End Frustrating Shifting Issues in Your GMC Envoy
If your 2006-2009 GMC Envoy is suffering from harsh shifts, getting stuck in gear, or throwing transmission codes, the problem is very likely a failing Transmission Control Module (TCM). As a technician with over two decades of experience, I’ve seen how a faulty TCM can make a perfectly good vehicle feel unreliable and unsafe. This isn’t just an annoyance; it affects your vehicle’s performance, fuel economy, and longevity. This T42 Transmission Control Module, part number 24243921, is the definitive solution, arriving pre-programmed to your vehicle’s VIN for a direct, hassle-free installation.
Case Study: A Tricky Diagnosis
A customer brought in a 2008 Chevy Tahoe with classic symptoms: it would slam into gear from a stop and occasionally refuse to shift past 2nd gear. They’d already replaced a shift solenoid with no luck. After connecting my scanner, I saw a generic P0700 code and an intermittent solenoid circuit code. Instead of just throwing more parts at it, I checked the TCM wiring and found it was fine. Experience told me the logic board inside the T42 TCM itself was failing, causing erratic commands. We installed a VIN-programmed module just like this one, and the truck was shifting like new in under an hour. This is a common failure point on these GM platforms, and a pre-programmed module is the fastest, most reliable fix.
Is Your Envoy Exhibiting These Symptoms?
A failing TCM will give you clear warning signs. If you’re experiencing any of the following, it’s time for a replacement. This module is designed to resolve these specific issues:
- ✔ Harsh, jerky, or delayed gear shifts.
- ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear).
- ✔ The Check Engine Light or a transmission warning light is illuminated.
- ✔ You have Diagnostic Trouble Codes (DTCs) such as P0700, P0750, P0753, P0758, or other solenoid-related faults.
- ✔ Inconsistent upshifting or downshifting.
- ✔ Poor fuel mileage and a feeling of lost power.
A Straightforward Guide to Installation
One of the best features of this module is its simple, plug-and-play installation. No need for a trip to the dealership. For a 2006-2009 Envoy TCM, the process is quick and requires basic hand tools.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: On the GMC Envoy and similar platforms (like the Trailblazer), the TCM is typically found in the engine compartment on the driver’s side (LH side).
- Disconnect and Remove: Carefully unplug the electrical connectors. Press the release tabs firmly to avoid breaking them. Then, unbolt the old module from its mounting bracket.
- Install the New TCM: Mount the new module securely onto the bracket and reconnect the electrical harnesses. You’ll hear a click as they lock into place.
- Final Steps: Reconnect the battery terminal. While our VIN programming handles the critical setup, it’s good practice to use a basic OBD2 scanner to clear any stored fault codes from the vehicle’s memory.
Verified Vehicle Compatibility
This T42 TCM is a direct replacement for part number 24243921 and is interchangeable with many other service numbers. It fits a wide range of General Motors vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. While this page focuses on the 2006-2009 Envoy TCM, it also fits:
- GMC: Envoy (06-09), Sierra, Yukon, Savana, Canyon
- Chevrolet: Trailblazer, Tahoe, Silverado, Suburban, Impala, Cobalt, HHR, Colorado, Express
- Buick: Rainier, LaCrosse, Lucerne, Allure
- Pontiac: G6, Grand Prix, Pursuit
- Cadillac: DTS
- And many more GM models. Always verify fitment with your vehicle’s year and model.
Frequently Asked Questions
What does ‘VIN Programmed’ actually mean?
It means we load your vehicle’s unique 17-digit 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 engine computer and other systems 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. For most vehicles, the TCM is easily accessible in the engine bay. With basic tools, the swap takes less than 30 minutes. Our step-by-step guide makes it a straightforward job for any DIY enthusiast.
Will this fix a P0700 transmission code?
Yes, in many cases. The P0700 code is a general fault code indicating the TCM has detected a problem. Often, the problem is the TCM itself. Replacing a faulty module with our programmed unit frequently resolves the root cause of the P0700 code and related specific codes.
Do I need to return my old TCM? Is there a core charge?
No. We do not require you to return your old part, and there is absolutely no core charge. This simplifies your repair process and saves you the hassle and cost of shipping the old unit back.
What is the warranty on this part?
This transmission control module is backed by our one-year, hassle-free warranty, giving you confidence and peace of mind in your repair.