If you’re seeing the dreaded “Service Trailer Brake System” message on your dash, you know the frustration and safety concerns that come with it. As a technician with over two decades of experience, I’ve seen countless GM truck owners deal with this exact issue. Your ability to tow safely and confidently depends on a fully functional Trailer Brake Control Module (TBCM). This isn’t just a convenience; it’s a critical safety component that ensures your trailer’s brakes work in sync with your truck.
We’re offering a direct-fit, reliable solution: a genuine GM Trailer Brake Control Module, compatible with part numbers 20850923 and 20964299. The best part? We take the biggest headache out of the repair. Simply provide us with your vehicle’s VIN during checkout, and we will program the module with the latest GM software specifically for your truck. This means no expensive trip to the dealership for programming. It arrives at your door ready to install, making this a true plug-and-play fix.
Case Study: A Tricky Diagnosis
A customer brought his 2013 Sierra 2500 into my shop, frustrated after another garage couldn’t solve his intermittent “Service Trailer Brake” light. They suggested it might be a wiring issue, a costly and time-consuming repair. After hooking up my scan tool, I saw no communication with the TBCM. Instead of tearing into the harness, I went straight to the module’s location on the left frame rail. It showed signs of water intrusion—a very common failure point. We installed a new, pre-programmed 2013 Yukon XL 2500 TBCM, and the problem was solved in under 30 minutes. He saved hundreds of dollars by avoiding a misdiagnosis and unnecessary labor.
Is Your Truck Showing These Symptoms?
A failing TBCM can manifest in several ways. If you’re experiencing any of the following, this module is the likely solution:
- ✔ “Service Trailer Brake System” message on the Driver Information Center (DIC).
- ✔ Trailer brakes do not engage or engage erratically when you apply the vehicle’s brakes.
- ✔ The manual trailer brake slide activator does not work.
- ✔ The trailer is not detected by the truck, or the connection appears to drop out intermittently.
- ✔ Diagnostic Trouble Codes (DTCs) are stored in the system, such as C1512, C1522, or U0138 (Lost Communication With All-Terrain Control Module).
A Straightforward Guide to Installation
Because this module comes pre-programmed, installation is simple enough for a DIY enthusiast with basic tools. You’ll have your truck back to full towing capacity in no time.
- Safety First: Disconnect the negative terminal from your vehicle’s battery.
- Locate the Module: On most compatible trucks and SUVs, the TBCM is mounted to the frame rail. For pickups, it’s on the left-hand (driver’s side) rear frame. For Suburbans and Yukons, it’s on the left-hand middle of the frame.
- Disconnect and Remove: Carefully unplug the electrical connectors. Be gentle with the locking tabs. Then, unbolt the old module from the frame.
- Install the New Module: Bolt the new, programmed TBCM into the same location.
- Reconnect: Securely plug the electrical connectors into the new module. You should hear a click as they lock into place.
- Final Step: Reconnect the negative battery terminal. Start the vehicle and verify that the “Service Trailer Brake System” message is gone.
Guaranteed Fitment for Your GM HD Vehicle
This module is a verified fit for the following vehicles equipped with the factory trailer brake control system. Please confirm your model and year before ordering.
SIERRA 2500 PICKUP 2013-2014 (Towing Control; LH rear frame)
SIERRA 3500 PICKUP 2013-2014 (Towing Control; LH rear frame)
SIERRA DENALI 2500 2013-2014 (Towing Control; LH rear frame)
SIERRA DENALI 3500 2013-2014 (Towing Control; LH rear frame)
YUKON XL 2500 2013 (Towing Control; LH middle of frame)
Chevrolet:
SILVERADO 2500 PICKUP 2013-2014 (Towing Control; LH rear frame)
SILVERADO 3500 PICKUP 2013-2014 (Towing Control; LH rear frame)
SUBURBAN 2500 2013 (Towing Control; LH middle of frame)
Don’t let a faulty module compromise your safety or your towing plans. This pre-programmed 2013 Yukon XL 2500 TBCM is the most efficient and reliable way to restore your vehicle’s critical towing functions.
Frequently Asked Questions
Frequently Asked Questions
Do I need to take my truck to a dealer for programming after installation?
No. We program the module to your vehicle’s specific VIN before shipping it to you. This makes the unit plug-and-play, saving you time and the high cost of dealership programming.
Where do I find my vehicle’s VIN?
Your 17-digit Vehicle Identification Number (VIN) can be found on the driver’s side of the dashboard (visible through the windshield), on the driver’s side door jamb sticker, or on your vehicle’s registration and insurance documents.
Is this part difficult to replace myself?
For most individuals with basic mechanical skills and tools, this is a straightforward replacement. The module is typically held on by a few bolts on the vehicle’s frame rail, making it accessible without major disassembly.
Will this fix the “Service Trailer Brake System” message on my dash?
In the vast majority of cases, a failed TBCM is the root cause of this specific warning message. Replacing it with our programmed module is the definitive fix for this common problem.
What is the difference between part numbers 20850923 and 20964299?
Part number 20964299 is a later, superseding part number for 20850923. They are functionally identical and fully interchangeable. We supply the correct, compatible module for your vehicle.