If your 2006-2007 Buick Terraza is suffering from harsh shifts, getting stuck in gear, or has the check engine light on, you’re likely dealing with a failed Transmission Control Module (TCM). As the electronic brain of your automatic transmission, a faulty TCM can make your family minivan unreliable and frustrating to drive. This is a common issue I’ve diagnosed hundreds of times in my shop on these GM platforms. The good news is that there’s a straightforward, reliable fix that doesn’t require an expensive trip to the dealership.
This is a direct-replacement, OEM-quality T42 TCM, part number YNXS, which comes fully pre-programmed to your Terraza’s specific Vehicle Identification Number (VIN). This critical step ensures it works perfectly right out of the box, restoring the precise shifting logic, torque converter clutch control, and fuel efficiency your vehicle had when it was new. You can bypass the dealer’s programming fees and long wait times, getting your van back on the road quickly and safely.
A Technician’s Notebook
I remember a customer bringing in their ’07 Terraza. The complaint was intermittent—sometimes it would shift perfectly, other times it would slam into gear or refuse to shift out of 2nd. They’d already replaced a shift solenoid with no luck. After hooking up my scan tool, I saw a generic P0700 (Transmission Control System Malfunction) code, but no specific solenoid codes. Live data showed erratic pressure commands from the TCM. This is a classic sign. The module’s internal processors were failing under heat, causing the unpredictable behavior. A new, programmed TCM like this one solved the problem instantly. The customer was thrilled to have their smooth, reliable family vehicle back without a massive repair bill.
Is Your Terraza Showing These Telltale Signs?
A failing TCM will often give clear warnings. If you’re experiencing any of the following, it’s time to consider a replacement 2006-2007 Terraza Transmission Module:
- ✔ Harsh, jerky, or delayed gear shifts.
- ✔ Vehicle is stuck in “limp mode” (usually second or third gear).
- ✔ The check engine light or a dedicated transmission warning light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) are present, especially P0700 or various solenoid-related codes (e.g., P0750, P0751, etc.).
- ✔ Complete loss of shifting capability or failure to engage a gear from park.
- ✔ A noticeable drop in fuel economy due to inefficient shifting.
Straightforward Installation Guide for Your Buick Terraza
Replacing the TCM on your Buick Terraza is a job most DIYers can handle in under 30 minutes with basic tools. The module is conveniently located for easy access.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electronic component replacement.
- Locate the Module: On the 2006-2007 Terraza, the TCM is typically found mounted on the driver’s side strut tower in the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Press the release tabs firmly to avoid damaging them. 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 should 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 OBD-II scan tool to clear any stored fault codes from the vehicle’s memory. Start the engine and take a test drive to confirm smooth shifting.
Verified Fitment Across a Range of GM Vehicles
While this is the correct 2006-2007 Terraza Transmission Module, this versatile T42 TCM is also a direct fit for a wide array of other General Motors vehicles. Please confirm your specific model and options below.
This part is a confirmed fit for:
BUICK TERRAZA 2006-2007 (Transmission; LH strut tower)
… and many other GM cars, trucks, and SUVs from 2006-2014 including the Chevrolet Silverado, Tahoe, Impala; GMC Sierra, Yukon; Pontiac G6; Saturn Vue, and more. Refer to the full compatibility list for details.
Frequently Asked Questions
Do I need to take this part to a dealer for programming?
No. This transmission control module comes fully programmed to your vehicle’s VIN. It is a true plug-and-play solution, saving you time and money.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old module without any hassle or need to return it.
Will this fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. In many cases where the TCM itself is the root cause of the issue, replacing it with this module will resolve the P0700 and any related codes.
What tools do I need for installation on my Terraza?
You will typically only need a basic socket set to remove the mounting bolts and potentially a flathead screwdriver to help release the electrical connector tabs. No special tools are required.