac: DTS
- Pontiac: G6, Grand Prix, G5, Pursuit
- Saturn: Vue, Aura, Ion
- Hummer: H3
- Saab: 9-7X
Frequently Asked Questions
Do I need to take my vehicle to the dealer for programming?
No. This module comes fully 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 there a core charge for this part?
No, there is no core charge. You can keep your old part without any hassle or extra cost.
What tools do I need for installation?
Basic hand tools are all that’s required, typically a small socket set to remove the mounting bolts. No specialized equipment is needed for the installation itself.
Will this fix a P0700 code?
A P0700 is a general code indicating the TCM has detected a fault. While this module often resolves the underlying issue causing the P0700 (like internal circuit failure or solenoid driver faults), it’s important to ensure there are no external wiring or sensor issues. In the vast majority of cases I’ve diagnosed, a faulty TCM is the cause.
How do I provide my VIN for programming?
You will be prompted to enter your vehicle’s 17-digit VIN during the checkout process. Please double-check it for accuracy to ensure perfect compatibility.