Is your 2006-2008 Pontiac Grand Prix suffering from unpredictable shifting, getting stuck in gear, or illuminating the check engine light? These are classic signs of a failing Transmission Control Module (TCM). The TCM is the electronic brain of your automatic transmission, responsible for orchestrating gear changes, managing torque converter lockup, and monitoring system health. When it fails, it can cause a cascade of problems that affect drivability, fuel economy, and safety. This replacement T42 TCM, part number 24239926, is the definitive solution to restore your vehicle’s transmission performance to factory standards.
From the Diagnostic Bay
We once had a 2007 Grand Prix in the shop with classic transmission failure symptoms: harsh 1-2 shifts and a P0752 code for Shift Solenoid A Stuck On. The owner had already replaced the solenoid twice with no luck. After a quick data scan, we noticed the command signals from the TCM were erratic. The solenoids were fine; the TCM was sending faulty instructions. Installing a VIN-programmed T42 module like this one solved the problem instantly. It’s a reminder that what seems like an internal mechanical failure is often an external electronic issue, and starting with the TCM can save hundreds in unnecessary transmission work.
Common Symptoms of a Failing Grand Prix TCM
A faulty TCM can manifest in various ways. If you’re experiencing any of the following issues, it’s highly likely your transmission control module is the culprit:
- ✔ Erratic and Harsh Shifting: Your vehicle may slam into gear, hesitate between shifts, or feel jerky during acceleration.
- ✔ Stuck in Limp Mode: The transmission may refuse to shift out of a single gear (often 2nd or 3rd) to prevent further damage.
- ✔ Warning Lights: The Check Engine Light or a dedicated transmission warning light will illuminate on your dashboard.
- ✔ Diagnostic Trouble Codes (DTCs): Common codes associated with a bad TCM include P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid errors), and other communication-related codes.
- ✔ Delayed Engagement: A noticeable delay when shifting from Park into Drive or Reverse.
- ✔ Poor Fuel Economy: Inefficient shifting and torque converter operation can lead to a significant drop in MPG.
- ✔ Complete Loss of Shifting: In severe cases, the vehicle may not shift gears at all.
The Plug-and-Play Solution: VIN-Programmed 2006-2008 Grand Prix TCM
The biggest hurdle in replacing a modern electronic module is programming. Dealerships often charge significant fees for this service. Our T42 TCMs eliminate this step entirely. Before shipping, we program the module with your vehicle’s specific Vehicle Identification Number (VIN) and load the latest GM software updates. This ensures that the module is perfectly calibrated for your Grand Prix’s engine, transmission (like the 4L60E or 4L65E), and tire size. The result is a true plug-and-play installation—no expensive scan tools or trips to the dealer required. It’s ready to work correctly the moment it’s connected.
Installation and Compatibility
For the 2006-2008 Pontiac Grand Prix, the TCM is typically located under the lower air cleaner housing in the engine bay, making it accessible for a straightforward replacement. The process generally takes less than 30 minutes.
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Locate and Remove the Old TCM: Access the module by removing the air cleaner box. Carefully disconnect the electrical connectors and unbolt the module from its bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the electrical harnesses.
- Reconnect Battery and Clear Codes: Reconnect the battery. While the new module should resolve the underlying issue, it’s good practice to use a basic OBD2 scanner to clear any stored trouble codes from the vehicle’s memory.
This module is a direct replacement for multiple part numbers, including 24239926, 24252114, 24234503, and others. It is also compatible with a vast range of other GM vehicles from 2006-2014, such as the Chevrolet Impala, GMC Sierra, Buick LaCrosse, and Cadillac DTS, making it a versatile and reliable component built to OEM specifications.
Frequently Asked Questions
What does ‘VIN-programmed’ actually mean?
It means we flash the module with your car’s unique 17-digit Vehicle Identification Number (VIN) before it ships. This loads the correct software and calibrations for your specific vehicle configuration, ensuring it works perfectly out of the box without needing a trip to the dealership for expensive programming.
Is this a difficult part to install myself?
For most DIY mechanics, this is a relatively simple installation. On a 2006-2008 Grand Prix, the TCM is located under the air cleaner housing. Basic hand tools are all that’s required, and the process typically takes under 30 minutes. The key is that our pre-programming removes the most difficult, software-related part of the job.
Will this TCM fix a P0700 trouble code?
A P0700 code is a general fault code indicating that the TCM has detected a problem and has requested the Check Engine Light to be turned on. While P0700 itself doesn’t pinpoint the TCM as the failure, it is very often present when the TCM has failed and set other, more specific codes. Replacing a faulty TCM will resolve the underlying issue and allow the P0700 code to be cleared.
Do I need to send my old module back? Is there a core charge?
No, there is no core charge for this part. You can keep your old module, which saves you the time, hassle, and expense of shipping it back.
How can I be certain this is the correct part for my car?
This module fits 2006-2008 Pontiac Grand Prix models. The best way to confirm is to match the part number 24239926 (or one of the interchangeable numbers listed) to your existing module. If you are unsure, please contact us with your VIN, and we will be happy to verify the exact fitment for you.