Restore Flawless Shifting to Your GMC Envoy
If your 2006-2009 GMC Envoy is suffering from harsh shifting, getting stuck in gear, or has an illuminated check engine light, a failing Transmission Control Module (TCM) is the most likely culprit. As a mechanic with over two decades of experience, I’ve seen these T42 modules fail frequently due to heat and vibration in the engine bay. This isn’t just an annoyance; it’s a critical failure that can leave you stranded. This direct-fit Envoy Transmission Control Module, part number 24235754, is the definitive solution, arriving pre-programmed to your vehicle’s VIN for a simple, plug-and-play installation that gets you back on the road with confidence.
Case Study: A Tricky Diagnosis
A customer brought in a 2008 Trailblazer (a sibling to the Envoy) that was stuck in what he called ‘get-home mode’—it wouldn’t shift out of 3rd gear. The dash was lit up with a check engine light and a transmission warning. His local shop had replaced two shift solenoids with no change. After pulling the codes, I saw a P0700 (Transmission Control System Malfunction) and an intermittent communication fault. Instead of throwing more parts at it, we went straight for the brain. The original TCM had failed internally. We installed one of these pre-programmed modules, and within 20 minutes, the truck was shifting perfectly through all gears. This is the fix that solves the problem at its source.
Is Your Envoy Showing These Warning Signs?
A failing TCM will give you clear signals. Don’t ignore them, as they can lead to more significant transmission damage over time. Look out for:
- ✔ Harsh, slamming shifts or delayed gear engagement.
- ✔ The vehicle being stuck in a single gear (limp mode), often 2nd or 3rd.
- ✔ An active Check Engine Light or Transmission Warning Light on your dash.
- ✔ Diagnostic Trouble Codes (DTCs) such as P0700, P0750-P0758 (solenoid circuit faults), or U-series communication codes.
- ✔ A sudden drop in fuel economy or the transmission overheating.
- ✔ Complete loss of communication with the module, preventing shifting altogether.
A Straightforward Guide to Installation
Replacing your Envoy Transmission Control Module is a job most DIYers can handle in their own garage in under 30 minutes. No specialized tools are needed.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and help reset the system.
- Locate the Module: On the GMC Envoy and similar platforms, the TCM is typically found in the engine compartment on the driver’s side (LH), often near the strut tower or air cleaner box.
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place and securely reconnect the electrical harnesses. You should hear a click as they lock in.
- Final Steps: Reconnect the battery terminal. Start the vehicle and allow it to idle for a minute. 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 previous failure.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24235754 and is interchangeable with many other GM service numbers. It provides a guaranteed fit for the following models, among others:
- GMC Envoy / Envoy XL / Trailblazer / Trailblazer EXT: 2006-2009 (8-cylinder models)
- Chevrolet Silverado 1500 / GMC Sierra 1500: 2007-2013 (non-hybrid)
- Chevrolet Tahoe / Suburban / GMC Yukon: 2007-2009
- Chevrolet Impala / Monte Carlo: 2006-2011
- Chevrolet Cobalt / HHR / Pontiac G5 / G6: 2006-2011
- Cadillac DTS / Buick Lucerne: 2006-2011
- Chevrolet Express / GMC Savana Vans: 2006-2014
- …and many more GM vehicles. Please verify fitment using your vehicle information.
Frequently Asked Questions
Do I need to take my vehicle to the dealership for programming?
Absolutely not. We program the module to your vehicle’s specific VIN before shipping. This ensures it’s ready for immediate installation right out of the box, saving you time and the high cost of dealer programming.
What makes this Envoy Transmission Control Module fail?
From my experience, the number one cause of failure for these T42 modules is their location in the engine bay. Constant exposure to heat cycles and engine vibration eventually causes internal solder joints and electronic components to fail, leading to the common shifting problems.
Is this a difficult part to install myself?
Not at all. This is one of the more accessible electronic repairs. With basic hand tools and our step-by-step guide, most people can complete the swap in under 30 minutes. The key is simply locating the module and swapping the connectors.
Will this fix a P0700 trouble code?
Yes, in many cases it will. A P0700 code is a general fault code indicating the TCM has detected a problem. If the TCM itself is the source of the electrical fault, replacing it with this programmed unit will resolve the code and the underlying issue.
What is the warranty on this part?
This module comes with a one-year, hassle-free warranty, giving you peace of mind that you’re installing a quality, dependable part in your vehicle.