Is Your Buick LaCrosse Shifting Erratically?
If you’re experiencing harsh shifts, delayed gear engagement, or your 2006-2009 Buick LaCrosse is stuck in limp mode, a failing Transmission Control Module (TCM) is the most likely cause. The TCM is the electronic brain of your automatic transmission, responsible for orchestrating every shift with precision. When it fails, it can lead to a cascade of performance issues, from poor fuel economy to a complete inability to drive. This T42 Transmission Control Module, part number 24238856, is the definitive solution to restore your vehicle’s smooth, reliable operation.
From the Diagnostic Bay
We recently had a 2008 LaCrosse come into the shop with classic symptoms of a bad transmission. The owner had already spent a significant amount of money replacing shift solenoids, thinking that was the issue, but the harsh 1-2 shift and P0700 code persisted. After a quick diagnostic, we identified the root cause: the original TCM was failing intermittently. Instead of another costly internal transmission repair, we installed one of our VIN-programmed T42 modules. The car was shifting perfectly within 30 minutes, saving the customer hundreds of dollars and the headache of further misdiagnosis.
The Direct-Fit Solution: Your 2006-2009 LaCrosse TCM
Don’t let a faulty module sideline your vehicle. Our T42 TCM is meticulously prepared to meet and exceed original equipment specifications. The most critical feature is our complimentary VIN programming service. We flash the module with your vehicle’s specific Vehicle Identification Number and the latest GM software updates before it ships. This ensures that it communicates flawlessly with your car’s powertrain control module (PCM) and other systems right out of the box. You get a true plug-and-play component that eliminates the need for expensive dealership programming or specialized scan tools.
Common Symptoms of a Failing LaCrosse TCM
- ✔ Harsh, slamming, or delayed gear shifts.
- ✔ The vehicle gets stuck in a single gear (limp mode).
- ✔ Check Engine Light or Transmission Warning Light is illuminated on the dash.
- ✔ Diagnostic Trouble Codes (DTCs) are stored, such as P0700, P0750, or other solenoid-related faults.
- ✔ Inconsistent upshifting or downshifting, leading to poor acceleration.
- ✔ A noticeable decrease in fuel efficiency.
- ✔ In severe cases, a complete loss of transmission function.
Installation and Compatibility
For the 2006-2009 Buick LaCrosse, the TCM is conveniently located under the lower air cleaner housing, making it accessible for a straightforward replacement. The process typically takes less than an hour for a DIY mechanic. Simply disconnect the battery, remove the air cleaner assembly, unplug the electrical connectors from the old module, unbolt it, and install the new one in its place. Once reconnected, the pre-programmed module is ready to go. This module is a direct replacement for a wide range of GM service numbers, including 24252114, 24234503, 24230461, 24238856, and more, ensuring broad compatibility across many GM vehicles equipped with 4-speed automatic transmissions like the 4L60E and 4L65E.
Frequently Asked Questions
Why is VIN programming necessary for this TCM?
VIN programming loads your vehicle’s specific software and calibrations onto the module. This ensures it communicates correctly with the engine and other vehicle systems, controlling shift points, line pressure, and torque converter lockup exactly as the manufacturer intended. Without it, the transmission will not function correctly.
Is this a difficult part to install myself?
For most individuals with basic mechanical skills, this is a straightforward installation. On the LaCrosse, it’s located under the air cleaner box. The process involves disconnecting the battery, removing the airbox, and swapping the module. Since our modules are pre-programmed, no special tools are needed for software flashing.
Will this module fix a P0700 trouble code?
A P0700 code is a general transmission fault request, meaning the TCM has detected a problem and asked the main computer to turn on the check engine light. While a faulty TCM is a very common cause for a P0700 code, it’s essential to diagnose any other codes that are present. This module will resolve the issue if the TCM itself is the source of the fault.
What is the warranty on this transmission control module?
This module comes with a one-year, unlimited mileage warranty, giving you peace of mind and confidence in your repair.
Do I need to return my old TCM (core charge)?
No, there is no core charge for this part. You can keep your old module without any extra fees or hassle, making the process simpler and more convenient for you.