Restore Safe Towing and Clear Annoying Dash Warnings
Seeing the “Service Trailer Brake System” message on your 2013-2014 Sierra Denali 2500’s information center is more than just an annoyance—it’s a critical safety alert. This message indicates a problem with your Trailer Brake Control Module (TBCM), the electronic brain responsible for activating your trailer’s brakes in sync with your truck. Driving with a faulty TBCM means you’ve lost that crucial stopping power, putting you, your cargo, and others at risk. This module is the definitive solution, restoring full functionality and peace of mind.
This isn’t just a replacement part; it’s a complete, ready-to-install solution. We professionally program each module to your truck’s specific Vehicle Identification Number (VIN) before it ships. This crucial step loads the latest GM-approved software, ensuring seamless communication with your truck’s other systems and eliminating the need for an expensive and time-consuming trip to the dealership for programming. Simply provide your VIN at checkout, and we handle the rest.
A Technician’s Notebook
I remember a customer with a 2014 Silverado 2500 who was about to leave on a cross-country trip with his fifth-wheel. The “Service Trailer Brake” light came on the day before he was set to depart. He was in a panic. After a quick scan, we found codes pointing to a TBCM failure. These modules are mounted on the frame rail, where they’re constantly exposed to water, salt, and road debris. In his case, corrosion had compromised the internal circuits. We replaced it with a VIN-programmed module just like this one. The total repair took less than 30 minutes in his driveway, the codes cleared, and he was safely on his way the next morning. It’s a perfect example of how the right part can save you from major headaches.
Common Signs of a Failing TBCM
If you’re experiencing any of these issues, a failing TBCM is the likely culprit. This module is designed to resolve these specific problems.
- âś” “Service Trailer Brake System” message displayed on the DIC.
- âś” “Trailer Connected” / “Trailer Disconnected” messages cycling randomly.
- âś” No output from the manual trailer brake controller slide.
- âś” Trailer brakes don’t engage when you press the truck’s brake pedal.
- âś” Diagnostic Trouble Codes (DTCs) such as C1512, C1522, or U0428 stored in the system.
A Straightforward Guide to Installation
Installing your new 2013-2014 Sierra 2500 TBCM is a simple process that most DIYers can complete in under an hour with basic hand tools. Since it arrives pre-programmed, no special electronic tools are needed.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the Module: Find the old TBCM. On most 2500/3500 pickups, it’s mounted to the driver’s side frame rail, just in front of the rear axle.
- Disconnect and Remove: Carefully unplug the main electrical connector. Then, remove the bolts or nuts (typically 2 or 3) securing the module to the frame.
- Install the New Module: Mount the new module in the same location using the original hardware. Ensure it is securely fastened.
- Reconnect: Plug the electrical connector firmly into the new module until it clicks.
- Final Step: Reconnect the negative battery terminal. Start the truck and verify that the “Service Trailer Brake System” message is gone.
Verified Vehicle Compatibility
This module is a direct-fit replacement for the original equipment on a wide range of GM heavy-duty vehicles. It is compatible with part numbers 20850923 and 20964299.
- 2013-2014 GMC Sierra 2500 & 3500 Pickup: Towing Control (LH rear frame)
- 2013-2014 GMC Sierra Denali 2500 & 3500: Towing Control (LH rear frame)
- 2013-2014 Chevrolet Silverado 2500 & 3500 Pickup: Towing Control (LH rear frame)
- 2013 Chevrolet Suburban 2500: Towing Control (LH middle of frame)
- 2013 GMC Yukon XL 2500: Towing Control (LH middle of frame)
Frequently Asked Questions
How do I provide my VIN for programming?
After you complete your purchase, you can send us a message with your 17-digit VIN. We cannot ship the module until we receive this information, as programming is essential for it to function in your truck.
Does this part require any additional programming by a dealer?
No. This is the primary benefit of our service. We program the module with the latest GM software matched to your VIN, so it is 100% plug-and-play. You can install it yourself and avoid a trip to the dealership.
Is this a genuine GM part?
This is a high-quality, tested component that is fully compatible with the original GM system. It is programmed using official GM software to ensure perfect operation.
Where is the TBCM located on my 2013 Sierra 2500?
On the 2013-2014 Sierra and Silverado 2500/3500 models, the Trailer Brake Control Module is typically mounted on the inside of the driver-side frame rail, toward the rear of the truck.
What if I install it and the warning light is still on?
While this module fixes the most common cause of the ‘Service Trailer Brake’ message, other issues like wiring problems or a faulty trailer plug can cause similar symptoms. We recommend checking the wiring harness for damage if the problem persists after installation.