If your 2007-2008 Chevrolet Avalanche 1500 is suffering from delayed shifts, getting stuck in gear, or throwing transmission codes, you’re not just dealing with an annoyance—you’re facing a critical component failure. The Transmission Control Module (TCM), the electronic brain of your automatic transmission, is likely the culprit. This replacement T42 TCM, part number 24243921, is the definitive solution to restore the crisp, reliable performance your truck was built for.
As a technician with over two decades of experience, I’ve seen countless GM trucks and SUVs come into the bay with these exact issues. The T42 module is a known failure point, but the fix doesn’t have to involve a costly trip to the dealership. We solve the biggest hurdle for you: programming. This module arrives at your door pre-programmed to your truck’s specific Vehicle Identification Number (VIN), making it a true plug-and-play repair. You get a reliable, OEM-spec part that communicates flawlessly with your vehicle’s systems right out of the box.
A Technician’s Notebook
I remember a 2007 Avalanche that came in with a classic case of what the owner called ‘transmission confusion.’ It would slam into gear from a stop and refuse to downshift on the highway. He was convinced he needed a full transmission rebuild, a multi-thousand-dollar job. After pulling the codes, I saw a P0752 for a stuck shift solenoid. While it could have been the solenoid itself, my experience with these 4L60E-equipped trucks pointed me straight to the TCM. We swapped in a VIN-programmed T42 module, cleared the codes, and the truck shifted like it just rolled off the assembly line. That’s the power of a correct diagnosis and a quality part—it saved the customer a massive headache and a ton of money.
Is Your Avalanche Exhibiting These Telltale Signs?
A failing TCM doesn’t always mean total transmission failure. Often, it presents as a series of frustrating electronic and mechanical symptoms. If you’re noticing any of the following, it’s a strong indicator that your 2007-2008 Avalanche 1500 TCM needs replacement:
- ✔ Unpredictable or harsh gear changes that slam or jerk the vehicle.
- ✔ The transmission seems to slip between gears or struggles to engage from Park.
- ✔ Your truck is stuck in ‘limp mode,’ often locked in 2nd or 3rd gear to prevent further damage.
- ✔ The Check Engine Light or a specific transmission warning light is illuminated on your dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as the general P0700 (Transmission Control System Malfunction) or specific solenoid codes (e.g., P0750, P0751, P0752).
- ✔ A noticeable drop in fuel efficiency as the transmission isn’t operating in the optimal gear.
A Straightforward Guide to Installation
One of the best parts of this solution is its simplicity. For the 2007-2008 Avalanche 1500, this is a job most DIYers can handle in their driveway in under 30 minutes. No specialized tools are needed.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electronic work. This prevents electrical shorts and helps reset the vehicle’s systems.
- Locate the Module: On your Avalanche, the TCM is conveniently located in the engine bay, right next to the battery. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, VIN-programmed TCM into place. Securely plug in the wiring harnesses, ensuring they click and lock into position.
- Final Steps: Reconnect the battery terminal. While our programming handles the critical setup, it’s good practice to use a basic OBD2 scan tool to clear any lingering fault codes from the system’s memory. Start the engine and take it for a test drive to confirm smooth shifting.
Verified Vehicle Compatibility List
This T42 Transmission Control Module is a direct-fit replacement for a wide range of General Motors vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. While this page is focused on the 2007-2008 Avalanche 1500 TCM, it also fits the following models. Please confirm your specific model and year.
- AVALANCHE 1500 07-08 Transmission; (next to battery)
- COLORADO 08-12 Transmission; (RH rear engine compartment)
- CANYON 08-12 Transmission; (RH rear engine compartment)
- ENVOY & ENVOY XL 06-09 Transmission; (LH engine compartment)
- EXPRESS / SAVANA VANS 1500/2500/3500 06-14 Transmission; (RH engine compartment)
- HUMMER H3 08-10 Transmission; (RH rear engine compartment)
- SILVERADO / SIERRA 1500 07-13 Transmission; (next to battery)
- SUBURBAN 1500 07-08 Transmission; (next to battery)
- TAHOE / YUKON 07-09 Transmission; (next to battery)
- TRAILBLAZER & TRAILBLAZER EXT 06-09 Transmission; (LH engine compartment)
- And many other Buick, Cadillac, Chevrolet, GMC, Pontiac, and Saturn cars and SUVs.
Frequently Asked Questions
What exactly does ‘VIN Programmed’ mean for me?
It means this module is ready for installation the moment you receive it. We flash it with the latest GM software calibrated specifically to your truck’s VIN. This eliminates the need for expensive programming at a dealership, saving you time and money and ensuring perfect compatibility.
Is this part difficult for a DIYer to install?
Not at all. For the Avalanche, the TCM is located right next to the battery, making it one of the easiest modules to access and replace. With basic hand tools, the entire job can typically be completed in under 30 minutes.
Will this fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. While this module often resolves the root cause (which could be an internal failure triggering the P0700), you should always diagnose any other codes that appear alongside it. In many cases, a faulty TCM is the primary issue.
Do I need to return my old part (core)?
No. There is no core charge for this part. You can keep, recycle, or dispose of your old module without any hassle or extra fees.
What kind of warranty is included?
This module is backed by our one-year warranty, giving you peace of mind and confidence in your repair. We stand by the quality and reliability of our programmed electronics.