If your 2007 GMC Sierra 2500 is struggling with harsh shifts, getting stuck in gear, or throwing transmission codes, you’re not just dealing with an annoyance—you’re facing a potential loss of drivability and towing capability. As a technician with over two decades of experience, I’ve seen countless work trucks sidelined by a faulty Transmission Control Module (TCM). The T42 TCM is the electronic brain of your 4-speed automatic transmission (like the 4L80E in your Sierra), and when it fails, your truck’s performance grinds to a halt. This isn’t just a part; it’s the solution to restoring the reliable, smooth-shifting performance your truck was built for.
This replacement T42 TCM, part number 24243921, arrives at your door fully programmed to your truck’s specific Vehicle Identification Number (VIN). This is a critical step that many overlook. Without proper programming, a new module is just a paperweight. We handle the programming for you, using the latest GM software updates. This means no expensive trips to the dealership, no special scan tools for programming—just a straightforward installation that gets you back on the road or to the job site fast. This is the definitive fix for the issues caused by a failing 2007 Sierra 2500 Transmission Control Module.
Case Study: The Sierra That Wouldn’t Shift
A contractor brought his ’07 Sierra 2500 HD into my shop, frustrated. His truck, essential for his business, was stuck in what we call ‘limp mode’—it wouldn’t shift out of 3rd gear. He was worried he was looking at a full transmission rebuild, a costly and time-consuming job. After plugging in my scanner, I saw a P0700 (Transmission Control System Malfunction) and a few solenoid circuit codes. Instead of tearing into the transmission, I checked the TCM first. After swapping in a VIN-programmed module, all the codes cleared, and the truck shifted perfectly on the test drive. What he thought was a $3,000+ problem was a simple, 30-minute fix. This is the power of accurate diagnostics and the right part.
Diagnosing a Faulty 2007 Sierra 2500 Transmission Control Module
Transmission problems can be tricky, but a failing TCM often leaves a clear trail of evidence. If your truck is acting up, check if it’s showing any of the symptoms below. Catching it early can prevent further damage to your transmission’s mechanical components.
- ✔ Harsh, slamming shifts or erratic gear changes.
- ✔ The transmission feels like it’s slipping between gears.
- ✔ Vehicle is stuck in one gear (limp mode), often 2nd or 3rd.
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, P0753, P0758, or other solenoid-related faults.
- ✔ Delayed engagement when shifting from Park to Drive or Reverse.
- ✔ A noticeable decrease in fuel economy.
A Straightforward Guide to Installation
One of the best features of this part is its ease of installation. For the 2007 Sierra 2500 (new body style), the process is simple and requires only basic hand tools. You can have your truck running right in your own driveway in under half an hour.
- Safety First: Disconnect the negative terminal from your truck’s battery to prevent any electrical shorts and to help reset the system.
- Locate the TCM: On your Sierra 2500, the Transmission Control Module is typically located in the engine bay, right next to the battery. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the electrical harness connectors from the old module. Press the release tabs firmly. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, VIN-programmed TCM into place. Securely reconnect the electrical harnesses, ensuring they click into place.
- Final Steps: Reconnect the negative battery terminal. Start the truck and let it idle for a few minutes. If you have a basic OBD2 scanner, it’s a good practice to clear any stored fault codes. Take the truck for a test drive to confirm smooth shifting.
Verified Vehicle Compatibility
While this is the correct 2007 Sierra 2500 Transmission Control Module, the T42 platform was used across a wide range of GM vehicles. This module is guaranteed to be a direct-fit replacement for the following models and configurations. It is interchangeable with part numbers 24252114, 24234503, 24230461, 24239224, and others listed in the original specifications.
- GMC Sierra 2500 Pickup (2007): New style (smooth door skin), 6.0L, located next to the battery.
- Chevrolet Silverado 2500 Pickup (2007): New style (smooth door skin), 6.0L, located next to the battery.
- GMC & Chevrolet 1500/3500 Series Trucks & Vans (2006-2014): Check specific location notes (e.g., next to battery, RH engine compartment).
- Chevrolet Tahoe & GMC Yukon (2007-2009): Located next to the battery.
- Cadillac, Buick, Pontiac, Saturn, Hummer & Saab Models (2006-2011): Compatible with various models like the DTS, LaCrosse, G6, Vue, H3, and 9-7X. Always verify location and engine type.
Do I need to do any programming myself?
Do I need to do any programming myself?
No. This module comes pre-programmed to your vehicle’s VIN. Just provide your VIN at checkout, and we handle the rest. It’s ready for installation right out of the box, with no need for a trip to the dealer.
Is a core charge required?
No, there is no core charge. You can keep your old part, so you don’t have to worry about the hassle and expense of shipping it back.
What tools are needed for installation on a Sierra 2500?
You’ll only need basic hand tools. A simple socket set to unbolt the module from its bracket and a wrench to disconnect the battery terminal are typically all that’s required.
Will this fix a P0700 check engine light code?
Yes, in many cases. The P0700 code is a general fault code indicating the TCM has detected a problem. If the TCM itself is the source of the failure, replacing it will resolve the P0700 code and any related solenoid or sensor codes it was setting.