Restore Smooth Shifting to Your GM Vehicle
If you’re battling erratic shifting, a check engine light, or a transmission stuck in limp mode, you’re not alone. As a technician with over two decades of experience, I’ve seen countless GM vehicles sidelined by a faulty Transmission Control Module (TCM). This VIN-programmed T42 TCM, part number 24240400, is the direct-fit, reliable solution for your 2006 Envoy XL and a wide range of other GM models. It’s designed to restore the precise, factory-level communication between your engine and transmission, eliminating the guesswork and frustration of a failing electronic component.
The TCM is the brain of your automatic transmission, controlling everything from shift points and line pressure to torque converter lockup. When it fails, the symptoms can range from annoying to dangerous. This replacement module is pre-programmed to your vehicle’s specific VIN, ensuring it works perfectly right out of the box. You can skip the expensive trip to the dealership for programming; this is a true plug-and-play fix for the common issues plaguing the 4L60E, 4L65E, and 4L70E transmissions.
A Technician’s Notebook: The Case of the Slipping Silverado
A customer brought in his 2008 Silverado, complaining of harsh 1-2 shifts and occasionally getting stuck in 3rd gear. He’d already replaced a shift solenoid with no luck. After a quick scan, I saw a P0752 (Shift Solenoid A Stuck On) code, but my diagnostic tests on the solenoid and wiring showed they were fine. This is a classic scenario I’ve diagnosed hundreds of times. The root cause wasn’t the solenoid itself, but the driver circuit inside the T42 TCM failing under heat and load. We installed a VIN-programmed module just like this one, cleared the codes, and the truck was shifting like new in less than an hour. It’s a textbook fix that saves customers time and money by addressing the real problem directly.
Is Your GM Vehicle Showing These Telltale TCM Failure Signs?
A failing 2006 Envoy XL TCM can manifest in several ways. If you’re experiencing any of the following, it’s a strong indicator that your module needs replacement:
- ✔ Harsh, delayed, or unpredictable gear shifts that bang into gear.
- ✔ The vehicle enters a “limp mode,” often stuck in 2nd or 3rd gear, with limited power.
- ✔ An illuminated Check Engine Light or Transmission Warning Light on your dashboard.
- ✔ Diagnostic Trouble Codes (DTCs) stored in the system, such as P0700, P0750-P0758, or other solenoid-related faults.
- ✔ A noticeable decrease in fuel economy due to inefficient shifting and torque converter operation.
- ✔ Complete loss of communication with the transmission, resulting in a no-shift condition.
DIY Guide: Installing Your T42 TCM in Under 30 Minutes
Replacing the TCM is a straightforward job that most DIY mechanics can handle with basic tools. The location varies by model, but it’s typically easy to access in the engine bay. Follow these steps for a successful installation.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the vehicle’s electronic systems.
- Locate the Module: Find the old TCM. Common locations include the LH or RH side of the engine compartment, next to the battery, under the air cleaner box, or on the LH strut tower. It’s a silver box with large electrical connectors.
- Disconnect and Remove: Carefully unclip the wiring harness connectors. Then, unbolt the module from its mounting bracket. Keep the mounting hardware, as you will reuse it.
- Install the New Module: Mount your new, pre-programmed TCM using the original hardware. Securely reconnect the wiring harnesses, ensuring the clips click into place.
- Final Steps: Reconnect the negative battery terminal. Start the vehicle and let it idle for a few minutes. While the module is plug-and-play, it’s good practice to use a basic OBD2 scan tool to clear any old fault codes from the computer’s memory.
Verified Fitment for Your General Motors Car, Truck, or SUV
This T42 TCM is a direct replacement for part number 24240400 and interchanges with numerous other service numbers, including 24252114, 24234503, 24230461, and more. It is confirmed to fit the following vehicles:
Buick: Allure (06-09), LaCrosse (06-09), Lucerne (06-11), Rainier (06-07), Rendezvous (06-07)
Cadillac: DTS (06-11)
Chevrolet: Avalanche 1500 (07-08), Cobalt (06-10), Colorado (08-12), Express 1500/2500/3500 Van (06-14), HHR (06-11), Impala (06-11), Malibu (06-10), Monte Carlo (06-07), Silverado 1500/2500 (07-13), SSR (05-06), Suburban 1500 (07-08), Tahoe (07-09), Trailblazer & EXT (06-09)
GMC: Canyon (08-12), Envoy & XL (06-09), Savana 1500/2500/3500 Van (06-14), Sierra 1500/2500 (07-13), Yukon & XL 1500 (07-08)
Hummer: H3 (08-10)
Pontiac: G5 (07-10), G6 (06-10), Grand Prix (06-08), Pursuit (06)
Saab: 9-7X (06-09)
Saturn: Aura (07-09), Ion (06-07), Vue (07-10)
Uplander/Montana/Terraza/Relay Vans: (06-09)
Do I need to take my car to the dealer for programming?
Do I need to take my car to the dealer for programming?
No. This module comes fully programmed to your vehicle’s VIN. It is a true plug-and-play solution, saving you the time and expense of a dealership visit. Just provide your VIN at checkout.
Is there a core charge for this part?
No, there is no core charge. You are not required to send your old, faulty module back to us, which simplifies the repair process for you.
Will this fix a P0700 trouble code?
A P0700 is a generic code indicating the TCM has detected a fault. Often, the root cause is the TCM itself. Replacing a faulty module with this unit will resolve the underlying issue that triggers the P0700 and other related transmission codes.
What tools are required for installation?
Basic hand tools are all that’s needed. Typically, a socket set (e.g., 10mm or 13mm sockets), a ratchet, and possibly a small flathead screwdriver to help release the connector clips are sufficient for the job.
What is the warranty on this 2006 Envoy XL TCM?
This transmission control module is backed by a one-year warranty, giving you peace of mind and confidence in your repair.