If your 2006-2009 Buick LaCrosse is suffering from erratic shifting, getting stuck in gear, or has an illuminated check engine light, a failing Transmission Control Module (TCM) is often the culprit. I’ve seen it hundreds of times in the shop: a great car sidelined by a frustrating electronic issue. This T42 TCM, part number 24235340, is the reliable, straightforward solution to restore your vehicle’s performance and get you back on the road with confidence.
The TCM is the brain of your automatic transmission, responsible for managing every gear change, controlling torque converter lockup for fuel efficiency, and communicating with the main engine computer. When it fails, the symptoms can range from annoying to dangerous. Our module is meticulously prepared to solve these issues permanently.
Case Study: A Tricky Diagnosis
A customer brought in a 2008 LaCrosse with classic transmission symptoms: harsh 1-2 shifts and occasionally getting stuck in 3rd gear (limp mode). He had already replaced two shift solenoids based on some forum advice, but the problem persisted. A quick scan showed a P0700 (Transmission Control System Malfunction) and an intermittent solenoid circuit code. In my experience, when you see a general code like P0700 paired with what seems to be a moving target electrical fault, the TCM itself is the most likely point of failure. The internal drivers that control the solenoids had weakened. We installed a VIN-programmed TCM, and the car drove like new. This part saved him from a costly and unnecessary transmission rebuild.
Is Your LaCrosse Showing These Symptoms?
A faulty TCM can manifest in several ways. If you’re experiencing any of the following, this module is your likely solution:
- ✔ Harsh, delayed, or unpredictable gear shifts.
- ✔ The vehicle is stuck in a single gear (often called limp mode).
- ✔ Check Engine Light is on with transmission-related Diagnostic Trouble Codes (DTCs) like P0700, P0750, or other solenoid codes.
- ✔ Failure to upshift or downshift correctly.
- ✔ A noticeable drop in fuel economy.
- ✔ The ‘PRNDL’ display on your dash is not showing the correct gear.
A Straightforward Guide to Installation
For the 2006-2009 Buick LaCrosse, this job is well within the reach of a DIY enthusiast. The module is conveniently located under the lower air cleaner housing, making it accessible without special lifts. You can have this swapped in about 30 minutes.
- Safety First: Disconnect the negative terminal from your car’s battery to prevent any electrical shorts and to help reset the vehicle’s electronic systems.
- Access the Module: Remove the air cleaner assembly to gain clear access to the old TCM. It’s held in place by a few bolts.
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly and pull straight out. Avoid wiggling them too much. Once disconnected, unbolt and remove the old module.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Reconnect the electrical harnesses securely—you should hear a click.
- Final Steps: Reinstall the air cleaner assembly and reconnect the battery terminal. Start the car and let it idle for a few minutes. It’s a good practice to use a basic OBD2 scanner to clear any stored fault codes after the repair.
Why Our Programmed 2006-2009 LaCrosse TCM is the Best Choice
The single biggest advantage of this module is our expert VIN programming service. We flash the module with your car’s specific Vehicle Identification Number and the latest GM software updates before it ships. This means it’s a true plug-and-play part. You avoid the time, hassle, and significant expense of having a dealership program it for you. This is the same process we use in our own repair facility to guarantee a successful repair every time.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24235340 and is interchangeable with other service numbers such as 24252114, 24234503, 24230461, and more. While this page focuses on the 2006-2009 LaCrosse TCM, this module also fits a wide range of other GM vehicles, including:
- Buick Allure (2006-2009) – Transmission; (lower air cleaner housing)
- Chevrolet Impala (2006-2011) – Transmission; (lower air cleaner housing)
- Chevrolet Monte Carlo (2006-2007) – Transmission; (lower air cleaner housing)
- Pontiac Grand Prix (2006-2008) – Transmission; (lower air cleaner housing)
- …and many other GM cars, trucks, and SUVs from 2006-2014. Please verify your part number for an exact match.
Frequently Asked Questions
Do I need to get this programmed by a dealer?
No. This module comes pre-programmed to your vehicle’s VIN. It is ready for installation right out of the box, saving you a trip to the dealership and additional programming fees.
Where is the TCM located on my 2007 Buick LaCrosse?
On the 2006-2009 Buick LaCrosse, the Transmission Control Module is located in the engine bay, underneath the lower air cleaner housing. It’s a relatively easy part to access for replacement.
Is this part difficult to install myself?
Not at all. For someone with basic hand tools, this is a straightforward job that typically takes less than an hour. Our installation guide above provides the key steps.
What is a core charge?
A core charge is a deposit you pay until you return your old part. We do not require a core charge for this module, so you can keep your old part without any hassle.
Will this fix a P0700 trouble code?
Yes, in many cases. The P0700 code is a general fault code indicating a problem within the transmission control system. A failing TCM is one of the most common causes for this code, especially when accompanied by other transmission symptoms.