Restore Smooth, Reliable Shifting to Your GMC Sierra
If your 2007-2013 GMC Sierra 1500 is suffering from harsh shifting, getting stuck in gear, or throwing transmission codes, a failing Transmission Control Module (TCM) is the likely culprit. As a mechanic with over two decades of experience, I’ve seen firsthand how a faulty TCM can sideline a perfectly good truck. This T42 TCM, corresponding to part number YNXS, is the definitive solution to get your workhorse back on the road, performing as it should. It arrives expertly programmed to your truck’s specific VIN, eliminating the need for expensive dealership programming and ensuring a true plug-and-play installation.
Case Study: A Tricky Diagnosis
Just last month, a 2011 Sierra 1500 was towed into my shop. The owner was frustrated; his truck was stuck in what he called “limp mode” (3rd gear) and the check engine light was on. He’d already replaced a shift solenoid on a hunch, but the problem persisted. A quick scan showed a P0700 (Transmission Control System Malfunction) and a P0752 (Shift Solenoid ‘A’ Stuck On). While the P0752 pointed to a solenoid, the generic P0700 code told me the TCM itself was commanding the fault. After verifying the wiring was intact, we installed one of our pre-programmed T42 modules. The codes cleared, and after a short test drive, the truck was shifting flawlessly through all gears. It’s a classic case where the “brain” (the TCM) is the real issue, not the component it controls.
Is Your Sierra Exhibiting These Telltale Signs?
A failing Sierra 1500 TCM doesn’t always lead to a complete breakdown. Often, the symptoms start small and worsen over time. Here’s what to look for:
- ✔ Harsh, jerky, or delayed gear shifts, especially when the truck is cold.
- ✔ The vehicle feels stuck in one gear (often 2nd or 3rd) and will not upshift or downshift.
- ✔ An illuminated Check Engine Light or Transmission Warning Light on your dash.
- ✔ Diagnostic Trouble Codes (DTCs) such as P0700, U0100, or various solenoid-specific codes (P0750-P0774).
- ✔ A sudden drop in fuel economy as the transmission operates inefficiently.
- ✔ The torque converter failing to lock up at highway speeds, causing higher RPMs.
A Straightforward Guide to Installation
One of the best features of this module is its simple installation. For a GMT900 platform truck like the 2007-2013 Sierra, the job is very accessible. You don’t need a vehicle lift or specialized tools—just basic hand tools and about 30 minutes.
- Safety First: Always disconnect the negative terminal from your truck’s battery before working on any electronic components.
- Locate the TCM: On your Sierra 1500, the TCM is typically mounted in the engine bay, right next to the battery. It’s a silver box with several large electrical connectors.
- Disconnect and Remove: Carefully unclip the wiring harness connectors. They have locking tabs, so be gentle. Then, unbolt the module from its mounting bracket.
- Install the New Module: Bolt the new, VIN-programmed TCM into place. Securely reconnect the wiring harnesses, ensuring they click into place.
- Final Steps: Reconnect the battery terminal. While our programming handles the critical setup, it’s good practice to use a basic OBD2 scan tool to clear any stored fault codes from the ECU. Start the truck and enjoy smooth shifting!
Verified Fitment for Your GM Truck or SUV
While this listing is focused on the Sierra 1500 TCM, this versatile T42 module is compatible with a wide range of GM vehicles equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E. It is a direct replacement for multiple part numbers, including 24252114, 24234503, and YNXS. Please verify your vehicle in the list below:
- GMC Sierra 1500 Pickup (2007-2013): Located next to the battery (2007 models are new body style with smooth door skin).
- Chevrolet Silverado 1500 Pickup (2007-2013): Found next to the battery.
- GMC/Chevrolet Savana & Express Vans (2006-2014): Located in the RH engine compartment.
- Chevrolet Tahoe & GMC Yukon (2007-2009): Positioned next to the battery.
- Chevrolet Avalanche (2007-2008): Mounted next to the battery.
- Hummer H3 (2008-2010): Found in the RH rear of the engine compartment.
- …and many other GM cars, trucks, and SUVs from 2006-2014.
Do I need to take my truck to the dealer after installing this?
Do I need to take my truck to the dealer after installing this?
No. This is the primary benefit of our service. We program the module to your vehicle’s VIN before shipping it. This ensures it communicates correctly with your truck’s other computers right out of the box, saving you time and the high cost of dealership programming.
How do I provide my VIN?
You can enter your 17-digit Vehicle Identification Number (VIN) during the checkout process. Please double-check it for accuracy, as the programming is specific to this number.
Is this a reliable fix for a P0700 code on my Sierra 1500 TCM?
A P0700 code is a general fault code indicating the TCM has detected a problem. In many cases, the TCM itself is the root cause. If you’ve ruled out wiring issues or specific solenoid failures, replacing the TCM with our programmed unit is a very common and effective repair.
Do you require my old part back (a core charge)?
No, there is no core charge for this part. You can keep your old module or recycle it locally without the hassle of shipping it back to us.