Restore Smooth Shifting to Your Pontiac Grand Prix
If your 2006, 2007, or 2008 Pontiac Grand Prix is suffering from harsh shifting, getting stuck in gear, or throwing transmission codes, the culprit is often a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen countless GM vehicles, especially sedans like the Grand Prix, develop erratic transmission behavior due to a faulty T42 TCM. This isn’t just an annoyance; it can affect fuel economy and even be a safety concern. This replacement TCM, part number 24239926, is the reliable, straightforward solution you need.
We take the guesswork and dealership hassle out of the equation. Each module is professionally programmed to your vehicle’s specific VIN before it ships. This means it arrives ready for a true plug-and-play installation, with the latest GM software updates already loaded. You get a part that communicates perfectly with your car’s engine computer and other systems, restoring the crisp, predictable shifting you expect from your Grand Prix.
Is Your Grand Prix Showing These Symptoms?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, it’s a strong indicator that your module needs replacement. In my shop, these are the classic signs I look for when diagnosing a 2006-2008 Grand Prix TCM issue:
- ✔ Sudden, harsh clunks when shifting between gears.
- ✔ The transmission refuses to shift up or down, or feels like it’s slipping.
- ✔ Your vehicle enters ‘limp mode,’ often stuck in 2nd or 3rd gear.
- ✔ The Check Engine Light is on with transmission-related Diagnostic Trouble Codes (DTCs) like P0700 (Transmission Control System Malfunction) or various solenoid codes (P0750-P0774).
- ✔ Delayed engagement when shifting from Park to Drive or Reverse.
- ✔ A noticeable drop in fuel efficiency and potential transmission overheating.
Case Study: The Ghost in the Transmission
A customer brought in his ’07 Grand Prix with a frustrating problem: it would shift perfectly for days, then suddenly start banging into gear and get stuck in 3rd. He’d already replaced a shift solenoid with no luck. After scanning it, I found a P0700 code but no specific solenoid faults stored. The intermittent nature pointed away from a purely mechanical issue. We tested the wiring and found it solid. Based on experience with these T42 modules, I suspected an internal electronic failure in the TCM. We installed one of our VIN-programmed modules, and the problem was solved instantly. The ‘ghost’ was the failing computer, and the pre-programmed unit saved the customer hundreds compared to a dealership visit.
A Straightforward Guide to Installation
For the Pontiac Grand Prix, this is a job most DIY enthusiasts can handle in their own garage in under an hour. No specialized tools are required.
- Safety First: Always disconnect the negative terminal from your car’s battery and wait a few minutes before starting work. This prevents electrical shorts and helps reset the vehicle’s electronic systems.
- Locate the TCM: On the 2006-2008 Grand Prix, the Transmission Control Module is conveniently located under the lower air cleaner housing in the engine bay. You will need to remove the airbox to access it.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old TCM. They have locking tabs, so be gentle. Once disconnected, 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. You should hear a ‘click’ as they lock in.
- Final Steps: Reinstall the air cleaner housing and reconnect the battery terminal. Start the vehicle and allow it to idle. While our programming resolves most issues, it’s good practice to use a basic OBD2 scan tool to clear any old fault codes from the computer’s memory.
Verified Vehicle Compatibility
This T42 Transmission Control Module is a direct replacement for part number 24239926 and other interchangeable numbers. While it fits a wide range of GM vehicles, it is guaranteed to be the correct part for the following models:
- Pontiac Grand Prix (2006-2008) – Located at the lower air cleaner housing.
- Chevrolet Impala (2006-2011)
- Buick LaCrosse / Allure (2006-2009)
- Chevrolet Monte Carlo (2006-2007)
- And many more GM cars, trucks, and SUVs equipped with 4-speed automatic transmissions.
Do I need to take my car to the dealer for programming?
Do I need to take my car to the dealer for programming?
No. The main benefit of our service is that this module comes fully programmed to your car’s VIN. It is ready for installation right out of the box, saving you the time, cost, and hassle of a dealership visit.
Is this a simple DIY installation?
Yes, for most people with basic mechanical skills. On the Grand Prix, it involves removing the airbox for access, unplugging the old module, and plugging in the new one. It typically takes less than an hour.
What is the warranty on this part?
This transmission control module is backed by our one-year, hassle-free warranty. We stand by the quality and reliability of our programmed electronics.
Will this fix my Check Engine Light?
If your Check Engine Light is on due to transmission-related fault codes (like P0700 or solenoid codes) caused by a failing TCM, then yes, this part is designed to resolve those specific issues. After installation, you should clear the codes with a scan tool.
Is there a core charge?
No, there is no core charge for this part. You are not required to send your old, faulty module back to us, making the process simpler and faster for you.