End Erratic Shifting and Restore Your Trailblazer’s Performance
Is your 2006-2009 Chevrolet Trailblazer suffering from harsh shifting, getting stuck in gear, or throwing transmission-related check engine lights? As a technician with over two decades of experience, I’ve seen these symptoms countless times. The culprit is almost always a failing Transmission Control Module (TCM). This critical component is the brain of your automatic transmission, and when it malfunctions, it can make your reliable SUV feel unpredictable and unsafe. Don’t let a faulty module sideline your vehicle. This direct-replacement T42 TCM, part number 24235340, is the definitive solution, arriving pre-programmed to your Trailblazer’s specific VIN for a true plug-and-play fix.
Case Study: A Tricky Diagnosis
A customer brought in an ’08 Trailblazer with a frustrating problem: it would occasionally refuse to shift out of 2nd gear, but only after driving for 20+ minutes. There were no consistent codes, just a general P0700 (Transmission Control System Malfunction) that would pop up intermittently. We checked the fluid, solenoids, and wiring harness—all looked fine. From experience, I know that heat-soak can cause hairline cracks in the TCM’s circuit board to expand, creating these ghost-like electrical issues. We swapped in one of our VIN-programmed T42 modules, and the problem vanished instantly. The customer saved hundreds compared to a dealership diagnosis that might have needlessly replaced other parts first. This is why a quality, pre-programmed 2006-2009 Trailblazer TCM is often the fastest and most cost-effective repair.
Is Your Trailblazer’s Transmission Acting Up?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, it’s a strong indicator that your module needs replacement:
- ✔ Abrupt, jerky, or delayed gear shifts that disrupt your drive.
- ✔ The vehicle enters “limp mode,” often getting stuck in 2nd or 3rd gear.
- ✔ The Check Engine Light or a dedicated transmission warning light is illuminated.
- ✔ Your scan tool shows Diagnostic Trouble Codes (DTCs) like P0700, P0750, P0753, P0758, or other solenoid-related faults.
- ✔ A sudden and unexplained drop in fuel economy.
- ✔ Complete failure to shift, leaving you stranded.
Your 30-Minute Path to a Smooth Ride
One of the best features of this module is its simple, DIY-friendly installation. You don’t need a lift or specialized transmission tools. For the 2006-2009 Trailblazer TCM, the process is straightforward:
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Locate the TCM: On the Trailblazer, the TCM is typically found in the engine compartment on the driver’s side (LH side).
- Disconnect and Remove: Carefully unplug the electrical connectors. Use a socket wrench to remove the bolts holding the old module in place.
- Install the New Module: Mount your new, pre-programmed TCM and securely fasten the bolts. Reconnect the electrical harnesses until they click.
- Final Steps: Reconnect the battery terminal. While our programming handles the critical setup, it’s good practice to use a basic OBD-II scan tool to clear any stored fault codes from the ECU. Start the vehicle and enjoy restored, smooth shifting!
Confirmed Vehicle Compatibility
This T42 Transmission Control Module is a guaranteed fit for the 2006, 2007, 2008, and 2009 Chevrolet Trailblazer (including models with the 8-cylinder engine). It also serves as a direct replacement for a wide range of other GM vehicles. Please verify your vehicle is on the list below. This part is interchangeable with service numbers: 24242391, 24234503, 24252114, 24230461, 24234274, and more.
- Chevrolet Trailblazer: 2006-2007 (8 cylinder, LH engine compartment)
- Chevrolet Trailblazer: 2008-2009 (LH engine compartment)
- GMC Envoy: 2006-2009 (LH engine compartment)
- Chevrolet Silverado 1500: 2007-2013 (Next to battery)
- GMC Sierra 1500: 2007-2013 (Next to battery)
- Chevrolet Tahoe / GMC Yukon: 2007-2009 (Next to battery)
- …and many more GM models. Please use our vehicle selector tool to confirm.