If your 2006-2009 Buick LaCrosse is suffering from harsh, erratic shifting or is stuck in limp mode, you’re not just dealing with an annoyance—you’re facing a critical component failure. As a technician with over two decades of experience, I’ve seen countless GM vehicles sidelined by a faulty Transmission Control Module (TCM). The good news is that the fix can be straightforward, affordable, and permanent with our VIN-programmed T42 TCM, part number 24230461.
This isn’t just a replacement part; it’s a complete solution. The TCM is the brain of your automatic transmission, responsible for every gear change, torque converter lockup, and line pressure adjustment. When it fails, communication between the engine and transmission breaks down, leading to the frustrating and potentially damaging symptoms you’re experiencing. Our module arrives pre-programmed to your LaCrosse’s specific VIN, eliminating the need for an expensive trip to the dealership for software flashing. It’s a true plug-and-play repair that restores the crisp, predictable shifting your car had when it was new.
From the Diagnostic Bay: The Intermittent LaCrosse
A customer brought in an ’08 LaCrosse with a complaint that stumped two other shops: intermittent, violent 1-2 shifts and occasional failure to shift out of 3rd gear, but with no consistent check engine light. They’d already replaced a shift solenoid with no luck. After a test drive, I suspected the TCM. On these T42 modules, internal circuit board failures due to heat and vibration are common. We swapped in one of our pre-programmed units, and the problem vanished instantly. The customer saved hundreds on further diagnostic guesswork and avoided a potential transmission rebuild. This is a classic failure I’ve fixed hundreds of times with this exact part.
Is Your Buick LaCrosse Showing These Transmission Faults?
A failing TCM will give you clear warning signs. If you’re noticing any of the following, it’s time to diagnose the module. This 2006-2009 LaCrosse TCM is the definitive fix for these issues.
- ✔ Harsh, banging, or delayed gear shifts.
- ✔ Vehicle is stuck in a single gear (limp mode), often 2nd or 3rd.
- ✔ Check Engine Light or Transmission Warning Light is on with codes like P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid Errors), or other communication codes.
- ✔ Complete loss of upshifting or downshifting capabilities.
- ✔ Poor fuel economy and a feeling of sluggish performance.
- ✔ Inaccurate gear indicator on the dashboard.
Your Straightforward 30-Minute Installation Guide
You don’t need to be a master mechanic to install this part. With basic hand tools, you can have your LaCrosse back on the road in under an hour.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the TCM: On the 2006-2009 Buick LaCrosse, the TCM is conveniently located under the lower air cleaner housing. You will need to remove the airbox to access it.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old TCM. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the electrical harnesses. Ensure they click into place.
- Final Steps: Reinstall the air cleaner housing and reconnect the battery terminal. Start the vehicle and allow it to idle for a few minutes. While our programming clears most faults, it’s good practice to use a basic OBD2 scan tool to clear any stored codes.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24230461 and other service numbers. While this page is focused on the Buick LaCrosse, it is also compatible with a wide range of GM vehicles. Please verify your part number before ordering.
Fits 2006-2009 Buick LaCrosse with transmission located in the lower air cleaner housing. Also fits numerous other GM models including, but not limited to: Chevrolet Impala, Monte Carlo, Cobalt, HHR; Pontiac G6, Grand Prix; Saturn Aura, Vue, and more. This module works with 4L60E, 4L65E, and 4L70E transmissions.
Frequently Asked Questions
Do I need to have this module programmed by a dealer?
No. This is the biggest benefit of our service. We program the module to your vehicle’s exact VIN before shipping. It arrives ready for immediate installation, saving you time and hundreds of dollars in dealership fees.
Is there a core charge for my old part?
Absolutely not. We do not require you to send back your old, faulty module. You can keep it or dispose of it at your convenience, making the process hassle-free.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the main computer (ECM) to turn on the check engine light. While this module often resolves the underlying issue causing the P0700, you should scan for more specific transmission codes (e.g., P07xx) to confirm the diagnosis.
What tools are required for installation on a LaCrosse?
You’ll typically only need a basic socket set and a screwdriver or nut driver to remove the air cleaner housing and the module’s mounting bolts. No specialized tools are necessary.