Is your 2007-2008 Chevrolet Avalanche 1500 struggling with harsh shifts, getting stuck in gear, or throwing transmission codes? A failing Transmission Control Module (TCM) is one of the most common culprits behind these frustrating and potentially damaging issues. This replacement T42 TCM, part number 24238856, is the reliable, cost-effective solution to restore your truck’s performance and get you back on the road with confidence. Forget expensive dealership visits and programming fees—this module arrives pre-programmed to your truck’s specific VIN for a true plug-and-play installation.
A Technician’s Notebook
I remember a 2008 Avalanche that came into my shop with a classic complaint: intermittent ‘limp mode.’ The owner had already replaced a shift solenoid with no luck. On the highway, it would drive fine, but around town, it would suddenly refuse to shift out of 3rd gear. After hooking up my scan tool, I saw a generic P0700 code but also intermittent communication loss with the TCM. Instead of a costly transmission teardown, we started with the brain. A quick swap to a VIN-programmed TCM like this one solved the problem instantly. Heat soak and vibrations are the biggest enemies of these modules, causing internal solder joints to fail over time—a common issue I’ve diagnosed on hundreds of GM trucks.
Is Your Avalanche Exhibiting These Transmission Faults?
A faulty TCM can manifest in various ways, often mimicking mechanical transmission failure. If you’re experiencing any of the following, this module is the likely solution for your 2007-2008 Avalanche 1500 TCM issues:
- ✔ Harsh, jerky, or delayed gear shifts that make driving uncomfortable.
- ✔ The vehicle is stuck in a single gear (often called ‘limp mode’) to prevent further damage.
- ✔ Check Engine Light or Transmission Warning Light is illuminated on the dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction) or specific solenoid codes (e.g., P0751, P0756).
- ✔ A noticeable drop in fuel economy as the transmission isn’t operating efficiently.
- ✔ Complete loss of communication with the module, preventing diagnostics.
DIY-Friendly Installation in Under 30 Minutes
One of the biggest advantages of this module is its straightforward installation. Since it’s pre-programmed, you don’t need any specialized dealer tools. For the 2007-2008 Avalanche, the TCM is conveniently located in the engine bay.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the Module: On your Avalanche 1500, the TCM is typically found next to the battery in the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors. Use a socket wrench to remove the bolts holding the old module in place.
- Install the New TCM: Mount the new module securely and reconnect the electrical harnesses. Ensure they click into place.
- Final Steps: Reconnect the 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.
Verified Vehicle Compatibility
This T42 Transmission Control Module is a direct replacement for part number 24238856 and other interchangeable numbers. It is guaranteed to fit the following models and configurations:
- AVALANCHE 1500 07-08 Transmission; (next to battery)
- TAHOE 07-09 Transmission; (next to battery)
- SUBURBAN 1500 07-08 Transmission; (next to battery)
- YUKON 07-09 Transmission; (next to battery)
- YUKON XL 1500 07-08 Transmission; (next to battery)
- SIERRA 1500 PICKUP 07-13 Transmission; (new style, smooth door skin), (next to battery), w/o hybrid
- SILVERADO 1500 PICKUP 07-13 Transmission; (new style, smooth door skin), (next to battery), w/o hybrid
- …and many other GM cars, trucks, and SUVs from 2006-2014. Please verify your part number for an exact match.
Frequently Asked Questions
Do I need to take my truck to the dealership for programming?
No. This module comes fully programmed to your vehicle’s VIN. It is a true plug-and-play solution, saving you the time and expense of a dealer visit.
Is this a reliable fix for my 2007-2008 Avalanche 1500 TCM?
Absolutely. This module is built to meet or exceed OEM specifications and addresses the common failure points of the original T42 TCMs. It’s a durable, long-term solution backed by our one-year warranty.
What tools are required for installation?
You only need basic hand tools, such as a socket set to remove the mounting bolts and disconnect the battery. No special diagnostic equipment is required for the installation itself.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part, which means no extra deposits and no hassle of shipping a core back to us.
Will this clear my Check Engine Light?
If the Check Engine Light is on due to a faulty TCM (e.g., codes like P0700), replacing the module will resolve the root cause. After installation, you should clear the codes with a scan tool to turn off the light.