Restore Your GM’s Shifting Performance
If you’re dealing with the frustration of a transmission that won’t shift correctly, bangs into gear, or has left you stranded in limp mode, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen countless GM vehicles, from hardworking Silverado trucks to family-hauling Envoy XLs, sidelined by a failed Transmission Control Module (TCM). This isn’t just an inconvenience; it’s a safety concern that affects your vehicle’s reliability and your peace of mind. This VIN-programmed T42 TCM, part number 24255280, is the definitive, hassle-free solution to get your vehicle driving smoothly again.
The TCM is the brain of your automatic transmission, controlling everything from shift points to torque converter lockup. When it fails, the symptoms can be dramatic and confusing. This module is a direct-fit replacement, pre-programmed to your vehicle’s specific VIN. That means you can skip the expensive trip to the dealership for programming—it arrives ready for a straightforward installation. This is the exact type of reliable fix I’d use in my own service bay to solve complex electronic transmission problems for good.
Case Study: A Tricky Diagnosis
A customer brought in a 2008 GMC Sierra with a complaint that stumped two other shops: intermittent, violent 1-2 shifts and occasional slipping out of gear on the highway. They’d already replaced a shift solenoid to no avail. The scanner showed a P0752 (Shift Solenoid A Stuck On) code, but live data showed the solenoid was functioning correctly. Experience pointed me toward the TCM. These T42 modules can develop internal faults that send incorrect signals, causing the exact symptoms the customer described. After installing a VIN-programmed 2006 Envoy XL TCM (which shares the same T42 architecture), the truck shifted perfectly. The pre-programming saved the customer hundreds in dealership fees and got their work truck back on the road the same day.
Is Your GM Exhibiting These Telltale Symptoms?
- ✔ Harsh, delayed, or erratic 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, P0751, P0752, P0756, or other solenoid-related faults.
- ✔ A noticeable drop in fuel economy or signs of the transmission overheating.
- ✔ Complete loss of communication with the transmission module.
A Straightforward Guide to Installation
- ✔ Safety First: Before you begin, disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- ✔ Locate the Module: The TCM’s location varies by model. On a 2006 Envoy XL, it’s typically in the LH engine compartment. Other common locations include next to the battery, under the air cleaner box, or on a frame rail.
- ✔ Disconnect and Remove: Carefully unplug the electrical connectors. Use a small screwdriver to gently release the locking tabs if necessary. Then, unbolt the module from its mounting bracket.
- ✔ Install the New TCM: Mount the new, pre-programmed module in place and securely fasten it. Reconnect the electrical harnesses, ensuring they click into place.
- ✔ Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s best practice to use a basic OBD2 scan tool to clear any stored trouble codes from the vehicle’s memory.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for a wide range of General Motors vehicles. It is interchangeable with part numbers 24252114, 24234503, 24230461, 24234274, 24235340, 24255280, and others. While it is the correct part for a 2006 Envoy XL TCM with an 8-cylinder engine, it also fits many other models:
Fits Models Including: Chevrolet Silverado, Tahoe, Suburban, Impala, Cobalt, HHR; GMC Sierra, Yukon, Savana, Envoy; Buick LaCrosse, Lucerne; Cadillac DTS; Pontiac G6; Hummer H3, and many more from 2006-2014. Please use the vehicle selector tool to confirm an exact match for your application.
Frequently Asked Questions
What does ‘VIN Programmed’ actually mean for me?
It means we load your vehicle’s specific Vehicle Identification Number (VIN) and the latest GM software onto the module before we ship it. This ensures it communicates perfectly with your vehicle’s other computers right out of the box, eliminating the need for expensive dealership programming.
Is this a difficult part for a DIYer to install?
Not at all. With basic hand tools and our installation guide, most people can replace their TCM in under 30 minutes. The most important part is correctly identifying its location on your specific vehicle.
Do I need to send my old part back (core charge)?
No, there is no core charge for this part. You can keep your old module or dispose of it without any hassle or extra cost.
Will this fix a P0700 trouble code?
A P0700 code is a general fault request from the TCM to the main engine computer (ECM) to turn on the Check Engine Light. Often, a faulty TCM is the root cause. Replacing the module should clear the P0700 and any other related transmission codes once the repair is complete.
What kind of warranty is included?
This module is backed by our comprehensive one-year warranty, giving you confidence and peace of mind in your repair.