Restore the Smooth, Reliable Shifting Your Buick LaCrosse Deserves
Is your 2006, 2007, 2008, or 2009 Buick LaCrosse suffering from harsh shifting, delayed gear engagement, or getting stuck in limp mode? These are classic signs of a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen how a faulty TCM can make a great car feel unpredictable and unsafe. This isn’t just an annoyance; it’s a critical failure that impacts your vehicle’s performance, fuel economy, and overall health. This direct-fit T42 TCM, part number 24238856, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
A Technician’s Notebook: The Jerky LaCrosse Case
A customer brought in a 2008 LaCrosse with a complaint I’ve heard hundreds of times: “It feels like it gets kicked from behind when it shifts.” The check engine light was on, and a quick scan revealed code P0700 (Transmission Control System Malfunction) and a few solenoid performance codes. Instead of jumping to a costly transmission rebuild, we checked the basics. The fluid was fine, and the wiring was intact. The culprit, as it so often is with these symptoms, was the original TCM. After installing one of our VIN-programmed modules—a job that took less time than the initial diagnostic—the car shifted like it just rolled off the factory floor. The codes were cleared and never returned. This is the fix that gets your car back to normal without guesswork.
Is Your LaCrosse Showing These Telltale Signs?
A failing TCM doesn’t heal itself; it only gets worse. If you’re noticing any of the following issues, it’s time to address the problem before it causes more serious transmission damage. A new 2006-2009 LaCrosse TCM is often the most direct path to a solution.
- ✔ Erratic and Harsh Shifting: Abrupt, jerky gear changes or a noticeable slam when shifting between gears.
- ✔ Vehicle Stuck in Limp Mode: The transmission defaults to a single gear (usually 2nd or 3rd) to prevent further damage, severely limiting your speed.
- ✔ Check Engine Light and Warning Lights: The Check Engine or Transmission warning light is illuminated, often with Diagnostic Trouble Codes (DTCs) like P0700, P0750, P0751, or other solenoid-related faults.
- ✔ Delayed Engagement: A long pause after shifting from Park into Drive or Reverse before the gear engages.
- ✔ Poor Fuel Economy: Inefficient shifting and failure of the torque converter to lock up properly can cause a significant drop in MPG.
- ✔ No Communication with Scan Tool: In some cases, the module fails completely and will not communicate with diagnostic tools.
Your 30-Minute Path to a Smooth Ride
One of the best features of this module is its accessibility. For the Buick LaCrosse, the TCM is located in the engine bay, not buried inside the transmission. This makes it a perfect job for a DIY enthusiast with basic hand tools. No lifts, no dropping pans, no mess.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the TCM: On your 2006-2009 LaCrosse, you’ll find the TCM bolted to the lower air cleaner housing. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unclip the wiring harness connectors. Then, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Reconnect the wiring harnesses, ensuring they click securely into place.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it idle for a few minutes. While the module is plug-and-play, it’s always good practice to use a basic scan tool to clear any stored fault codes from the computer’s memory.
Verified Fitment for Your Buick LaCrosse
This Transmission Control Module is guaranteed to be a direct-fit replacement for the following vehicle, providing a seamless repair. This module is the correct solution for your 2006-2009 LaCrosse TCM replacement.
- Buick LaCrosse: 2006, 2007, 2008, 2009 (Located at the lower air cleaner housing)
This T42 TCM is also compatible with a wide range of other GM vehicles, including various models of the Chevrolet Silverado, Tahoe, Impala; GMC Sierra, Yukon; Pontiac G6; and Saturn Aura. It is interchangeable with part numbers 24252114, 24234503, 24238856, and others.
Frequently Asked Questions
Do I need to take my car to the dealership for programming?
No. This is the biggest benefit. We program the module to your car’s VIN before it ships. When you receive it, it’s ready for installation right out of the box, saving you hundreds in dealership fees.
Is this a difficult part to install myself?
Not at all. For the Buick LaCrosse, the TCM is in the engine compartment and easily accessible. With basic tools, most people can complete the swap in under 30 minutes. Just follow our installation guide above.
Will this fix my P0700 code?
A P0700 code is a general fault code indicating the TCM has detected a problem. Often, a failing TCM is the root cause. Replacing it with this pre-programmed unit is a very common and effective way to resolve P0700 and related transmission codes.
What is a core charge?
A core charge is a deposit you pay until you return your old part. We don’t require one. You can keep your old module, which simplifies the process for you.
What information do you need to program the module?
We only need your vehicle’s 17-digit Vehicle Identification Number (VIN). You can typically find this on your dashboard (visible through the windshield) or on your vehicle registration or insurance card.