If your 2006-2009 GMC Envoy is suffering from erratic shifting, getting stuck in gear, or throwing transmission-related trouble codes, you’ve come to the right place. As a technician with over two decades of experience, I’ve seen firsthand how a failing Transmission Control Module (TCM) can mimic a catastrophic transmission failure, causing unnecessary stress and costly misdiagnoses. This T42 TCM, part number 24239926, is the definitive solution to restore your vehicle’s performance and reliability.
The TCM is the brain of your automatic transmission, responsible for orchestrating every gear change, managing torque converter lockup, and monitoring system health. When it fails, the symptoms can be alarming. This replacement module is expertly pre-programmed to your vehicle’s specific VIN, ensuring it works seamlessly right out of the box. This eliminates the need for a trip to the dealership for expensive programming, making it a perfect fix for both seasoned mechanics and DIY enthusiasts looking to save time and money. By installing this module, you’re not just replacing a part; you’re restoring the precise, smooth operation your Envoy was designed for.
From the Diagnostic Bay
I recall a customer with a 2007 Envoy who was told he needed a complete transmission rebuild, a quote that ran into the thousands. His symptoms were intermittent—one day it would shift perfectly, the next it would slam into gear and get stuck in limp mode. After connecting my scan tool, I saw a generic P0700 code and a few intermittent solenoid circuit faults. Instead of jumping to the worst-case scenario, I checked the TCM. Sure enough, heat soak was causing internal board failure. We swapped in a VIN-programmed module like this one, and the Envoy drove like new. It’s a classic case where a simple, targeted repair saved the customer from a massive, unnecessary expense.
Is Your Envoy Exhibiting These Transmission Problems?
- ✔ Harsh, jerky, or delayed 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 the dash.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction) or various solenoid codes (e.g., P0751, P0756).
- ✔ A noticeable drop in fuel economy due to inefficient shifting.
- ✔ Complete loss of communication with the module, preventing diagnostics.
A Straightforward Guide to Installation
Replacing the 2006-2009 Envoy TCM is a job you can handle in your own garage with basic tools. On the GMC Envoy, it’s typically located in the left-hand (driver’s side) of the engine compartment, making it easily accessible.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Module: Find the TCM in the LH engine compartment. It will have several large electrical connectors attached.
- Disconnect and Remove: Carefully unplug the wiring harnesses. Press the release tabs firmly. Then, unbolt the module from its mounting bracket.
- Install the New TCM: Mount the new, VIN-programmed module in place and securely tighten the bolts. Reconnect the wiring harnesses, ensuring they click into place.
- Final Steps: Reconnect the battery terminal. Start the vehicle and allow it to idle for a few minutes. If you have a scan tool, it’s good practice to clear any stored codes. A short test drive will confirm the shifting issues are resolved.
Verified Fitment for Your GM Vehicle
This module is a direct replacement for part number 24239926 and other interchangeable numbers. While this page focuses on the 2006-2009 Envoy TCM, it is also compatible with a wide range of other GM vehicles. Please verify your part number or consult the list below.
- GMC Envoy / Envoy XL / Trailblazer / Trailblazer EXT: 2006-2009 (V8 models for 06-07)
- Chevrolet Silverado & GMC Sierra 1500/2500: 2007-2013 (Non-hybrid)
- Chevrolet Tahoe, Suburban & GMC Yukon, Yukon XL: 2007-2009
- Chevrolet Impala & Monte Carlo: 2006-2011
- Chevrolet Cobalt, HHR & Pontiac G5/G6: 2006-2011
- Cadillac DTS & Buick Lucerne: 2006-2011
- And many more models including Saab 9-7X, Hummer H3, Saturn Vue, etc.
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 shipping. This ensures it communicates perfectly with your vehicle’s other computers (like the ECU and BCM) for optimal shift patterns and performance, without requiring a dealership visit.
Do I need to send my old TCM back?
No, there is no core charge for this part. You can keep your old module or dispose of it, making the process hassle-free.
Will this fix my P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. This module often resolves the root cause, but it’s crucial to ensure the issue isn’t a wiring or solenoid problem. In my experience, a faulty TCM is the culprit in a high percentage of these cases.
Is this compatible with the 4L60E or 4L65E transmission?
Yes, this T42 TCM is designed to control the popular 4-speed automatic transmissions found in these GM vehicles, including the 4L60E, 4L65E, and 4L70E.