End Your Buick’s Shifting Nightmares
If your 2006-2009 Buick LaCrosse is suffering from harsh shifts, getting stuck in gear, or throwing transmission-related check engine lights, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen countless drivers worry they need a full transmission rebuild when the real culprit is a faulty Transmission Control Module (TCM). This VIN-programmed T42 TCM, part number 24239926, is the reliable, direct-fit solution to restore the smooth, predictable performance your vehicle had when it was new.
The TCM is the electronic brain of your automatic transmission. It processes data from various sensors to command precise gear changes and manage torque converter operation. When it fails, the symptoms can be alarming and make your car feel unsafe to drive. This module is meticulously prepared with your vehicle’s specific VIN, ensuring it communicates flawlessly with your car’s systems right out of the box—no expensive dealership programming needed.
A Technician’s Notebook: The Misdiagnosed Transmission
A customer brought in their ’08 LaCrosse with classic symptoms: banging into gear and a transmission warning light. They were convinced the transmission was shot and were bracing for a multi-thousand dollar bill. After a quick scan, I saw a P0700 code (Transmission Control System Malfunction) and several solenoid circuit codes. Instead of pulling the pan, I first checked the TCM. In these vehicles, the TCM is located under the air cleaner housing, exposed to heat and vibration. After swapping in a VIN-programmed module—a 30-minute job—all the codes cleared and the car shifted like a dream. It’s a textbook case of how this simple part can solve what appears to be a catastrophic failure.
Is Your LaCrosse Showing These Symptoms?
A failing TCM will give you clear warning signs. If you’re experiencing any of the following, this module is your likely solution.
- ✔ Harsh, erratic, or delayed gear shifts that make driving uncomfortable.
- ✔ The vehicle is stuck in “limp mode,” often refusing to shift out of 2nd or 3rd gear.
- ✔ Check Engine Light or Transmission Warning Light is illuminated on the dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750, P0753, or other solenoid-related faults.
- ✔ A noticeable drop in fuel economy due to inefficient shifting.
- ✔ Complete loss of communication with the transmission, leading to a no-shift condition.
A Straightforward Guide to Installation
This is a repair you can confidently tackle in your own driveway. For the 2006-2009 Buick LaCrosse, the TCM is located under the lower air cleaner housing, making it easily accessible.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electronic work.
- Access the Module: Remove the air cleaner assembly to expose the TCM mounted below it.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old TCM. Then, unbolt the module from its mounting bracket.
- Install the New TCM: Mount the new module securely, reconnect the electrical harnesses, and reinstall the air cleaner assembly.
- Final Steps: Reconnect the battery. While our VIN programming handles the critical setup, it’s good practice to use a basic OBD2 scanner to clear any stored fault codes.
Guaranteed Vehicle Compatibility
This T42 TCM is the correct replacement for part number 24239926 and is interchangeable with a wide range of other service numbers. While it is a guaranteed fit for the 2006-2009 Buick LaCrosse, it also fits many other GM vehicles, including:
- Buick Allure, Lucerne, Rendezvous
- Chevrolet Cobalt, HHR, Impala, Malibu, Monte Carlo, Silverado, Tahoe, Express Van
- GMC Canyon, Envoy, Sierra, Yukon, Savana Van
- Pontiac G5, G6, Grand Prix
- Cadillac DTS
- Saturn Aura, Ion, Vue
- And more…
Frequently Asked Questions
Frequently Asked Questions
Do I need to take my car to a dealer after installing this part?
No. This Transmission Control Module is pre-programmed to your vehicle’s VIN. This means it is ready for immediate installation and operation without any additional programming or dealer visits, saving you time and money.
What is the warranty on this 2006-2009 LaCrosse TCM?
This part comes with a one-year, hassle-free warranty. We stand behind the quality and reliability of our electronic components.
Is this a difficult part to install for a DIYer?
Not at all. For the LaCrosse, the TCM is located under the air cleaner box. With basic hand tools, the replacement typically takes less than 30 minutes, making it a very DIY-friendly repair.
Will this fix a P0700 check engine light code?
Yes, in many cases. The P0700 code is a general fault request from the TCM to the main computer. If the root cause is a failing TCM, replacing it with this module will resolve the issue and allow the code to be cleared.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part without the hassle of returning it.