Restore Your Buick’s Smooth Ride
Is your 2006-2009 Buick LaCrosse suffering from jarring shifts, delayed gear engagement, or a frustrating Check Engine light? Before you consider a costly transmission overhaul, the problem often lies with a faulty Transmission Control Module (TCM). As the electronic brain of your automatic transmission, the T42 TCM is responsible for every gear change. Over time, constant heat cycles and vibrations can cause internal components to fail, leading to the erratic performance you’re experiencing. This replacement T42 TCM, part number YNXS, is the reliable, cost-effective solution to get your LaCrosse driving like new again.
We take the guesswork and dealership hassle out of the equation. Each module is expertly programmed to your vehicle’s specific VIN before it ships. This means it arrives ready for a true plug-and-play installation, with the latest GM software updates already loaded. You get optimized shift points, correct torque converter lockup, and a permanent fix for common transmission-related Diagnostic Trouble Codes (DTCs). Don’t let a small electronic module sideline your car; this is a repair that both professional technicians and capable DIYers can perform with confidence.
A Technician’s Notebook: The Misdiagnosed Transmission
A customer brought in their ’08 LaCrosse with a classic complaint: harsh 1-2 shifts and occasionally getting stuck in 3rd gear (limp mode). Another shop had quoted them over $2,500 for a transmission rebuild, assuming mechanical failure. I pulled the codes and saw a P0752 (Shift Solenoid A Stuck On). In my 20 years of experience, I’ve learned that on these GM platforms, the solenoid code is often a symptom, not the cause. The T42 TCM is a known weak point. Instead of tearing down the transmission, we installed one of our pre-programmed TCMs. The total repair time was under an hour, the codes were cleared, and the car shifted perfectly on the test drive. The customer saved thousands and drove away with a reliable fix, not an unnecessary rebuild.
Diagnosing a Faulty Transmission Control Module
A failing TCM can mimic the symptoms of a major mechanical transmission problem. Identifying it correctly can save you a significant amount of time and money. If your vehicle is exhibiting any of the following behaviors, the TCM is a primary suspect. This is especially true if the issues are intermittent or worsen as the vehicle warms up. A faulty 2006-2009 LaCrosse Transmission Module can be the root cause of these headaches.
- ✔ Check Engine Light or Transmission Warning Light is illuminated on the dash.
- ✔ Your scanner shows DTCs like P0700 (Transmission Control System Malfunction), P0750-P0758 (Solenoid Codes), or U-series communication codes.
- ✔ Harsh, banging, or erratic gear shifts.
- ✔ The transmission hesitates or delays when shifting between Park, Reverse, and Drive.
- ✔ Vehicle feels stuck in one gear (often called ‘limp mode’).
- ✔ A noticeable drop in fuel economy.
- ✔ Inability to shift into higher gears.
Your 30-Minute Path to Smooth Shifting
Installing your new 2006-2009 LaCrosse Transmission Module is a straightforward process that most DIYers can complete in their own driveway. For the Buick LaCrosse, the TCM is conveniently located underneath the air cleaner housing.
- Step 1: Safety First Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Step 2: Access the Module Remove the engine cover and the air cleaner assembly. This will give you clear access to the old TCM.
- Step 3: Disconnect and Remove Carefully unplug the electrical connectors from the old module. Then, unbolt the module from its mounting bracket and remove it from the vehicle.
- Step 4: Install the New TCM Mount your new, VIN-programmed TCM onto the bracket and securely tighten the bolts. Reconnect the electrical harnesses, ensuring they click firmly into place.
- Step 5: Reassemble Reinstall the air cleaner assembly and engine cover. Reconnect the negative battery terminal.
- Step 6: Final Steps Start the vehicle. While our programming resolves most codes, it’s good practice to use a basic OBD2 scan tool to clear any stored or historical DTCs from the vehicle’s memory. Take the car for a test drive to confirm the smooth shifting performance.
Verified Vehicle Compatibility
This T42 TCM is a direct-fit replacement for a wide range of General Motors vehicles. While this page is focused on the 2006-2009 LaCrosse Transmission Module, it is also compatible with the following models. Please verify your model and the location notes.
- Buick Allure: 2006-2009 (lower air cleaner housing)
- Buick LaCrosse: 2006-2009 (lower air cleaner housing)
- Buick Lucerne: 2006-2011 (LH engine compartment)
- Buick Rainier: 2006-2007
- Buick Rendezvous: 2006-2007 (air cleaner box)
- Cadillac DTS: 2006-2011 (RH front engine compartment)
- Chevrolet Cobalt: 2006-2010 (LH strut tower)
- Chevrolet HHR: 2006-2011 (LH engine compartment)
- Chevrolet Impala: 2006-2011 (lower air cleaner housing)
- Chevrolet Malibu: 2006-2010 (LH frame rail)
- Chevrolet Monte Carlo: 2006-2007 (lower air cleaner housing)
- GMC Envoy / Envoy XL: 2006-2009 (LH engine compartment)
- Pontiac G6 / Grand Prix: 2006-2010 (LH strut tower / lower air cleaner housing)
- Saturn Aura / Ion / Vue: 2006-2010
…and many more GM trucks, vans, and SUVs. This module interchanges with part numbers: 24242391, 24234503, 24252114, 24230461, 24234274, 24235340, 24239224, 24256960, and YNXS.
Frequently Asked Questions
Frequently Asked Questions
What does VIN programming actually do?
VIN programming loads your vehicle’s specific software and calibrations onto the module before shipping. This ensures it communicates perfectly with your engine computer and other systems, providing correct shift points and performance without requiring a trip to the dealer for expensive programming.