Restore Peak Performance to Your GM Truck with a VIN-Programmed T42 TCM
If you’re dealing with the frustration of a GMC Sierra that shifts hard, gets stuck in gear, or throws transmission codes, you’ve come to the right place. As a technician with over two decades of experience under the hood, I’ve seen countless drivers worry they need a full transmission rebuild when the real culprit is a faulty Transmission Control Module (TCM). This replacement T42 TCM, part number 24243921, is the definitive solution for your 2007-2013 Sierra 1500 TCM issues and a wide range of other GM vehicles.
The TCM is the brain of your automatic transmission, controlling everything from shift points and line pressure to torque converter lockup. When it fails, communication breaks down, leading to the unpredictable and often unsafe performance you’re experiencing. Our modules are meticulously prepared and programmed to your vehicle’s specific VIN, ensuring they work perfectly right out of the box. This isn’t just a replacement part; it’s a restoration of your truck’s original drivability and reliability.
From the Diagnostic Bay: The Sierra That Saved Thousands
A customer brought in his ’08 Sierra 1500, convinced his 4L60E transmission was shot. It was slamming into gear and occasionally going into limp mode. Another shop had quoted him over $3,000 for a transmission rebuild. I hooked up my scan tool and saw a classic P0752 (Shift Solenoid A Stuck On) code, but my pressure tests on the solenoid circuit were inconclusive. Experience told me to look at the controller first. Internal shorts in the T42 TCM can send erratic signals, mimicking a mechanical failure. We swapped in one of our VIN-programmed modules—a 30-minute job—cleared the codes, and the truck shifted like it just rolled off the factory line. He saved thousands of dollars by correctly identifying the electronic failure instead of jumping to a costly mechanical repair.
Is Your Truck Showing These Telltale Signs?
A failing TCM doesn’t always mean a complete shutdown. Often, the symptoms start small and get worse. Here are the most common indicators I see in the shop that point directly to a faulty module:
- ✔ Harsh, banging shifts or delayed gear engagement.
- ✔ The vehicle is stuck in “limp mode” (usually 2nd or 3rd gear) to protect the transmission.
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction), P0750-P0758 (solenoid circuit codes), or U-series communication codes.
- ✔ The transmission refuses to upshift or downshift correctly.
- ✔ A noticeable drop in fuel economy due to inefficient shifting.
- ✔ Intermittent loss of communication with the TCM, causing erratic behavior.
A Straightforward Guide to Installation
One of the best features of this module is its simple, DIY-friendly installation. You don’t need a lift or specialized transmission tools. For most GMT900 trucks like the Sierra, the process is quick and easy.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- Locate the TCM: On your 2007-2013 Sierra 1500, the TCM is typically located in the engine bay, right next to the battery. It’s a silver box with large electrical connectors.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that need to be released. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the wiring harnesses. Ensure they click into place.
- Final Steps: Reconnect the battery terminal. While our programming handles the critical setup, it’s always best practice to use a basic OBD2 scan tool to clear any stored fault codes from the vehicle’s memory. Start the engine and enjoy smooth shifting!
Verified Compatibility for Your GM Vehicle
This T42 TCM is a direct replacement for a vast array of General Motors cars, trucks, and SUVs. It is interchangeable with part numbers 24252114, 24234503, 24230461, 24243921, and more. Please verify fitment for your specific model below:
- GMC Sierra 1500/2500 Pickup (2007-2013): Located next to the battery.
- Chevrolet Silverado 1500/2500 Pickup (2007-2013): Located next to the battery.
- Chevrolet Tahoe/Suburban & GMC Yukon/Yukon XL (2007-2009): Located next to the battery.
- GMC Savana & Chevrolet Express Vans (2006-2014): Located in the RH engine compartment.
- Cadillac DTS (2006-2011): Located in the RH front engine compartment.
- Chevrolet Impala (2006-2011): Located under the lower air cleaner housing.
- Hummer H3 (2008-2010): Located in the RH rear engine compartment.
- …and many other GM models including the Cobalt, HHR, G6, LaCrosse, and more.
Frequently Asked Questions
Do I need to take my truck to the dealership for programming?
No. This module comes fully pre-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 there a core charge for my old part?
No, there is no core charge. You can keep your old part or recycle it locally without the hassle of shipping it back.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the Engine Control Module (ECM) to turn on the check engine light. While a faulty TCM is a very common cause, this code indicates a transmission-related fault exists. Replacing a bad TCM will resolve the underlying issue that triggers the P0700 code.
What tools do I need for installation?
For most installations, you will only need basic hand tools, such as a socket wrench (commonly 10mm) to disconnect the battery and unbolt the module. No specialized equipment is required.