If you’re dealing with a 2006-2009 Chevrolet Trailblazer that shifts harshly, hesitates, or is stuck in limp mode, the Transmission Control Module (TCM) is a prime suspect. Over my two decades of diagnosing these exact issues, I’ve seen countless owners and even other shops chase down solenoid or sensor problems when the root cause was a failing T42 TCM. This isn’t just a replacement part; it’s a permanent fix for the frustrating and unpredictable behavior of a faulty transmission brain. This module, part number 24234503, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN for a true plug-and-play repair.
Is Your Trailblazer Showing These Symptoms?
A failing TCM can manifest in several ways. Before you consider a costly transmission rebuild, check if your vehicle is experiencing any of the following common signs of failure. Catching it early can save you from further component damage.
- ✔ Harsh, banging shifts or delayed gear engagement.
- ✔ The vehicle is stuck in a single gear (often 2nd or 3rd), known as “limp mode.”
- ✔ Check Engine Light or Transmission Warning Light is on with codes like P0700, P0750, P0753, P0758, or other solenoid-related DTCs.
- ✔ Inability to upshift or downshift, leading to poor acceleration and terrible fuel mileage.
- ✔ Unexplained loss of communication with the transmission module on a scan tool.
- ✔ The transmission seems to slip out of gear intermittently.
A Technician’s Notebook: The Intermittent Gremlin
A customer brought in his ’08 Trailblazer with a complaint that stumped two other shops. The truck would drive perfectly for days, then suddenly start slamming into gear and get stuck in 3rd. They had replaced two shift solenoids to no avail. When I hooked up my scanner and monitored live data, I saw the command signals from the TCM were dropping out randomly under heat soak. The solenoids were fine; the TCM was the culprit. We installed a VIN-programmed module, and the problem was solved instantly. This is a classic failure pattern for the T42, where heat and vibration cause internal circuit board failures over time.
A Straightforward Guide to Installation
One of the best features of this module is its ease of installation. Because it comes programmed, you can do this job in your own driveway in under 30 minutes with basic hand tools. For the 2006-2009 Trailblazer, the TCM is conveniently located in the engine compartment.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work. This prevents short circuits and helps reset the vehicle’s electronic systems.
- Locate the TCM: On the Trailblazer and its siblings (Envoy, Rainier), the TCM is mounted in the left-hand (driver’s side) engine compartment. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the electrical harnesses. There are typically release tabs you’ll need to press. Once disconnected, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, VIN-programmed TCM into place. Reconnect the electrical harnesses, ensuring they click securely into place.
- Final Steps: Reconnect the negative battery terminal. While the module is plug-and-play, it’s good practice to use a basic OBD2 scan tool to clear any stored fault codes from the previous failure. Start the vehicle and enjoy smooth, reliable shifting.
Verified Vehicle Compatibility
This T42 TCM, part number 24234503, is a direct replacement for a wide range of General Motors vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. While this page focuses on the 2006-2009 Trailblazer TCM, it also fits the following models. Please verify your specific model and year from the list below.
- Chevrolet Trailblazer: 2006-2009 (8 cylinder and standard models)
- GMC Envoy / Envoy XL: 2006-2009
- Buick Rainier: 2006-2007
- Saab 9-7X: 2006-2009
- Chevrolet Silverado / GMC Sierra 1500/2500: 2007-2013 (Check specific options)
- Chevrolet Tahoe / GMC Yukon: 2007-2009
- Chevrolet Express / GMC Savana Vans: 2006-2014
- And many more GM cars, trucks, and SUVs. See the full fitment list for details.
Frequently Asked Questions
Frequently Asked Questions
Do I need to take my vehicle to the dealer after installation?
No. This module is pre-programmed to your vehicle’s VIN number. This means it is ready for immediate installation and operation, saving you the time and expense of a dealership visit.
Is this part number 24234503 the same as other service numbers?
Yes, GM often uses multiple service numbers for the same part over its lifespan. This module is a direct interchange for numbers like 24242391, 24252114, 24230461, and others listed in the product details.
What tools do I need for the installation?
For most vehicles, including the Trailblazer, you will only need basic hand tools, such as a socket set (commonly 10mm) to remove the mounting bolts and a flathead screwdriver to help release the connector tabs.
What is “limp mode”?
Limp mode is a protective feature where the vehicle’s computer locks the transmission into a single gear (usually 2nd or 3rd) to prevent further damage when a critical fault is detected. Replacing a faulty TCM is often the correct fix for this issue.
Is there a core charge for my old part?
No, there is no core charge required for this module. You can keep your old part without any hassle or need to return it.