Restore Your Envoy’s Shifting Performance
If your 2006-2009 GMC Envoy is suffering from harsh shifting, getting stuck in gear, or throwing transmission codes, a failing Transmission Control Module (TCM) is the most likely culprit. As an automotive diagnostician with over two decades of experience, I’ve seen firsthand how a faulty TCM can sideline an otherwise dependable SUV. This T42 Transmission Control Module, service part number 24243901, is the definitive solution to get your vehicle’s automatic transmission operating smoothly and reliably again.
The TCM is the brain of your transmission, responsible for managing every gear change, controlling torque converter lockup, and monitoring system pressures. When it fails, the symptoms can range from annoying to dangerous. This replacement module is meticulously prepared to OEM specifications and comes pre-programmed to your vehicle’s specific VIN. This crucial step eliminates the need for expensive dealership visits for programming, making it a true plug-and-play repair for both professional mechanics and DIY enthusiasts.
Case Study: A Tricky Diagnosis
A customer brought in their ’07 Envoy with classic ‘limp mode’ symptoms—stuck in 3rd gear with a Check Engine light on. Their local shop had replaced two shift solenoids with no success. A quick scan with my tool showed a P0700 (Transmission Control System Malfunction) and intermittent communication loss with the TCM. Instead of throwing more parts at it, we identified the root cause: the TCM itself was failing internally. After installing one of our VIN-programmed T42 modules, all codes cleared, and the Envoy was shifting perfectly within an hour. This is a common story for these vehicles and highlights why addressing the core electronic component is often the correct fix.
Is Your Envoy Exhibiting These Transmission Faults?
- ✔ Abrupt, harsh, or delayed gear shifts that make driving uncomfortable.
- ✔ The vehicle is stuck in a single gear (often called “limp mode”) and won’t shift up or down.
- ✔ Check Engine Light or Transmission Warning Light is illuminated on your dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700, P0750-series solenoid codes, or U-series communication codes.
- ✔ A noticeable decrease in fuel economy due to inefficient shifting.
- ✔ Complete loss of communication with the transmission module.
A Straightforward Guide to Installation
Replacing the 2006-2009 Envoy TCM is a job most owners can handle with basic tools. Because we program it to your VIN before shipping, you can skip the trip to the dealer. The module is typically located in the engine bay for easy access.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the vehicle’s computer systems.
- Locate the Module: On the GMC Envoy, the TCM is found 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 from the old TCM. 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 harnesses. Ensure they click into place.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it idle for a few minutes. While not always necessary, using a basic OBD2 scan tool to clear any stored historical codes is a good final step.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24243901 and is interchangeable with many other GM service numbers. It fits a wide array of vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. While this page focuses on the 2006-2009 Envoy TCM, please see the comprehensive list below for other compatible models.
This part will fit these makes and models with these options
ENVOY 06-09 Transmission; (LH engine compartment)
SAVANA & EXPRESS VANS 06-14 Transmission; (RH engine compartment)
SATURN VUE 07-10 Transmission; (LH front engine compartment)
CHEVROLET COBALT & PONTIAC G5/G6 06-10 Transmission; (LH strut tower)
SIERRA & SILVERADO 1500 07-13 Transmission; (next to battery)
BUICK LUCERNE & LACROSSE 06-11 Transmission; (LH engine compartment or under air cleaner housing)
CHEVROLET TAHOE & GMC YUKON 07-09 Transmission; (next to battery)
…and many more. Please verify your vehicle in the list above.
Frequently Asked Questions
Why is VIN programming so important for this TCM?
VIN programming loads your vehicle’s specific software, including shift points, transmission type, and tire size, onto the module. Without it, the TCM won’t communicate correctly with your vehicle, leading to continued shifting problems or a no-start condition. Our service saves you a costly trip to the dealership.
Is this a simple plug-and-play installation?
Yes. Because we handle the programming, you simply need to physically swap the old module with the new one. No special tools or software are required for installation.
Do I need to return my old TCM?
No, there is no core charge for this part. You can keep your old module or recycle it locally without any hassle or additional cost.
What if this part doesn’t solve my problem?
While this TCM is a common fix for many transmission issues, we recommend a proper diagnosis. If the part does not resolve your issue, it may point to a mechanical or wiring problem within the transmission itself. This part is backed by our one-year warranty against defects.
Will this work for my Envoy with the 8-cylinder engine?
Yes, this T42 TCM is compatible with both 6-cylinder and 8-cylinder (5.3L) GMC Envoy models within the 2006-2009 year range, as well as the Envoy XL and Trailblazer EXT models.