Restore Peak Performance to Your GM Vehicle’s Transmission
Is your 2006-2009 GMC Envoy, Chevrolet Trailblazer, or other compatible GM vehicle suffering from erratic shifting, delayed gear engagement, or a persistent check engine light? These are classic symptoms of a failing Transmission Control Module (TCM). The TCM is the electronic brain of your automatic transmission, responsible for executing smooth, precise gear changes. When it fails, it can lead to poor performance, decreased fuel economy, and even leave you stranded in limp mode. This genuine OEM-quality T42 TCM, service part number 24239926, is the definitive solution to restore your vehicle’s drivability and reliability.
From the Diagnostic Bay
We recently had a 2008 GMC Sierra come into the shop with what the owner described as a ‘completely shot transmission.’ It was banging into gear and occasionally wouldn’t shift past 2nd. Another shop had quoted him over $3,500 for a transmission rebuild. We hooked up our scanner and pulled a P0752 (Shift Solenoid ‘A’ Stuck On) code. While this can indicate an internal issue, on these GM 4-speed automatics, it’s often the TCM driver circuit that fails. We installed this exact VIN-programmed T42 module, cleared the codes, and the truck shifted perfectly. A 30-minute fix saved the customer thousands. Always diagnose the TCM before condemning the entire transmission.
Is Your Vehicle Showing Signs of a Faulty TCM?
A failing transmission computer can manifest in several ways. If you’re experiencing any of the following, it’s highly likely your TCM is the culprit:
- ✔ Unpredictable, harsh, or slamming gear changes.
- ✔ Delayed engagement when shifting from Park to Drive or Reverse.
- ✔ Vehicle is stuck in a single gear (often called ‘limp mode’).
- ✔ The check engine light or a specific transmission warning light is illuminated.
- ✔ Diagnostic trouble codes (DTCs) are present, such as P0700, P0750, P0751, P0753, P0756, or other solenoid-related faults.
- ✔ A sudden and unexplained drop in fuel efficiency.
- ✔ The torque converter fails to lock up at highway speeds, causing high RPMs.
The Direct-Fit Solution: Your Envoy Transmission Control Module
This isn’t just a replacement part; it’s a complete, ready-to-install solution. The most critical feature is our complimentary VIN programming service. We flash the module with your vehicle’s specific Vehicle Identification Number and the latest GM software updates before it ships. This ensures that the TCM communicates flawlessly with your vehicle’s engine computer and other systems, eliminating the need for an expensive trip to the dealership for programming. It’s a true plug-and-play fix that restores OEM functionality right out of the box. Built to strict factory standards, this module ensures long-lasting durability and performance for your Envoy Transmission Control Module and a wide range of other GM trucks and cars.
Effortless Installation
Designed for both professional technicians and capable DIYers, installation is straightforward. The TCM is typically located in the engine bay for easy access. Common locations include the LH strut tower, next to the battery, under the air cleaner box, or on the RH side of the engine compartment, depending on your specific model. The entire process can usually be completed in under 30 minutes. Simply disconnect the battery, unplug the electrical connectors from the old module, unbolt it, and install the new one in its place. Reconnect everything, and you’re ready to go. We recommend using a basic scan tool to clear any stored fault codes after installation is complete.
Frequently Asked Questions
What is VIN programming and why is it required?
VIN programming loads your vehicle’s specific software and calibration files onto the module. This ensures the TCM operates correctly with your engine, gear ratios, and tire size. Without it, the vehicle may not start, shift properly, or may display error messages. Our service handles this for you, making it a plug-and-play part.
Will this fix my specific error code, like P0700?
This module is the direct remedy for failures causing codes like P0700 (Transmission Control System Malfunction) and various solenoid circuit codes (P0750-P0758, etc.). While P0700 is a general code indicating a transmission fault, it is very commonly triggered by a failing TCM.
Is this part difficult to install myself?
For most models, this is a very DIY-friendly repair. The module is located in the engine bay and requires only basic hand tools to replace. The most important steps are disconnecting the battery first and ensuring the electrical connectors are securely seated on the new module.
Do I need to send my old TCM back?
No, there is absolutely no core charge for this part. You can keep your old module or recycle it locally, saving you the time and hassle of a return shipment.
How can I confirm this fits my vehicle?
This T42 TCM fits a vast range of 2006-2014 GM vehicles. The best way to confirm fitment is to match your original part number to one in our interchange list (e.g., 24252114, 24234503, 24239926). You can also use the fitment guide on this page or contact our support team with your VIN.