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 the most likely culprit. As the electronic brain of your automatic transmission, a faulty TCM can make your daily drive frustrating and unreliable. This replacement T42 TCM, part number 24240449, is the definitive solution to restore your vehicle’s performance and peace of mind.
Over my 20 years in diagnostics, I’ve seen countless GM vehicles sidelined by these exact issues. The problem often isn’t a catastrophic mechanical failure but a breakdown in communication from the TCM. This module is expertly pre-programmed to your vehicle’s specific VIN, eliminating the need for expensive dealership visits for software flashing. It arrives ready for a true plug-and-play installation, making it a perfect project for a DIY enthusiast or a time-saving part for a professional mechanic.
From the Diagnostic Bay: A LaCrosse Limp Mode Mystery Solved
A customer brought in their ’07 LaCrosse, complaining it wouldn’t shift past 2nd gear and the transmission warning light was on. The car was in classic ‘limp mode.’ A quick scan pulled a generic P0700 (Transmission Control System Malfunction) code, which points to a problem within the transmission’s control circuit. Instead of immediately quoting a costly transmission rebuild, I checked the basics. The fluid was clean and full. My experience pointed directly to the T42 TCM. We ordered a VIN-programmed module, and I had it installed in under 20 minutes. After clearing the codes and a short test drive, the car shifted perfectly through all gears. The customer saved thousands and was back on the road the same day—a testament to diagnosing the electronics first.
Is Your LaCrosse Exhibiting These Transmission Issues?
- ✔ Abrupt, jerky, or hesitant gear changes during acceleration.
- ✔ The vehicle is stuck in a single gear (often 2nd or 3rd) and will not upshift or downshift.
- ✔ Check Engine Light or Transmission Warning Light is illuminated on your dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750-series solenoid codes, or communication errors.
- ✔ A noticeable drop in fuel economy due to inefficient shifting.
- ✔ Complete loss of communication with the transmission, preventing it from engaging.
DIY-Friendly Installation in Under 30 Minutes
Replacing the TCM on your Buick LaCrosse is a straightforward job that requires basic hand tools. You’ll find the module located under the lower air cleaner housing in the engine bay.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: Access the TCM by removing the air cleaner box assembly. It’s the silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the electrical harnesses from the old TCM. Then, unbolt the module from its mounting bracket.
- Install the New TCM: Mount the new, pre-programmed module in place, securely reconnect the wiring harnesses, and reinstall the air cleaner assembly.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s best practice to use a basic OBD-II scan tool to clear any stored fault codes.
Confirmed Vehicle Compatibility
This module is a direct-fit replacement for the 2006-2009 Buick LaCrosse with the TCM located in the lower air cleaner housing. It also interchanges with part numbers 24252114, 24234503, 24240449, and others, fitting a wide range of GM vehicles:
- ✔ Buick: LaCrosse (06-09), Allure (06-09), Lucerne (06-11), Rainier (06-07), Rendezvous (06-07)
- ✔ Chevrolet: Silverado, Tahoe, Suburban, Avalanche (07-13), Impala (06-11), Monte Carlo (06-07), Cobalt (06-10), HHR (06-11), Colorado (08-12), Express Van (06-14)
- ✔ GMC: Sierra, Yukon, Savana Van (06-14), Canyon (08-12), Envoy (06-09)
- ✔ Pontiac: G6 (06-10), Grand Prix (06-08), G5 (07-10)
- ✔ Saturn: Vue (07-10), Aura (07-09), Ion (06-07)
- ✔ And more: Cadillac DTS (06-11), Hummer H3 (08-10), Saab 9-7X (06-09)
Do I need to program this 2006-2009 LaCrosse TCM?
Do I need to program this 2006-2009 LaCrosse TCM?
No. This module comes fully pre-programmed to your vehicle’s VIN. It is a plug-and-play solution that requires no additional dealership programming, saving you time and money.
Where is the TCM located on my Buick LaCrosse?
For the 2006-2009 Buick LaCrosse, the Transmission Control Module is typically found in the engine compartment, situated within the lower air cleaner housing.
What happens if I don’t replace a failing TCM?
Ignoring a bad TCM can lead to worsening drivability, poor fuel efficiency, and potentially leave you stranded. In some cases, continued operation with harsh shifting can cause premature wear on internal transmission components, leading to more expensive mechanical repairs down the line.
Is there a core charge for this part?
No, there is no core charge required. You can keep your old part, eliminating the hassle and expense of shipping a core back.