If your 2007-2008 GMC Yukon XL 1500 is giving you transmission headaches—like harsh shifting, getting stuck in gear, or a persistent check engine light—you’ve come to the right place. As a technician with over two decades of experience, I’ve seen countless drivers worry they need a complete transmission rebuild when the real culprit is a faulty Transmission Control Module (TCM). This T42 TCM, part number 24238856, is the solution you need. It’s the electronic brain of your 4L60E, 4L65E, or 4L70E automatic transmission, and a failure here can mimic catastrophic mechanical problems.
We take the guesswork and high cost out of the repair. Each module is expertly programmed to your vehicle’s specific VIN before it ships. This means no expensive trips to the dealership for programming. It arrives at your door ready for a true plug-and-play installation, restoring the crisp, predictable shifting your Yukon XL had from the factory.
From the Diagnostic Bay
I remember a customer with a 2007 Yukon XL who was quoted over $3,500 for a transmission rebuild. His truck was stuck in 3rd gear (limp mode) and showing a P0700 code. He was ready to give up on his family’s road trip vehicle. I hooked up my scan tool and saw communication errors with the TCM. Instead of a rebuild, we installed one of these pre-programmed modules. In about 25 minutes, the truck was shifting perfectly. He saved thousands and, more importantly, his peace of mind. Often, the most complex symptoms have a simple electronic solution.
Is Your Yukon XL Showing These Symptoms?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, this module is the likely fix for your 2007-2008 Yukon XL TCM issues:
- ✔ Harsh, slamming shifts or delayed gear engagement.
- ✔ Vehicle is stuck in “limp mode” and won’t shift out of 2nd or 3rd gear.
- ✔ Check Engine Light or Transmission Warning Light is on.
- ✔ Diagnostic Trouble Codes (DTCs) are present, such as P0700 (Transmission Control System Malfunction), P0750-series (Shift Solenoid), or other transmission-related codes.
- ✔ The transmission refuses to upshift or downshift correctly.
- ✔ A noticeable drop in fuel economy or signs of the transmission overheating.
A Straightforward Guide to Installation
You don’t have to be a master mechanic to replace this module. The process is simple and can be done with basic hand tools in your driveway in under 30 minutes.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts and to help reset the system.
- Locate the Old TCM: On your 2007-2008 Yukon XL 1500, the TCM is typically located in the engine bay, right next to the battery. It’s a silver box with electrical connectors.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt your new, pre-programmed TCM into place and securely reconnect the wiring harnesses. Ensure 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 scan tool to clear any stored fault codes from the vehicle’s memory. Start the engine and take it for a test drive to confirm smooth shifting.
Verified Vehicle Compatibility
This T42 TCM is a direct-fit replacement for a wide range of General Motors vehicles. While this page is focused on the 2007-2008 Yukon XL, please verify your vehicle in the list below. This module interchanges with part numbers 24252114, 24234503, 24238856, and more.
This part will fit these makes and models with these options
AVALANCHE 1500 07-08 Transmission; (next to battery)
CANYON 08-12 Transmission; (RH rear engine compartment)
COLORADO 08-12 Transmission; (RH rear engine compartment)
ENVOY 06-07 Transmission; (LH engine compartment), (8 cylinder)
ENVOY 08-09 Transmission; (LH engine compartment)
EXPRESS 1500 VAN 06-14 Transmission; (RH engine compartment)
EXPRESS 2500 VAN 06-14 Transmission; (RH engine compartment)
EXPRESS 3500 VAN 06-14 Transmission; (RH engine compartment)
HUMMER H3 08-10 Transmission; (RH rear engine compartment)
SAVANA 1500 VAN 06-14 Transmission; (RH engine compartment)
SAVANA 2500 VAN 06-14 Transmission; (RH engine compartment)
SAVANA 3500 VAN 06-14 Transmission; (RH engine compartment)
SIERRA 1500 PICKUP 07 Transmission; (new style, smooth door skin), (next to battery)
SIERRA 1500 PICKUP 08 Transmission; (next to battery)
SIERRA 1500 PICKUP 09-13 Transmission; (next to battery), w/o hybrid option
SILVERADO 1500 PICKUP 07 Transmission; (new style, smooth door skin), (next to battery)
SILVERADO 1500 PICKUP 08 Transmission; (next to battery)
SILVERADO 1500 PICKUP 09-13 Transmission; (next to battery), w/o hybrid option
SUBURBAN 1500 07-08 Transmission; (next to battery)
TAHOE 07 Transmission; (next to battery)
TAHOE 08-09 Transmission; (next to battery), w/o auxiliary oil cooler pump
TRAILBLAZER 06-07 Transmission; (LH engine compartment), (8 cylinder)
TRAILBLAZER 08-09 Transmission; (LH engine compartment)
YUKON 07 Transmission; (next to battery)
YUKON 08 Transmission; (next to battery), w/o auxiliary oil cooler control
YUKON 09 Transmission; (next to battery), w/o auxiliary oil cooler pump
YUKON XL 1500 07-08 Transmission; (next to battery)
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 engine computer and other systems, just like an original part from the dealer, but without the extra programming fees.
Do I need any special tools for this installation?
No special tools are required. Basic hand tools, like a socket set to remove the mounting bolts and your hands to unplug the connectors, are all you need. An OBD2 scanner is recommended for clearing codes but not strictly necessary for the module to function.
Is there a core charge for my old TCM?
No, there is no core charge. You can keep your old part or dispose of it without the hassle of shipping it back to us, saving you time and money.
Will this fix a P0700 code on my Yukon?
A P0700 code is a general fault code indicating the TCM has detected a problem. In many cases, a faulty TCM is itself the root cause. Replacing the module often resolves the P0700 code and any other related transmission codes it was setting.
How can I be sure this part will fit my truck?
This module is a confirmed fit for the 2007-2008 GMC Yukon XL 1500. We also provide your VIN during programming as a final check. You can also match the part number 24238856 or other service numbers listed to your original part.