Restore Smooth, Reliable Shifting to Your Buick LaCrosse
If your 2006-2009 Buick LaCrosse is suffering from harsh shifts, getting stuck in gear, or throwing transmission-related error codes, you’ve likely pinpointed the culprit: a failing Transmission Control Module (TCM). As a seasoned technician, I’ve seen countless GM vehicles, including the LaCrosse, sidelined by these exact issues. The T42 TCM is the electronic brain of your automatic transmission, and when it fails, it creates frustrating and potentially unsafe driving conditions. This replacement module, part number 24239224, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
From the Diagnostic Bay: The Case of the Hesitant LaCrosse
A customer brought in their ’08 LaCrosse complaining of a violent 1-2 shift and intermittent ‘limp mode’ where the car wouldn’t shift past 2nd gear. The check engine light was on, and my scan tool pulled a P0700 (Transmission Control System Malfunction) and a P0752 (Shift Solenoid ‘A’ Stuck On). While a solenoid could be the cause, my experience with these T42 modules pointed elsewhere. After verifying the solenoid’s wiring and resistance were fine, I knew the TCM’s internal driver for that circuit had failed. It’s a classic failure mode I’ve diagnosed over a hundred times. We installed a VIN-programmed module just like this one, and the car was shifting like new in under an hour. This part saves you from chasing phantom electrical gremlins.
Is Your Buick LaCrosse Showing These Telltale Signs?
A faulty TCM doesn’t get better on its own. It can lead to severe transmission damage if ignored. Watch for these common indicators:
- âś” Abrupt, jerky, or delayed gear changes that disrupt your drive.
- âś” The vehicle refuses to shift, often getting stuck in 2nd or 3rd gear (limp mode).
- âś” Check Engine Light or Transmission Warning Light is illuminated on your dash.
- âś” Diagnostic Trouble Codes (DTCs) are present, especially P0700, P0750, P0751, or other solenoid-specific codes.
- âś” A noticeable drop in fuel economy as the transmission operates inefficiently.
- âś” Complete loss of communication with the module, preventing diagnostics and causing a no-start or no-shift condition.
Your Step-by-Step LaCrosse TCM Installation Guide
Replacing the 2006-2009 LaCrosse TCM is a straightforward job that most DIY enthusiasts can complete in their own garage. For this specific vehicle, you’ll find the module located under the lower air cleaner housing.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and reset the system.
- Access the Module: Remove the air cleaner box assembly to gain clear access to the old TCM. It’s held in place by a few bolts or clips.
- Disconnect and Remove: Carefully unplug the electrical connectors. Note their orientation. Unbolt the old module and remove it from the vehicle.
- Install the New TCM: Mount your new, pre-programmed module in the same location. Securely reconnect the electrical harnesses until they click into place.
- Reassemble and Reconnect: Reinstall the air cleaner housing. Once everything is back in place, reconnect the negative battery terminal.
- Final Check: Start the vehicle. The pre-programmed module should allow for immediate proper function. While not always necessary, using a basic scan tool to clear any stored historical codes is good practice.
Verified Vehicle Compatibility List
This T42 TCM is a direct replacement for part number 24239224 and is interchangeable with a wide range of other GM service numbers. While this page is focused on the 2006-2009 LaCrosse TCM, this module also fits many other vehicles. Please verify your part number or consult the list below.
This part fits the following vehicles:
- Buick Allure (2006-2009) – lower air cleaner housing
- Buick LaCrosse (2006-2009) – lower air cleaner housing
- Buick Lucerne (2006-2011) – LH engine compartment
- Chevrolet Cobalt (2006-2010) – LH strut tower
- Chevrolet HHR (2006-2011) – LH engine compartment
- Chevrolet Impala (2006-2011) – lower air cleaner housing
- Pontiac G6 (2006-2010) – LH strut tower
- And many more GM trucks, vans, and SUVs from 2006-2014.
Do I need to take this part to the dealership for programming?
Do I need to take this part to the dealership for programming?
No. The single biggest benefit of this module is that we program it to your vehicle’s VIN before shipping. It arrives ready for installation, saving you the time, cost, and hassle of a dealership visit.
Is this part difficult to install myself?
Not at all. For the Buick LaCrosse, the TCM is located under the air cleaner box. With basic hand tools, the replacement process typically takes less than 30 minutes, making it an ideal DIY-friendly repair.
What is a core charge? Do I need to send my old part back?
There is absolutely no core charge for this part. You are not required to return your old, faulty module. You can keep it or dispose of it at your convenience.
Will this fix a P0700 check engine light code?
Yes, in most cases. The P0700 code is a general fault code indicating the TCM has detected a problem. If the TCM itself is the source of the fault (which is very common), replacing it with this module will resolve the issue and allow the code to be cleared.