Are you tired of seeing the dreaded “Service Trailer Brake System” message on your 2013-2014 Sierra or Silverado’s dashboard? As a technician with over two decades of experience, I’ve seen firsthand how a faulty Trailer Brake Control Module (TBCM) can undermine your confidence and compromise safety when you’re hauling a heavy load. This isn’t just an annoyance; it’s a critical safety component that needs to function flawlessly. That’s why we offer this direct-fit, VIN-programmed TBCM, designed to get you back on the road with peace of mind.
This module, part number 20964299 (interchangeable with 20850923), is the definitive solution. Unlike parts that require a costly and time-consuming trip to the dealership, this unit arrives at your door fully programmed with the latest GM software specific to your truck’s Vehicle Identification Number (VIN). This ensures seamless communication with your vehicle’s other systems right out of the box. It’s a true plug-and-play fix that restores the original braking performance and reliability you depend on.
From the Diagnostic Bay
I remember a 2014 Silverado 2500 that came into my shop with a frustratingly intermittent issue. The owner explained that his trailer brakes would sometimes work perfectly, and other times they wouldn’t engage at all. The “Service Trailer Brake” light would pop on and off randomly. He’d already replaced the trailer-side wiring. My initial scan showed a U0100 Lost Communication code with the TBCM. Knowing these modules are mounted on the frame rail, exposed to road salt and moisture, I put the truck on the lift. Sure enough, the module’s housing was intact, but a close inspection of the connectors revealed green corrosion seeping into the pins. This corrosion was causing the intermittent connection and the phantom warnings. We replaced it with a VIN-programmed module just like this one, and the problem was solved permanently. It’s a classic failure mode for these hard-working trucks.
Common Signs of a Failing TBCM
If your truck is experiencing any of the following, a faulty TBCM is the likely culprit. Replacing it can prevent further diagnostic headaches and ensure your safety.
- ✔ “Service Trailer Brake System” message displayed on the Driver Information Center (DIC).
- ✔ Trailer brakes do not apply, or apply erratically and inconsistently.
- ✔ The manual trailer brake slide controller is unresponsive.
- ✔ Diagnostic Trouble Codes (DTCs) stored in the system, such as U0100 (Lost Communication With TBCM) or various C-codes related to circuit faults.
- ✔ No output signal to the 7-pin trailer connector’s brake pin.
A Straightforward Guide to Installation
You can install this module at home with basic hand tools. Since it comes pre-programmed, no special electronic tools are needed.
- Safety First: Disconnect the negative terminal from your truck’s battery to prevent any electrical shorts.
- Locate the Module: On most Sierra and Silverado pickups, the TBCM is mounted to the driver’s side (LH) frame rail, typically near the spare tire. For Suburbans and Yukon XLs, it’s often on the LH frame rail, closer to the middle of the vehicle.
- Disconnect and Remove: Carefully unplug the electrical connectors. Note any locking tabs to avoid breaking them. Then, unbolt the old module from the frame.
- Install the New Module: Bolt the new, pre-programmed TBCM into the same location. Apply a small amount of dielectric grease to the connector pins for added protection against moisture.
- Reconnect and Test: Securely plug in the electrical connectors. Reconnect the battery terminal. Start the truck and verify that the “Service Trailer Brake System” message is gone. If possible, connect a trailer to confirm proper operation.
Verified Vehicle Compatibility
This module is a guaranteed fit for the following vehicles, replacing the original towing control module. Please provide your VIN upon purchase for programming.
- 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
Do I need to take this part to a dealer for programming?
No. We program the module to your vehicle’s specific VIN before we ship it. It arrives ready for installation, saving you time and money on dealer fees.
Where is this module located on my 2014 Sierra 2500?
The Trailer Brake Control Module (TBCM) is located on the driver’s side frame rail, toward the rear of the truck, usually near the spare tire.
How do I provide my VIN?
After you complete your purchase, please send us a message with your 17-digit Vehicle Identification Number (VIN). We cannot ship the part until we have programmed it.
Is this compatible with part number 20850923?
Yes, this part number 20964299 is a fully compatible and direct replacement for part number 20850923.
What does “TBCM” stand for?
TBCM stands for Trailer Brake Control Module. It is the computer responsible for managing and activating your trailer’s electric or electric-over-hydraulic brakes.