Is your 2006 GMC Envoy XL suffering from frustrating and unpredictable transmission issues? As a technician with over two decades of experience, I’ve seen countless GM vehicles come into the shop with harsh shifting, delayed gear engagement, or stuck in limp mode. More often than not, the culprit is a failing Transmission Control Module (TCM). This VIN-programmed T42 TCM, part number 24240400, is the direct-fit, reliable solution to restore your vehicle’s performance and get you back on the road with confidence.
This isn’t just a replacement part; it’s a complete fix. We pre-program this module to your vehicle’s specific VIN before shipping. This crucial step eliminates the need for expensive dealership visits for programming, making it a true plug-and-play repair for both DIY enthusiasts and professional mechanics. It’s engineered to OEM specifications to seamlessly manage your 4-speed automatic transmission (like the 4L60E or 4L65E), correcting shift commands, torque converter lockup, and communication errors that trigger those dreaded warning lights.
From the Diagnostic Bay: The Case of the Slipping Sierra
A customer brought in his Sierra last month, completely fed up. It would slam into gear from a stop and sometimes refuse to shift past 2nd gear. He’d already replaced a shift solenoid based on a code, but the problem persisted. After connecting my scanner, I saw the classic signs: a P0700 code (Transmission Control System Malfunction) and erratic data from the TCM. The internal logic was failing. We installed one of our pre-programmed T42 modules, and in under 30 minutes, the truck was shifting like new. This is a common story, and a pre-flashed module is the fastest, most reliable way to solve it.
Is Your GM Vehicle Showing These Telltale Signs?
- ✔ Harsh, jerky, or erratic gear shifts that make driving uncomfortable.
- ✔ The transmission seems to slip or fails to engage a gear promptly.
- ✔ Your vehicle is stuck in “limp mode,” usually in 2nd or 3rd gear.
- ✔ The Check Engine Light or a dedicated transmission warning light is illuminated.
- ✔ Diagnostic scans reveal codes like P0700, P0750, or other solenoid-related faults.
- ✔ A noticeable decrease in fuel economy due to inefficient shifting.
A Straightforward Guide to Your TCM Replacement
Installing your new 2006 Envoy XL Transmission Control Module is a job most people can handle in their own driveway. The module is typically located in the engine bay for easy access.
- Step 1: Safety First. Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
- Step 2: Locate the Old TCM. On your Envoy XL, it’s usually in the left-hand (driver’s side) of the engine compartment. On other GM models, it might be next to the battery, under the air cleaner box, or on a frame rail.
- Step 3: Disconnect and Remove. Carefully unplug the electrical connectors. Use a socket wrench to remove the bolts or nuts holding the module in place.
- Step 4: Install the New Module. Mount your new, pre-programmed TCM and securely tighten the fasteners. Reconnect the electrical harnesses until they click.
- Step 5: Finalize the Job. Reconnect the battery terminal. While the module is plug-and-play, it’s good practice to use a basic 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 24240400 and interchanges with several other service numbers. It is confirmed to fit the following General Motors vehicles equipped with a 4-speed automatic transmission. Please verify your specific model and options.
- GMC Envoy / Envoy XL / Trailblazer / Trailblazer EXT (2006-2009): 8-cylinder models, located in LH engine compartment.
- Chevrolet Silverado 1500 / GMC Sierra 1500 (2007-2013): Located next to the battery.
- Chevrolet Tahoe / Suburban / GMC Yukon / Yukon XL (2007-2009): Located next to the battery.
- Chevrolet Express / GMC Savana Vans (2006-2014): Located in RH engine compartment.
- Chevrolet Impala / Monte Carlo (2006-2011): Found in the lower air cleaner housing.
- Pontiac G6 / Grand Prix (2006-2010): Located on the LH strut tower.
- Buick LaCrosse / Allure / Lucerne (2006-2011): Location varies from lower air cleaner housing to LH engine compartment.
- Hummer H3 (2008-2010): Located in RH rear engine compartment.
- …and many other GM models including the Cobalt, HHR, Saturn Vue, Saab 9-7X, and Cadillac DTS.
Frequently Asked Questions
Do I need to take my vehicle to the dealer after installation?
No. This module comes fully programmed to your vehicle’s VIN. It is a plug-and-play solution that requires no further programming or dealership intervention, saving you time and money.
Will this fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. If the root cause is a failing TCM, replacing it with this part will resolve the code and the underlying issue.
Is this the same as an ECM or PCM?
No. The TCM (Transmission Control Module) specifically manages the automatic transmission. The ECM (Engine Control Module) or PCM (Powertrain Control Module) manages engine functions, and while they communicate, they are separate components.
What is the warranty on this part?
This part comes with a one-year warranty, giving you peace of mind and assurance in the quality and reliability of your repair.
Do I need to send my old part back?
No, there is no core charge for this module. You can keep or dispose of your old part without any hassle.