Restore Peak Performance to Your GMC Truck
Is your 2007-2013 GMC Sierra 1500 suffering from erratic shifting, getting stuck in gear, or displaying a check engine light related to the transmission? These are classic signs of a failing Transmission Control Module (TCM). The TCM is the electronic brain of your automatic transmission, responsible for orchestrating smooth gear changes, managing torque converter lockup, and ensuring overall drivetrain efficiency. When it fails, it can cripple your truck’s performance and reliability. This genuine OEM-quality T42 TCM, part number 24238856, is the definitive solution to get your Sierra running right again.
From the Diagnostic Bay
We recently had a 2011 Sierra 1500 towed in that was stuck in what the owner called ‘highway gear’—it was limp mode, locked in 3rd. The dashboard was lit up with a check engine light and a transmission warning. A quick scan showed a P0700 (Transmission Control System Malfunction) code. After confirming the wiring harness was intact, we identified a faulty TCM. We installed one of our VIN-programmed T42 modules. After a 20-minute installation and clearing the codes, the truck was shifting perfectly through all gears on the test drive. The customer drove away with a truck that felt brand new, avoiding a costly dealership visit and extended downtime.
Symptoms of a Failing Sierra 1500 TCM
A problematic TCM can manifest in several ways. If you’re experiencing any of the following issues, it’s highly likely your module needs replacement. Ignoring these symptoms can lead to more severe transmission damage and costly repairs down the line.
- ✔ Harsh or Erratic Shifting: Your truck may slam into gear, hesitate, or shift at the wrong times.
- ✔ Stuck in Limp Mode: The transmission may refuse to shift out of a single gear (often 2nd or 3rd) to protect itself from further damage.
- ✔ Warning Lights: The Check Engine Light or a specific transmission warning light will illuminate on your dashboard.
- ✔ Diagnostic Trouble Codes (DTCs): You may find codes such as P0700, P0750, P0753, or other solenoid-related faults when scanning the vehicle.
- ✔ Delayed Engagement: A noticeable delay when shifting from Park into Drive or Reverse.
- ✔ Poor Fuel Economy: Inefficient shifting directly leads to increased fuel consumption.
- ✔ No Communication: In severe cases, a scan tool may be unable to communicate with the TCM at all.
The Critical Advantage: Pre-Programmed to Your VIN
What sets this module apart is our expert VIN programming service. A generic TCM from a parts store or salvage yard won’t work correctly—it must be programmed specifically for your truck’s unique configuration. We handle this for you before shipping. By providing your vehicle’s VIN at checkout, you receive a module that is loaded with the latest GM software updates and calibrated for your exact vehicle. This makes installation a true plug-and-play process, eliminating the need for expensive programming tools or a mandatory trip to the dealership. Simply install the part, and you’re ready to go.
Installation and Compatibility
For the 2007-2013 GMC Sierra 1500, the TCM is conveniently located in the engine bay, typically right next to the battery. Installation is straightforward for a DIY mechanic and usually takes less than 30 minutes.
- Disconnect the Battery: Always disconnect the negative battery terminal first for safety.
- Locate and Remove the Old TCM: Unplug the electrical connectors and unbolt the old module from its bracket.
- Install the New Module: Bolt the new, pre-programmed TCM in place and securely reconnect the electrical connectors.
- Reconnect the Battery: Reattach the negative battery terminal.
- Clear Codes: Use a basic OBD2 scanner to clear any stored transmission codes.
This T42 module is a direct replacement for a wide range of part numbers, including 24252114, 24234503, 24230461, 24238856, and more. While it’s a perfect fit for the Sierra, it’s also compatible with dozens of other GM vehicles from 2006-2014, such as the Chevrolet Silverado, Tahoe, Suburban, Express Van, and GMC Yukon, making it a versatile and reliable solution for the entire GM family of trucks and SUVs equipped with 4-speed automatic transmissions like the 4L60E, 4L65E, and 4L70E.
Frequently Asked Questions
What is VIN programming and why do I need it?
VIN programming loads your vehicle’s specific software and calibrations onto the TCM. Without it, the module cannot communicate correctly with the engine and other systems, leading to shifting problems or a no-start condition. Our service ensures it works perfectly out of the box.
Do I need to go to a dealership after installing this part?
No. Because we pre-program the module to your vehicle’s VIN, no further programming or dealership visits are required. This saves you time and hundreds of dollars in labor costs.
Where is the TCM located on my 2008 GMC Sierra 1500?
On most 2007-2013 Sierra and Silverado models, the TCM is a silver box located in the engine compartment, mounted on a bracket right next to the battery.
Will this fix transmission code P0700?
A P0700 code is a general fault code indicating the TCM has detected a problem. While a failing TCM is a very common cause, this code can also be triggered by other transmission issues. However, if you’re experiencing other symptoms like erratic shifting, replacing the TCM is the most likely solution.
Is there a core charge for this module?
No, there is no core charge. You are not required to send your old, faulty part back to us, making the process simple and hassle-free.