If your 2006 GMC Envoy XL is suffering from harsh shifting, getting stuck in gear, or has an illuminated Check Engine Light, you’re likely dealing with a failed Transmission Control Module (TCM). I’ve seen this exact issue hundreds of times in my shop—it’s a common point of failure on these GM vehicles. This OEM-quality T42 TCM, part number 24238856, is the definitive solution, arriving pre-programmed to your vehicle’s specific VIN. This means no expensive trips to the dealership for programming; it’s a true plug-and-play fix that restores the precise, smooth shifting you expect.
The TCM is the brain of your automatic transmission, managing everything from shift points and line pressure to torque converter lockup. When it fails, usually due to heat and vibration in the engine bay, the symptoms can range from annoying to dangerous. This replacement module is built to meet or exceed original factory specifications, ensuring reliable performance and long-term durability for your 4L60E, 4L65E, or 4L70E transmission.
Case Study: A Tricky Diagnosis
A customer brought in their ’06 Envoy XL with a classic complaint: it would randomly refuse to shift out of 2nd gear and the transmission temp light would flicker. They had already replaced two shift solenoids with no luck. A quick scan showed a P0700 (Transmission Control System Malfunction) and an intermittent U0101 (Lost Communication with TCM). Instead of chasing ghosts in the wiring, we went straight for the module. After installing one of our pre-programmed TCMs, all communication was restored, the codes cleared, and the vehicle shifted perfectly. It’s a textbook example of how a faulty module can mimic internal transmission problems, making a correct diagnosis crucial.
Is Your Envoy Showing These Telltale Signs?
- ✔ Harsh, banging shifts or delayed gear engagement.
- ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear).
- ✔ Check Engine Light is on with transmission-related Diagnostic Trouble Codes (DTCs) like P0700, P0750, P0753, P0758, or other solenoid circuit codes.
- ✔ Inability to upshift or downshift, leading to poor acceleration and terrible fuel economy.
- ✔ Unpredictable electrical behavior related to the transmission.
- ✔ A complete loss of communication with the scan tool.
A Straightforward Guide to Your 2006 Envoy XL TCM Installation
- ✔ Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work. This prevents short circuits and helps reset the vehicle’s internal systems.
- ✔ Locate the Module: On the 2006 Envoy XL (with the 8-cylinder engine), the TCM is typically found in the engine compartment on the driver’s side (LH). Check near the strut tower or main fuse block.
- ✔ Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket.
- ✔ Install the New TCM: Mount the new, pre-programmed module in the same location and securely fasten it. Reconnect the electrical harnesses, ensuring they click firmly into place.
- ✔ Final Steps: Reconnect the negative battery terminal. Start the vehicle and allow it to idle for a few minutes. While the module is pre-programmed, it’s good practice to use a basic OBD2 scan tool to clear any stored fault codes from the ECU. Test drive to confirm smooth shifting.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for a wide range of General Motors vehicles equipped with 4-speed automatic transmissions. While this page is for the 2006 Envoy XL, it also fits many other models. Please verify your part number (24238856) or check the list below. Interchangeable part numbers include: 24252114, 24234503, 24230461, 24234274, 24235340, 24235754, 24239224, 24239926, and more.
Partial Fitment List:
- GMC Envoy / Envoy XL / Trailblazer (8-cylinder): 2006-2009
- Chevrolet Silverado & GMC Sierra 1500/2500: 2007-2013 (check location notes)
- Chevrolet Tahoe / Suburban & GMC Yukon / Yukon XL: 2007-2009
- Chevrolet Impala / Monte Carlo: 2006-2011
- Buick LaCrosse / Lucerne: 2006-2011
- Cadillac DTS: 2006-2011
- Chevrolet Express & GMC Savana Vans: 2006-2014
- …and many other GM cars, trucks, and SUVs from 2006-2014.
Frequently Asked Questions
Frequently Asked Questions
Do I need to take my vehicle to a dealer after installation?
No. This module is delivered pre-programmed to your vehicle’s VIN. This eliminates the need for any additional programming or calibration. It is a true plug-and-play solution.
What is a core charge?
There is no core charge for this part. You are not required to send your old, faulty module back to us, saving you time and shipping costs.
Will this fix a P0700 code?
A P0700 is a generic code indicating the TCM has detected a fault. While a failing TCM is a very common cause, this code can also be triggered by other issues. However, if you’re experiencing shifting problems along with the P0700, replacing the TCM is the most probable fix.
Where is the TCM located on my vehicle?
The location varies by model. For the 2006 Envoy XL, it’s in the LH engine compartment. On Silverado/Sierra trucks, it’s often next to the battery. On cars like the Impala, it may be under the air cleaner housing. Always verify the location on your specific vehicle before starting.
What kind of warranty is included?
This part comes with a one-year, hassle-free warranty, giving you confidence in the quality and reliability of your repair.