Restore Peak Transmission Performance in Your GM Vehicle
Is your 2006-2009 Chevrolet Trailblazer, GMC Envoy, or other compatible GM vehicle suffering from erratic shifting, getting stuck in gear, or displaying transmission-related warning lights? These are classic signs of a failing Transmission Control Module (TCM). The TCM acts as the central computer for your automatic transmission, managing everything from gear changes to torque converter clutch engagement. When it fails, drivability is compromised, and fuel economy suffers. This OEM-quality T42 TCM, service part number 24243921, is the definitive solution to restore your vehicle’s smooth and reliable operation.
From the Diagnostic Bay
We recently had a 2008 GMC Sierra in the shop that was stuck in third gear—a classic ‘limp mode’ case. The owner was worried about a costly transmission rebuild. After a quick scan, we pulled a P0700 code, pointing to a general transmission fault. Further diagnostics isolated the issue to an internal failure in the original TCM. Instead of a multi-day repair, we installed one of our VIN-programmed T42 modules. In under an hour, the truck was shifting perfectly, all codes were cleared, and the customer was back on the road, saving thousands compared to a dealership visit or transmission replacement. This part is a common-sense fix for a very common problem.
Symptoms of a Failing T42 TCM
A faulty TCM can manifest in various ways. If you’re experiencing any of the following, it’s highly likely your transmission module needs replacement:
- ✔ Harsh, delayed, or unpredictable gear shifts.
- ✔ Vehicle is stuck in a single gear (limp mode) and will not shift up or down.
- ✔ The Check Engine Light or a dedicated transmission warning light is illuminated.
- ✔ Diagnostic Trouble Codes (DTCs) such as P0700, P0750, P0755, or other solenoid-related faults are present.
- ✔ A noticeable decrease in fuel efficiency.
- ✔ The transmission feels like it’s slipping between gears.
- ✔ Complete loss of communication with the transmission module during a diagnostic scan.
Why Choose Our Programmed Trailblazer Transmission Module?
Not all replacement parts are created equal. Our T42 modules offer a seamless repair experience designed to get you back on the road with confidence. The most significant advantage is our complimentary VIN programming service. When you order, we flash the module with your vehicle’s specific Vehicle Identification Number and the latest GM software updates. This ensures the Trailblazer Transmission Module communicates perfectly with your vehicle’s engine computer and other systems right out of the box. There is no need for expensive trips to the dealership for programming or special tools for installation.
Built to strict OEM specifications, this module directly replaces a wide range of original part numbers, including 24252114, 24234503, and 24243921. It’s the ideal component for a wide array of GM trucks, SUVs, and cars equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. With a one-year warranty and no core charge, you can complete your repair without hidden fees or the hassle of returning your old part.
Frequently Asked Questions
Do I need to have this module programmed?
No. We handle all the programming for you before shipment. Simply provide your vehicle’s VIN during checkout, and the module will arrive ready for plug-and-play installation.
Where is the TCM located on my vehicle?
The location varies by model. On a 2006-2009 Trailblazer or Envoy, it’s typically in the LH (driver’s side) engine compartment. On trucks like the Silverado or Sierra, it’s often found next to the battery. Always consult a service manual for your specific vehicle to confirm the location.
Is this a difficult part to install myself?
For someone with basic mechanical skills, this is a very straightforward installation. It typically involves disconnecting the battery, unplugging the electrical connectors from the old module, unbolting it, and then reversing the process. The entire job can usually be done in under 30 minutes.
Will this fix a P0700 trouble code?
A P0700 code is a generic fault code indicating that the TCM has detected a problem and has requested the Check Engine Light be turned on. While a failing TCM is a very common cause, this code can also be triggered by other transmission issues. However, if you are also experiencing shifting problems, replacing the TCM is the most likely solution.
What happens if I continue driving with a bad TCM?
Continuing to operate a vehicle with a failing Trailblazer Transmission Module can lead to more severe damage. Poor shifting can cause excessive wear on internal transmission components like clutches and bands, potentially leading to a complete transmission failure that is far more expensive to repair.