Restore Your Trailblazer’s Shifting Performance
If your 2006-2009 Chevrolet Trailblazer is suffering from harsh shifting, getting stuck in gear, or throwing transmission codes, the culprit is often a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen these T42 modules cause some of the most frustrating and misdiagnosed issues. This replacement TCM, part number 24243921, is the definitive solution to get your SUV’s transmission operating smoothly and reliably again.
The biggest hurdle with electronic module replacement has always been the expensive and time-consuming trip to the dealership for programming. We eliminate that step completely. By providing your vehicle’s VIN during checkout, we program the module with the latest GM software before it even ships. This ensures it communicates perfectly with your Trailblazer’s engine computer and other systems right out of the box, making for a true plug-and-play repair.
Case Study: A Tricky Diagnosis
A customer brought in his ’08 Trailblazer with a classic complaint: it felt like it was starting in third gear and wouldn’t shift. The check engine light was on, and his local shop quoted him for a full transmission rebuild after seeing a P0750 shift solenoid code. I’ve seen this exact scenario dozens of times. We hooked up our pro-level scan tool and saw erratic data from the TCM. Instead of a costly internal repair, we installed one of our pre-programmed T42 modules. In under 30 minutes, the codes were cleared, the transmission was shifting perfectly, and the customer saved thousands of dollars. It’s often the brain, not the brawn, of the transmission that fails.
Is Your Trailblazer Showing These Symptoms?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, this module is the likely solution for your 2006-2009 Trailblazer TCM issues:
- ✔ Harsh, delayed, or erratic gear shifts.
- ✔ Vehicle is stuck in “limp mode” (usually second or third gear).
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750-P0758, or other solenoid-related faults.
- ✔ Failure to upshift or downshift properly.
- ✔ A noticeable decrease in fuel economy.
- ✔ Complete loss of communication with the TCM.
A Straightforward Guide to Installation
For the average DIYer, replacing the TCM is a simple job that typically takes less than 30 minutes. On the 2006-2009 Trailblazer, the TCM is conveniently located in the engine compartment on the driver’s side (LH).
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electronic repair.
- Locate the Module: Open the hood and find the TCM, which is typically mounted in the LH engine compartment. It’s a silver box with several large electrical connectors.
- Disconnect and Remove: Carefully unclip and remove the electrical connectors. Then, unbolt the module from its mounting bracket.
- Install the New TCM: Mount the new, VIN-programmed module in place and securely fasten the bolts. Reconnect the electrical connectors, ensuring 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 basic scan tool to clear any stored 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 Transmission Control Module is a direct-fit replacement for the original part in the following vehicles, among others. It is engineered to OEM specifications for a perfect match.
- Chevrolet Trailblazer: 2006-2009 (8-cylinder and standard models)
- GMC Envoy / Envoy XL: 2006-2009 (8-cylinder and standard models)
- Saab 9-7X: 2006-2009
- Chevrolet Silverado & GMC Sierra: 2007-2013 (various configurations)
- Chevrolet Tahoe & GMC Yukon: 2007-2009
- Chevrolet Impala: 2006-2011
- Pontiac G6 / Grand Prix: 2006-2010
This module also interchanges with part numbers: 24242391, 24234503, 24252114, 24230461, 24234274, 24239224, 24243901, and more. If you’re unsure about fitment, our expert support team is here to help.
Frequently Asked Questions
Do I need to take my vehicle to a dealer after installation?
No. This module is fully pre-programmed to your vehicle’s VIN number before shipping. This makes it a true plug-and-play solution, saving you the time and expense of a dealership visit.
Is this a new or used part?
This is a high-quality, OEM-standard replacement part, not a used component from a junkyard. It is tested to ensure reliability and is backed by our one-year warranty.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the main engine computer (ECM) to turn on the check engine light. While this module often resolves the underlying issue causing the P0700 code (like a solenoid fault), you should diagnose the specific transmission codes that are also present to confirm the TCM is the root cause.
Where is the TCM located on my 2007 Trailblazer?
On the 2006-2009 Trailblazer and its platform mates (Envoy, Rainier, 9-7X), the TCM is located in the engine compartment on the driver’s side (LH).
Is there a core charge for my old part?
No, there is no core charge. You can keep your old module or dispose of it without the hassle of returning it.