Restore Your Yukon’s Shifting Performance
If your 2007, 2008, or 2009 GMC Yukon is suffering from jarring shifts, 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 symptoms countless times. Drivers come into the shop worried they need a costly transmission rebuild, only to find relief when we pinpoint the issue to this critical electronic component. This T42 TCM, part number 24256960, is the definitive solution to restore the smooth, predictable performance your vehicle had when it was new.
This isn’t just a replacement part; it’s a complete, hassle-free fix. We pre-program each module to your vehicle’s specific VIN before shipping. This crucial step ensures that the TCM communicates perfectly with your Yukon’s engine computer and other systems right out of the box, eliminating the need for an expensive and time-consuming trip to the dealership for programming. Get your truck back on the road quickly and confidently.
Case Study: A Tricky Diagnosis
A customer brought in their ’08 Yukon XL with classic transmission trouble: harsh 1-2 shifts and occasionally getting stuck in 3rd gear (limp mode). They had already replaced two shift solenoids at another shop with no success. After a quick scan, I saw a P0700 (Transmission Control System Malfunction) code, but the solenoid codes were intermittent. Drawing on experience, I knew these T42 modules can fail internally, sending faulty commands that mimic solenoid issues. Instead of chasing ghosts, we installed a VIN-programmed TCM. The test drive was perfect—smooth shifts, no codes. It saved the customer from a potential transmission teardown and hundreds of dollars in unnecessary labor.
Common Signs of a Failing TCM
A faulty TCM can cause a range of frustrating and concerning issues. If you’re noticing any of the following, it’s time to inspect your module. A faulty 2007-2009 Yukon TCM will often trigger these symptoms:
- ✔ Harsh, erratic, or delayed gear shifting.
- ✔ Vehicle stuck in “limp mode” (usually 2nd or 3rd gear).
- ✔ Check Engine Light or Transmission Warning Light is on.
- ✔ Diagnostic Trouble Codes (DTCs) such as P0700, P0750, or other solenoid-related faults.
- ✔ Inability to upshift or downshift properly.
- ✔ A noticeable decrease in fuel efficiency.
- ✔ The transmission seems to be overheating for no reason.
A Straightforward Guide to a 30-Minute Fix
One of the best parts about this solution is how accessible it is for the DIY mechanic. You don’t need a lift or specialized transmission tools. The TCM on these Yukons is located in the engine bay, typically next to the battery.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the TCM: On most 2007-2009 Yukon, Sierra, and Tahoe models, you’ll find the module mounted right next to the battery in the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Once unplugged, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, pre-programmed TCM into place. Securely reconnect the electrical harnesses, making sure they click into place.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s always good practice to use a basic OBD2 scanner to clear any stored fault codes from the vehicle’s memory. Start the engine and take it for a test drive to confirm smooth operation.
Verified Vehicle Compatibility
This T42 TCM is a direct-fit replacement for a wide range of General Motors vehicles. While this listing focuses on the 2007-2009 Yukon TCM, it is also compatible with the following models and more. Please verify your part number (24256960) or contact us with your VIN.
- GMC Yukon / Yukon XL 1500 (2007-2009)
- GMC Sierra 1500 / 2500 (2007-2013)
- GMC Savana 1500 / 2500 / 3500 (2006-2014)
- GMC Envoy (2006-2009)
- Chevrolet Tahoe / Suburban 1500 (2007-2009)
- Chevrolet Silverado 1500 / 2500 (2007-2013)
- Chevrolet Express 1500 / 2500 / 3500 (2006-2014)
- Chevrolet Avalanche 1500 (2007-2008)
- Chevrolet Impala (2006-2011)
- Cadillac DTS (2006-2011)
- Hummer H3 (2008-2010)
Frequently Asked Questions
What exactly does VIN programming do for me?
VIN programming loads your vehicle’s specific software and calibrations onto the TCM before it ships. This makes the module a true plug-and-play part, ensuring it works seamlessly with your engine and transmission without requiring a trip to the dealer for expensive computer flashing.
Can I install this myself if I’m not a professional mechanic?
Absolutely. The TCM is located in an easily accessible spot in the engine bay, and the replacement process requires only basic hand tools. Our step-by-step guide makes it a straightforward job for most DIY enthusiasts, typically taking less than 30 minutes.
Do I need to return my old part? Is there a core charge?
No, there is absolutely no core charge. You can keep your old module, recycle it, or dispose of it at your convenience. This saves you the time and hassle of shipping a part back.
Will this fix a P0700 check engine light code?
Yes, in many cases. The P0700 code is a general fault code indicating the TCM has detected a problem. If the TCM itself is the source of the failure, replacing it with our pre-programmed module will resolve the issue and allow the code to be cleared.