Restore Flawless Shifting to Your 2006 Trailblazer EXT
If you’re dealing with the frustration of a transmission that won’t shift correctly, bangs into gear, or has put your SUV into limp mode, 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 sideline an otherwise reliable vehicle. This isn’t just a part; it’s the brain of your automatic transmission. This OEM-quality T42 2006 Trailblazer EXT Transmission Module is the definitive solution, arriving pre-programmed to your vehicle’s VIN for a true plug-and-play repair.
A Technician’s Notebook: The Intermittent Shifting Mystery
A customer brought in a 2006 Trailblazer EXT with a maddening issue: it would shift perfectly when cold, but after 20 minutes of driving, it would start slamming into gear and occasionally get stuck in 3rd. No check engine light, no consistent codes. We checked fluid levels and solenoids—all fine. The problem was heat soak. The original TCM, located in the hot engine bay, had developed internal micro-fractures that only caused issues when the module got hot. Replacing the TCM with a quality, pre-programmed unit like this one solved the problem instantly. It’s a classic failure mode for these modules.
Is Your Trailblazer Exhibiting These Telltale Signs?
A failing TCM doesn’t always mean a complete transmission failure. Often, the signs are electronic. If you’re experiencing any of the following, this module is the likely solution.
- ✔ Harsh, erratic, or delayed gear shifts that make driving uncomfortable and unpredictable.
- ✔ The vehicle is stuck in “limp mode,” usually in 2nd or 3rd gear, with limited power.
- ✔ Your check engine light or transmission warning light is on, with Diagnostic Trouble Codes (DTCs) like P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid errors), or other communication codes.
- ✔ A complete failure to upshift or downshift, leading to poor acceleration and terrible fuel economy.
- ✔ The torque converter refusing to lock up at highway speeds, causing RPMs to stay high.
DIY Installation Guide: Get Your SUV Back on the Road
One of the best features of this module is its simple installation. You don’t need a trip to the dealership or specialized programming tools. For your specific 2006 Trailblazer EXT Transmission Module, the process is straightforward.
- Safety First: Before you begin, disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Old Module: On your 2006 Trailblazer EXT (with the 8-cylinder engine), the TCM is located in the left-hand (driver’s side) engine compartment. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the wiring harnesses. They have locking tabs, so be gentle. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed module into place. Securely plug in the wiring harnesses until they click, ensuring a solid connection.
- Final Steps: Reconnect the negative battery terminal. While the module is plug-and-play, it’s always a good practice to use a basic OBD2 scan tool to clear any lingering fault codes from the vehicle’s memory. Start the engine and take it for a test drive to confirm smooth shifting.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24256960 and other interchangeable numbers. It is guaranteed to fit the following vehicles and configurations:
This part will fit these makes and models with these options
TRAILBLAZER EXT 06 Transmission; (LH engine compartment), (8 cylinder)
ALLURE 06-09 Transmission; (lower air cleaner housing)
AVALANCHE 1500 07-08 Transmission; (next to battery)
AURA 07-09 Transmission; (LH frame rail front)
CANYON 08-12 Transmission; (RH rear engine compartment)
COBALT 06-10 Transmission; (LH strut tower)
COLORADO 08-12 Transmission; (RH rear engine compartment)
DTS 06-11 Transmission; (RH front engine compartment)
ENVOY 06-07 Transmission; (LH engine compartment), (8 cylinder)
ENVOY 08-09 Transmission; (LH engine compartment)
ENVOY XL 06 Transmission; (LH engine compartment), (8 cylinder)
EXPRESS 1500 VAN 06-14 Transmission; (RH engine compartment)
EXPRESS 2500 VAN 06-14 Transmission; (RH engine compartment)
EXPRESS 3500 VAN 06-14 Transmission; (RH engine compartment)
G5 07-10 Transmission; (LH strut tower)
G6 06-10 Transmission; (LH strut tower)
GRAND PRIX 06-08 Transmission; (lower air cleaner housing)
HHR 06-11 Transmission; (LH engine compartment)
HUMMER H3 08-10 Transmission; (RH rear engine compartment)
IMPALA 06-11 Transmission; (lower air cleaner housing)
ION 06-07 Transmission; (behind LH strut tower)
LACROSSE 06-09 Transmission; (lower air cleaner housing)
LUCERNE 06-07 Transmission; (4.6L), (LH engine compartment)
LUCERNE 08-11 Transmission; (LH engine compartment)
MALIBU 06-10 Transmission; (LH frame rail)
MONTANA 06-09 Transmission; (LH strut tower)
MONTE CARLO 06-07 Transmission; (lower air cleaner housing)
PURSUIT 06 Transmission; (LH strut tower)
RAINIER 06-07 Transmission
RENDEZVOUS 06-07 Transmission; (air cleaner box)
SAAB 9-7X 06-09 Transmission; (LH engine compartment)
SAVANA 1500 VAN 06-14 Transmission; (RH engine compartment)
SAVANA 2500 VAN 06-14 Transmission; (RH engine compartment)
SAVANA 3500 VAN 06-14 Transmission; (RH engine compartment)
SIERRA 1500 PICKUP 07 Transmission; (new style, smooth door skin), (next to battery)
SIERRA 1500 PICKUP 08 Transmission; (next to battery)
SIERRA 1500 PICKUP 09-13 Transmission; (next to battery), w/o hybrid option
SIERRA 2500 PICKUP 07 Transmission; new style (smooth door skin), 6.0L, (next to battery)
SILVERADO 1500 PICKUP 07 Transmission; (new style, smooth door skin), (next to battery)
SILVERADO 1500 PICKUP 08 Transmission; (next to battery)
SILVERADO 1500 PICKUP 09-13 Transmission; (next to battery), w/o hybrid option
SILVERADO 2500 PICKUP 07 Transmission; new style (smooth door skin), 6.0L, (next to battery)
SSR 05-06 Transmission; (front LH frame)
SUBURBAN 1500 07-08 Transmission; (next to battery)
TAHOE 07 Transmission; (next to battery)
TAHOE 08-09 Transmission; (next to battery), w/o auxiliary oil cooler pump
TERRAZA 06-07 Transmission; (LH strut tower)
TRAILBLAZER 06-07 Transmission; (LH engine compartment), (8 cylinder)
TRAILBLAZER 08-09 Transmission; (LH engine compartment)
UPLANDER 06-09 Transmission; (LH strut tower)
VUE 07-08 Transmission; 2.4L, (LH front engine compartment)
VUE 09 Transmission; 2.4L, w/hybrid, LH side front engine compartment, (shift control)
VUE 09 Transmission; 2.4L, w/o hybrid; (LH front engine compartment)
VUE 10 Transmission
YUKON 07 Transmission; (next to battery)
YUKON 08 Transmission; (next to battery), w/o auxiliary oil cooler control
YUKON 09 Transmission; (next to battery), w/o auxiliary oil cooler pump
YUKON XL 1500 07-08 Transmission; (next to battery)
Frequently Asked Questions
Do I need to take my vehicle to a dealer for programming?
Absolutely not. This module is delivered to you pre-programmed using your vehicle’s VIN. This ensures it communicates perfectly with your engine computer and other systems right out of the box, saving you hundreds in dealership fees.
What tools are required for installation?
Installation is simple and requires only basic hand tools. You’ll typically need a socket set to remove the module’s mounting bolts and a flathead screwdriver to help release the clips on the wiring harnesses. No special equipment is needed.
Is there a core charge for my old part?
No, there is no core charge. You are not required to send your old, faulty module back to us. This makes the process faster and more convenient for you.
How can I be sure the TCM is the problem and not the transmission itself?
While a full diagnosis is always best, TCM failure is characterized by electronic symptoms: erratic behavior, specific fault codes (like P0700), and limp mode. If your transmission fluid is clean and at the correct level, and the problems are intermittent or accompanied by warning lights, the TCM is a very common point of failure on these GM vehicles.
What kind of warranty is included?
We stand behind our products. This transmission control module comes with a one-year warranty, giving you peace of mind that you’re making a reliable, long-term repair.