Is Your GMC Envoy Shifting Erratically or Stuck in Limp Mode?
As a mechanic with over two decades of experience, one of the most common complaints I hear from owners of 2006-2009 GMC Envoys involves frustrating transmission behavior. You might be experiencing harsh, banging shifts, a long delay when shifting from park to drive, or the dreaded ‘limp mode’ where the truck refuses to shift out of 2nd or 3rd gear. These aren’t just annoyances; they are classic signs of a failing Transmission Control Module (TCM), the electronic brain that orchestrates every gear change.
A faulty TCM can turn a reliable SUV into a source of constant stress. You’ll likely see a Check Engine Light and pull codes like P0700 (Transmission Control System Malfunction) or various solenoid-specific faults. In my shop, I’ve diagnosed hundreds of these T42 modules. The culprit is often internal circuit failure from years of heat cycles and vibration, leading to the unpredictable performance you’re seeing now.
The Direct Solution: A VIN-Programmed Replacement
Forget expensive dealership visits and the hassle of finding a shop that can program a new module. This OEM-quality T42 Transmission Control Module, part number 24235340, is the definitive solution. We pre-program it to your Envoy’s specific Vehicle Identification Number (VIN) before it ships. This ensures it communicates perfectly with your vehicle’s engine computer and other systems right out of the box, restoring the smooth, decisive shifting you remember.
- âś” Eliminate Guesswork: Solves common issues like harsh 1-2 shifts, no upshifting, and intermittent communication loss.
- âś” Ready for Installation: Arrives programmed with the latest GM software updates for your specific vehicle. No additional flashing or dealer tools are required.
- âś” Restore Drivability: Regains precise control over shift points and torque converter lockup, which can improve fuel efficiency and reduce transmission heat.
- âś” Built to Last: Constructed to meet or exceed original equipment standards for long-term reliability, backed by a one-year warranty.
Expert Pro Tip: Check Your Connectors First
Before you install your new TCM, take a moment to closely inspect the vehicle’s wiring harness connectors. Over time, moisture can lead to green or white corrosion on the pins, and pins can sometimes get bent or pushed back into the connector. This creates a poor connection that can mimic the symptoms of a failed module. Cleaning the terminals with a small brush and electrical contact cleaner can prevent a simple wiring issue from being misdiagnosed as a faulty part.
Plug-and-Play Installation for the 2006-2009 Envoy TCM
Replacing the TCM on your Envoy is a straightforward job that can be done in your driveway in under 30 minutes with basic hand tools. This gets your vehicle back on the road quickly without the cost of a shop’s labor.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the vehicle’s adaptive memory.
- Locate the Module: On the 2006-2009 GMC Envoy, the TCM is conveniently located in the engine compartment on the driver’s side (LH side), making it easy to access.
- Swap the Part: Carefully unplug the electrical connectors from the old module. Unbolt it from its mounting bracket, install the new module in its place, and securely reconnect the wiring harnesses. You’ll hear a ‘click’ when they are properly seated.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s always a good practice to use a basic OBD2 scan tool to clear any lingering diagnostic trouble codes (DTCs) from the system.
Guaranteed Compatibility
This module is a direct replacement for a wide range of GM vehicles using the T42 controller and is interchangeable with part numbers like 24252114, 24234503, 24230461, and your specific part 24235340. By providing your VIN, you guarantee a part that is perfectly matched to your Envoy’s factory specifications. End the shifting headaches and restore your vehicle’s performance and reliability today.