If your 2006-2009 Chevrolet Trailblazer is suffering from erratic shifting, getting stuck in gear, or throwing transmission codes, you’ve likely pinpointed the culprit: a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen firsthand how a faulty TCM can sideline a perfectly good vehicle. This isn’t just an annoyance; it’s a critical failure that compromises your Trailblazer’s performance and safety. This T42 series TCM, part number 24234274, is the definitive, reliable solution to get your SUV driving smoothly again.
The biggest hurdle with electronic module replacement has always been the expensive and time-consuming trip to the dealership for programming. We eliminate that step entirely. By providing your vehicle’s VIN at checkout, we program the module with the latest GM software before it even ships. This ensures it communicates perfectly with your vehicle’s engine computer and transmission components right out of the box. This is the same process we’d use in the shop to guarantee a successful repair on the first try.
A Technician’s Notebook
I remember a 2008 Trailblazer that came into the bay with a classic complaint: ‘It shifts hard sometimes, but not always.’ The owner had already replaced a shift solenoid with no luck. We scanned it and found a generic P0700 code, but the specific solenoid codes were intermittent. After checking the wiring harness for damage (a common issue on these GMT360 platforms), we focused on the TCM. Heat cycles and vibrations are the enemy of these modules. We swapped in a pre-programmed T42 TCM, and the problem was instantly gone. The inconsistent voltage from the old module was causing the solenoids to act up, but it wasn’t failing consistently enough to set a hard code. This part saved hours of further diagnostic guesswork.
Is Your Trailblazer Exhibiting These Transmission Issues?
A failing TCM will give you clear warning signs. If you’re experiencing any of the following, it’s time for a replacement:
- ✔ Harsh, banging shifts or delayed gear engagement.
- ✔ Vehicle is stuck in ‘limp mode’ (usually 2nd or 3rd gear).
- ✔ The Check Engine Light is on with codes like P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid Errors), or other transmission-related DTCs.
- ✔ Failure to upshift or downshift, leading to poor acceleration.
- ✔ A noticeable drop in fuel economy.
- ✔ Intermittent loss of communication with the scan tool or other modules.
A Straightforward Guide to Installation
For most DIYers, this is a job you can complete in your driveway in under 30 minutes. The TCM on the 2006-2009 Trailblazer is conveniently located in the engine compartment.
- 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: On the Trailblazer, you’ll typically find the TCM mounted in the left-hand (driver’s side) engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the electrical connectors. You should hear a click as they lock.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it idle for a few minutes. While the module is plug-and-play, it’s always good practice to use a basic scan tool to clear any stored fault codes from the computer’s memory.
Verified Vehicle Compatibility
This T42 Transmission Control Module is a direct fit for the 2006-2009 Chevrolet Trailblazer. It also serves as a direct replacement for a wide array of other GM vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. It is interchangeable with numerous part numbers, including 24252114, 24234503, 24230461, and more, ensuring broad compatibility. Some other popular applications include:
- ✔ Chevrolet Silverado, Tahoe, Suburban, Impala, HHR
- ✔ GMC Sierra, Yukon, Envoy, Savana
- ✔ Cadillac DTS, Hummer H3, Saab 9-7X
Frequently Asked Questions
Do I need to have this module programmed by a dealer?
No. This is the biggest benefit of our service. We pre-program the module to your vehicle’s specific VIN before shipping, so it’s ready for immediate installation right out of the box.
Is this a difficult part to install myself?
Not at all. For the 2006-2009 Trailblazer, the TCM is easily accessible in the engine bay. With basic hand tools, most people can swap the module in under 30 minutes.
What is the warranty on this part?
This module comes with a one-year warranty, giving you peace of mind and confidence in your repair.
Will this fix a P0700 check engine light code?
A P0700 code simply means the TCM has detected a fault and has requested the check engine light be turned on. In many cases where the TCM itself has failed internally, replacing it with this module will resolve the root cause of the P0700 and related transmission codes.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part or dispose of it without the hassle of returning it.