Restore Your Grand Prix’s Shifting Performance
If your 2006-2008 Pontiac Grand Prix is suffering from erratic shifting, getting stuck in gear, or throwing transmission codes, you’re not just dealing with an annoyance—you’re facing a critical component failure. The Transmission Control Module (TCM) is the brain of your automatic transmission, and when it fails, it can make your car feel unreliable and unsafe. This replacement T42 TCM, part number 24240400, is the definitive solution, arriving expertly programmed to your vehicle’s VIN for a true plug-and-play repair.
Case Study: A Tricky Diagnosis
I remember a 2007 Grand Prix that came into my shop with a complaint of intermittent, harsh 1-2 shifts and occasionally getting stuck in 3rd gear (limp mode) after highway driving. The owner had already replaced a shift solenoid with no luck. A scan showed a generic P0700 code. After checking the wiring harness for damage, we focused on the TCM. In these GM platforms, heat cycles and vibrations under the hood can cause hairline cracks in the TCM’s circuit board, leading to these exact unpredictable symptoms. We installed a VIN-programmed module, and the car shifted like new. It’s a common failure point I’ve seen dozens of times, and a new module is almost always the fix.
Is Your Grand Prix Showing These Transmission Warning Signs?
A failing TCM doesn’t heal itself; it only gets worse. Ignoring these signs can lead to more significant transmission damage. See if any of these sound familiar:
- âś” Harsh, banging shifts or delayed gear engagement.
- âś” The car is stuck in a single gear (often called “limp mode”).
- âś” Check Engine Light is on with codes like P0700, P0750, or other solenoid-related faults.
- âś” The transmission refuses to upshift or downshift correctly.
- âś” A noticeable drop in fuel economy.
- âś” Complete loss of communication with the transmission.
A Straightforward Guide to Installation
For the 2006-2008 Pontiac Grand Prix, this is a job most DIYers can handle in their driveway in under 30 minutes. Our pre-programmed module eliminates the need for expensive scan tools or a trip to the dealership.
- Safety First: Disconnect the negative terminal from your car’s battery to prevent electrical shorts and help reset the system.
- Locate the TCM: On your Grand Prix, the TCM is typically found under the lower air cleaner housing. You will need to remove the airbox to access it.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new VIN-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. Start the vehicle and allow it to idle for a few minutes. While not always necessary, clearing any old codes with a basic OBD2 scanner is good practice.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24240400 and other interchangeable numbers. While this page focuses on the 2006-2008 Grand Prix TCM, it also fits a wide range of other GM vehicles. Please verify your specific model below:
- Pontiac Grand Prix (2006-2008) – Transmission; (lower air cleaner housing)
- Chevrolet Cobalt (2006-2010) – Transmission; (LH strut tower)
- Chevrolet HHR (2006-2011) – Transmission; (LH engine compartment)
- Chevrolet Impala (2006-2011) – Transmission; (lower air cleaner housing)
- Chevrolet Silverado 1500 (2007-2013) – Transmission; (next to battery)
- GMC Sierra 1500 (2007-2013) – Transmission; (next to battery)
- Buick LaCrosse / Allure (2006-2009) – Transmission; (lower air cleaner housing)
- And many more models including the Tahoe, Yukon, Savana, Express, G6, and Saturn Vue.