Fix Your Buick’s Shifting Problems for Good

If you’re dealing with the frustration of a 2006-2009 Buick LaCrosse that shifts harshly, gets stuck in gear, or has a persistent check engine light, you’ve come to the right place. A faulty Transmission Control Module (TCM) is one of the most common culprits behind these issues. As a technician with over two decades of experience, I’ve seen how a failing TCM can make a reliable car feel unpredictable. This VIN-programmed T42 TCM, service number YNXS, is the definitive solution to restore the smooth, responsive performance your vehicle had when it was new.

This isn’t just a part; it’s a permanent fix. The module is the electronic brain of your 4-speed automatic transmission (like the 4L60E), managing everything from gear selection to torque converter clutch engagement. When it fails, communication breaks down, leading to the problems you’re experiencing. Our module comes pre-programmed to your vehicle’s specific VIN, making it a true plug-and-play component that requires no expensive trip to the dealership for additional programming. Get your car back on the road with confidence.

Is Your Buick LaCrosse Showing These Symptoms?

A failing TCM can manifest in several ways. If you’re noticing any of the following, it’s a strong indicator that your module needs replacement. Addressing it now can prevent more significant transmission damage down the line.

• ✔ Harsh, erratic, or delayed gear shifts.
• ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear).
• ✔ Check Engine Light or Transmission Warning Light is on.
• ✔ Diagnostic Trouble Codes (DTCs) are present, such as the general P0700 or specific solenoid codes (e.g., P0751, P0756).
• ✔ The transmission refuses to upshift or downshift properly.
• ✔ A noticeable drop in fuel economy.
• ✔ The torque converter doesn’t lock up, causing higher RPMs at highway speeds.

Your Straightforward 30-Minute Installation Guide

One of the best features of this module is its ease of installation. For the 2006-2009 LaCrosse TCM, the process is simple enough for a confident DIYer to complete in their own driveway.

1. Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
2. Locate the Module: On the Buick LaCrosse, the TCM is typically found bolted to the lower air cleaner housing in the engine bay. It’s a silver box with electrical connectors.
3. Disconnect and Remove: Carefully unplug the electrical harnesses from the old TCM. Then, unbolt the module from its mounting bracket and remove it from the vehicle.
4. Install the New Module: Bolt the new, pre-programmed TCM into place. Securely plug in the electrical connectors, ensuring they click into place.
5. Final Steps: Reconnect the negative battery terminal. Start the car and let it idle for a few minutes. If you have a basic OBD2 scan tool, use it to clear any remaining stored fault codes from the vehicle’s memory.

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 Buick LaCrosse, please verify your model and part number below. This part is interchangeable with service numbers 24252114, 24234503, 24230461, 24234274, 24235340, and YNXS among others.

• Buick Allure (2006-2009): Transmission; (lower air cleaner housing)
• Buick LaCrosse (2006-2009): Transmission; (lower air cleaner housing)
• Buick Lucerne (2006-2011): Transmission; (LH engine compartment)
• Chevrolet Cobalt (2006-2010): Transmission; (LH strut tower)
• Chevrolet HHR (2006-2011): Transmission; (LH engine compartment)
• Chevrolet Impala (2006-2011): Transmission; (lower air cleaner housing)
• Chevrolet Monte Carlo (2006-2007): Transmission; (lower air cleaner housing)
• Pontiac G6 (2006-2010): Transmission; (LH strut tower)
• Pontiac Grand Prix (2006-2008): Transmission; (lower air cleaner housing)
• And many more GM trucks, vans, and SUVs.