If you’re dealing with the frustrating and unpredictable behavior of a failing transmission, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen countless GM vehicles, including the 2006 GMC Envoy XL, sidelined by a faulty Transmission Control Module (TCM). This isn’t just an inconvenience; it’s a safety concern. This T42 series TCM, part number 24235340, is the definitive solution to restore your vehicle’s performance and your peace of mind.
The TCM is the brain of your automatic transmission, orchestrating every gear change, managing torque converter lockup, and monitoring system health. When it fails, the symptoms can range from jarring shifts to being stuck in limp mode. Our module arrives expertly programmed to your vehicle’s specific VIN, eliminating the need for expensive dealership visits and complex programming tools. It’s a direct, plug-and-play fix designed to get you back on the road quickly and reliably.
Case Study: A Tricky Diagnosis
A customer brought in his Chevy Silverado with a classic complaint: intermittent harsh shifting and a P0700 code that would come and go. He had already replaced two shift solenoids based on other advice, but the problem persisted. After connecting my scan tool, I noticed the data stream from the TCM was erratic. Voltage would drop intermittently, causing the processor to command incorrect line pressure. This is a tell-tale sign of internal TCM failure, not a mechanical issue. We installed one of our VIN-programmed T42 modules, and the truck has been shifting perfectly ever since. This is why addressing the root cause—the module itself—is critical.
Is Your Envoy XL Exhibiting These Transmission Faults?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, this module is likely the solution you need. In my shop, these are the most common indicators I see for a needed 2006 Envoy XL Transmission Control Module replacement.
- ✔ Erratic, harsh, or delayed gear shifts that make driving uncomfortable.
- ✔ The vehicle is stuck in a single gear (often 2nd or 3rd), a condition known as “limp mode.”
- ✔ Check Engine Light or Transmission Warning Light is illuminated on the dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid codes), or other communication errors.
- ✔ A sudden drop in fuel economy or the transmission overheating.
- ✔ Complete loss of communication with the transmission module.
A Straightforward Guide to Installation
One of the biggest benefits of this module is its simple, DIY-friendly installation. No specialized tools are needed, and the process typically takes less than 30 minutes. Your 2006 Envoy XL Transmission Control Module is located in the engine compartment on the left-hand side.
- 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 your 2006 Envoy XL, you will find the TCM mounted in the left-hand (driver’s side) of the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors from the old module. Then, unbolt the module from its mounting bracket.
- Install the New Module: Mount the new, pre-programmed TCM in place of the old one and securely reconnect the electrical connectors. Ensure they click into place.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s best practice to use a standard OBD2 scan tool to clear any stored fault codes from the ECU. Start the vehicle and enjoy smooth shifting!
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24235340 and is interchangeable with a wide range of other service numbers, including 24252114, 24234503, 24230461, 24234274, and more. It is engineered to fit the following GM vehicles:
GMC: Envoy (06-09), Envoy XL (06), Savana 1500/2500/3500 (06-14), Sierra 1500/2500 (07-13), Yukon (07-09), Yukon XL 1500 (07-08), Canyon (08-12)
Chevrolet: Tahoe (07-09), Silverado 1500/2500 (07-13), Express 1500/2500/3500 (06-14), Impala (06-11), Monte Carlo (06-07), HHR (06-11), Cobalt (06-10), SSR (05-06), Trailblazer (06-09), Avalanche 1500 (07-08), Colorado (08-12), Malibu (06-10)
Buick: LaCrosse (06-09), Lucerne (06-11), Allure (06-09), Rainier (06-07), Rendezvous (06-07)
Cadillac: DTS (06-11)
Pontiac: G6 (06-10), Grand Prix (06-08), G5 (07-10), Pursuit (06)
Saturn: Vue (07-10), Aura (07-09), Ion (06-07)
Hummer: H3 (08-10)
Saab: 9-7X (06-09)
…and other models. Please verify your specific application using the fitment tool.
Frequently Asked Questions
What does ‘VIN Programmed’ mean for me?
It means this module is delivered ready for installation. We load your vehicle’s specific Vehicle Identification Number (VIN) and the latest GM software onto the module before shipping. This ensures it communicates perfectly with your vehicle’s other computers, eliminating the need for a trip to the dealership for expensive programming.
Will this fix my transmission’s limp mode and check engine light?
Yes, in most cases. Limp mode, along with codes like P0700, are classic symptoms of a failed TCM. By replacing the faulty module with this pre-programmed unit, you are addressing the root cause of those electronic faults, which should resolve the symptoms and allow you to clear the codes.
Is this a difficult part for a DIYer to install?
Not at all. This is one of the more straightforward electronic component replacements. It’s typically located in an accessible part of the engine bay and requires only basic hand tools to unbolt and unplug the old unit and install the new one. The entire process should take less than 30 minutes.
Do I need to send my old part back?
No, there is no core charge for this part. You can keep your old module or dispose of it responsibly without any extra hassle or cost.
How do I know this is the correct part for my 2006 Envoy XL?
This module, part number 24235340, is the correct fitment for the 2006 GMC Envoy XL with the 8-cylinder engine. Our comprehensive fitment list also confirms compatibility. Providing your VIN at checkout guarantees we program it correctly for your specific vehicle configuration.