Restore Smooth, Reliable Shifting to Your Pontiac Grand Prix
If you’re dealing with the frustration of a 2006, 2007, or 2008 Pontiac Grand Prix that shifts harshly, hesitates, or is stuck in limp mode, a failing Transmission Control Module (TCM) is the most likely culprit. As a technician with over two decades of experience, I’ve seen these exact symptoms hundreds of times. The internal electronics of the original T42 TCM can degrade from heat and vibration, leading to communication errors that the vehicle interprets as a major transmission fault. This replacement module, part number 24256960, is the definitive solution to restore the crisp, predictable performance your car once had.
From the Diagnostic Bay: The Grand Prix That Wouldn’t Shift
A customer brought in a 2007 Grand Prix with the check engine light on and the transmission stuck in 3rd gear. They’d been told by another shop they needed a full transmission rebuild, a quote that ran into the thousands. After hooking up my scan tool, I saw the classic P0700 (Transmission Control System Malfunction) and several solenoid-specific codes. Instead of tearing down the transmission, I checked the TCM. In my experience, these symptoms on GM vehicles from this era almost always point to the module. We installed a VIN-programmed 2006-2008 Grand Prix TCM, cleared the codes, and the car shifted perfectly on the test drive. The customer saved a fortune and avoided an unnecessary, complex repair.
Is Your Grand Prix Showing These Telltale Signs?
A faulty TCM can manifest in several ways, often mistaken for mechanical failure. If you’re experiencing any of the following, this module is your likely fix:
- ✔ Harsh, banging, or erratic gear shifts.
- ✔ Vehicle is stuck in a single gear (often called “limp mode”).
- ✔ Delayed engagement when shifting from Park to Drive or Reverse.
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) like P0700, P0750, or other solenoid-related faults are present.
- ✔ Poor fuel economy and a feeling of sluggish performance.
- ✔ Complete loss of communication with the transmission.
A Straightforward 30-Minute Installation
One of the best parts of this solution is its simplicity. You don’t need to be a professional mechanic to install this part. For your 2006-2008 Grand Prix TCM, the module is located under the air cleaner housing, making it easily accessible.
- 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: Remove the air cleaner box assembly to access the old TCM mounted below it.
- Swap the Connectors: Carefully unclip the electrical connectors from the old module and plug them securely into your new, pre-programmed TCM.
- Mount the New Module: Secure the new module in the same location as the old one. Reinstall the air cleaner assembly.
- Final Steps: Reconnect the battery terminal. While the system may reset, it’s always best practice to use a basic OBD2 scan tool to clear any stored fault codes. Start the vehicle and enjoy your smooth-shifting transmission!
Verified Vehicle Compatibility
This T42 Transmission Control Module is a direct replacement for a wide range of General Motors vehicles. While this page is dedicated to the Pontiac Grand Prix, please verify your model in the list below. The location notes can help you find your existing module.
GRAND PRIX 06-08 Transmission; (lower air cleaner housing)
ALLURE 06-09 Transmission; (lower air cleaner housing)
AVALANCHE 1500 07-08 Transmission; (next to battery)
CANYON 08-12 Transmission; (RH rear engine compartment)
COBALT 06-10 Transmission; (LH strut tower)
COLORADO 08-12 Transmission; (RH rear engine compartment)
DTS 06-11 Transmission; (RH front engine compartment)
ENVOY 06-09 Transmission; (LH engine compartment)
EXPRESS VANS 06-14 Transmission; (RH engine compartment)
G5 07-10 Transmission; (LH strut tower)
G6 06-10 Transmission; (LH strut tower)
HHR 06-11 Transmission; (LH engine compartment)
HUMMER H3 08-10 Transmission; (RH rear engine compartment)
IMPALA 06-11 Transmission; (lower air cleaner housing)
ION 06-07 Transmission; (behind LH strut tower)
LACROSSE 06-09 Transmission; (lower air cleaner housing)
LUCERNE 06-11 Transmission; (LH engine compartment)
MALIBU 06-10 Transmission; (LH frame rail)
MONTE CARLO 06-07 Transmission; (lower air cleaner housing)
SAVANA VANS 06-14 Transmission; (RH engine compartment)
SIERRA & SILVERADO TRUCKS 07-13 Transmission; (next to battery)
TAHOE & YUKON 07-09 Transmission; (next to battery)
VUE 07-10 Transmission; (LH front engine compartment)
…and many more GM models. This module is interchangeable with part numbers 24252114, 24234503, 24230461, 24234274, 24255280, 24256960, and others.
Frequently Asked Questions
What does “VIN Programmed” mean for me?
It means this module arrives at your door ready for installation. We program it with your vehicle’s specific Vehicle Identification Number (VIN) and the latest GM software before shipping. This ensures perfect communication with your car’s other computers and eliminates the need for a costly trip to the dealership for programming.
Is this part difficult to install on my Grand Prix?
Not at all. For the 2006-2008 Grand Prix, the TCM is located under the air cleaner box. The replacement process is a simple bolt-off, bolt-on job that typically takes less than 30 minutes with basic hand tools. No specialized equipment is required.
Will this fix a P0700 diagnostic code?
Yes, in most cases. A P0700 code is a general fault code indicating the TCM has detected a problem. It’s often accompanied by other, more specific codes. A failing TCM is the most common root cause for these codes, and replacing it with this programmed unit will resolve the issue.
Do I need to send my old TCM back?
No. There is no core charge or requirement to return your old part. You can dispose of it or keep it without any hassle.
What is the warranty on this module?
This module is backed by a comprehensive one-year warranty, giving you peace of mind and assurance in the quality and reliability of your repair.