If your 2006-2007 Buick Terraza is suffering from jerky shifting, getting stuck in gear, or throwing transmission codes, you’re not just dealing with an annoyance—you’re facing a critical failure that compromises your vehicle’s reliability. As a technician with over two decades of experience, I’ve seen countless GM vehicles sidelined by a faulty Transmission Control Module (TCM). The T42 module, in particular, is the electronic brain of your automatic transmission, and when it fails, the symptoms can range from poor fuel economy to a complete inability to shift. This isn’t a problem you can ignore.
This is the definitive solution: a high-quality, VIN-programmed T42 Transmission Control Module, compatible with service part number 24252114. We take the guesswork and extra expense out of the repair. Before we ship it, we program the module to your Terraza’s specific Vehicle Identification Number (VIN), loading it with the latest GM software. This means it arrives ready for a true plug-and-play installation, restoring the precise, smooth shifting you expect without a costly trip to the dealership for programming.
Case Study: The Ghost in the Transmission
A customer brought in a 2007 Terraza with a frustratingly intermittent issue. It would shift perfectly for days, then suddenly slam into gear or refuse to upshift. No single solenoid code was consistent. After checking the wiring harness and fluid levels, my experience pointed to the TCM. These modules can develop internal fractures on the circuit board from years of heat cycles, causing unpredictable electrical faults. We installed one of our pre-programmed T42 modules, and the problem vanished instantly. The customer saved hundreds compared to a dealership diagnosis and repair, and the van was back to being a reliable family hauler.
Diagnosing a Faulty Terraza TCM: Common Symptoms
A failing TCM will give you clear warning signs. If you’re experiencing any of the following, the module is the most likely culprit, especially after you’ve ruled out low fluid levels or major mechanical issues.
- ✔ Harsh, banging shifts or erratic gear changes.
- ✔ The vehicle is stuck in “limp mode” (usually second or third gear).
- ✔ Check Engine Light or Transmission Warning Light is on with codes like P0700 (Transmission Control System Malfunction) or various solenoid-specific codes (e.g., P0751, P0756).
- ✔ Failure to upshift or downshift, leading to poor acceleration and high RPMs.
- ✔ A noticeable drop in fuel efficiency.
- ✔ Complete loss of communication with the module, preventing the vehicle from starting or shifting out of Park.
A Straightforward Guide to Installation
One of the best features of this part is its ease of installation, making it a perfect job for a DIY enthusiast. For the 2006-2007 Terraza, the TCM is conveniently located and accessible. The entire process should take less than 30 minutes.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the vehicle’s adaptive memory.
- Locate the Module: On the Terraza, the TCM is typically found on the driver’s side of the engine bay, mounted to the LH strut tower. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the electrical 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. Securely plug in the harness connectors, making sure they click to confirm they are fully seated.
- Final Steps: Reconnect the battery terminal. Start the vehicle and allow it to idle for a few minutes. While not always necessary, using a basic OBD2 scan tool to clear any stored fault codes is good practice. Take the vehicle for a test drive to confirm smooth shifting.
Verified Fitment Across GM Models
While this is the ideal 2006-2007 Terraza Transmission Control Module, the T42 platform was used extensively across the General Motors family. This part is a direct replacement for numerous models and is interchangeable with part numbers like 24234503, 24242391, and more. Please verify your specific model in the list below.
This part will fit these makes and models with these options
TERRAZA 06-07 Transmission; (LH strut tower)
… and many other GM vehicles including the Uplander, Montana, Impala, Cobalt, HHR, and more.
Frequently Asked Questions
Do I need to take my van to the dealer after installing this TCM?
No. This module comes fully programmed to your vehicle’s VIN. It is a plug-and-play solution that does not require any additional programming or flashing at a dealership, saving you time and money.
What is a core charge? Do I need to send my old part back?
There is no core charge for this part. You can keep your old module or dispose of it without any need to return it to us.
Will this fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. In a vast majority of cases where the TCM itself is the source of the failure, replacing it with this programmed unit will resolve the P0700 code and any related solenoid codes.
What tools do I need for installation?
Installation is simple and typically only requires basic hand tools, such as a socket set to remove the mounting bolts and potentially a small flathead screwdriver to help release the connector tabs.
Is this part covered by a warranty?
Yes, this part comes with a one-year warranty, giving you confidence and peace of mind in your repair.