Restore Flawless Shifting to Your 2006 Trailblazer EXT
As a technician with over two decades of experience under the hood, I’ve seen countless GM vehicles, especially SUVs like the Trailblazer, come into the shop with frustrating transmission problems. Hard bangs into gear, getting stuck in limp mode, or a check engine light that just won’t quit—these are classic signs of a failing Transmission Control Module (TCM). The TCM is the brain of your automatic transmission, and when it goes, your vehicle’s performance and reliability go with it. This isn’t just an inconvenience; it’s a safety concern. That’s why we offer this OEM-quality T42 TCM, specifically for your 2006 Trailblazer EXT TCM needs.
What makes this part the definitive solution is our expert VIN programming service. Before this module ships, we flash it with the latest GM software calibrated precisely to your vehicle’s VIN. This eliminates the need for expensive dealership visits or specialized scan tools for programming. It’s a true plug-and-play fix that gets you back on the road with confidence, knowing your transmission is operating exactly as the factory intended.
Case Study: The Ghost in the Transmission
A customer brought in his ’06 Trailblazer EXT complaining of intermittent, violent downshifts when coming to a stop. He’d already replaced a shift solenoid based on a code, but the problem persisted. Diagnostics were tricky because it wouldn’t act up consistently. After hooking up my scope and monitoring solenoid command signals from the TCM, I saw erratic voltage drops that didn’t match vehicle speed or throttle position. The TCM itself was failing internally, sending faulty commands. We installed one of our VIN-programmed T42 modules, and the problem was solved instantly. It’s a common failure point I’ve seen fix hundreds of these GM trucks and SUVs.
Is Your Trailblazer Exhibiting These Transmission Faults?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, it’s highly likely your module is the culprit.
- ✔ Harsh, delayed, or erratic gear shifts.
- ✔ Vehicle is stuck in one gear (often called “limp mode”).
- ✔ Check Engine Light is on with transmission-related Diagnostic Trouble Codes (DTCs) like P0700, P0750, P0753, P0758, or other solenoid circuit codes.
- ✔ The transmission refuses to upshift or downshift properly.
- ✔ A noticeable decrease in fuel economy.
- ✔ Intermittent loss of communication with the TCM, causing unpredictable behavior.
Your 30-Minute Path to a Smooth-Shifting Ride
For the average DIYer, this is a straightforward job. You don’t need a vehicle lift or complex tools. The module is located in the engine bay, making access simple.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the TCM: On your 2006 Trailblazer EXT, the TCM is typically found in the left-hand (driver’s side) engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs, so be gentle. 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. You should hear a ‘click’ as they lock.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it run for a minute. While our programming resolves most codes, it’s good practice to use a basic OBD2 scanner to clear any stored DTCs. Take a test drive to confirm smooth shifting.
Verified Fitment for Your General Motors Vehicle
This T42 TCM, also known by part numbers 24230461, 24252114, 24234503, and others, is a direct-fit replacement for a wide range of GM vehicles equipped with 4-speed automatic transmissions (4L60E, 4L65E, 4L70E, 4L80E). While this page focuses on the 2006 Trailblazer EXT TCM, it also fits:
- Chevrolet: Silverado, Tahoe, Suburban, Avalanche, Express, Impala, Cobalt, HHR, Colorado
- GMC: Sierra, Yukon, Savana, Canyon, Envoy
- Buick: LaCrosse, Lucerne, Rainier, Allure
- Cadillac: DTS
- Pontiac: G6, Grand Prix, G5
- Saturn: Vue, Aura, Ion
- Hummer: H3
- Saab: 9-7X
Please use the fitment checker to confirm compatibility for your specific year and model.
Frequently Asked Questions
What exactly is VIN programming and why do I need it?
VIN programming involves loading your vehicle’s specific Vehicle Identification Number (VIN) and the latest factory software onto the module. This ensures the TCM communicates perfectly with your vehicle’s engine computer and other systems, controlling shift points, line pressure, and torque converter lockup for optimal performance and fuel economy. Without it, the transmission will not function correctly.
Will I have to take this to a dealership after installation?
No. Our service pre-programs the module, so it is ready for installation right out of the box. This saves you the time and expense of a dealership visit for programming.
Is this a difficult part to install myself?
Not at all. For most DIYers with basic hand tools, this is a very manageable job that typically takes less than 30 minutes. The module is easily accessible in the engine compartment.
Does this module come with a warranty?
Yes, this transmission control module is backed by our one-year warranty, giving you peace of mind with your purchase.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part or dispose of it without the hassle of returning it.