Is your 2006-2008 Pontiac Grand Prix suffering from jarring shifts, getting stuck in gear, or throwing transmission codes? You’re not alone. As a technician with over two decades of experience, I’ve seen countless GM vehicles sidelined by a faulty Transmission Control Module (TCM). This critical component is the brain of your automatic transmission, and when it fails, it can make your car feel unpredictable and unsafe. This isn’t just an inconvenience; it’s a problem that impacts your car’s reliability and your peace of mind.
This is the definitive solution: a direct-replacement T42 Transmission Control Module for your 2006-2008 Grand Prix TCM, part number 24239224. The biggest advantage? We pre-program it to your car’s specific Vehicle Identification Number (VIN) before it ships. This means you can skip the expensive trip to the dealership for programming. It arrives at your door ready for a true plug-and-play installation, restoring the smooth, precise shifting you expect from your Pontiac.
A Technician’s Notebook
A customer brought in his ’07 Grand Prix complaining of what he called ‘transmission bipolar disorder.’ One day it would shift fine, the next it would bang into gear and get stuck in 3rd (limp mode), flashing a Check Engine light. He’d already replaced a shift solenoid on a guess, which didn’t fix it. After a quick scan, I saw the classic P0700 (Transmission Control System Malfunction) code. Experience pointed directly to the TCM. The internal electronics on these modules can degrade from heat and vibration, causing intermittent communication loss. We installed a VIN-programmed TCM, and the car drove off the lift shifting like it just left the factory. This part saved him from a potential transmission rebuild misdiagnosis.
Is Your Grand Prix Showing These Symptoms?
- ✔ Harsh, erratic, or delayed gear shifts that make driving uncomfortable.
- ✔ The vehicle is stuck in a single gear (limp mode) and won’t shift up or down.
- ✔ Check Engine Light or Transmission Warning Light is illuminated on your dash.
- ✔ Your scanner shows Diagnostic Trouble Codes (DTCs) like P0700, P0750, or other solenoid-related faults.
- ✔ A noticeable drop in fuel economy or the transmission seems to be overheating.
- ✔ Complete loss of communication with the transmission module.
A Straightforward Guide to Installation
You don’t need to be a master mechanic to replace the 2006-2008 Grand Prix TCM. The module is located under the lower air cleaner housing, making it accessible for a straightforward swap in under 30 minutes.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- Locate the Module: On your Grand Prix, you’ll find the TCM situated beneath the air cleaner box in the engine compartment.
- Remove and Replace: Carefully unplug the electrical connectors and unbolt the old module. Secure the new, VIN-programmed module in its place and reconnect the wiring harnesses.
- Final Steps: Reconnect the battery. While the module is pre-programmed, it’s good practice to use a basic OBD-II scan tool to clear any stored fault codes from the vehicle’s memory.
Verified Vehicle Compatibility
This T42 TCM, part number 24239224, is the correct fit for the following vehicles, specifically noting the module’s location:
- Pontiac Grand Prix: 2006, 2007, 2008 (Located under the lower air cleaner housing)
- This module also fits a wide range of other GM vehicles. Please verify the part number or contact our support team to confirm fitment for other models like the Impala, LaCrosse, Monte Carlo, and more.
Frequently Asked Questions
Do I need to have this module programmed by a dealer?
No. We program the module to your vehicle’s VIN before shipping. It is ready to install right out of the box, saving you time and money.
What is a TCM and what does it do?
The Transmission Control Module (TCM) is a computer that controls your automatic transmission’s shifting, torque converter lockup, and line pressure for optimal performance and fuel efficiency.
Where is the TCM located on my 2007 Pontiac Grand Prix?
The TCM is located in the engine bay, underneath the lower air cleaner housing assembly. This makes it relatively easy to access for replacement.
Will this fix a P0700 trouble code?
A P0700 code indicates a general fault in the transmission control system. While a failing TCM is a very common cause, you should ensure other potential issues like wiring or solenoids have been checked. In many cases, replacing a faulty TCM will resolve this code.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part without any hassle or need to return it.