Restore Flawless Shifting to Your GM Truck or SUV
If your 2007-2009 GMC Yukon is suffering from delayed shifts, getting stuck in gear, or throwing transmission codes, the problem is very likely a failing Transmission Control Module (TCM). As the electronic brain of your automatic transmission, the T42 TCM is responsible for every gear change, torque converter lockup, and pressure regulation. When it fails, it can mimic a major mechanical issue, causing immense frustration for drivers and diagnostic headaches for technicians. In my 20+ years of experience, I’ve seen countless GM vehicles with these exact symptoms, where a simple TCM replacement was the definitive fix.
This isn’t just a replacement part; it’s a complete solution. We pre-program this module to your vehicle’s specific VIN, loading the latest GM software updates. This means you can skip the expensive and time-consuming trip to the dealership for programming. For the professional mechanic, this means a faster bay turnover. For the DIY enthusiast, it means you can confidently complete the entire job in your own driveway. This is the most effective way to address issues related to the original 2007-2009 Yukon TCM and restore the crisp, reliable performance you expect.
A Technician’s Notebook: The Intermittent Gremlin
A customer brought in his ’08 Sierra with a classic complaint: “Sometimes it shifts hard, sometimes it won’t shift out of 2nd gear, but if I shut it off and turn it back on, it’s fine for a while.” He’d already replaced a shift solenoid with no luck. We scanned it and found a P0700 (Transmission Control System Malfunction) and an intermittent solenoid circuit code. Instead of chasing electrical gremlins through the harness, we checked the known failure points. The T42 TCM on these platforms is notorious for internal solder joint fractures and component failure from heat cycles. We installed one of our VIN-programmed modules, cleared the codes, and the truck’s shifting issues were gone for good. It’s a textbook example of how a faulty module can send you down the wrong diagnostic path.
Is Your Vehicle Showing These Telltale Signs?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, a faulty module is the likely culprit:
- ✔ Unpredictable, harsh, or slamming gear changes.
- ✔ The transmission feels like it’s slipping or hesitating between gears.
- ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear) to protect the transmission.
- ✔ Check Engine Light or Transmission Warning Light is on with codes like P0700, P0750, P0753, P0758, or other solenoid-related DTCs.
- ✔ Failure to upshift or downshift properly, leading to poor acceleration and bad fuel economy.
- ✔ Complete loss of communication with the module, preventing the vehicle from starting or shifting out of Park.
Your 30-Minute Path to a Smooth-Shifting Ride
Installation is a straightforward process that most DIYers can handle with basic tools. No complex procedures or dealer-specific equipment is needed.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent electrical shorts and help reset the system.
- Locate the Module: On most GM trucks and SUVs like the Yukon, Tahoe, and Silverado, the TCM is conveniently located in the engine bay, often next to the battery or under the air cleaner box. Refer to the fitment list for specific locations.
- Disconnect and Remove: Carefully unplug the electrical connectors. Be gentle with the locking tabs, as they can become brittle over time. Then, unbolt the old module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Securely reconnect the electrical connectors, ensuring they click into place.
- Final Steps: Reconnect the battery terminal. Start the vehicle and let it idle for a few minutes. While the module is plug-and-play, it’s good practice to use a basic scan tool to clear any stored fault codes from the ECU.
Verified Compatibility for Your GM Vehicle
This T42 TCM is a direct replacement for part number 24239926 and is interchangeable with a wide range of other service numbers. It is designed for vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. Please verify your model and year from the list below:
Partial Fitment List:
- GMC Yukon / Yukon XL 1500: 2007-2009 (Typically next to battery)
- Chevrolet Tahoe / Suburban 1500: 2007-2008 (Typically next to battery)
- Chevrolet Silverado 1500 / GMC Sierra 1500: 2007-2013 (New body style, next to battery)
- Chevrolet Avalanche 1500: 2007-2008 (Next to battery)
- Cadillac DTS: 2006-2011 (RH front engine compartment)
- Chevrolet Impala: 2006-2011 (Lower air cleaner housing)
- Hummer H3: 2008-2010 (RH rear engine compartment)
- Chevrolet Colorado / GMC Canyon: 2008-2012 (RH rear engine compartment)
- …and many more GM models from 2006-2014.
Frequently Asked Questions
Frequently Asked Questions
Do I need to take my vehicle to the dealer after installation?
No. This module comes fully programmed to your VIN. It is a true plug-and-play solution, saving you the cost and hassle of dealership programming.
What does the TCM actually do?
The Transmission Control Module is the computer that controls all electronic functions of your automatic transmission. It takes data from vehicle sensors to determine the perfect time to shift gears, control line pressure, and engage the torque converter clutch for optimal performance and fuel efficiency.
Is this part difficult to install myself?
Not at all. For most vehicles on the fitment list, the TCM is easily accessible in the engine compartment. With basic hand tools, the replacement typically takes less than 30 minutes.
Will this fix a P0700 check engine light code?
A P0700 code is a general fault code indicating the TCM has detected a problem. While this module often resolves the root cause (like a faulty solenoid circuit inside the TCM itself), you should always clear codes after installation to confirm the fix.
Is there a core charge for my old part?
No, there is no core charge. You can keep your old part or dispose of it without needing to send it back, simplifying your repair process.
What if I order the wrong part?
We’re here to help. To ensure a perfect fit, please double-check your vehicle in our compatibility list or contact our expert support team with your VIN before ordering. We’ll make sure you get the right part the first time.