If your 2006-2009 Chevrolet Trailblazer is suffering from erratic shifting, getting stuck in gear, or has the check engine light on with transmission codes, you’re likely dealing with a faulty Transmission Control Module (TCM). As the electronic brain of your automatic transmission, a failing T42 TCM can make driving frustrating and even unsafe. This is a direct-fit, OEM-quality replacement, pre-programmed to your vehicle’s specific VIN, eliminating the need for an expensive trip to the dealership.
This isn’t just a part; it’s a complete solution. By providing us with your Trailblazer’s VIN during checkout, we flash the module with the latest GM software updates. This ensures it communicates flawlessly with your vehicle’s engine computer and other systems right out of the box. Restore the crisp, predictable shifting and reliable performance you expect from your truck with a part designed for a perfect fit and long-term durability.
Is Your Trailblazer Exhibiting These Telltale Signs?
- ✔️ Harsh, banging shifts or delayed gear engagement.
- ✔️ Vehicle is stuck in a single gear (often called “limp mode”).
- ✔️ Check Engine Light or Transmission Warning Light is illuminated.
- ✔️ Diagnostic Trouble Codes (DTCs) are present, such as the general code P0700 or specific solenoid codes like P0750, P0753, P0758.
- ✔️ Unexplained drops in fuel economy or a transmission that seems to be overheating.
- ✔️ The transmission fails to upshift or downshift properly.
A Technician’s Notebook
I had a 2008 Trailblazer come into the shop last month with a complaint that was driving the owner crazy. The truck would shift perfectly for days, then suddenly start slamming into gear at stoplights. He’d already replaced a shift solenoid on another mechanic’s advice, but the problem persisted. We scanned it and found an intermittent solenoid circuit code. Instead of just throwing more parts at it, we monitored the data stream from the TCM. We saw the command signals from the module were dropping out randomly. The culprit wasn’t the solenoid; it was the TCM itself failing internally. We installed a VIN-programmed 2006-2009 Trailblazer Transmission Module, and the truck has been shifting like new ever since. It’s a classic case where the root cause is the controller, not the mechanical parts.
A Straightforward Guide to Installation
For the DIY mechanic, replacing the TCM on a Trailblazer is a very manageable job that typically takes less than 30 minutes. Our pre-programmed module makes it a true plug-and-play repair.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: On the 2006-2009 Trailblazer, the TCM is typically found in the engine compartment on the driver’s side (LH side).
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Press the release tabs firmly to avoid damaging them. 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 in.
- Final Steps: Reconnect the battery terminal. While our programming handles the critical setup, it’s always good practice to use a basic OBD2 scan tool to clear any stored fault codes from the ECU. Start the vehicle and test drive to confirm smooth shifting.
Verified Vehicle Compatibility
This T42 Transmission Control Module is a guaranteed fit for your 2006-2009 Trailblazer (including models with the 8-cylinder engine). It is also a direct replacement for numerous other GM vehicles, including:
- ✔️ Chevrolet Silverado, Tahoe, Suburban, Impala, HHR, Cobalt
- ✔️ GMC Sierra, Yukon, Savana, Envoy
- ✔️ Buick LaCrosse, Lucerne, Rainier
- ✔️ Cadillac DTS
- ✔️ Pontiac G6, Grand Prix
- ✔️ Hummer H3 and Saab 9-7X
This part is interchangeable with service numbers 24235340, 24242391, 24234503, 24252114, and others to ensure wide-ranging compatibility.
Frequently Asked Questions
Do I need to take my truck to the dealer after installing this?
No. This module comes fully programmed to your vehicle’s VIN. It is ready for installation right out of the box, with no additional programming or dealer visits required.
Is this a difficult part to install myself?
Not at all. For most DIYers with basic hand tools, this is a simple, sub-30-minute job. The module is easily accessible in the engine bay on the Trailblazer.
Will this 2006-2009 Trailblazer Transmission Module fix a P0700 code?
A P0700 code is a general fault request from the TCM to the main engine computer. While a faulty TCM is a very common cause, this code indicates that a more specific transmission code is stored. This module often resolves the underlying issue causing the P0700, but you should scan for all codes to be certain.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old module, so there’s no need to worry about the cost or hassle of sending it back.