If you’re dealing with the frustrating and unpredictable performance of a failing transmission control module in your 2007-2008 Chevrolet Avalanche 1500, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen firsthand how a faulty TCM can turn a reliable truck into a source of constant stress. This VIN-programmed T42 Transmission Control Module is the definitive, no-hassle solution to restore the crisp, smooth shifting your truck had from the factory.
The TCM is the electronic brain of your 4L60E, 4L65E, or 4L70E automatic transmission. It precisely manages hydraulic pressure, shift solenoid timing, and torque converter lockup. When it begins to fail—often due to heat cycles and electronic wear—the symptoms can range from merely annoying to downright dangerous. This module is the key to resolving those issues permanently, without the high cost and inconvenience of a dealership visit for programming.
From the Diagnostic Bay: The Intermittent Limp Mode Mystery
A customer brought in his ’08 Silverado, a sister truck to the Avalanche, with a maddening problem. It would drive perfectly for days, then suddenly slam into gear and get stuck in what we call ‘limp mode’ (3rd gear only). He’d already replaced a shift solenoid with no luck. After hooking up my scan tool, I noticed intermittent communication loss with the TCM. These T42 modules are notorious for developing internal connection faults. We installed one of our VIN-programmed TCMs, and the problem was solved instantly. It’s a classic case where chasing individual codes can be misleading; the root cause is often the module itself.
Is Your Avalanche Exhibiting These Transmission Issues?
A failing 2007-2008 Avalanche 1500 TCM will often display clear warning signs. If you’re experiencing any of the following, a faulty module is the likely culprit:
- âś” Harsh, banging shifts or delayed gear engagement.
- âś” The truck gets stuck in one gear (limp mode) and won’t shift up or down.
- âś” Check Engine Light or Transmission Warning Light is on with codes like P0700 (Transmission Control System Malfunction) or various solenoid codes (P0751, P0756, etc.).
- âś” A noticeable drop in fuel economy as the transmission operates inefficiently.
- âś” Complete loss of communication with the transmission module, preventing diagnostics.
A Straightforward Guide to Installation
One of the best features of this part is its simple, DIY-friendly installation. For your Avalanche, the process is incredibly accessible and requires only basic tools.
- Safety First: Disconnect the negative terminal from your truck’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: On the 2007-2008 Avalanche, the TCM is conveniently located in the engine bay, right next to the battery.
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly. 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’ll hear a click as they lock in.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s good practice to use a basic OBD2 scanner to clear any stored fault codes from the vehicle’s memory.
Verified Vehicle Compatibility
This T42 TCM, part number 24239926, is a direct replacement for a wide range of General Motors vehicles. Please verify your model and the module’s location below:
- AVALANCHE 1500 07-08 (next to battery)
- SILVERADO 1500 PICKUP 07-13 (next to battery)
- TAHOE 07-09 (next to battery)
- SUBURBAN 1500 07-08 (next to battery)
- SIERRA 1500 PICKUP 07-13 (next to battery)
- YUKON / YUKON XL 1500 07-09 (next to battery)
- SAVANA/EXPRESS VANS 1500/2500/3500 06-14 (RH engine compartment)
- HUMMER H3 08-10 (RH rear engine compartment)
- COLORADO / CANYON 08-12 (RH rear engine compartment)
- TRAILBLAZER / ENVOY 06-09 (LH engine compartment)
- IMPALA 06-11 (lower air cleaner housing)
- GRAND PRIX 06-08 (lower air cleaner housing)
- LACROSSE / ALLURE 06-09 (lower air cleaner housing)
- COBALT / G5 / PURSUIT 06-10 (LH strut tower)
- …and many more GM models.
Frequently Asked Questions About This 2007-2008 Avalanche 1500 TCM
What does ‘VIN Programmed’ mean for me?
It means this module arrives at your door fully programmed with your truck’s specific Vehicle Identification Number and the latest GM software. It is a true plug-and-play part, requiring no expensive trips to the dealership for flashing or setup.
Will this fix my P0700 check engine light code?
Yes, in most cases. The P0700 code is a general fault code indicating the TCM has detected a problem. Replacing a faulty TCM is the correct fix for this code and any related solenoid or sensor codes originating from the module itself.
Is this a reliable part?
Absolutely. This module is built to meet or exceed OEM specifications for performance and durability. It comes with a one-year warranty, giving you peace of mind for your repair.
Do I need to send my old TCM back?
No. There is no core charge or requirement to return your old part. You can dispose of it at your convenience, making the repair process simpler and faster.